"""
Database connection module for Python service
Uses asyncpg for async PostgreSQL connections
"""
import os
import asyncio
import asyncpg
from typing import Optional
from dotenv import load_dotenv

load_dotenv()

# Database connection pool
_pool: Optional[asyncpg.Pool] = None

# Connection timeout in seconds (reduced from default 60s to fail faster)
CONNECTION_TIMEOUT = 10


async def get_pool() -> asyncpg.Pool:
    """Get or create database connection pool with timeout"""
    global _pool
    
    if _pool is None:
        # Check for local database first
        use_local_db = os.getenv('USE_LOCAL_DB', 'false').lower() == 'true'
        
        if use_local_db:
            config = {
                'host': os.getenv('LOCAL_DB_HOST', 'localhost'),
                'port': int(os.getenv('LOCAL_DB_PORT', '5432')),
                'user': os.getenv('LOCAL_DB_USER', 'postgres'),
                'password': os.getenv('LOCAL_DB_PASSWORD', 'postgres'),
                'database': os.getenv('LOCAL_DB_NAME', 'institutional_trader')
            }
        elif os.getenv('DATABASE_URL'):
            # Parse connection string
            import urllib.parse
            url = urllib.parse.urlparse(os.getenv('DATABASE_URL'))
            config = {
                'host': url.hostname,
                'port': url.port or 5432,
                'user': url.username,
                'password': url.password,
                'database': url.path.lstrip('/')
            }
        else:
            raise ValueError(
                'No database configuration found. Set either:\n'
                '  - USE_LOCAL_DB=true with LOCAL_DB_* variables\n'
                '  - OR DATABASE_URL'
            )
        
        # Create pool with timeout to prevent hanging
        # Use min_size=1 to speed up initial connection (pool will grow as needed)
        try:
            _pool = await asyncio.wait_for(
                asyncpg.create_pool(
                    **config,
                    min_size=1,  # Start with 1 connection, pool grows as needed
                    max_size=20,
                    command_timeout=60,
                    timeout=CONNECTION_TIMEOUT  # Connection timeout per connection
                ),
                timeout=CONNECTION_TIMEOUT  # Overall timeout for pool creation
            )
        except asyncio.TimeoutError:
            raise ConnectionError(
                f'Database connection timeout after {CONNECTION_TIMEOUT}s. '
                f'Check if database is reachable at {config.get("host", "unknown")}:{config.get("port", "unknown")}'
            )
        except Exception as e:
            raise ConnectionError(
                f'Failed to create database connection pool: {str(e)}. '
                f'Check database configuration and network connectivity.'
            )
    
    return _pool


async def close_pool():
    """Close database connection pool"""
    global _pool
    if _pool:
        await _pool.close()
        _pool = None


async def query(sql: str, *args) -> list:
    """Execute a SQL query and return results"""
    pool = await get_pool()
    async with pool.acquire() as conn:
        return await conn.fetch(sql, *args)


async def query_one(sql: str, *args) -> Optional[dict]:
    """Execute a SQL query and return first result"""
    pool = await get_pool()
    async with pool.acquire() as conn:
        row = await conn.fetchrow(sql, *args)
        return dict(row) if row else None