import aiosqlite
import asyncio
import json
import logging
from datetime import datetime, timedelta, timezone
from config import settings

logger = logging.getLogger("mqtt.database")

_db: aiosqlite.Connection | None = None

SCHEMA_STATEMENTS = [
    """CREATE TABLE IF NOT EXISTS device_logs (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        device_serial TEXT NOT NULL,
        level TEXT NOT NULL,
        message TEXT NOT NULL,
        device_timestamp INTEGER,
        received_at TEXT NOT NULL DEFAULT (datetime('now'))
    )""",
    """CREATE TABLE IF NOT EXISTS heartbeats (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        device_serial TEXT NOT NULL,
        device_id TEXT,
        firmware_version TEXT,
        ip_address TEXT,
        gateway TEXT,
        uptime_ms INTEGER,
        uptime_display TEXT,
        received_at TEXT NOT NULL DEFAULT (datetime('now'))
    )""",
    """CREATE TABLE IF NOT EXISTS commands (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        device_serial TEXT NOT NULL,
        command_name TEXT NOT NULL,
        command_payload TEXT,
        status TEXT NOT NULL DEFAULT 'pending',
        response_payload TEXT,
        sent_at TEXT NOT NULL DEFAULT (datetime('now')),
        responded_at TEXT
    )""",
    "CREATE INDEX IF NOT EXISTS idx_logs_serial_time ON device_logs(device_serial, received_at)",
    "CREATE INDEX IF NOT EXISTS idx_logs_level ON device_logs(level)",
    "CREATE INDEX IF NOT EXISTS idx_heartbeats_serial_time ON heartbeats(device_serial, received_at)",
    "CREATE INDEX IF NOT EXISTS idx_commands_serial_time ON commands(device_serial, sent_at)",
    "CREATE INDEX IF NOT EXISTS idx_commands_status ON commands(status)",
    # Melody drafts table
    """CREATE TABLE IF NOT EXISTS melody_drafts (
        id TEXT PRIMARY KEY,
        status TEXT NOT NULL DEFAULT 'draft',
        data TEXT NOT NULL,
        created_at TEXT NOT NULL DEFAULT (datetime('now')),
        updated_at TEXT NOT NULL DEFAULT (datetime('now'))
    )""",
    "CREATE INDEX IF NOT EXISTS idx_melody_drafts_status ON melody_drafts(status)",
]


async def init_db():
    global _db
    _db = await aiosqlite.connect(settings.sqlite_db_path)
    _db.row_factory = aiosqlite.Row
    for stmt in SCHEMA_STATEMENTS:
        await _db.execute(stmt)
    await _db.commit()
    logger.info(f"SQLite database initialized at {settings.sqlite_db_path}")


async def close_db():
    global _db
    if _db:
        await _db.close()
        _db = None


async def get_db() -> aiosqlite.Connection:
    if _db is None:
        await init_db()
    return _db


# --- Insert Operations ---

async def insert_log(device_serial: str, level: str, message: str,
                     device_timestamp: int | None = None):
    db = await get_db()
    cursor = await db.execute(
        "INSERT INTO device_logs (device_serial, level, message, device_timestamp) VALUES (?, ?, ?, ?)",
        (device_serial, level, message, device_timestamp)
    )
    await db.commit()
    return cursor.lastrowid


async def insert_heartbeat(device_serial: str, device_id: str,
                           firmware_version: str, ip_address: str,
                           gateway: str, uptime_ms: int, uptime_display: str):
    db = await get_db()
    cursor = await db.execute(
        """INSERT INTO heartbeats
           (device_serial, device_id, firmware_version, ip_address, gateway, uptime_ms, uptime_display)
           VALUES (?, ?, ?, ?, ?, ?, ?)""",
        (device_serial, device_id, firmware_version, ip_address, gateway, uptime_ms, uptime_display)
    )
    await db.commit()
    return cursor.lastrowid


async def insert_command(device_serial: str, command_name: str,
                         command_payload: dict) -> int:
    db = await get_db()
    cursor = await db.execute(
        "INSERT INTO commands (device_serial, command_name, command_payload) VALUES (?, ?, ?)",
        (device_serial, command_name, json.dumps(command_payload))
    )
    await db.commit()
    return cursor.lastrowid


async def update_command_response(command_id: int, status: str,
                                  response_payload: dict | None = None):
    db = await get_db()
    await db.execute(
        """UPDATE commands SET status = ?, response_payload = ?,
           responded_at = datetime('now') WHERE id = ?""",
        (status, json.dumps(response_payload) if response_payload else None, command_id)
    )
    await db.commit()


