"""Postgres connection pool + small query helpers for the yaris-obd remote server."""
import os
from contextlib import contextmanager

from psycopg_pool import ConnectionPool

_POOL = None


def _dsn():
    return (
        f"host={os.environ.get('POSTGRES_HOST', 'db')} "
        f"port={os.environ.get('POSTGRES_PORT', '5432')} "
        f"dbname={os.environ.get('POSTGRES_DB', 'yarisobd')} "
        f"user={os.environ.get('POSTGRES_USER', 'yarisobd')} "
        f"password={os.environ.get('POSTGRES_PASSWORD', '')}"
    )


def get_pool():
    global _POOL
    if _POOL is None:
        _POOL = ConnectionPool(conninfo=_dsn(), min_size=1, max_size=5, open=True)
    return _POOL


@contextmanager
def get_cursor(commit=False):
    """Yield a cursor from the pool, optionally committing on clean exit."""
    pool = get_pool()
    with pool.connection() as conn:
        with conn.cursor() as cur:
            yield cur
            if commit:
                conn.commit()


def get_device_by_name(name):
    with get_cursor() as cur:
        cur.execute(
            "SELECT id, name, api_key_hash FROM devices WHERE name = %s",
            (name,),
        )
        row = cur.fetchone()
        if row is None:
            return None
        return {"id": row[0], "name": row[1], "api_key_hash": row[2]}


def touch_device_last_seen(device_id):
    with get_cursor(commit=True) as cur:
        cur.execute(
            "UPDATE devices SET last_seen_at = now() WHERE id = %s",
            (device_id,),
        )


def insert_tracking_points(device_id, points):
    """Bulk-insert tracking points, skipping any that already exist
    (device_id, recorded_at) so a client can safely re-send a batch after a
    partial-failure retry without creating duplicates."""
    if not points:
        return 0
    with get_cursor(commit=True) as cur:
        cur.executemany(
            """
            INSERT INTO tracking_points
                (device_id, vehicle_name, driver_name, recorded_at, gps_lat, gps_lon, speed, odometer)
            VALUES (%(device_id)s, %(vehicle_name)s, %(driver_name)s, %(recorded_at)s,
                    %(gps_lat)s, %(gps_lon)s, %(speed)s, %(odometer)s)
            ON CONFLICT (device_id, recorded_at) DO NOTHING
            """,
            [
                {
                    "device_id": device_id,
                    "vehicle_name": p.get("vehicle_name"),
                    "driver_name": p.get("driver_name"),
                    "recorded_at": p["recorded_at"],
                    "gps_lat": p.get("gps_lat"),
                    "gps_lon": p.get("gps_lon"),
                    "speed": p.get("speed"),
                    "odometer": p.get("odometer"),
                }
                for p in points
            ],
        )
    return len(points)


def dashcam_file_exists(device_id, relative_path, sha256):
    with get_cursor() as cur:
        cur.execute(
            "SELECT 1 FROM dashcam_files WHERE device_id = %s AND relative_path = %s AND sha256 = %s",
            (device_id, relative_path, sha256),
        )
        return cur.fetchone() is not None


def insert_dashcam_file(device_id, relative_path, size_bytes, sha256, storage_path):
    with get_cursor(commit=True) as cur:
        cur.execute(
            """
            INSERT INTO dashcam_files (device_id, relative_path, size_bytes, sha256, storage_path)
            VALUES (%s, %s, %s, %s, %s)
            ON CONFLICT (device_id, relative_path, sha256) DO NOTHING
            """,
            (device_id, relative_path, size_bytes, sha256, storage_path),
        )