# -*- coding: utf-8 -*-
"""Location: ./mcpgateway/services/log_aggregator.py
Copyright 2026
SPDX-License-Identifier: Apache-2.0
Authors: Mihai Criveti

Log Aggregation Service.

This module provides aggregation of performance metrics from structured logs
into time-windowed statistics for analysis and monitoring.
"""

# Standard
from datetime import datetime, timedelta, timezone
import logging
import math
import statistics
from typing import Any, Dict, List, Optional, Tuple

# Third-Party
from sqlalchemy import and_, func, select, text
from sqlalchemy.orm import Session

# First-Party
from mcpgateway.config import settings
from mcpgateway.db import engine, PerformanceMetric, SessionLocal, StructuredLogEntry

logger = logging.getLogger(__name__)


def _is_postgresql() -> bool:
    """Check if the database backend is PostgreSQL.

    Returns:
        True if using PostgreSQL, False otherwise.
    """
    return engine.dialect.name == "postgresql"


class LogAggregator:
    """Aggregates structured logs into performance metrics."""

    def __init__(self):
        """Initialize log aggregator."""
        self.aggregation_window_minutes = getattr(settings, "metrics_aggregation_window_minutes", 5)
        self.enabled = getattr(settings, "metrics_aggregation_enabled", True)
        self._use_sql_percentiles = _is_postgresql()

    def aggregate_performance_metrics(
        self, component: Optional[str], operation_type: Optional[str], window_start: Optional[datetime] = None, window_end: Optional[datetime] = None, db: Optional[Session] = None
    ) -> Optional[PerformanceMetric]:
        """Aggregate performance metrics for a component and operation.

        Args:
            component: Component name
            operation_type: Operation name
            window_start: Start of aggregation window (defaults to N minutes ago)
            window_end: End of aggregation window (defaults to now)
            db: Optional database session

        Returns:
            Created PerformanceMetric or None if no data
        """
        if not self.enabled:
            return None
        if not component or not operation_type:
            return None

        window_start, window_end = self._resolve_window_bounds(window_start, window_end)

        should_close = False
        if db is None:
            db = SessionLocal()
            should_close = True

        try:
            # Use SQL-based aggregation for PostgreSQL, Python fallback for SQLite
            if self._use_sql_percentiles:
                stats = self._compute_stats_postgresql(db, component, operation_type, window_start, window_end)
            else:
                stats = self._compute_stats_python(db, component, operation_type, window_start, window_end)

            if stats is None:
                return None

            count = stats["count"]
            avg_duration = stats["avg_duration"]
            min_duration = stats["min_duration"]
            max_duration = stats["max_duration"]
            p50 = stats["p50"]
            p95 = stats["p95"]
            p99 = stats["p99"]
            error_count = stats["error_count"]
            error_rate = error_count / count if count > 0 else 0.0

            metric = self._upsert_metric(
                component=component,
                operation_type=operation_type,
                window_start=window_start,
                window_end=window_end,
                request_count=count,
                error_count=error_count,
                error_rate=error_rate,
                avg_duration_ms=avg_duration,
                min_duration_ms=min_duration,
                max_duration_ms=max_duration,
                p50_duration_ms=p50,
                p95_duration_ms=p95,
                p99_duration_ms=p99,
                metric_metadata={
                    "sample_size": count,
                    "generated_at": datetime.now(timezone.utc).isoformat(),
                },
                db=db,
            )

            logger.info(f"Aggregated performance metrics for {component}.{operation_type}: " f"{count} requests, {avg_duration:.2f}ms avg, {error_rate:.2%} error rate")

            if should_close:
                db.commit()  # Commit transaction on success
            return metric

        except Exception as e:
            logger.error(f"Failed to aggregate performance metrics: {e}")
            if should_close and db:
                db.rollback()
            return None

        finally:
            if should_close:
                db.close()

    def aggregate_all_components_batch(self, window_starts: List[datetime], window_minutes: int, db: Optional[Session] = None) -> List[PerformanceMetric]:
        """Aggregate metrics for all components/operations for multiple windows in a single batch.

        This reduces the number of database round-trips by fetching logs for the full
        time span once per component/operation and partitioning them into windows in
        Python, then upserting per-window metrics.

