"""
Database configuration and session management
"""
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
from sqlalchemy.orm import declarative_base
from sqlalchemy import event
import logging
import os
from pathlib import Path

from app.config import settings

logger = logging.getLogger(__name__)

# Create database directory if it doesn't exist
db_path = Path(settings.database_url.replace("sqlite+aiosqlite:///", ""))
db_path.parent.mkdir(parents=True, exist_ok=True)

# Create async engine
engine = create_async_engine(
    settings.database_url,
    echo=False,  # Set to True for SQL debugging
    pool_size=settings.performance.db_pool_size,
    pool_recycle=settings.performance.db_pool_recycle,
    connect_args={
        "check_same_thread": False,  # SQLite specific
        "timeout": 30
    } if "sqlite" in settings.database_url else {}
)

# Create async session factory
AsyncSessionLocal = async_sessionmaker(
    engine,
    class_=AsyncSession,
    expire_on_commit=False
)

# Base class for models
Base = declarative_base()

async def get_db() -> AsyncSession:
    """Dependency to get database session"""
    async with AsyncSessionLocal() as session:
        try:
            yield session
        finally:
            await session.close()

async def init_db():
    """Initialize database, create tables if they don't exist"""
    async with engine.begin() as conn:
        # Import all models to register them with Base
        from app.models import Photo, Folder, SourceRoot, Tag, PhotoTag, Heap, HeapPhoto, Embedding
        
        # Create all tables
        await conn.run_sync(Base.metadata.create_all)
        
        # Enable WAL mode for SQLite (better concurrency)
        if "sqlite" in settings.database_url:
            await conn.execute("PRAGMA journal_mode=WAL")
            await conn.execute("PRAGMA synchronous=NORMAL")
            await conn.execute("PRAGMA cache_size=10000")
            await conn.execute("PRAGMA temp_store=MEMORY")
        
        logger.info("Database initialized successfully")

async def create_fts_table():
    """Create Full-Text Search table for SQLite"""
    if "sqlite" in settings.database_url:
        async with engine.begin() as conn:
            # Create FTS5 virtual table for full-text search
            await conn.execute("""
                CREATE VIRTUAL TABLE IF NOT EXISTS photos_fts USING fts5(
                    photo_id UNINDEXED,
                    filename,
                    user_title,
                    user_notes,
                    exif_text,
                    tokenize='unicode61'
                )
            """)
            logger.info("FTS5 table created successfully")