import sqlite3
import contextlib
from typing import Generator
from app import config

def get_db_connection() -> sqlite3.Connection:
    conn = sqlite3.connect(
        config.DB_PATH,
        timeout=15.0
    )
    conn.row_factory = sqlite3.Row
    conn.execute("PRAGMA journal_mode=WAL;")
    conn.execute("PRAGMA synchronous=NORMAL;")
    conn.execute("PRAGMA foreign_keys=ON;")
    return conn

@contextlib.contextmanager
def get_db() -> Generator[sqlite3.Connection, None, None]:
    conn = get_db_connection()
    try:
        yield conn
        conn.commit()
    except Exception:
        conn.rollback()
        raise
    finally:
        conn.close()

def init_db():
    config.DB_PATH.parent.mkdir(parents=True, exist_ok=True)
    with get_db() as conn:
        conn.executescript("""
        CREATE TABLE IF NOT EXISTS users (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            username TEXT UNIQUE NOT NULL COLLATE NOCASE,
            password_hash TEXT NOT NULL,
            salt TEXT NOT NULL,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        );

        CREATE TABLE IF NOT EXISTS sessions (
            token TEXT PRIMARY KEY,
            user_id INTEGER NOT NULL,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
            expires_at TIMESTAMP NOT NULL,
            user_agent TEXT,
            ip TEXT,
            FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
        );

        CREATE TABLE IF NOT EXISTS vocabulary_cards (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            user_id INTEGER NOT NULL,
            term TEXT NOT NULL,
            translation TEXT NOT NULL,
            context_sentence TEXT,
            phonetic TEXT,
            audio_url TEXT,
            part_of_speech TEXT,
            definition_en TEXT,
            tags TEXT,
            notes TEXT,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
            updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
            FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
        );

        CREATE INDEX IF NOT EXISTS idx_vocab_user ON vocabulary_cards(user_id);
        CREATE INDEX IF NOT EXISTS idx_vocab_term ON vocabulary_cards(term);
        CREATE INDEX IF NOT EXISTS idx_vocab_created ON vocabulary_cards(created_at DESC);

        CREATE TABLE IF NOT EXISTS dictionary_cache (
            query TEXT PRIMARY KEY COLLATE NOCASE,
            response_json TEXT NOT NULL,
            cached_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        );
        """)