        Args:
            window_starts: List of window start datetimes (UTC)
            window_minutes: Window size in minutes
            db: Optional database session

        Returns:
            List of created/updated PerformanceMetric records

        Raises:
            Exception: If a database operation fails during aggregation.
        """
        if not self.enabled:
            return []

        if not window_starts:
            return []

        should_close = False
        if db is None:
            db = SessionLocal()
            should_close = True

        try:
            window_delta = timedelta(minutes=window_minutes)
            # Determine full range to query once
            full_start = min(window_starts)
            full_end = max(window_starts) + window_delta

            # Validate window_starts is contiguous - warn if sparse (batch generates all windows in range)
            expected_window_count = int((full_end - full_start).total_seconds() / (window_minutes * 60))
            if len(window_starts) != expected_window_count:
                logger.warning(
                    "Batch aggregation received %d windows but range spans %d; sparse windows will generate extra metrics",
                    len(window_starts),
                    expected_window_count,
                )

            # If PostgreSQL is available, use a single SQL rollup with generate_series and ordered-set aggregates
            if _is_postgresql():
                sql = text("""
                    WITH windows AS (
                      SELECT generate_series(:full_start::timestamptz, (:full_end - (:window_minutes || ' minutes')::interval)::timestamptz, (:window_minutes || ' minutes')::interval) AS window_start
                    ), pairs AS (
                      SELECT DISTINCT component, operation_type FROM structured_log_entries
                      WHERE timestamp >= :full_start AND timestamp < :full_end
                        AND duration_ms IS NOT NULL
                        AND component IS NOT NULL AND component <> ''
                        AND operation_type IS NOT NULL AND operation_type <> ''
                    )
                    SELECT
                      w.window_start,
                      p.component,
                      p.operation_type,
                      COUNT(sle.duration_ms) AS cnt,
                      AVG(sle.duration_ms) AS avg_duration,
                      MIN(sle.duration_ms) AS min_duration,
                      MAX(sle.duration_ms) AS max_duration,
                      percentile_cont(0.50) WITHIN GROUP (ORDER BY sle.duration_ms) AS p50,
                      percentile_cont(0.95) WITHIN GROUP (ORDER BY sle.duration_ms) AS p95,
                      percentile_cont(0.99) WITHIN GROUP (ORDER BY sle.duration_ms) AS p99,
                      SUM(CASE WHEN upper(sle.level) IN ('ERROR','CRITICAL') OR sle.error_details IS NOT NULL THEN 1 ELSE 0 END) AS error_count
                    FROM windows w
                    CROSS JOIN pairs p
                    JOIN structured_log_entries sle
                      ON sle.timestamp >= w.window_start AND sle.timestamp < w.window_start + (:window_minutes || ' minutes')::interval
                      AND sle.component = p.component AND sle.operation_type = p.operation_type
                      AND sle.duration_ms IS NOT NULL
                    GROUP BY w.window_start, p.component, p.operation_type
                    HAVING COUNT(sle.duration_ms) > 0
                    ORDER BY w.window_start, p.component, p.operation_type
                    """)

                rows = db.execute(
                    sql,
                    {
                        "full_start": full_start,
                        "full_end": full_end,
                        "window_minutes": str(window_minutes),
                    },
                ).fetchall()

                created_metrics: List[PerformanceMetric] = []
                for row in rows:
                    ws = row.window_start if row.window_start.tzinfo else row.window_start.replace(tzinfo=timezone.utc)
                    component = row.component
                    operation = row.operation_type
                    count = int(row.cnt)
                    avg_duration = float(row.avg_duration) if row.avg_duration is not None else 0.0
                    min_duration = float(row.min_duration) if row.min_duration is not None else 0.0
                    max_duration = float(row.max_duration) if row.max_duration is not None else 0.0
                    p50 = float(row.p50) if row.p50 is not None else 0.0
                    p95 = float(row.p95) if row.p95 is not None else 0.0
                    p99 = float(row.p99) if row.p99 is not None else 0.0
                    error_count = int(row.error_count) if row.error_count is not None else 0

                    metric = self._upsert_metric(
                        component=component,
                        operation_type=operation,
                        window_start=ws,
                        window_end=ws + window_delta,
                        request_count=count,
                        error_count=error_count,
                        error_rate=(error_count / count) if count else 0.0,
                        avg_duration_ms=avg_duration,
                        min_duration_ms=min_duration,
                        max_duration_ms=max_duration,
                        p50_duration_ms=p50,
                        p95_duration_ms=p95,
                        p99_duration_ms=p99,
                        metric_metadata={
                            "sample_size": count,
                            "generated_at": datetime.now(timezone.utc).isoformat(),
                        },
                        db=db,
                    )
                    if metric:
                        created_metrics.append(metric)

                if should_close:
                    db.commit()
                return created_metrics