# --- Query Operations ---

async def get_logs(device_serial: str, level: str | None = None,
                   search: str | None = None,
                   limit: int = 100, offset: int = 0) -> tuple[list, int]:
    db = await get_db()
    where_clauses = ["device_serial = ?"]
    params: list = [device_serial]

    if level:
        where_clauses.append("level = ?")
        params.append(level)
    if search:
        where_clauses.append("message LIKE ?")
        params.append(f"%{search}%")

    where = " AND ".join(where_clauses)

    count_row = await db.execute_fetchall(
        f"SELECT COUNT(*) as cnt FROM device_logs WHERE {where}", params
    )
    total = count_row[0][0]

    rows = await db.execute_fetchall(
        f"SELECT * FROM device_logs WHERE {where} ORDER BY received_at DESC LIMIT ? OFFSET ?",
        params + [limit, offset]
    )
    return [dict(r) for r in rows], total


async def get_heartbeats(device_serial: str, limit: int = 100,
                         offset: int = 0) -> tuple[list, int]:
    db = await get_db()
    count_row = await db.execute_fetchall(
        "SELECT COUNT(*) FROM heartbeats WHERE device_serial = ?", (device_serial,)
    )
    total = count_row[0][0]
    rows = await db.execute_fetchall(
        "SELECT * FROM heartbeats WHERE device_serial = ? ORDER BY received_at DESC LIMIT ? OFFSET ?",
        (device_serial, limit, offset)
    )
    return [dict(r) for r in rows], total


async def get_commands(device_serial: str, limit: int = 100,
                       offset: int = 0) -> tuple[list, int]:
    db = await get_db()
    count_row = await db.execute_fetchall(
        "SELECT COUNT(*) FROM commands WHERE device_serial = ?", (device_serial,)
    )
    total = count_row[0][0]
    rows = await db.execute_fetchall(
        "SELECT * FROM commands WHERE device_serial = ? ORDER BY sent_at DESC LIMIT ? OFFSET ?",
        (device_serial, limit, offset)
    )
    return [dict(r) for r in rows], total


async def get_latest_heartbeats() -> list:
    db = await get_db()
    rows = await db.execute_fetchall("""
        SELECT h.* FROM heartbeats h
        INNER JOIN (
            SELECT device_serial, MAX(received_at) as max_time
            FROM heartbeats GROUP BY device_serial
        ) latest ON h.device_serial = latest.device_serial
        AND h.received_at = latest.max_time
    """)
    return [dict(r) for r in rows]


async def get_pending_command(device_serial: str) -> dict | None:
    db = await get_db()
    rows = await db.execute_fetchall(
        """SELECT * FROM commands WHERE device_serial = ? AND status = 'pending'
           ORDER BY sent_at DESC LIMIT 1""",
        (device_serial,)
    )
    return dict(rows[0]) if rows else None


# --- Cleanup ---

async def purge_old_data(retention_days: int | None = None):
    days = retention_days or settings.mqtt_data_retention_days
    cutoff = (datetime.now(timezone.utc) - timedelta(days=days)).isoformat()
    db = await get_db()
    await db.execute("DELETE FROM device_logs WHERE received_at < ?", (cutoff,))
    await db.execute("DELETE FROM heartbeats WHERE received_at < ?", (cutoff,))
    await db.execute("DELETE FROM commands WHERE sent_at < ?", (cutoff,))
    await db.commit()
    logger.info(f"Purged MQTT data older than {days} days")


async def purge_loop():
    while True:
        await asyncio.sleep(86400)
        try:
            await purge_old_data()
        except Exception as e:
            logger.error(f"Purge failed: {e}")