import os
import re
from dataclasses import dataclass
from typing import ClassVar

# from typing import final
import configparser


from tenacity import (
    retry,
    stop_after_attempt,
    wait_exponential,
    retry_if_exception_type,
)

import logging
from ..utils import logger, validate_workspace
from ..base import BaseGraphStorage
from ..types import KnowledgeGraph, KnowledgeGraphNode, KnowledgeGraphEdge
from ..kg.shared_storage import get_data_init_lock
import pipmaster as pm

if not pm.is_installed("neo4j"):
    pm.install("neo4j")

from neo4j import (  # type: ignore
    AsyncGraphDatabase,
    exceptions as neo4jExceptions,
    AsyncDriver,
    AsyncManagedTransaction,
)

from dotenv import load_dotenv

# use the .env that is inside the current folder
# allows to use different .env file for each lightrag instance
# the OS environment variables take precedence over the .env file
load_dotenv(dotenv_path=".env", override=False)

config = configparser.ConfigParser()
config.read("config.ini", "utf-8")


# Set neo4j logger level to ERROR to suppress warning logs
logging.getLogger("neo4j").setLevel(logging.ERROR)


READ_RETRY_EXCEPTIONS = (
    neo4jExceptions.ServiceUnavailable,
    neo4jExceptions.TransientError,
    neo4jExceptions.SessionExpired,
    ConnectionResetError,
    OSError,
    AttributeError,
)

READ_RETRY = retry(
    stop=stop_after_attempt(3),
    wait=wait_exponential(multiplier=1, min=4, max=10),
    retry=retry_if_exception_type(READ_RETRY_EXCEPTIONS),
    reraise=True,
)


# @final (removed per request in Issue #3130)
@dataclass
class Neo4JStorage(BaseGraphStorage):
    # Lucene query-syntax reserved characters. The full-text query parser
    # interprets these (e.g. '-' as NOT) before the analyzer runs, so a raw
    # 'tb-' becomes a NOT clause and silently matches nothing. Replace them
    # with spaces so the parser sees plain terms — the index already tokenizes
    # on these boundaries anyway. Annotated as ClassVar so @dataclass does not
    # treat it as an instance field.
    _LUCENE_RESERVED: ClassVar[re.Pattern[str]] = re.compile(
        r'[+\-&|!(){}\[\]^"~*?:\\/]'
    )

    def __init__(self, namespace, global_config, embedding_func, workspace=None):
        # Read env and override the arg if present
        neo4j_workspace = os.environ.get("NEO4J_WORKSPACE")
        original_workspace = workspace  # Save original value for logging
        if neo4j_workspace and neo4j_workspace.strip():
            workspace = neo4j_workspace

        # Default to 'base' when both arg and env are empty
        if not workspace or not str(workspace).strip():
            workspace = "base"

        super().__init__(
            namespace=namespace,
            workspace=workspace,
            global_config=global_config,
            embedding_func=embedding_func,
        )
        validate_workspace(self.workspace)

        # Log after super().__init__() to ensure self.workspace is initialized
        if neo4j_workspace and neo4j_workspace.strip():
            logger.info(
                f"Using NEO4J_WORKSPACE environment variable: '{neo4j_workspace}' (overriding '{original_workspace}/{namespace}')"
            )

        self._driver = None

    def _get_raw_workspace_label(self) -> str:
        """Return the actual Neo4j label name for this workspace (no escaping).

        This is the un-escaped label as it is stored on nodes. It is safe to
        bind as a query parameter (for example, APOC ``labelFilter``), where
        Neo4j handles the value without string interpolation and therefore
        without any risk of Cypher injection. It must NOT be interpolated
        directly into a query string.
        """
        workspace = self.workspace.strip()
        return workspace if workspace else "base"

    def _get_workspace_label(self) -> str:
        """Return sanitized workspace label safe for use as a backtick-quoted identifier in Cypher queries.

        Escapes backticks by doubling them to prevent Cypher injection
        via the LIGHTRAG-WORKSPACE header, while preserving a 1-to-1 mapping
        for all other characters. The returned value is intended to be used
        inside backticks (for example, MATCH (n:`{label}`)) and is not
        validated as a standalone unquoted identifier.

        For string-literal contexts (such as the APOC ``labelFilter`` config),
        do NOT interpolate this value; bind ``_get_raw_workspace_label()`` as a
        query parameter instead.
        """
        return self._get_raw_workspace_label().replace("`", "``")

    def _normalize_index_suffix(self, workspace_label: str) -> str:
        """Normalize workspace label for safe use in index names."""
        normalized = re.sub(r"[^A-Za-z0-9_]+", "_", workspace_label).strip("_")
        if not normalized:
            normalized = "base"
        if not re.match(r"[A-Za-z_]", normalized[0]):
            normalized = f"ws_{normalized}"
        return normalized

    def _get_fulltext_index_name(self, workspace_label: str) -> str:
        """Return a full-text index name derived from the normalized workspace label."""
        suffix = self._normalize_index_suffix(workspace_label)
        return f"entity_id_fulltext_idx_{suffix}"

    def _is_chinese_text(self, text: str) -> bool:
        """Check if text contains Chinese/CJK characters.

        Covers:
        - CJK Unified Ideographs (U+4E00-U+9FFF)
        - CJK Extension A (U+3400-U+4DBF)
        - CJK Compatibility Ideographs (U+F900-U+FAFF)
        - CJK Extension B-F (U+20000-U+2FA1F) - supplementary planes
        """
        cjk_pattern = re.compile(
            r"[\u3400-\u4dbf\u4e00-\u9fff\uf900-\ufaff]|[\U00020000-\U0002fa1f]"
        )
        return bool(cjk_pattern.search(text))

    @classmethod
    def _sanitize_fulltext_query(cls, text: str) -> str:
        """Replace Lucene reserved characters with spaces and collapse whitespace.

        Lets the full-text query parser see plain terms instead of misreading
        reserved characters as operators (e.g. '-' as NOT). Returns an empty
        string when the input is composed entirely of reserved characters.
        """
        cleaned = cls._LUCENE_RESERVED.sub(" ", text)
        return " ".join(cleaned.split())

    async def initialize(self):
        async with get_data_init_lock():
            URI = os.environ.get("NEO4J_URI", config.get("neo4j", "uri", fallback=None))
            USERNAME = os.environ.get(
                "NEO4J_USERNAME", config.get("neo4j", "username", fallback=None)
            )
            PASSWORD = os.environ.get(
                "NEO4J_PASSWORD", config.get("neo4j", "password", fallback=None)
            )
            MAX_CONNECTION_POOL_SIZE = int(
                os.environ.get(
                    "NEO4J_MAX_CONNECTION_POOL_SIZE",
                    config.get("neo4j", "connection_pool_size", fallback=100),
                )
            )
            CONNECTION_TIMEOUT = float(
                os.environ.get(
                    "NEO4J_CONNECTION_TIMEOUT",
                    config.get("neo4j", "connection_timeout", fallback=30.0),
                ),
            )
            CONNECTION_ACQUISITION_TIMEOUT = float(
                os.environ.get(
                    "NEO4J_CONNECTION_ACQUISITION_TIMEOUT",
                    config.get(
                        "neo4j", "connection_acquisition_timeout", fallback=30.0
                    ),
                ),
            )
            MAX_TRANSACTION_RETRY_TIME = float(
                os.environ.get(
                    "NEO4J_MAX_TRANSACTION_RETRY_TIME",
                    config.get("neo4j", "max_transaction_retry_time", fallback=30.0),
                ),
            )
            MAX_CONNECTION_LIFETIME = float(
                os.environ.get(
                    "NEO4J_MAX_CONNECTION_LIFETIME",
                    config.get("neo4j", "max_connection_lifetime", fallback=300.0),
                ),
            )
            LIVENESS_CHECK_TIMEOUT = float(
                os.environ.get(
                    "NEO4J_LIVENESS_CHECK_TIMEOUT",
                    config.get("neo4j", "liveness_check_timeout", fallback=30.0),
                ),
            )
            KEEP_ALIVE = os.environ.get(
                "NEO4J_KEEP_ALIVE",
                config.get("neo4j", "keep_alive", fallback="true"),
            ).lower() in ("true", "1", "yes", "on")
            DATABASE = os.environ.get(
                "NEO4J_DATABASE", re.sub(r"[^a-zA-Z0-9-]", "-", self.namespace)
            )
            """The default value approach for the DATABASE is only intended to maintain compatibility with legacy practices."""