            # Fallback: in-Python bucketing (previous implementation)
            # Warning: This path loads all entries into memory; for very large ranges this may spike memory usage
            range_hours = (full_end - full_start).total_seconds() / 3600
            if range_hours > 168:  # > 1 week
                logger.warning("Large aggregation range (%.1f hours) may cause high memory usage in non-PostgreSQL fallback", range_hours)

            # Get unique component/operation pairs for the full range
            pair_stmt = (
                select(StructuredLogEntry.component, StructuredLogEntry.operation_type)
                .where(
                    and_(
                        StructuredLogEntry.timestamp >= full_start,
                        StructuredLogEntry.timestamp < full_end,
                        StructuredLogEntry.duration_ms.isnot(None),
                        StructuredLogEntry.component.isnot(None),
                        StructuredLogEntry.component != "",
                        StructuredLogEntry.operation_type.isnot(None),
                        StructuredLogEntry.operation_type != "",
                    )
                )
                .distinct()
            )

            pairs = db.execute(pair_stmt).all()

            created_metrics: List[PerformanceMetric] = []

            # helper to align timestamp to window start
            def _align_to_window_local(dt: datetime, minutes: int) -> datetime:
                """Align a datetime to the start of its aggregation window.

                Args:
                    dt: The datetime to align.
                    minutes: The window size in minutes.

                Returns:
                    The datetime aligned to the start of the window.
                """
                ts = dt.astimezone(timezone.utc)
                total_minutes = int(ts.timestamp() // 60)
                aligned_minutes = (total_minutes // minutes) * minutes
                return datetime.fromtimestamp(aligned_minutes * 60, tz=timezone.utc)

            for component, operation in pairs:
                if not component or not operation:
                    continue

                # Fetch all relevant log entries for this component/operation in the full range
                entries_stmt = select(StructuredLogEntry).where(
                    and_(
                        StructuredLogEntry.component == component,
                        StructuredLogEntry.operation_type == operation,
                        StructuredLogEntry.timestamp >= full_start,
                        StructuredLogEntry.timestamp < full_end,
                        StructuredLogEntry.duration_ms.isnot(None),
                    )
                )

                entries = db.execute(entries_stmt).scalars().all()
                if not entries:
                    continue

                # Bucket entries into windows
                buckets: Dict[datetime, List[StructuredLogEntry]] = {}
                for e in entries:
                    ts = e.timestamp if e.timestamp.tzinfo else e.timestamp.replace(tzinfo=timezone.utc)
                    bucket_start = _align_to_window_local(ts, window_minutes)
                    if bucket_start not in buckets:
                        buckets[bucket_start] = []
                    buckets[bucket_start].append(e)

                # For each requested window, compute stats if we have data
                for window_start in window_starts:
                    bucket_entries = buckets.get(window_start)
                    if not bucket_entries:
                        continue

                    durations = sorted([b.duration_ms for b in bucket_entries if b.duration_ms is not None])
                    if not durations:
                        continue

                    count = len(durations)
                    avg_duration = float(sum(durations) / count) if count else 0.0
                    min_duration = float(durations[0])
                    max_duration = float(durations[-1])
                    p50 = float(self._percentile(durations, 0.5))
                    p95 = float(self._percentile(durations, 0.95))
                    p99 = float(self._percentile(durations, 0.99))
                    error_count = self._calculate_error_count(bucket_entries)

                    try:
                        metric = self._upsert_metric(
                            component=component,
                            operation_type=operation,
                            window_start=window_start,
                            window_end=window_start + window_delta,
                            request_count=count,
                            error_count=error_count,
                            error_rate=(error_count / count) if count else 0.0,
                            avg_duration_ms=avg_duration,
                            min_duration_ms=min_duration,
                            max_duration_ms=max_duration,
                            p50_duration_ms=p50,
                            p95_duration_ms=p95,
                            p99_duration_ms=p99,
                            metric_metadata={
                                "sample_size": count,
                                "generated_at": datetime.now(timezone.utc).isoformat(),
                            },
                            db=db,
                        )
                        if metric:
                            created_metrics.append(metric)
                    except Exception:
                        logger.exception("Failed to upsert metric for %s.%s window %s", component, operation, window_start)

            if should_close:
                db.commit()
            return created_metrics
        except Exception:
            if should_close:
                db.rollback()
            raise
        finally:
            if should_close:
                db.close()

    def aggregate_all_components(self, window_start: Optional[datetime] = None, window_end: Optional[datetime] = None, db: Optional[Session] = None) -> List[PerformanceMetric]:
        """Aggregate metrics for all components and operations.

