import os
import sys
from logging.config import fileConfig
from pathlib import Path

from sqlalchemy import engine_from_config, pool

from alembic import context

# Add src directory to Python path for imports
# Note: This must happen before importing our models
sys.path.insert(0, str(Path(__file__).parent.parent / "src"))

from nexus.storage.models import Base  # noqa: E402

# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config

# Override database URL from environment variables if present
# Priority: NEXUS_DATABASE_URL > POSTGRES_URL > alembic.ini
db_url = os.getenv("NEXUS_DATABASE_URL") or os.getenv("POSTGRES_URL")
if db_url:
    config.set_main_option("sqlalchemy.url", db_url)

# Interpret the config file for Python logging.
# This line sets up loggers basically.
if config.config_file_name is not None:
    fileConfig(config.config_file_name, disable_existing_loggers=False)

# add your model's MetaData object here
# for 'autogenerate' support
target_metadata = Base.metadata


def _run_with_connection(connection):
    """Configure context and run migrations against the given connection.

    render_as_batch=True enables batch mode for ALTER operations on SQLite
    (uses copy-table strategy). No effect on PostgreSQL.
    """
    context.configure(
        connection=connection,
        target_metadata=target_metadata,
        render_as_batch=True,
    )
    with context.begin_transaction():
        context.run_migrations()


def run_migrations_offline() -> None:
    """Run migrations in 'offline' mode.

    This configures the context with just a URL
    and not an Engine, though an Engine is acceptable
    here as well.  By skipping the Engine creation
    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        render_as_batch=True,
    )

    with context.begin_transaction():
        context.run_migrations()


def run_migrations_online() -> None:
    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine
    and associate a connection with the context.

    When called via pytest-alembic, the test fixture passes the engine
    through config.attributes["connection"] so migrations run against the
    test database (e.g. in-memory SQLite) instead of the alembic.ini URL.
    """
    connectable = config.attributes.get("connection", None)

    if connectable is not None:
        # Engine or connection provided by pytest-alembic — use the test DB
        if hasattr(connectable, "connect"):
            with connectable.connect() as connection:
                _run_with_connection(connection)
        else:
            _run_with_connection(connectable)
    else:
        # Normal CLI usage — create engine from config
        connectable = engine_from_config(
            config.get_section(config.config_ini_section, {}),
            prefix="sqlalchemy.",
            poolclass=pool.NullPool,
        )

        with connectable.connect() as connection:
            _run_with_connection(connection)


if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online()
