"""Image-generation timing statistics (moving-average estimate)."""

from __future__ import annotations

import logging

from vibe_bot.db.connection import connect

logger = logging.getLogger(__name__)

# Moving-average window (most recent generations) for the time estimate.
IMAGE_GEN_TIME_WINDOW = 10
# Maximum number of generation times retained in the database.
IMAGE_GEN_TIME_LIMIT = 100


def record_image_generation_time(db_path: str, duration_seconds: float) -> bool:
    """Record how long an image generation took.

    Args:
        duration_seconds: Wall-clock seconds the generation took.

    """
    logger.debug("Recording image generation time: %.2fs", duration_seconds)
    conn = connect(db_path)
    cursor = conn.cursor()

    try:
        cursor.execute(
            """
            INSERT INTO image_generation_times (duration_seconds)
            VALUES (?)
        """,
            (duration_seconds,),
        )

        # Cap the table so it doesn't grow unbounded.
        cursor.execute(
            """
            DELETE FROM image_generation_times
            WHERE id NOT IN (
                SELECT id FROM image_generation_times
                ORDER BY id DESC
                LIMIT ?
            )
        """,
            (IMAGE_GEN_TIME_LIMIT,),
        )

        conn.commit()
    except Exception:
        logger.exception("Error recording image generation time")
        conn.rollback()
        return False
    else:
        return True
    finally:
        conn.close()


def get_image_generation_time_estimate(db_path: str) -> float | None:
    """Get a moving-average estimate of image generation time.

    Returns:
        The average duration in seconds over the most recent generations,
        or None if there is no generation history yet.

    """
    logger.debug("Computing moving-average image generation time estimate")
    conn = connect(db_path)
    cursor = conn.cursor()

    try:
        cursor.execute(
            """
            SELECT AVG(duration_seconds)
            FROM (
                SELECT duration_seconds
                FROM image_generation_times
                ORDER BY id DESC
                LIMIT ?
            )
        """,
            (IMAGE_GEN_TIME_WINDOW,),
        )
        row = cursor.fetchone()
    except Exception:
        logger.exception("Error reading image generation times")
        return None
    finally:
        conn.close()

    if row is None or row[0] is None:
        return None
    return float(row[0])