        Args:
            window_start: Start of aggregation window
            window_end: End of aggregation window
            db: Optional database session

        Returns:
            List of created PerformanceMetric records

        Raises:
            Exception: If database operation fails
        """
        if not self.enabled:
            return []

        should_close = False
        if db is None:
            db = SessionLocal()
            should_close = True

        try:
            window_start, window_end = self._resolve_window_bounds(window_start, window_end)

            stmt = (
                select(StructuredLogEntry.component, StructuredLogEntry.operation_type)
                .where(
                    and_(
                        StructuredLogEntry.timestamp >= window_start,
                        StructuredLogEntry.timestamp < window_end,
                        StructuredLogEntry.duration_ms.isnot(None),
                        StructuredLogEntry.operation_type.isnot(None),
                    )
                )
                .distinct()
            )

            pairs = db.execute(stmt).all()

            metrics = []
            for component, operation in pairs:
                if component and operation:
                    metric = self.aggregate_performance_metrics(component=component, operation_type=operation, window_start=window_start, window_end=window_end, db=db)
                    if metric:
                        metrics.append(metric)

            if should_close:
                db.commit()  # Commit on success
            return metrics

        except Exception:
            if should_close:
                db.rollback()
            raise

        finally:
            if should_close:
                db.close()

    def get_recent_metrics(self, component: Optional[str] = None, operation: Optional[str] = None, hours: int = 24, db: Optional[Session] = None) -> List[PerformanceMetric]:
        """Get recent performance metrics.

        Args:
            component: Optional component filter
            operation: Optional operation filter
            hours: Hours of history to retrieve
            db: Optional database session

        Returns:
            List of PerformanceMetric records

        Raises:
            Exception: If database operation fails
        """
        should_close = False
        if db is None:
            db = SessionLocal()
            should_close = True

        try:
            since = datetime.now(timezone.utc) - timedelta(hours=hours)

            stmt = select(PerformanceMetric).where(PerformanceMetric.window_start >= since)

            if component:
                stmt = stmt.where(PerformanceMetric.component == component)
            if operation:
                stmt = stmt.where(PerformanceMetric.operation_type == operation)

            stmt = stmt.order_by(PerformanceMetric.window_start.desc())

            result = db.execute(stmt).scalars().all()
            if should_close:
                db.commit()  # Commit on success
            return result

        except Exception:
            if should_close:
                db.rollback()
            raise

        finally:
            if should_close:
                db.close()

    def get_degradation_alerts(self, threshold_multiplier: float = 1.5, hours: int = 24, db: Optional[Session] = None) -> List[Dict[str, Any]]:
        """Identify performance degradations by comparing recent vs baseline.

        Args:
            threshold_multiplier: Alert if recent is X times slower than baseline
            hours: Hours of recent data to check
            db: Optional database session

        Returns:
            List of degradation alerts with details

        Raises:
            Exception: If database operation fails
        """
        should_close = False
        if db is None:
            db = SessionLocal()
            should_close = True

        try:
            recent_cutoff = datetime.now(timezone.utc) - timedelta(hours=hours)
            baseline_cutoff = recent_cutoff - timedelta(hours=hours * 2)

            # Get unique component/operation pairs
            stmt = select(PerformanceMetric.component, PerformanceMetric.operation_type).distinct()

            pairs = db.execute(stmt).all()

            alerts = []
            for component, operation in pairs:
                # Get recent metrics
                recent_stmt = select(PerformanceMetric).where(
                    and_(PerformanceMetric.component == component, PerformanceMetric.operation_type == operation, PerformanceMetric.window_start >= recent_cutoff)
                )
                recent_metrics = db.execute(recent_stmt).scalars().all()