            self._driver: AsyncDriver = AsyncGraphDatabase.driver(
                URI,
                auth=(USERNAME, PASSWORD),
                max_connection_pool_size=MAX_CONNECTION_POOL_SIZE,
                connection_timeout=CONNECTION_TIMEOUT,
                connection_acquisition_timeout=CONNECTION_ACQUISITION_TIMEOUT,
                max_transaction_retry_time=MAX_TRANSACTION_RETRY_TIME,
                max_connection_lifetime=MAX_CONNECTION_LIFETIME,
                liveness_check_timeout=LIVENESS_CHECK_TIMEOUT,
                keep_alive=KEEP_ALIVE,
            )

            # Try to connect to the database and create it if it doesn't exist
            for database in (DATABASE, None):
                self._DATABASE = database
                connected = False

                try:
                    async with self._driver.session(database=database) as session:
                        try:
                            result = await session.run("MATCH (n) RETURN n LIMIT 0")
                            await result.consume()  # Ensure result is consumed
                            logger.info(
                                f"[{self.workspace}] Connected to {database} at {URI}"
                            )
                            connected = True
                        except neo4jExceptions.ServiceUnavailable as e:
                            logger.error(
                                f"[{self.workspace}] "
                                + f"Database {database} at {URI} is not available"
                            )
                            raise e
                except neo4jExceptions.AuthError as e:
                    logger.error(
                        f"[{self.workspace}] Authentication failed for {database} at {URI}"
                    )
                    raise e
                except neo4jExceptions.ClientError as e:
                    if e.code == "Neo.ClientError.Database.DatabaseNotFound":
                        logger.info(
                            f"[{self.workspace}] "
                            + f"Database {database} at {URI} not found. Try to create specified database."
                        )
                        try:
                            async with self._driver.session() as session:
                                result = await session.run(
                                    f"CREATE DATABASE `{database}` IF NOT EXISTS"
                                )
                                await result.consume()  # Ensure result is consumed
                                logger.info(
                                    f"[{self.workspace}] "
                                    + f"Database {database} at {URI} created"
                                )
                                connected = True
                        except (
                            neo4jExceptions.ClientError,
                            neo4jExceptions.DatabaseError,
                        ) as e:
                            if (
                                e.code
                                == "Neo.ClientError.Statement.UnsupportedAdministrationCommand"
                            ) or (
                                e.code == "Neo.DatabaseError.Statement.ExecutionFailed"
                            ):
                                if database is not None:
                                    logger.warning(
                                        f"[{self.workspace}] This Neo4j instance does not support creating databases. Try to use Neo4j Desktop/Enterprise version or DozerDB instead. Fallback to use the default database."
                                    )
                            if database is None:
                                logger.error(
                                    f"[{self.workspace}] Failed to create {database} at {URI}"
                                )
                                raise e

                if connected:
                    workspace_label = self._get_workspace_label()
                    # Create B-Tree index for entity_id for faster lookups
                    try:
                        async with self._driver.session(database=database) as session:
                            await session.run(
                                f"CREATE INDEX IF NOT EXISTS FOR (n:`{workspace_label}`) ON (n.entity_id)"
                            )
                            logger.info(
                                f"[{self.workspace}] Ensured B-Tree index on entity_id for {workspace_label} in {database}"
                            )
                    except Exception as e:
                        logger.warning(
                            f"[{self.workspace}] Failed to create B-Tree index: {str(e)}"
                        )

                    # Create full-text index for entity_id for faster text searches
                    await self._create_fulltext_index(
                        self._driver, self._DATABASE, workspace_label
                    )
                    break

    async def _create_fulltext_index(
        self, driver: AsyncDriver, database: str, workspace_label: str
    ):
        """Create a full-text index on the entity_id property with Chinese tokenizer support."""
        index_name = self._get_fulltext_index_name(workspace_label)
        legacy_index_name = "entity_id_fulltext_idx"
        try:
            async with driver.session(database=database) as session:
                # Check if the full-text index exists and get its configuration
                check_index_query = "SHOW FULLTEXT INDEXES"
                result = await session.run(check_index_query)
                indexes = await result.data()
                await result.consume()

                existing_index = None
                legacy_index = None
                for idx in indexes:
                    if idx["name"] == index_name:
                        existing_index = idx
                    elif idx["name"] == legacy_index_name:
                        legacy_index = idx
                    # Break early if we found both indexes
                    if existing_index and legacy_index:
                        break

                # Handle legacy index migration
                if legacy_index and not existing_index:
                    logger.info(
                        f"[{self.workspace}] Found legacy index '{legacy_index_name}'. Migrating to '{index_name}'."
                    )
                    try:
                        # Drop the legacy index (use IF EXISTS for safety)
                        drop_query = f"DROP INDEX {legacy_index_name} IF EXISTS"
                        result = await session.run(drop_query)
                        await result.consume()
                        logger.info(
                            f"[{self.workspace}] Dropped legacy index '{legacy_index_name}'"
                        )
                    except Exception as drop_error:
                        logger.warning(
                            f"[{self.workspace}] Failed to drop legacy index: {str(drop_error)}"
                        )

                # Check if index exists and is online
                if existing_index:
                    index_state = existing_index.get("state", "UNKNOWN")
                    logger.info(
                        f"[{self.workspace}] Found existing index '{index_name}' with state: {index_state}"
                    )

                    if index_state == "ONLINE":
                        logger.info(
                            f"[{self.workspace}] Full-text index '{index_name}' already exists and is online. Skipping recreation."
                        )
                        return
                    else:
                        logger.warning(
                            f"[{self.workspace}] Existing index '{index_name}' is not online (state: {index_state}). Will recreate."
                        )
                else:
                    logger.info(
                        f"[{self.workspace}] No existing index '{index_name}' found. Creating new index."
                    )

                # Create or recreate the index if needed
                needs_recreation = (
                    existing_index is not None
                    and existing_index.get("state") != "ONLINE"
                )
                needs_creation = existing_index is None

                if needs_recreation or needs_creation:
                    # Drop existing index if it needs recreation (use IF EXISTS for safety)
                    if needs_recreation:
                        try:
                            drop_query = f"DROP INDEX {index_name} IF EXISTS"
                            result = await session.run(drop_query)
                            await result.consume()
                            logger.info(
                                f"[{self.workspace}] Dropped existing index '{index_name}'"
                            )
                        except Exception as drop_error:
                            logger.warning(
                                f"[{self.workspace}] Failed to drop existing index: {str(drop_error)}"
                            )

                    # Create new index with CJK analyzer
                    logger.info(
                        f"[{self.workspace}] Creating full-text index '{index_name}' with Chinese tokenizer support."
                    )

                    try:
                        create_index_query = f"""
                        CREATE FULLTEXT INDEX {index_name}
                        FOR (n:`{workspace_label}`) ON EACH [n.entity_id]
                        OPTIONS {{
                            indexConfig: {{
                                `fulltext.analyzer`: 'cjk',
                                `fulltext.eventually_consistent`: true
                            }}
                        }}
                        """
                        result = await session.run(create_index_query)
                        await result.consume()
                        logger.info(
                            f"[{self.workspace}] Successfully created full-text index '{index_name}' with CJK analyzer."
                        )
                    except Exception as cjk_error:
                        # Fallback to standard analyzer if CJK is not supported
                        logger.warning(
                            f"[{self.workspace}] CJK analyzer not supported: {str(cjk_error)}. "
                            "Falling back to standard analyzer."
                        )
                        create_index_query = f"""
                        CREATE FULLTEXT INDEX {index_name}
                        FOR (n:`{workspace_label}`) ON EACH [n.entity_id]
                        """
                        result = await session.run(create_index_query)
                        await result.consume()
                        logger.info(
                            f"[{self.workspace}] Successfully created full-text index '{index_name}' with standard analyzer."
                        )

        except Exception as e:
            # Handle cases where the command might not be supported
            if "Unknown command" in str(e) or "invalid syntax" in str(e).lower():
                logger.warning(
                    f"[{self.workspace}] Could not create or verify full-text index '{index_name}'. "
                    "This might be because you are using a Neo4j version that does not support it. "
                    "Search functionality will fall back to slower, non-indexed queries."
                )
            else:
                logger.error(
                    f"[{self.workspace}] Failed to create or verify full-text index '{index_name}': {str(e)}"
                )

    async def finalize(self):
        """Close the Neo4j driver and release all resources"""
        if self._driver:
            await self._driver.close()
            self._driver = None

    async def __aexit__(self, exc_type, exc, tb):
        """Ensure driver is closed when context manager exits"""
        await self.finalize()

    async def index_done_callback(self) -> None:
        # Neo4J handles persistence automatically
        pass

