"""
PostgreSQL database connection and session management for SCM microservice.
Following TMS pattern with SQLAlchemy async engine.
"""
import logging
import ssl
from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession
from sqlalchemy.orm import sessionmaker
from sqlalchemy import MetaData, text

from app.core.config import settings

logger = logging.getLogger(__name__)

# Database URL validation
DATABASE_URI = settings.POSTGRES_URI
if not DATABASE_URI:
    logger.error("POSTGRES_URI is empty or missing from settings")
    raise ValueError("POSTGRES_URI is not set. Check environment variables.")

# Parse and log connection details (with masked password)
def mask_connection_string(uri: str) -> str:
    """Mask password in connection string for safe logging"""
    if not uri:
        return "EMPTY"
    
    try:
        # Format: postgresql+asyncpg://user:password@host:port/database
        if "@" in uri:
            protocol_user_pass, host_db = uri.split("@", 1)
            
            if "://" in protocol_user_pass:
                protocol, user_pass = protocol_user_pass.split("://", 1)
                
                if ":" in user_pass:
                    user, _ = user_pass.split(":", 1)
                    masked_uri = f"{protocol}://{user}:***@{host_db}"
                else:
                    masked_uri = f"{protocol}://{user_pass}:***@{host_db}"
            else:
                masked_uri = f"{protocol_user_pass}:***@{host_db}"
        else:
            masked_uri = uri
        
        return masked_uri
    except Exception:
        return "INVALID_FORMAT"

def parse_connection_details(uri: str) -> dict:
    """Parse connection string to extract host, port, database"""
    try:
        # Extract host:port/database from URI
        if "@" in uri:
            _, host_db = uri.split("@", 1)
            
            if "/" in host_db:
                host_port, database = host_db.split("/", 1)
                
                if ":" in host_port:
                    host, port = host_port.split(":", 1)
                else:
                    host = host_port
                    port = "5432"
                
                return {
                    "host": host,
                    "port": port,
                    "database": database.split("?")[0]  # Remove query params
                }
    except Exception:
        pass
    
    return {"host": "unknown", "port": "unknown", "database": "unknown"}

masked_uri = mask_connection_string(DATABASE_URI)
conn_details = parse_connection_details(DATABASE_URI)

logger.info(
    "PostgreSQL connection configured",
    extra={
        "connection_string": masked_uri,
        "host": conn_details["host"],
        "port": conn_details["port"],
        "database": conn_details["database"],
        "ssl_mode": settings.POSTGRES_SSL_MODE
    }
)

# Build connect args including optional SSL
CONNECT_ARGS = {
    "server_settings": {
        "application_name": "cuatrolabs-scm-ms",
        "jit": "off"
    },
    "command_timeout": 60,
    "statement_cache_size": 0
}

mode = (settings.POSTGRES_SSL_MODE or "disable").lower()
if mode != "disable":
    ssl_context: ssl.SSLContext
    if mode == "verify-full":
        ssl_context = ssl.create_default_context(cafile=settings.POSTGRES_SSL_ROOT_CERT) if settings.POSTGRES_SSL_ROOT_CERT else ssl.create_default_context()
        if settings.POSTGRES_SSL_CERT and settings.POSTGRES_SSL_KEY:
            try:
                ssl_context.load_cert_chain(certfile=settings.POSTGRES_SSL_CERT, keyfile=settings.POSTGRES_SSL_KEY)
            except Exception as e:
                logger.warning("Failed to load client SSL cert/key for PostgreSQL", exc_info=e)
        ssl_context.check_hostname = True
        ssl_context.verify_mode = ssl.CERT_REQUIRED
    else:
        # sslmode=require: encrypt but don't verify server cert
        ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
        ssl_context.check_hostname = False
        ssl_context.verify_mode = ssl.CERT_NONE
    CONNECT_ARGS["ssl"] = ssl_context
    logger.info("PostgreSQL SSL enabled", extra={"ssl_mode": settings.POSTGRES_SSL_MODE})