                # Get baseline metrics
                baseline_stmt = select(PerformanceMetric).where(
                    and_(
                        PerformanceMetric.component == component,
                        PerformanceMetric.operation_type == operation,
                        PerformanceMetric.window_start >= baseline_cutoff,
                        PerformanceMetric.window_start < recent_cutoff,
                    )
                )
                baseline_metrics = db.execute(baseline_stmt).scalars().all()

                if not recent_metrics or not baseline_metrics:
                    continue

                recent_avg = statistics.mean([m.avg_duration_ms for m in recent_metrics])
                baseline_avg = statistics.mean([m.avg_duration_ms for m in baseline_metrics])

                if recent_avg > baseline_avg * threshold_multiplier:
                    alerts.append(
                        {
                            "component": component,
                            "operation": operation,
                            "recent_avg_ms": recent_avg,
                            "baseline_avg_ms": baseline_avg,
                            "degradation_ratio": recent_avg / baseline_avg,
                            "recent_error_rate": statistics.mean([m.error_rate for m in recent_metrics]),
                            "baseline_error_rate": statistics.mean([m.error_rate for m in baseline_metrics]),
                        }
                    )

            if should_close:
                db.commit()  # Commit on success
            return alerts

        except Exception:
            if should_close:
                db.rollback()
            raise

        finally:
            if should_close:
                db.close()

    def backfill(self, hours: float, db: Optional[Session] = None) -> int:
        """Backfill metrics for a historical time range.

        Args:
            hours: Number of hours of history to aggregate (supports fractional hours)
            db: Optional shared database session

        Returns:
            Count of performance metric windows processed

        Raises:
            Exception: If database operation fails
        """
        if not self.enabled or hours <= 0:
            return 0

        window_minutes = self.aggregation_window_minutes
        window_delta = timedelta(minutes=window_minutes)
        total_windows = max(1, math.ceil((hours * 60) / window_minutes))

        should_close = False
        if db is None:
            db = SessionLocal()
            should_close = True

        try:
            _, latest_end = self._resolve_window_bounds(None, None)
            current_start = latest_end - (window_delta * total_windows)
            processed = 0

            while current_start < latest_end:
                current_end = current_start + window_delta
                created = self.aggregate_all_components(
                    window_start=current_start,
                    window_end=current_end,
                    db=db,
                )
                if created:
                    processed += 1
                current_start = current_end

            if should_close:
                db.commit()  # Commit on success
            return processed

        except Exception:
            if should_close:
                db.rollback()
            raise

        finally:
            if should_close:
                db.close()

    @staticmethod
    def _percentile(sorted_values: List[float], percentile: float) -> float:
        """Calculate percentile from sorted values.

        Args:
            sorted_values: Sorted list of values
            percentile: Percentile to calculate (0.0 to 1.0)

        Returns:
            float: Calculated percentile value
        """
        if not sorted_values:
            return 0.0

        if len(sorted_values) == 1:
            return float(sorted_values[0])

        k = (len(sorted_values) - 1) * percentile
        f = math.floor(k)
        c = math.ceil(k)

        if f == c:
            return float(sorted_values[int(k)])

        d0 = sorted_values[f] * (c - k)
        d1 = sorted_values[c] * (k - f)
        return float(d0 + d1)

    @staticmethod
    def _calculate_error_count(entries: List[StructuredLogEntry]) -> int:
        """Calculate error occurrences for a batch of log entries.

        Args:
            entries: List of log entries to analyze

        Returns:
            int: Count of error entries
        """
        error_levels = {"ERROR", "CRITICAL"}
        return sum(1 for entry in entries if (entry.level and entry.level.upper() in error_levels) or entry.error_details)

    def _compute_stats_postgresql(
        self,
        db: Session,
        component: str,
        operation_type: str,
        window_start: datetime,
        window_end: datetime,
    ) -> Optional[Dict[str, Any]]:
        """Compute aggregation statistics using PostgreSQL SQL functions.

        Uses PostgreSQL's percentile_cont for efficient in-database percentile
        computation, avoiding loading all rows into Python memory.