    @READ_RETRY
    async def has_node(self, node_id: str) -> bool:
        """
        Check if a node with the given label exists in the database

        Args:
            node_id: Label of the node to check

        Returns:
            bool: True if node exists, False otherwise

        Raises:
            ValueError: If node_id is invalid
            Exception: If there is an error executing the query
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            result = None
            try:
                query = f"MATCH (n:`{workspace_label}` {{entity_id: $entity_id}}) RETURN count(n) > 0 AS node_exists"
                result = await session.run(query, entity_id=node_id)
                single_result = await result.single()
                await result.consume()  # Ensure result is fully consumed
                return single_result["node_exists"]
            except Exception as e:
                logger.error(
                    f"[{self.workspace}] Error checking node existence for {node_id}: {str(e)}"
                )
                if result is not None:
                    await result.consume()  # Ensure results are consumed even on error
                raise

    @READ_RETRY
    async def has_edge(self, source_node_id: str, target_node_id: str) -> bool:
        """
        Check if an edge exists between two nodes

        Args:
            source_node_id: Label of the source node
            target_node_id: Label of the target node

        Returns:
            bool: True if edge exists, False otherwise

        Raises:
            ValueError: If either node_id is invalid
            Exception: If there is an error executing the query
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            result = None
            try:
                query = (
                    f"MATCH (a:`{workspace_label}` {{entity_id: $source_entity_id}})-[r]-(b:`{workspace_label}` {{entity_id: $target_entity_id}}) "
                    "RETURN COUNT(r) > 0 AS edgeExists"
                )
                result = await session.run(
                    query,
                    source_entity_id=source_node_id,
                    target_entity_id=target_node_id,
                )
                single_result = await result.single()
                await result.consume()  # Ensure result is fully consumed
                return single_result["edgeExists"]
            except Exception as e:
                logger.error(
                    f"[{self.workspace}] Error checking edge existence between {source_node_id} and {target_node_id}: {str(e)}"
                )
                if result is not None:
                    await result.consume()  # Ensure results are consumed even on error
                raise

    @READ_RETRY
    async def get_node(self, node_id: str) -> dict[str, str] | None:
        """Get node by its label identifier, return only node properties

        Args:
            node_id: The node label to look up

        Returns:
            dict: Node properties if found
            None: If node not found

        Raises:
            ValueError: If node_id is invalid
            Exception: If there is an error executing the query
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            try:
                query = (
                    f"MATCH (n:`{workspace_label}` {{entity_id: $entity_id}}) RETURN n"
                )
                result = await session.run(query, entity_id=node_id)
                try:
                    records = await result.fetch(
                        2
                    )  # Get 2 records for duplication check

                    if len(records) > 1:
                        logger.warning(
                            f"[{self.workspace}] Multiple nodes found with label '{node_id}'. Using first node."
                        )
                    if records:
                        node = records[0]["n"]
                        node_dict = dict(node)
                        # Remove workspace label from labels list if it exists
                        if "labels" in node_dict:
                            node_dict["labels"] = [
                                label
                                for label in node_dict["labels"]
                                if label != workspace_label
                            ]
                        # logger.debug(f"Neo4j query node {query} return: {node_dict}")
                        return node_dict
                    return None
                finally:
                    await result.consume()  # Ensure result is fully consumed
            except Exception as e:
                logger.error(
                    f"[{self.workspace}] Error getting node for {node_id}: {str(e)}"
                )
                raise

    @READ_RETRY
    async def get_nodes_batch(self, node_ids: list[str]) -> dict[str, dict]:
        """
        Retrieve multiple nodes in one query using UNWIND.

        Args:
            node_ids: List of node entity IDs to fetch.

        Returns:
            A dictionary mapping each node_id to its node data (or None if not found).
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            query = f"""
            UNWIND $node_ids AS id
            MATCH (n:`{workspace_label}` {{entity_id: id}})
            RETURN n.entity_id AS entity_id, n
            """
            result = await session.run(query, node_ids=node_ids)
            nodes = {}
            async for record in result:
                entity_id = record["entity_id"]
                node = record["n"]
                node_dict = dict(node)
                # Remove the workspace label if present in a 'labels' property
                if "labels" in node_dict:
                    node_dict["labels"] = [
                        label
                        for label in node_dict["labels"]
                        if label != workspace_label
                    ]
                nodes[entity_id] = node_dict
            await result.consume()  # Make sure to consume the result fully
            return nodes

    @READ_RETRY
    async def node_degree(self, node_id: str) -> int:
        """Get the degree (number of relationships) of a node with the given label.
        If multiple nodes have the same label, returns the degree of the first node.
        If no node is found, returns 0.

        Args:
            node_id: The label of the node

        Returns:
            int: The number of relationships the node has, or 0 if no node found

        Raises:
            ValueError: If node_id is invalid
            Exception: If there is an error executing the query
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            try:
                query = f"""
                    MATCH (n:`{workspace_label}` {{entity_id: $entity_id}})
                    OPTIONAL MATCH (n)-[r]-()
                    RETURN COUNT(r) AS degree
                """
                result = await session.run(query, entity_id=node_id)
                try:
                    record = await result.single()

                    if not record:
                        logger.warning(
                            f"[{self.workspace}] No node found with label '{node_id}'"
                        )
                        return 0

                    degree = record["degree"]
                    # logger.debug(
                    #     f"[{self.workspace}] Neo4j query node degree for {node_id} return: {degree}"
                    # )
                    return degree
                finally:
                    await result.consume()  # Ensure result is fully consumed
            except Exception as e:
                logger.error(
                    f"[{self.workspace}] Error getting node degree for {node_id}: {str(e)}"
                )
                raise

    @READ_RETRY
    async def node_degrees_batch(self, node_ids: list[str]) -> dict[str, int]:
        """
        Retrieve the degree for multiple nodes in a single query using UNWIND.

        Args:
            node_ids: List of node labels (entity_id values) to look up.

        Returns:
            A dictionary mapping each node_id to its degree (number of relationships).
            If a node is not found, its degree will be set to 0.
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            query = f"""
                UNWIND $node_ids AS id
                MATCH (n:`{workspace_label}` {{entity_id: id}})
                RETURN n.entity_id AS entity_id, count {{ (n)--() }} AS degree;
            """
            result = await session.run(query, node_ids=node_ids)
            degrees = {}
            async for record in result:
                entity_id = record["entity_id"]
                degrees[entity_id] = record["degree"]
            await result.consume()  # Ensure result is fully consumed

            # For any node_id that did not return a record, set degree to 0.
            for nid in node_ids:
                if nid not in degrees:
                    logger.warning(
                        f"[{self.workspace}] No node found with label '{nid}'"
                    )
                    degrees[nid] = 0

            # logger.debug(f"[{self.workspace}] Neo4j batch node degree query returned: {degrees}")
            return degrees

    async def edge_degree(self, src_id: str, tgt_id: str) -> int:
        """Get the total degree (sum of relationships) of two nodes.

        Args:
            src_id: Label of the source node
            tgt_id: Label of the target node

        Returns:
            int: Sum of the degrees of both nodes
        """
        src_degree = await self.node_degree(src_id)
        trg_degree = await self.node_degree(tgt_id)

        # Convert None to 0 for addition
        src_degree = 0 if src_degree is None else src_degree
        trg_degree = 0 if trg_degree is None else trg_degree

        degrees = int(src_degree) + int(trg_degree)
        return degrees

    @READ_RETRY
    async def edge_degrees_batch(
        self, edge_pairs: list[tuple[str, str]]
    ) -> dict[tuple[str, str], int]:
        """
        Calculate the combined degree for each edge (sum of the source and target node degrees)
        in batch using the already implemented node_degrees_batch.

        Args:
            edge_pairs: List of (src, tgt) tuples.