# Create async engine with connection pool settings
async_engine = create_async_engine(
    DATABASE_URI,
    echo=settings.DEBUG,  # Enable SQL logging in debug mode
    future=True,
    pool_size=10,
    max_overflow=20,
    pool_timeout=30,
    pool_recycle=3600,
    pool_pre_ping=True,
    connect_args=CONNECT_ARGS
)

# Create async session factory
async_session = sessionmaker(
    async_engine, 
    expire_on_commit=False, 
    class_=AsyncSession
)

# Metadata for table creation
metadata = MetaData()

logger.info("PostgreSQL configuration loaded successfully")

# ────────────────────────────────────────────────────────────────────────────────
# Lifecycle helpers
# ────────────────────────────────────────────────────────────────────────────────

async def connect_to_database() -> None:
    """Initialize database connection when the application starts."""
    import asyncio
    
    # Log connection details at startup (once per worker)
    print(f"\n{'='*70}")
    print(f"[POSTGRES] Starting Database Connection")
    print(f"{'='*70}")
    print(f"[POSTGRES] Connection String: {masked_uri}")
    print(f"[POSTGRES] Host: {conn_details['host']}")
    print(f"[POSTGRES] Port: {conn_details['port']}")
    print(f"[POSTGRES] Database: {conn_details['database']}")
    print(f"[POSTGRES] SSL Mode: {settings.POSTGRES_SSL_MODE}")
    print(f"{'='*70}\n")
    
    # Log connection attempt start
    logger.info(
        "Starting PostgreSQL connection attempts",
        extra={
            "max_retries": settings.POSTGRES_CONNECT_MAX_RETRIES,
            "initial_delay_ms": settings.POSTGRES_CONNECT_INITIAL_DELAY_MS,
            "backoff_multiplier": settings.POSTGRES_CONNECT_BACKOFF_MULTIPLIER
        }
    )
    print(f"[POSTGRES] Attempting to connect (max retries: {settings.POSTGRES_CONNECT_MAX_RETRIES})...")
    
    attempts = 0
    max_attempts = settings.POSTGRES_CONNECT_MAX_RETRIES
    delay = settings.POSTGRES_CONNECT_INITIAL_DELAY_MS / 1000.0
    last_error = None
    
    while attempts < max_attempts:
        try:
            async with async_engine.begin() as conn:
                await conn.execute(text("SELECT 1"))
            
            logger.info("Successfully connected to PostgreSQL database")
            print(f"[POSTGRES] ✅ Connection successful after {attempts + 1} attempt(s)")
            return
            
        except Exception as e:
            last_error = e
            attempts += 1
            
            error_msg = str(e)
            error_type = type(e).__name__
            
            logger.warning(
                "PostgreSQL connection attempt failed",
                extra={
                    "attempt": attempts,
                    "max_attempts": max_attempts,
                    "retry_delay_ms": int(delay * 1000),
                    "error_type": error_type,
                    "error_message": error_msg[:200]  # Truncate long errors
                }
            )
            
            print(f"[POSTGRES] ❌ Connection attempt {attempts}/{max_attempts} failed")
            print(f"[POSTGRES] Error: {error_type}: {error_msg[:150]}")
            
            if attempts < max_attempts:
                print(f"[POSTGRES] Retrying in {delay:.2f}s...")
                await asyncio.sleep(delay)
                delay = min(delay * settings.POSTGRES_CONNECT_BACKOFF_MULTIPLIER, 30.0)
    
