"""
Database Module
PostgreSQL connection and helpers using psycopg2
"""

import psycopg2
from psycopg2.extras import RealDictCursor
from psycopg2.pool import SimpleConnectionPool
from typing import Optional
import logging

from app.core.config import settings

logger = logging.getLogger(__name__)

# Connection pool
connection_pool: Optional[SimpleConnectionPool] = None


def init_db():
    """Initialize database connection pool"""
    global connection_pool
    
    try:
        connection_pool = SimpleConnectionPool(
            minconn=1,
            maxconn=10,
            dsn=settings.DATABASE_URL
        )
        logger.info("✅ Database connection pool initialized")
    except Exception as e:
        logger.error(f"❌ Failed to initialize database: {e}")
        raise


def get_db_connection():
    """Get a connection from the pool"""
    if connection_pool:
        return connection_pool.getconn()
    raise Exception("Database pool not initialized")


def release_db_connection(conn):
    """Return a connection to the pool"""
    if connection_pool:
        connection_pool.putconn(conn)


def get_db():
    """Context manager for database connections"""
    conn = get_db_connection()
    try:
        yield conn
    finally:
        release_db_connection(conn)


def execute_query(query: str, params: tuple = None, fetch: bool = True):
    """Execute a SQL query and return results"""
    conn = get_db_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cursor:
            cursor.execute(query, params)
            
            # Auto-detect write operations and commit
            query_upper = query.strip().upper()
            is_write = query_upper.startswith(('INSERT', 'UPDATE', 'DELETE'))
            
            if is_write:
                conn.commit()
            
            # Only fetch if there are results to fetch
            # (SELECT queries or INSERT/UPDATE/DELETE with RETURNING clause)
            if fetch and (not is_write or 'RETURNING' in query_upper):
                return cursor.fetchall()
            elif is_write:
                return cursor.rowcount
            return []
    except Exception as e:
        conn.rollback()
        logger.error(f"Query error: {e}")
        raise
    finally:
        release_db_connection(conn)


def execute_insert(query: str, params: tuple = None):
    """Execute INSERT query and return new ID (requires RETURNING id clause)"""
    conn = get_db_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cursor:
            cursor.execute(query, params)
            conn.commit()
            result = cursor.fetchone()
            return result['id'] if result and 'id' in result else None
    except Exception as e:
        conn.rollback()
        logger.error(f"Insert error: {e}")
        raise
    finally:
        release_db_connection(conn)


def execute_update(query: str, params: tuple = None):
    """Execute UPDATE/DELETE query and return affected rows"""
    conn = get_db_connection()
    try:
        with conn.cursor(cursor_factory=RealDictCursor) as cursor:
            cursor.execute(query, params)
            conn.commit()
            return cursor.rowcount
    except Exception as e:
        conn.rollback()
        logger.error(f"Update error: {e}")
        raise
    finally:
        release_db_connection(conn)


def execute_query_single(query: str, params: tuple = None):
    """Execute query and return single row (backwards compatibility for fetchone=True)"""
    result = execute_query(query, params)
    return result[0] if result and len(result) > 0 else None