        Returns:
            A dictionary mapping each (src, tgt) tuple to the sum of their degrees.
        """
        # Collect unique node IDs from all edge pairs.
        unique_node_ids = {src for src, _ in edge_pairs}
        unique_node_ids.update({tgt for _, tgt in edge_pairs})

        # Get degrees for all nodes in one go.
        degrees = await self.node_degrees_batch(list(unique_node_ids))

        # Sum up degrees for each edge pair.
        edge_degrees = {}
        for src, tgt in edge_pairs:
            edge_degrees[(src, tgt)] = degrees.get(src, 0) + degrees.get(tgt, 0)
        return edge_degrees

    @READ_RETRY
    async def get_edge(
        self, source_node_id: str, target_node_id: str
    ) -> dict[str, str] | None:
        """Get edge properties between two nodes.

        Args:
            source_node_id: Label of the source node
            target_node_id: Label of the target node

        Returns:
            dict: Edge properties if found, default properties if not found or on error

        Raises:
            ValueError: If either node_id is invalid
            Exception: If there is an error executing the query
        """
        workspace_label = self._get_workspace_label()
        try:
            async with self._driver.session(
                database=self._DATABASE, default_access_mode="READ"
            ) as session:
                query = f"""
                MATCH (start:`{workspace_label}` {{entity_id: $source_entity_id}})-[r]-(end:`{workspace_label}` {{entity_id: $target_entity_id}})
                RETURN properties(r) as edge_properties
                """
                result = await session.run(
                    query,
                    source_entity_id=source_node_id,
                    target_entity_id=target_node_id,
                )
                try:
                    records = await result.fetch(2)

                    if len(records) > 1:
                        logger.warning(
                            f"[{self.workspace}] Multiple edges found between '{source_node_id}' and '{target_node_id}'. Using first edge."
                        )
                    if records:
                        try:
                            edge_result = dict(records[0]["edge_properties"])
                            # logger.debug(f"Result: {edge_result}")
                            # Ensure required keys exist with defaults
                            required_keys = {
                                "weight": 1.0,
                                "source_id": None,
                                "description": None,
                                "keywords": None,
                            }
                            for key, default_value in required_keys.items():
                                if key not in edge_result:
                                    edge_result[key] = default_value
                                    logger.warning(
                                        f"[{self.workspace}] Edge between {source_node_id} and {target_node_id} "
                                        f"missing {key}, using default: {default_value}"
                                    )

                            # logger.debug(
                            #     f"{inspect.currentframe().f_code.co_name}:query:{query}:result:{edge_result}"
                            # )
                            return edge_result
                        except (KeyError, TypeError, ValueError) as e:
                            logger.error(
                                f"[{self.workspace}] Error processing edge properties between {source_node_id} "
                                f"and {target_node_id}: {str(e)}"
                            )
                            # Return default edge properties on error
                            return {
                                "weight": 1.0,
                                "source_id": None,
                                "description": None,
                                "keywords": None,
                            }

                    # logger.debug(
                    #     f"{inspect.currentframe().f_code.co_name}: No edge found between {source_node_id} and {target_node_id}"
                    # )
                    # Return None when no edge found
                    return None
                finally:
                    await result.consume()  # Ensure result is fully consumed

        except Exception as e:
            logger.error(
                f"[{self.workspace}] Error in get_edge between {source_node_id} and {target_node_id}: {str(e)}"
            )
            raise

    @READ_RETRY
    async def get_edges_batch(
        self, pairs: list[dict[str, str]]
    ) -> dict[tuple[str, str], dict]:
        """
        Retrieve edge properties for multiple (src, tgt) pairs in one query.

        Args:
            pairs: List of dictionaries, e.g. [{"src": "node1", "tgt": "node2"}, ...]

        Returns:
            A dictionary mapping (src, tgt) tuples to their edge properties.
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            query = f"""
            UNWIND $pairs AS pair
            MATCH (start:`{workspace_label}` {{entity_id: pair.src}})-[r:DIRECTED]-(end:`{workspace_label}` {{entity_id: pair.tgt}})
            RETURN pair.src AS src_id, pair.tgt AS tgt_id, collect(properties(r)) AS edges
            """
            result = await session.run(query, pairs=pairs)
            edges_dict = {}
            async for record in result:
                src = record["src_id"]
                tgt = record["tgt_id"]
                edges = record["edges"]
                if edges and len(edges) > 0:
                    edge_props = edges[0]  # choose the first if multiple exist
                    # Ensure required keys exist with defaults
                    for key, default in {
                        "weight": 1.0,
                        "source_id": None,
                        "description": None,
                        "keywords": None,
                    }.items():
                        if key not in edge_props:
                            edge_props[key] = default
                    edges_dict[(src, tgt)] = edge_props
                else:
                    # No edge found – set default edge properties
                    edges_dict[(src, tgt)] = {
                        "weight": 1.0,
                        "source_id": None,
                        "description": None,
                        "keywords": None,
                    }
            await result.consume()
            return edges_dict

    @READ_RETRY
    async def get_node_edges(self, source_node_id: str) -> list[tuple[str, str]] | None:
        """Retrieves all edges (relationships) for a particular node identified by its label.

        Args:
            source_node_id: Label of the node to get edges for

        Returns:
            list[tuple[str, str]]: List of (source_label, target_label) tuples representing edges
            None: If no edges found

        Raises:
            ValueError: If source_node_id is invalid
            Exception: If there is an error executing the query
        """
        try:
            async with self._driver.session(
                database=self._DATABASE, default_access_mode="READ"
            ) as session:
                results = None
                try:
                    workspace_label = self._get_workspace_label()
                    query = f"""MATCH (n:`{workspace_label}` {{entity_id: $entity_id}})
                            OPTIONAL MATCH (n)-[r]-(connected:`{workspace_label}`)
                            WHERE connected.entity_id IS NOT NULL
                            RETURN n, r, connected"""
                    results = await session.run(query, entity_id=source_node_id)

                    edges = []
                    async for record in results:
                        source_node = record["n"]
                        connected_node = record["connected"]

                        # Skip if either node is None
                        if not source_node or not connected_node:
                            continue

                        source_label = (
                            source_node.get("entity_id")
                            if source_node.get("entity_id")
                            else None
                        )
                        target_label = (
                            connected_node.get("entity_id")
                            if connected_node.get("entity_id")
                            else None
                        )

                        if source_label and target_label:
                            edges.append((source_label, target_label))

                    await results.consume()  # Ensure results are consumed
                    return edges
                except Exception as e:
                    logger.error(
                        f"[{self.workspace}] Error getting edges for node {source_node_id}: {str(e)}"
                    )
                    if results is not None:
                        await (
                            results.consume()
                        )  # Ensure results are consumed even on error
                    raise
        except Exception as e:
            logger.error(
                f"[{self.workspace}] Error in get_node_edges for {source_node_id}: {str(e)}"
            )
            raise

    @READ_RETRY
    async def get_nodes_edges_batch(
        self, node_ids: list[str]
    ) -> dict[str, list[tuple[str, str]]]:
        """
        Batch retrieve edges for multiple nodes in one query using UNWIND.
        For each node, returns both outgoing and incoming edges to properly represent
        the undirected graph nature.

        Args:
            node_ids: List of node IDs (entity_id) for which to retrieve edges.

        Returns:
            A dictionary mapping each node ID to its list of edge tuples (source, target).
            For each node, the list includes both:
            - Outgoing edges: (queried_node, connected_node)
            - Incoming edges: (connected_node, queried_node)
        """
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            # Query to get both outgoing and incoming edges
            workspace_label = self._get_workspace_label()
            query = f"""
                UNWIND $node_ids AS id
                MATCH (n:`{workspace_label}` {{entity_id: id}})
                OPTIONAL MATCH (n)-[r]-(connected:`{workspace_label}`)
                RETURN id AS queried_id, n.entity_id AS node_entity_id,
                       connected.entity_id AS connected_entity_id,
                       startNode(r).entity_id AS start_entity_id
            """
            result = await session.run(query, node_ids=node_ids)

            # Initialize the dictionary with empty lists for each node ID
            edges_dict = {node_id: [] for node_id in node_ids}

            # Process results to include both outgoing and incoming edges
            async for record in result:
                queried_id = record["queried_id"]
                node_entity_id = record["node_entity_id"]
                connected_entity_id = record["connected_entity_id"]
                start_entity_id = record["start_entity_id"]

                # Skip if either node is None
                if not node_entity_id or not connected_entity_id:
                    continue

                # Determine the actual direction of the edge
                # If the start node is the queried node, it's an outgoing edge
                # Otherwise, it's an incoming edge
                if start_entity_id == node_entity_id:
                    # Outgoing edge: (queried_node -> connected_node)
                    edges_dict[queried_id].append((node_entity_id, connected_entity_id))
                else:
                    # Incoming edge: (connected_node -> queried_node)
                    edges_dict[queried_id].append((connected_entity_id, node_entity_id))

            await result.consume()  # Ensure results are fully consumed
            return edges_dict

    @retry(
        stop=stop_after_attempt(3),
        wait=wait_exponential(multiplier=1, min=4, max=10),
        retry=retry_if_exception_type(
            (
                neo4jExceptions.ServiceUnavailable,
                neo4jExceptions.TransientError,
                neo4jExceptions.WriteServiceUnavailable,
                neo4jExceptions.ClientError,
                neo4jExceptions.SessionExpired,
                ConnectionResetError,
                OSError,
            )
        ),
    )
    async def upsert_node(self, node_id: str, node_data: dict[str, str]) -> None:
        """
        Upsert a node in the Neo4j database.