        Args:
            db: Database session
            component: Component name to filter by
            operation_type: Operation type to filter by
            window_start: Start of the aggregation window
            window_end: End of the aggregation window

        Returns:
            Dictionary with count, avg_duration, min_duration, max_duration,
            p50, p95, p99, and error_count, or None if no data.
        """
        # Build base filter conditions
        base_conditions = and_(
            StructuredLogEntry.component == component,
            StructuredLogEntry.operation_type == operation_type,
            StructuredLogEntry.timestamp >= window_start,
            StructuredLogEntry.timestamp < window_end,
            StructuredLogEntry.duration_ms.isnot(None),
        )

        # First, check if there are any rows and get error count
        # (error count requires examining level/error_details which can't be done purely in SQL aggregate)
        count_stmt = select(func.count()).select_from(StructuredLogEntry).where(base_conditions)  # pylint: disable=not-callable
        count_result = db.execute(count_stmt).scalar()

        if not count_result or count_result == 0:
            return None

        # PostgreSQL percentile_cont query using ordered-set aggregate functions
        # This computes all statistics in a single query
        stats_sql = text("""
            SELECT
                COUNT(duration_ms) as cnt,
                AVG(duration_ms) as avg_duration,
                MIN(duration_ms) as min_duration,
                MAX(duration_ms) as max_duration,
                percentile_cont(0.50) WITHIN GROUP (ORDER BY duration_ms) as p50,
                percentile_cont(0.95) WITHIN GROUP (ORDER BY duration_ms) as p95,
                percentile_cont(0.99) WITHIN GROUP (ORDER BY duration_ms) as p99
            FROM structured_log_entries
            WHERE component = :component
              AND operation_type = :operation_type
              AND timestamp >= :window_start
              AND timestamp < :window_end
              AND duration_ms IS NOT NULL
            """)

        result = db.execute(
            stats_sql,
            {
                "component": component,
                "operation_type": operation_type,
                "window_start": window_start,
                "window_end": window_end,
            },
        ).fetchone()

        if not result or result.cnt == 0:
            return None

        # Get error count separately (requires level/error_details examination)
        error_stmt = (
            select(func.count())  # pylint: disable=not-callable
            .select_from(StructuredLogEntry)
            .where(
                and_(
                    base_conditions,
                    ((func.upper(StructuredLogEntry.level).in_(["ERROR", "CRITICAL"])) | (StructuredLogEntry.error_details.isnot(None))),
                )
            )
        )
        error_count = db.execute(error_stmt).scalar() or 0

        return {
            "count": result.cnt,
            "avg_duration": float(result.avg_duration) if result.avg_duration else 0.0,
            "min_duration": float(result.min_duration) if result.min_duration else 0.0,
            "max_duration": float(result.max_duration) if result.max_duration else 0.0,
            "p50": float(result.p50) if result.p50 else 0.0,
            "p95": float(result.p95) if result.p95 else 0.0,
            "p99": float(result.p99) if result.p99 else 0.0,
            "error_count": error_count,
        }

    def _compute_stats_python(
        self,
        db: Session,
        component: str,
        operation_type: str,
        window_start: datetime,
        window_end: datetime,
    ) -> Optional[Dict[str, Any]]:
        """Compute aggregation statistics using Python (fallback for SQLite).

        Loads duration values into memory and computes statistics in Python.
        Used when database doesn't support native percentile functions.

        Args:
            db: Database session
            component: Component name to filter by
            operation_type: Operation type to filter by
            window_start: Start of the aggregation window
            window_end: End of the aggregation window

        Returns:
            Dictionary with count, avg_duration, min_duration, max_duration,
            p50, p95, p99, and error_count, or None if no data.
        """
        # Query structured logs for this component/operation in time window
        stmt = select(StructuredLogEntry).where(
            and_(
                StructuredLogEntry.component == component,
                StructuredLogEntry.operation_type == operation_type,
                StructuredLogEntry.timestamp >= window_start,
                StructuredLogEntry.timestamp < window_end,
                StructuredLogEntry.duration_ms.isnot(None),
            )
        )

        results = db.execute(stmt).scalars().all()

        if not results:
            return None

        # Extract durations
        durations = sorted(r.duration_ms for r in results if r.duration_ms is not None)

        if not durations:
            return None

        # Calculate statistics
        count = len(durations)
        avg_duration = statistics.fmean(durations) if hasattr(statistics, "fmean") else statistics.mean(durations)
        min_duration = durations[0]
        max_duration = durations[-1]

        # Calculate percentiles
        p50 = self._percentile(durations, 0.50)
        p95 = self._percentile(durations, 0.95)
        p99 = self._percentile(durations, 0.99)

        # Count errors
        error_count = self._calculate_error_count(results)

        return {
            "count": count,
            "avg_duration": avg_duration,
            "min_duration": min_duration,
            "max_duration": max_duration,
            "p50": p50,
            "p95": p95,
            "p99": p99,
            "error_count": error_count,
        }

    def _resolve_window_bounds(
        self,
        window_start: Optional[datetime],
        window_end: Optional[datetime],
    ) -> Tuple[datetime, datetime]:
        """Resolve and normalize aggregation window bounds.

