import os
import sqlite3
import logging
from typing import List, Tuple, Optional

logger = logging.getLogger(__name__)

DB_FOLDER = "db"
os.makedirs(DB_FOLDER, exist_ok=True)
DB_PATH = os.path.join(DB_FOLDER, "data.db")

_conn: Optional[sqlite3.Connection] = None


def get_db_connection() -> Optional[sqlite3.Connection]:
    global _conn
    if _conn:
        return _conn
    try:
        conn = sqlite3.connect(DB_PATH, check_same_thread=False, timeout=20)
        conn.row_factory = sqlite3.Row
        _conn = conn
        return conn
    except sqlite3.Error as e:
        logger.error("Database connection error: %s", e)
        return None


def init_db() -> None:
    conn = get_db_connection()
    if not conn:
        raise RuntimeError("Could not obtain database connection")
    try:
        cur = conn.cursor()
        cur.execute("PRAGMA journal_mode=WAL")
        cur.execute("""
        CREATE TABLE IF NOT EXISTS history (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            user_id TEXT NOT NULL,
            text TEXT NOT NULL,
            sentiment TEXT NOT NULL,
            confidence REAL NOT NULL,
            timestamp DATETIME DEFAULT CURRENT_TIMESTAMP
        )
        """)
        cur.execute("CREATE INDEX IF NOT EXISTS idx_user_id ON history(user_id)")
        cur.execute("CREATE INDEX IF NOT EXISTS idx_timestamp ON history(timestamp)")
        conn.commit()
        logger.info("Database initialized")
    except sqlite3.Error as e:
        logger.exception("Database initialization error: %s", e)
        raise


def save_message(user_id: str, text: str, sentiment: str, confidence: float) -> bool:
    conn = get_db_connection()
    if not conn:
        return False
    try:
        cur = conn.cursor()
        cur.execute(
            "INSERT INTO history (user_id, text, sentiment, confidence) VALUES (?, ?, ?, ?)",
            (user_id, text, sentiment, confidence),
        )
        conn.commit()
        return True
    except sqlite3.Error as e:
        logger.exception("Error saving message: %s", e)
        try:
            conn.rollback()
        except Exception:
            pass
        return False


def get_recent(user_id: str, limit: int = 10) -> List[Tuple]:
    conn = get_db_connection()
    if not conn:
        return []
    try:
        cur = conn.cursor()
        cur.execute("""
        SELECT text, sentiment, confidence, timestamp
        FROM history
        WHERE user_id = ?
        ORDER BY timestamp DESC
        LIMIT ?
        """, (user_id, limit))
        rows = cur.fetchall()
        return [tuple(r) for r in rows]
    except sqlite3.Error as e:
        logger.exception("Error fetching recent messages: %s", e)
        return []