        Args:
            node_id: The unique identifier for the node (used as label)
            node_data: Dictionary of node properties
        """
        workspace_label = self._get_workspace_label()
        properties = node_data
        if "entity_id" not in properties:
            raise ValueError("Neo4j: node properties must contain an 'entity_id' field")

        try:
            async with self._driver.session(database=self._DATABASE) as session:

                async def execute_upsert(tx: AsyncManagedTransaction):
                    query = f"""
                    MERGE (n:`{workspace_label}` {{entity_id: $entity_id}})
                    SET n += $properties
                    """
                    result = await tx.run(
                        query, entity_id=node_id, properties=properties
                    )
                    await result.consume()  # Ensure result is fully consumed

                await session.execute_write(execute_upsert)
        except Exception as e:
            logger.error(f"[{self.workspace}] Error during upsert: {str(e)}")
            raise

    @retry(
        stop=stop_after_attempt(3),
        wait=wait_exponential(multiplier=1, min=4, max=10),
        retry=retry_if_exception_type(
            (
                neo4jExceptions.ServiceUnavailable,
                neo4jExceptions.TransientError,
                neo4jExceptions.WriteServiceUnavailable,
                neo4jExceptions.ClientError,
                neo4jExceptions.SessionExpired,
                ConnectionResetError,
                OSError,
            )
        ),
    )
    async def upsert_nodes_batch(self, nodes: list[tuple[str, dict[str, str]]]) -> None:
        """Batch insert/update multiple nodes using a single UNWIND Cypher query.

        Significantly faster than calling upsert_node() in a loop for large imports
        because it executes all merges in one round-trip to the database.

        Args:
            nodes: List of (node_id, node_data) tuples.
        """
        if not nodes:
            return
        workspace_label = self._get_workspace_label()
        nodes_data = []
        for node_id, node_data in nodes:
            if "entity_id" not in node_data:
                raise ValueError(
                    "Neo4j: node properties must contain an 'entity_id' field"
                )
            nodes_data.append({"entity_id": node_id, "props": node_data})

        try:
            async with self._driver.session(database=self._DATABASE) as session:

                async def execute_batch(tx: AsyncManagedTransaction):
                    query = f"""
                    UNWIND $nodes AS row
                    MERGE (n:`{workspace_label}` {{entity_id: row.entity_id}})
                    SET n += row.props
                    """
                    result = await tx.run(query, nodes=nodes_data)
                    await result.consume()

                await session.execute_write(execute_batch)
        except Exception as e:
            logger.error(f"[{self.workspace}] Error during batch node upsert: {str(e)}")
            raise

    @READ_RETRY
    async def has_nodes_batch(self, node_ids: list[str]) -> set[str]:
        """Check existence of multiple nodes in a single UNWIND query.

        Args:
            node_ids: List of node IDs to check.

        Returns:
            Set of node_ids that exist in the graph.
        """
        if not node_ids:
            return set()
        workspace_label = self._get_workspace_label()
        try:
            async with self._driver.session(
                database=self._DATABASE, default_access_mode="READ"
            ) as session:
                query = f"""
                UNWIND $ids AS id
                MATCH (n:`{workspace_label}` {{entity_id: id}})
                RETURN n.entity_id AS entity_id
                """
                result = await session.run(query, ids=node_ids)
                records = await result.data()
                await result.consume()
                return {r["entity_id"] for r in records}
        except Exception as e:
            logger.error(
                f"[{self.workspace}] Error during batch node existence check: {str(e)}"
            )
            raise

    @retry(
        stop=stop_after_attempt(3),
        wait=wait_exponential(multiplier=1, min=4, max=10),
        retry=retry_if_exception_type(
            (
                neo4jExceptions.ServiceUnavailable,
                neo4jExceptions.TransientError,
                neo4jExceptions.WriteServiceUnavailable,
                neo4jExceptions.ClientError,
                neo4jExceptions.SessionExpired,
                ConnectionResetError,
                OSError,
            )
        ),
    )
    async def upsert_edges_batch(
        self, edges: list[tuple[str, str, dict[str, str]]]
    ) -> None:
        """Batch insert/update multiple edges using a single UNWIND Cypher query.

        Args:
            edges: List of (source_node_id, target_node_id, edge_data) tuples.
        """
        if not edges:
            return
        workspace_label = self._get_workspace_label()
        edges_data = [
            {"src": src, "tgt": tgt, "props": edge_data}
            for src, tgt, edge_data in edges
        ]
        try:
            async with self._driver.session(database=self._DATABASE) as session:

                async def execute_batch(tx: AsyncManagedTransaction):
                    query = f"""
                    UNWIND $edges AS row
                    MATCH (source:`{workspace_label}` {{entity_id: row.src}})
                    WITH source, row
                    MATCH (target:`{workspace_label}` {{entity_id: row.tgt}})
                    MERGE (source)-[r:DIRECTED]-(target)
                    SET r += row.props
                    """
                    result = await tx.run(query, edges=edges_data)
                    await result.consume()

                await session.execute_write(execute_batch)
        except Exception as e:
            logger.error(f"[{self.workspace}] Error during batch edge upsert: {str(e)}")
            raise

    @retry(
        stop=stop_after_attempt(3),
        wait=wait_exponential(multiplier=1, min=4, max=10),
        retry=retry_if_exception_type(
            (
                neo4jExceptions.ServiceUnavailable,
                neo4jExceptions.TransientError,
                neo4jExceptions.WriteServiceUnavailable,
                neo4jExceptions.ClientError,
                neo4jExceptions.SessionExpired,
                ConnectionResetError,
                OSError,
            )
        ),
    )
    async def upsert_edge(
        self, source_node_id: str, target_node_id: str, edge_data: dict[str, str]
    ) -> None:
        """
        Upsert an edge and its properties between two nodes identified by their labels.
        Ensures both source and target nodes exist and are unique before creating the edge.
        Uses entity_id property to uniquely identify nodes.

        Args:
            source_node_id (str): Label of the source node (used as identifier)
            target_node_id (str): Label of the target node (used as identifier)
            edge_data (dict): Dictionary of properties to set on the edge

        Raises:
            ValueError: If either source or target node does not exist or is not unique
        """
        try:
            edge_properties = edge_data
            async with self._driver.session(database=self._DATABASE) as session:

                async def execute_upsert(tx: AsyncManagedTransaction):
                    workspace_label = self._get_workspace_label()
                    query = f"""
                    MATCH (source:`{workspace_label}` {{entity_id: $source_entity_id}})
                    WITH source
                    MATCH (target:`{workspace_label}` {{entity_id: $target_entity_id}})
                    MERGE (source)-[r:DIRECTED]-(target)
                    SET r += $properties
                    RETURN r, source, target
                    """
                    result = await tx.run(
                        query,
                        source_entity_id=source_node_id,
                        target_entity_id=target_node_id,
                        properties=edge_properties,
                    )
                    try:
                        await result.fetch(2)
                    finally:
                        await result.consume()  # Ensure result is consumed

                await session.execute_write(execute_upsert)
        except Exception as e:
            logger.error(f"[{self.workspace}] Error during edge upsert: {str(e)}")
            raise

    async def get_knowledge_graph(
        self,
        node_label: str,
        max_depth: int = 3,
        max_nodes: int = None,
    ) -> KnowledgeGraph:
        """
        Retrieve a connected subgraph of nodes where the label includes the specified `node_label`.