        Args:
            window_start: Start of window or None to calculate
            window_end: End of window or None for current time

        Returns:
            Tuple[datetime, datetime]: Resolved window start and end
        """
        window_delta = timedelta(minutes=self.aggregation_window_minutes)

        if window_start is not None and window_end is not None:
            resolved_start = window_start.astimezone(timezone.utc)
            resolved_end = window_end.astimezone(timezone.utc)
            if resolved_end <= resolved_start:
                resolved_end = resolved_start + window_delta
            return resolved_start, resolved_end

        if window_end is None:
            reference = datetime.now(timezone.utc)
        else:
            reference = window_end.astimezone(timezone.utc)

        reference = reference.replace(second=0, microsecond=0)
        minutes_offset = reference.minute % self.aggregation_window_minutes
        if window_end is None and minutes_offset:
            reference = reference - timedelta(minutes=minutes_offset)

        resolved_end = reference

        if window_start is None:
            resolved_start = resolved_end - window_delta
        else:
            resolved_start = window_start.astimezone(timezone.utc)

        if resolved_end <= resolved_start:
            resolved_start = resolved_end - window_delta

        return resolved_start, resolved_end

    def _upsert_metric(
        self,
        component: str,
        operation_type: str,
        window_start: datetime,
        window_end: datetime,
        request_count: int,
        error_count: int,
        error_rate: float,
        avg_duration_ms: float,
        min_duration_ms: float,
        max_duration_ms: float,
        p50_duration_ms: float,
        p95_duration_ms: float,
        p99_duration_ms: float,
        metric_metadata: Optional[Dict[str, Any]],
        db: Session,
    ) -> PerformanceMetric:
        """Create or update a performance metric window.

        Args:
            component: Component name
            operation_type: Operation type
            window_start: Window start time
            window_end: Window end time
            request_count: Total request count
            error_count: Total error count
            error_rate: Error rate (0.0-1.0)
            avg_duration_ms: Average duration in milliseconds
            min_duration_ms: Minimum duration in milliseconds
            max_duration_ms: Maximum duration in milliseconds
            p50_duration_ms: 50th percentile duration
            p95_duration_ms: 95th percentile duration
            p99_duration_ms: 99th percentile duration
            metric_metadata: Additional metadata
            db: Database session

        Returns:
            PerformanceMetric: Created or updated metric
        """

        existing_stmt = select(PerformanceMetric).where(
            and_(
                PerformanceMetric.component == component,
                PerformanceMetric.operation_type == operation_type,
                PerformanceMetric.window_start == window_start,
                PerformanceMetric.window_end == window_end,
            )
        )

        existing_metrics = db.execute(existing_stmt).scalars().all()
        metric = existing_metrics[0] if existing_metrics else None

        if len(existing_metrics) > 1:
            logger.warning(
                "Found %s duplicate performance metric rows for %s.%s window %s-%s; pruning extras",
                len(existing_metrics),
                component,
                operation_type,
                window_start.isoformat(),
                window_end.isoformat(),
            )
            for duplicate in existing_metrics[1:]:
                db.delete(duplicate)

        if metric is None:
            metric = PerformanceMetric(
                component=component,
                operation_type=operation_type,
                window_start=window_start,
                window_end=window_end,
                window_duration_seconds=int((window_end - window_start).total_seconds()),
            )
            db.add(metric)

        metric.request_count = request_count
        metric.error_count = error_count
        metric.error_rate = error_rate
        metric.avg_duration_ms = avg_duration_ms
        metric.min_duration_ms = min_duration_ms
        metric.max_duration_ms = max_duration_ms
        metric.p50_duration_ms = p50_duration_ms
        metric.p95_duration_ms = p95_duration_ms
        metric.p99_duration_ms = p99_duration_ms
        metric.metric_metadata = metric_metadata

        db.commit()
        db.refresh(metric)
        return metric


# Global log aggregator instance
_log_aggregator: Optional[LogAggregator] = None


def get_log_aggregator() -> LogAggregator:
    """Get or create the global log aggregator instance.

    Returns:
        Global LogAggregator instance
    """
    global _log_aggregator  # pylint: disable=global-statement
    if _log_aggregator is None:
        _log_aggregator = LogAggregator()
    return _log_aggregator
