"""Usage logging and daily statistics aggregation."""

import time
from typing import Optional

from storage.db import get_connection, generate_id


def record_usage(
    backend_id: str,
    model: str,
    prompt_tokens: int,
    completion_tokens: int,
    cost: float,
    latency_ms: int,
    ttft_ms: int = 0,
    is_error: bool = False,
) -> None:
    """Record a single request's usage, hour-bucketed with UPSERT."""
    hour_bucket = time.strftime("%Y-%m-%dT%H:00:00Z", time.gmtime())
    uid = generate_id("use")

    with get_connection() as conn:
        # Try update existing hour bucket
        cursor = conn.execute(
            """UPDATE backend_usage_logs SET
               prompt_tokens = prompt_tokens + ?,
               completion_tokens = completion_tokens + ?,
               total_tokens = total_tokens + ?,
               cost = cost + ?,
               request_count = request_count + 1,
               error_count = error_count + ?,
               avg_latency_ms = CAST((avg_latency_ms * request_count + ?) / (request_count + 1) AS INTEGER),
               ttft_ms = CASE WHEN ? > 0 THEN CAST((ttft_ms * request_count + ?) / (request_count + 1) AS INTEGER) ELSE ttft_ms END
               WHERE backend_id = ? AND hour_bucket = ?""",
            (
                prompt_tokens, completion_tokens,
                prompt_tokens + completion_tokens,
                cost,
                1 if is_error else 0,
                latency_ms,
                ttft_ms, ttft_ms,
                backend_id, hour_bucket,
            ),
        )
        if cursor.rowcount == 0:
            # Insert new hour bucket
            conn.execute(
                """INSERT INTO backend_usage_logs
                   (id, backend_id, model, prompt_tokens, completion_tokens,
                    total_tokens, cost, request_count, error_count,
                    avg_latency_ms, ttft_ms, hour_bucket)
                   VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)""",
                (
                    uid, backend_id, model,
                    prompt_tokens, completion_tokens,
                    prompt_tokens + completion_tokens,
                    cost, 1, 1 if is_error else 0,
                    latency_ms, ttft_ms, hour_bucket,
                ),
            )
        conn.commit()


def get_hourly_usage(
    backend_id: Optional[str] = None,
    since: Optional[str] = None,
    limit: int = 168,
) -> list[dict]:
    """Get hourly usage data, optionally filtered by backend and time range."""
    with get_connection() as conn:
        if backend_id and since:
            rows = conn.execute(
                """SELECT * FROM backend_usage_logs
                   WHERE backend_id = ? AND hour_bucket >= ?
                   ORDER BY hour_bucket DESC LIMIT ?""",
                (backend_id, since, limit),
            ).fetchall()
        elif backend_id:
            rows = conn.execute(
                """SELECT * FROM backend_usage_logs
                   WHERE backend_id = ? ORDER BY hour_bucket DESC LIMIT ?""",
                (backend_id, limit),
            ).fetchall()
        elif since:
            rows = conn.execute(
                """SELECT * FROM backend_usage_logs
                   WHERE hour_bucket >= ? ORDER BY hour_bucket DESC LIMIT ?""",
                (since, limit),
            ).fetchall()
        else:
            rows = conn.execute(
                """SELECT * FROM backend_usage_logs
                   ORDER BY hour_bucket DESC LIMIT ?""",
                (limit,),
            ).fetchall()
    return [dict(row) for row in rows]


def get_total_stats() -> dict:
    """Get aggregate stats across all backends."""
    with get_connection() as conn:
        row = conn.execute(
            """SELECT
               SUM(request_count) as total_requests,
               SUM(error_count) as total_errors,
               SUM(total_tokens) as total_tokens,
               SUM(prompt_tokens) as total_prompt_tokens,
               SUM(completion_tokens) as total_completion_tokens,
               SUM(cost) as total_cost
               FROM backend_usage_logs"""
        ).fetchone()
    if row is None:
        return {
            "total_requests": 0, "total_errors": 0,
            "total_tokens": 0, "total_prompt_tokens": 0,
            "total_completion_tokens": 0, "total_cost": 0.0,
        }
    return dict(row)


def aggregate_daily_stats(date: str) -> None:
    """Aggregate hourly usage into daily stats table."""
    with get_connection() as conn:
        # Aggregate per pool
        conn.execute("""DELETE FROM daily_stats WHERE date = ?""", (date,))
        conn.execute(
            """INSERT INTO daily_stats (id, date, pool, total_requests,
               total_errors, total_tokens, total_cost, unique_backends)
               SELECT
                   ? || '-' || b.pool,
                   ?,
                   b.pool,
                   SUM(u.request_count),
                   SUM(u.error_count),
                   SUM(u.total_tokens),
                   SUM(u.cost),
                   COUNT(DISTINCT u.backend_id)
               FROM backend_usage_logs u
               JOIN backends b ON u.backend_id = b.id
               WHERE u.hour_bucket LIKE ?
               GROUP BY b.pool""",
            (generate_id("day"), date, date + "%"),
        )
        conn.commit()


def get_daily_stats(days: int = 30) -> list[dict]:
    """Get daily aggregated stats."""
    with get_connection() as conn:
        rows = conn.execute(
            """SELECT * FROM daily_stats ORDER BY date DESC LIMIT ?""",
            (days,),
        ).fetchall()
    return [dict(row) for row in rows]