        Args:
            node_label: Label of the starting node, * means all nodes
            max_depth: Maximum depth of the subgraph, Defaults to 3
            max_nodes: Maxiumu nodes to return by BFS, Defaults to 1000

        Returns:
            KnowledgeGraph object containing nodes and edges, with an is_truncated flag
            indicating whether the graph was truncated due to max_nodes limit
        """
        # Get max_nodes from global_config if not provided
        if max_nodes is None:
            max_nodes = self.global_config.get("max_graph_nodes", 1000)
        else:
            # Limit max_nodes to not exceed global_config max_graph_nodes
            max_nodes = min(max_nodes, self.global_config.get("max_graph_nodes", 1000))

        workspace_label = self._get_workspace_label()
        # Raw (un-escaped) label bound as a query parameter for APOC labelFilter,
        # which lives inside a Cypher string literal and must not be interpolated.
        workspace_label_raw = self._get_raw_workspace_label()
        result = KnowledgeGraph()
        seen_nodes = set()
        seen_edges = set()

        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            try:
                if node_label == "*":
                    # First check total node count to determine if graph is truncated
                    count_query = (
                        f"MATCH (n:`{workspace_label}`) RETURN count(n) as total"
                    )
                    count_result = None
                    try:
                        count_result = await session.run(count_query)
                        count_record = await count_result.single()

                        if count_record and count_record["total"] > max_nodes:
                            result.is_truncated = True
                            logger.info(
                                f"[{self.workspace}] Graph truncated: {count_record['total']} nodes found, limited to {max_nodes}"
                            )
                    finally:
                        if count_result:
                            await count_result.consume()

                    # Run main query to get nodes with highest degree
                    main_query = f"""
                    MATCH (n:`{workspace_label}`)
                    OPTIONAL MATCH (n)-[r]-()
                    WITH n, COALESCE(count(r), 0) AS degree
                    ORDER BY degree DESC
                    LIMIT $max_nodes
                    WITH collect({{node: n}}) AS filtered_nodes
                    UNWIND filtered_nodes AS node_info
                    WITH collect(node_info.node) AS kept_nodes, filtered_nodes
                    OPTIONAL MATCH (a)-[r]-(b)
                    WHERE a IN kept_nodes AND b IN kept_nodes
                    RETURN filtered_nodes AS node_info,
                           collect(DISTINCT r) AS relationships
                    """
                    result_set = None
                    try:
                        result_set = await session.run(
                            main_query,
                            {"max_nodes": max_nodes},
                        )
                        record = await result_set.single()
                    finally:
                        if result_set:
                            await result_set.consume()

                else:
                    # return await self._robust_fallback(node_label, max_depth, max_nodes)
                    # First try without limit to check if we need to truncate
                    full_query = f"""
                    MATCH (start:`{workspace_label}`)
                    WHERE start.entity_id = $entity_id
                    WITH start
                    CALL apoc.path.subgraphAll(start, {{
                        relationshipFilter: '',
                        labelFilter: $label_filter,
                        minLevel: 0,
                        maxLevel: $max_depth,
                        bfs: true
                    }})
                    YIELD nodes, relationships
                    WITH nodes, relationships, size(nodes) AS total_nodes
                    UNWIND nodes AS node
                    WITH collect({{node: node}}) AS node_info, relationships, total_nodes
                    RETURN node_info, relationships, total_nodes
                    """

                    # Try to get full result
                    full_result = None
                    try:
                        full_result = await session.run(
                            full_query,
                            {
                                "entity_id": node_label,
                                "max_depth": max_depth,
                                "label_filter": workspace_label_raw,
                            },
                        )
                        full_record = await full_result.single()

                        # If no record found, return empty KnowledgeGraph
                        if not full_record:
                            logger.debug(
                                f"[{self.workspace}] No nodes found for entity_id: {node_label}"
                            )
                            return result

                        # If record found, check node count
                        total_nodes = full_record["total_nodes"]

                        if total_nodes <= max_nodes:
                            # If node count is within limit, use full result directly
                            logger.debug(
                                f"[{self.workspace}] Using full result with {total_nodes} nodes (no truncation needed)"
                            )
                            record = full_record
                        else:
                            # If node count exceeds limit, set truncated flag and run limited query
                            result.is_truncated = True
                            logger.info(
                                f"[{self.workspace}] Graph truncated: {total_nodes} nodes found, breadth-first search limited to {max_nodes}"
                            )

                            # Run limited query
                            limited_query = f"""
                            MATCH (start:`{workspace_label}`)
                            WHERE start.entity_id = $entity_id
                            WITH start
                            CALL apoc.path.subgraphAll(start, {{
                                relationshipFilter: '',
                                labelFilter: $label_filter,
                                minLevel: 0,
                                maxLevel: $max_depth,
                                limit: $max_nodes,
                                bfs: true
                            }})
                            YIELD nodes, relationships
                            UNWIND nodes AS node
                            WITH collect({{node: node}}) AS node_info, relationships
                            RETURN node_info, relationships
                            """
                            result_set = None
                            try:
                                result_set = await session.run(
                                    limited_query,
                                    {
                                        "entity_id": node_label,
                                        "max_depth": max_depth,
                                        "max_nodes": max_nodes,
                                        "label_filter": workspace_label_raw,
                                    },
                                )
                                record = await result_set.single()
                            finally:
                                if result_set:
                                    await result_set.consume()
                    finally:
                        if full_result:
                            await full_result.consume()

                if record:
                    # Handle nodes (compatible with multi-label cases)
                    for node_info in record["node_info"]:
                        node = node_info["node"]
                        node_id = node.id
                        if node_id not in seen_nodes:
                            result.nodes.append(
                                KnowledgeGraphNode(
                                    id=f"{node_id}",
                                    labels=[node.get("entity_id")],
                                    properties=dict(node),
                                )
                            )
                            seen_nodes.add(node_id)

                    # Handle relationships (including direction information)
                    for rel in record["relationships"]:
                        edge_id = rel.id
                        if edge_id not in seen_edges:
                            start = rel.start_node
                            end = rel.end_node
                            result.edges.append(
                                KnowledgeGraphEdge(
                                    id=f"{edge_id}",
                                    type=rel.type,
                                    source=f"{start.id}",
                                    target=f"{end.id}",
                                    properties=dict(rel),
                                )
                            )
                            seen_edges.add(edge_id)

                    logger.info(
                        f"[{self.workspace}] Subgraph query successful | Node count: {len(result.nodes)} | Edge count: {len(result.edges)}"
                    )

            except neo4jExceptions.ClientError as e:
                logger.warning(f"[{self.workspace}] APOC plugin error: {str(e)}")
                if node_label != "*":
                    logger.warning(
                        f"[{self.workspace}] Neo4j: falling back to basic Cypher recursive search..."
                    )
                    return await self._robust_fallback(node_label, max_depth, max_nodes)
                else:
                    logger.warning(
                        f"[{self.workspace}] Neo4j: APOC plugin error with wildcard query, returning empty result"
                    )

        return result

    async def _robust_fallback(
        self, node_label: str, max_depth: int, max_nodes: int
    ) -> KnowledgeGraph:
        """
        Fallback implementation when APOC plugin is not available or incompatible.
        This method implements the same functionality as get_knowledge_graph but uses
        only basic Cypher queries and true breadth-first traversal instead of APOC procedures.
        """
        from collections import deque

        result = KnowledgeGraph()
        visited_nodes = set()
        visited_edges = set()
        visited_edge_pairs = set()

        # Get the starting node's data
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            query = f"""
            MATCH (n:`{workspace_label}` {{entity_id: $entity_id}})
            RETURN id(n) as node_id, n
            """
            node_result = await session.run(query, entity_id=node_label)
            try:
                node_record = await node_result.single()
                if not node_record:
                    return result

                # Create initial KnowledgeGraphNode
                start_node = KnowledgeGraphNode(
                    id=f"{node_record['n'].get('entity_id')}",
                    labels=[node_record["n"].get("entity_id")],
                    properties=dict(node_record["n"]._properties),
                )
            finally:
                await node_result.consume()  # Ensure results are consumed

        # Initialize queue for BFS with (node, edge, depth) tuples
        # edge is None for the starting node
        queue = deque([(start_node, None, 0)])

        # True BFS implementation using a queue
        while queue and len(visited_nodes) < max_nodes:
            # Dequeue the next node to process
            current_node, current_edge, current_depth = queue.popleft()

            # Skip if already visited or exceeds max depth
            if current_node.id in visited_nodes:
                continue

            if current_depth > max_depth:
                logger.debug(
                    f"[{self.workspace}] Skipping node at depth {current_depth} (max_depth: {max_depth})"
                )
                continue

            # Add current node to result
            result.nodes.append(current_node)
            visited_nodes.add(current_node.id)

            # Add edge to result if it exists and not already added
            if current_edge and current_edge.id not in visited_edges:
                result.edges.append(current_edge)
                visited_edges.add(current_edge.id)

            # Stop if we've reached the node limit
            if len(visited_nodes) >= max_nodes:
                result.is_truncated = True
                logger.info(
                    f"[{self.workspace}] Graph truncated: breadth-first search limited to: {max_nodes} nodes"
                )
                break

            # Get all edges and target nodes for the current node (even at max_depth)
            async with self._driver.session(
                database=self._DATABASE, default_access_mode="READ"
            ) as session:
                workspace_label = self._get_workspace_label()
                query = f"""
                MATCH (a:`{workspace_label}` {{entity_id: $entity_id}})-[r]-(b)
                WITH r, b, id(r) as edge_id, id(b) as target_id
                RETURN r, b, edge_id, target_id
                """
                results = await session.run(query, entity_id=current_node.id)

                # Get all records and release database connection
                records = await results.fetch(1000)  # Max neighbor nodes we can handle
                await results.consume()  # Ensure results are consumed

                # Process all neighbors - capture all edges but only queue unvisited nodes
                for record in records:
                    rel = record["r"]
                    edge_id = str(record["edge_id"])

                    if edge_id not in visited_edges:
                        b_node = record["b"]
                        target_id = b_node.get("entity_id")

                        if target_id:  # Only process if target node has entity_id
                            # Create KnowledgeGraphNode for target
                            target_node = KnowledgeGraphNode(
                                id=f"{target_id}",
                                labels=[target_id],
                                properties=dict(b_node._properties),
                            )

                            # Create KnowledgeGraphEdge
                            target_edge = KnowledgeGraphEdge(
                                id=f"{edge_id}",
                                type=rel.type,
                                source=f"{current_node.id}",
                                target=f"{target_id}",
                                properties=dict(rel),
                            )

                            # Sort source_id and target_id to ensure (A,B) and (B,A) are treated as the same edge
                            sorted_pair = tuple(sorted([current_node.id, target_id]))

                            # Check if the same edge already exists (considering undirectedness)
                            if sorted_pair not in visited_edge_pairs:
                                # Only add the edge if the target node is already in the result or will be added
                                if target_id in visited_nodes or (
                                    target_id not in visited_nodes
                                    and current_depth < max_depth
                                ):
                                    result.edges.append(target_edge)
                                    visited_edges.add(edge_id)
                                    visited_edge_pairs.add(sorted_pair)

                            # Only add unvisited nodes to the queue for further expansion
                            if target_id not in visited_nodes:
                                # Only add to queue if we're not at max depth yet
                                if current_depth < max_depth:
                                    # Add node to queue with incremented depth
                                    # Edge is already added to result, so we pass None as edge
                                    queue.append((target_node, None, current_depth + 1))
                                else:
                                    # At max depth, we've already added the edge but we don't add the node
                                    # This prevents adding nodes beyond max_depth to the result
                                    logger.debug(
                                        f"[{self.workspace}] Node {target_id} beyond max depth {max_depth}, edge added but node not included"
                                    )
                            else:
                                # If target node already exists in result, we don't need to add it again
                                logger.debug(
                                    f"[{self.workspace}] Node {target_id} already visited, edge added but node not queued"
                                )
                        else:
                            logger.warning(
                                f"[{self.workspace}] Skipping edge {edge_id} due to missing entity_id on target node"
                            )

        logger.info(
            f"[{self.workspace}] BFS subgraph query successful | Node count: {len(result.nodes)} | Edge count: {len(result.edges)}"
        )
        return result

    async def get_all_labels(self) -> list[str]:
        """
        Get all existing entity_ids(entity names) in the database
        Returns:
            ["Person", "Company", ...]  # Alphabetically sorted label list
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            # Method 1: Direct metadata query (Available for Neo4j 4.3+)
            # query = "CALL db.labels() YIELD label RETURN label"

            # Method 2: Query compatible with older versions
            query = f"""
            MATCH (n:`{workspace_label}`)
            WHERE n.entity_id IS NOT NULL
            RETURN DISTINCT n.entity_id AS label
            ORDER BY label
            """
            result = await session.run(query)
            labels = []
            try:
                async for record in result:
                    labels.append(record["label"])
            finally:
                await (
                    result.consume()
                )  # Ensure results are consumed even if processing fails
            return labels

    @retry(
        stop=stop_after_attempt(3),
        wait=wait_exponential(multiplier=1, min=4, max=10),
        retry=retry_if_exception_type(
            (
                neo4jExceptions.ServiceUnavailable,
                neo4jExceptions.TransientError,
                neo4jExceptions.WriteServiceUnavailable,
                neo4jExceptions.ClientError,
                neo4jExceptions.SessionExpired,
                ConnectionResetError,
                OSError,
            )
        ),
    )
    async def delete_node(self, node_id: str) -> None:
        """Delete a node with the specified label

        Args:
            node_id: The label of the node to delete
        """

        async def _do_delete(tx: AsyncManagedTransaction):
            workspace_label = self._get_workspace_label()
            query = f"""
            MATCH (n:`{workspace_label}` {{entity_id: $entity_id}})
            DETACH DELETE n
            """
            result = await tx.run(query, entity_id=node_id)
            logger.debug(f"[{self.workspace}] Deleted node with label '{node_id}'")
            await result.consume()  # Ensure result is fully consumed

        try:
            async with self._driver.session(database=self._DATABASE) as session:
                await session.execute_write(_do_delete)
        except Exception as e:
            logger.error(f"[{self.workspace}] Error during node deletion: {str(e)}")
            raise

    @retry(
        stop=stop_after_attempt(3),
        wait=wait_exponential(multiplier=1, min=4, max=10),
        retry=retry_if_exception_type(
            (
                neo4jExceptions.ServiceUnavailable,
                neo4jExceptions.TransientError,
                neo4jExceptions.WriteServiceUnavailable,
                neo4jExceptions.ClientError,
                neo4jExceptions.SessionExpired,
                ConnectionResetError,
                OSError,
            )
        ),
    )
    async def remove_nodes(self, nodes: list[str]):
        """Delete multiple nodes

        Args:
            nodes: List of node labels to be deleted
        """
        for node in nodes:
            await self.delete_node(node)

    @retry(
        stop=stop_after_attempt(3),
        wait=wait_exponential(multiplier=1, min=4, max=10),
        retry=retry_if_exception_type(
            (
                neo4jExceptions.ServiceUnavailable,
                neo4jExceptions.TransientError,
                neo4jExceptions.WriteServiceUnavailable,
                neo4jExceptions.ClientError,
                neo4jExceptions.SessionExpired,
                ConnectionResetError,
                OSError,
            )
        ),
    )
    async def remove_edges(self, edges: list[tuple[str, str]]):
        """Delete multiple edges

        Args:
            edges: List of edges to be deleted, each edge is a (source, target) tuple
        """
        for source, target in edges:

            async def _do_delete_edge(tx: AsyncManagedTransaction):
                workspace_label = self._get_workspace_label()
                query = f"""
                MATCH (source:`{workspace_label}` {{entity_id: $source_entity_id}})-[r]-(target:`{workspace_label}` {{entity_id: $target_entity_id}})
                DELETE r
                """
                result = await tx.run(
                    query, source_entity_id=source, target_entity_id=target
                )
                logger.debug(
                    f"[{self.workspace}] Deleted edge from '{source}' to '{target}'"
                )
                await result.consume()  # Ensure result is fully consumed

            try:
                async with self._driver.session(database=self._DATABASE) as session:
                    await session.execute_write(_do_delete_edge)
            except Exception as e:
                logger.error(f"[{self.workspace}] Error during edge deletion: {str(e)}")
                raise

    async def get_all_nodes(self) -> list[dict]:
        """Get all nodes in the graph.

        Returns:
            A list of all nodes, where each node is a dictionary of its properties
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            query = f"""
            MATCH (n:`{workspace_label}`)
            RETURN n
            """
            result = await session.run(query)
            nodes = []
            async for record in result:
                node = record["n"]
                node_dict = dict(node)
                # Add node id (entity_id) to the dictionary for easier access
                node_dict["id"] = node_dict.get("entity_id")
                nodes.append(node_dict)
            await result.consume()
            return nodes

    async def get_all_edges(self) -> list[dict]:
        """Get all edges in the graph.

        Returns:
            A list of all edges, where each edge is a dictionary of its properties
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            query = f"""
            MATCH (a:`{workspace_label}`)-[r]-(b:`{workspace_label}`)
            RETURN DISTINCT a.entity_id AS source, b.entity_id AS target, properties(r) AS properties
            """
            result = await session.run(query)
            edges = []
            async for record in result:
                edge_properties = record["properties"]
                edge_properties["source"] = record["source"]
                edge_properties["target"] = record["target"]
                edges.append(edge_properties)
            await result.consume()
            return edges

    async def get_popular_labels(self, limit: int = 300) -> list[str]:
        """Get popular labels(entity names) by node degree (most connected entities)

        Args:
            limit: Maximum number of labels to return

        Returns:
            List of labels(entity names) sorted by degree (highest first)
        """
        workspace_label = self._get_workspace_label()
        async with self._driver.session(
            database=self._DATABASE, default_access_mode="READ"
        ) as session:
            result = None
            try:
                query = f"""
                MATCH (n:`{workspace_label}`)
                WHERE n.entity_id IS NOT NULL
                OPTIONAL MATCH (n)-[r]-()
                WITH n.entity_id AS label, count(r) AS degree
                ORDER BY degree DESC, label ASC
                LIMIT $limit
                RETURN label
                """
                result = await session.run(query, limit=limit)
                labels = []
                async for record in result:
                    labels.append(record["label"])
                await result.consume()

                logger.debug(
                    f"[{self.workspace}] Retrieved {len(labels)} popular labels (limit: {limit})"
                )
                return labels
            except Exception as e:
                logger.error(
                    f"[{self.workspace}] Error getting popular labels: {str(e)}"
                )
                if result is not None:
                    await result.consume()
                raise

    async def search_labels(self, query: str, limit: int = 50) -> list[str]:
        """
        Search labels(entity names) with fuzzy matching, using a full-text index for performance if available.
        Enhanced with Chinese text support using CJK analyzer.
        Falls back to a slower CONTAINS search if the index is not available or fails.
        """
        workspace_label = self._get_workspace_label()
        query_strip = query.strip()
        if not query_strip:
            return []

        query_lower = query_strip.lower()
        is_chinese = self._is_chinese_text(query_strip)
        index_name = self._get_fulltext_index_name(workspace_label)

        # Strip Lucene reserved characters before handing the text to the
        # full-text query parser (see _sanitize_fulltext_query). The CASE-based
        # scoring below still uses the raw query_strip / query_lower.
        sanitized_query = self._sanitize_fulltext_query(query_strip)
        if not sanitized_query:
            # Query was composed entirely of reserved characters (e.g. "---").
            # Return empty rather than falling back to a full-graph CONTAINS scan.
            return []

        # Attempt to use the full-text index first
        try:
            async with self._driver.session(
                database=self._DATABASE, default_access_mode="READ"
            ) as session:
                if is_chinese:
                    # For Chinese text, use different search strategies
                    cypher_query = f"""
                    CALL db.index.fulltext.queryNodes($index_name, $search_query) YIELD node, score
                    WITH node, score
                    WHERE node:`{workspace_label}`
                    WITH node.entity_id AS label, score
                    WITH label, score,
                         CASE
                             WHEN label = $query_strip THEN score + 1000
                             WHEN label CONTAINS $query_strip THEN score + 500
                             ELSE score
                         END AS final_score
                    RETURN label
                    ORDER BY final_score DESC, label ASC
                    LIMIT $limit
                    """
                    # For Chinese, don't add wildcard as it may not work properly with CJK analyzer
                    search_query = sanitized_query
                else:
                    # For non-Chinese text, use the original logic with wildcard
                    cypher_query = f"""
                    CALL db.index.fulltext.queryNodes($index_name, $search_query) YIELD node, score
                    WITH node, score
                    WHERE node:`{workspace_label}`
                    WITH node.entity_id AS label, toLower(node.entity_id) AS label_lower, score
                    WITH label, label_lower, score,
                         CASE
                             WHEN label_lower = $query_lower THEN score + 1000
                             WHEN label_lower STARTS WITH $query_lower THEN score + 500
                             WHEN label_lower CONTAINS ' ' + $query_lower OR label_lower CONTAINS '_' + $query_lower THEN score + 50
                             ELSE score
                         END AS final_score
                    RETURN label
                    ORDER BY final_score DESC, label ASC
                    LIMIT $limit
                    """
                    search_query = f"{sanitized_query}*"

                result = await session.run(
                    cypher_query,
                    index_name=index_name,
                    search_query=search_query,
                    query_lower=query_lower,
                    query_strip=query_strip,
                    limit=limit,
                )
                labels = [record["label"] async for record in result]
                await result.consume()

                logger.debug(
                    f"[{self.workspace}] Full-text search ({'Chinese' if is_chinese else 'Latin'}) for '{query}' returned {len(labels)} results (limit: {limit})"
                )
                return labels

        except Exception as e:
            # If the full-text search fails, fall back to CONTAINS search
            logger.warning(
                f"[{self.workspace}] Full-text search failed with error: {str(e)}. "
                "Falling back to slower, non-indexed search."
            )

            # Enhanced fallback implementation
            async with self._driver.session(
                database=self._DATABASE, default_access_mode="READ"
            ) as session:
                if is_chinese:
                    # For Chinese text, use direct CONTAINS without case conversion
                    cypher_query = f"""
                    MATCH (n:`{workspace_label}`)
                    WHERE n.entity_id IS NOT NULL
                    WITH n.entity_id AS label
                    WHERE label CONTAINS $query_strip
                    WITH label,
                         CASE
                             WHEN label = $query_strip THEN 1000
                             WHEN label STARTS WITH $query_strip THEN 500
                             ELSE 100 - size(label)
                         END AS score
                    ORDER BY score DESC, label ASC
                    LIMIT $limit
                    RETURN label
                    """
                    result = await session.run(
                        cypher_query, query_strip=query_strip, limit=limit
                    )
                else:
                    # For non-Chinese text, use the original fallback logic
                    cypher_query = f"""
                    MATCH (n:`{workspace_label}`)
                    WHERE n.entity_id IS NOT NULL
                    WITH n.entity_id AS label, toLower(n.entity_id) AS label_lower
                    WHERE label_lower CONTAINS $query_lower
                    WITH label, label_lower,
                         CASE
                             WHEN label_lower = $query_lower THEN 1000
                             WHEN label_lower STARTS WITH $query_lower THEN 500
                             ELSE 100 - size(label)
                         END AS score
                    ORDER BY score DESC, label ASC
                    LIMIT $limit
                    RETURN label
                    """
                    result = await session.run(
                        cypher_query, query_lower=query_lower, limit=limit
                    )

                labels = [record["label"] async for record in result]
                await result.consume()
                logger.debug(
                    f"[{self.workspace}] Fallback search ({'Chinese' if is_chinese else 'Latin'}) for '{query}' returned {len(labels)} results (limit: {limit})"
                )
                return labels

    async def drop(self) -> dict[str, str]:
        """Drop all data from current workspace storage and clean up resources

        This method will delete all nodes and relationships in the current workspace only.

        Returns:
            dict[str, str]: Operation status and message
            - On success: {"status": "success", "message": "workspace data dropped"}
            - On failure: {"status": "error", "message": "<error details>"}
        """
        workspace_label = self._get_workspace_label()
        try:
            async with self._driver.session(database=self._DATABASE) as session:
                # Delete all nodes and relationships in current workspace only
                query = f"MATCH (n:`{workspace_label}`) DETACH DELETE n"
                result = await session.run(query)
                await result.consume()  # Ensure result is fully consumed

                # logger.debug(
                #     f"[{self.workspace}] Process {os.getpid()} drop Neo4j workspace '{workspace_label}' in database {self._DATABASE}"
                # )
                return {
                    "status": "success",
                    "message": f"workspace '{workspace_label}' data dropped",
                }
        except Exception as e:
            logger.error(
                f"[{self.workspace}] Error dropping Neo4j workspace '{workspace_label}' in database {self._DATABASE}: {e}"
            )
            return {"status": "error", "message": str(e)}