    # All attempts failed
    logger.error(
        "Failed to connect to PostgreSQL after all retries",
        extra={
            "total_attempts": attempts,
            "final_error_type": type(last_error).__name__,
            "final_error": str(last_error)[:500]
        },
        exc_info=last_error
    )
    
    print(f"[POSTGRES] ❌ FATAL: Failed to connect after {attempts} attempts")
    print(f"[POSTGRES] Last error: {type(last_error).__name__}: {str(last_error)[:200]}")
    print(f"[POSTGRES] Please check:")
    print(f"[POSTGRES]   1. Database host is reachable: {conn_details['host']}")
    print(f"[POSTGRES]   2. Database credentials are correct")
    print(f"[POSTGRES]   3. SSL mode is appropriate: {settings.POSTGRES_SSL_MODE}")
    print(f"[POSTGRES]   4. Firewall allows connections to port {conn_details['port']}")
    
    raise last_error

async def disconnect_from_database() -> None:
    """Close database connection when the application shuts down."""
    try:
        await async_engine.dispose()
        logger.info("Successfully disconnected from PostgreSQL database")
    except Exception as e:
        logger.exception("Error disconnecting from PostgreSQL database")
        raise

async def enforce_trans_schema() -> None:
    """Enforce that all tables use the TRANS schema and validate schema compliance."""
    try:
        async with async_engine.begin() as conn:
            # Ensure trans schema exists
            await conn.execute(text("CREATE SCHEMA IF NOT EXISTS trans"))
            logger.info("✅ TRANS schema exists")
            
            # Validate that all models use trans schema
            from app.core.database import Base
            
            # Import all models to ensure they're registered with Base
            from app.catalogues.models.model import CatalogueRef
            from app.inventory.stock.models.model import ScmStock, ScmStockLedger, ScmStockAdjustment
            from app.purchases.orders.models.model import ScmPo, ScmPoItem, ScmPoStatusLog
            from app.purchases.receipts.models.model import ScmGrn, ScmGrnItem, ScmGrnIssue
            from app.trade_sales.models.model import ScmTradeShipment, ScmTradeShipmentItem
            from app.trade_relationships.models.model import ScmTradeRelationship
            
            # Validate schema compliance
            non_trans_tables = []
            for table in Base.metadata.tables.values():
                if table.schema != 'trans':
                    non_trans_tables.append(f"{table.name} (schema: {table.schema})")
            
            if non_trans_tables:
                error_msg = f"❌ SCHEMA VIOLATION: The following tables are not using 'trans' schema: {', '.join(non_trans_tables)}"
                logger.error(error_msg)
                print(f"\n{'='*80}")
                print(f"[SCHEMA ERROR] {error_msg}")
                print(f"{'='*80}\n")
                raise ValueError(error_msg)
            
            logger.info("✅ All SCM tables correctly use 'trans' schema")
            print(f"[SCHEMA] ✅ All SCM tables correctly use 'trans' schema")
            
    except Exception as e:
        logger.exception("Error enforcing TRANS schema")
        raise

async def create_tables() -> None:
    """Create all tables defined in models after enforcing schema compliance."""
    try:
        # First enforce schema compliance
        await enforce_trans_schema()
        
        from app.core.database import Base
        
        async with async_engine.begin() as conn:
            # Create all tables (schema already validated)
            await conn.run_sync(Base.metadata.create_all)
        logger.info("✅ Database tables created successfully in TRANS schema")
        print(f"[SCHEMA] ✅ Database tables created successfully in TRANS schema")
    except Exception as e:
        logger.exception("Error creating database tables")
        raise
 
try:
    from app.postgres import (
        connect_to_postgres as _connect_to_postgres,
        close_postgres_connection as _close_postgres_connection,
        get_postgres_connection as _get_postgres_connection,
        release_postgres_connection as _release_postgres_connection,
        is_postgres_connected as _is_postgres_connected,
    )

    async def connect_to_postgres() -> None:
        await _connect_to_postgres()

    async def close_postgres_connection() -> None:
        await _close_postgres_connection()

    async def get_postgres_connection():
        return await _get_postgres_connection()

    async def release_postgres_connection(conn) -> None:
        await _release_postgres_connection(conn)

    def is_postgres_connected() -> bool:
        return _is_postgres_connected()
except Exception:
    pass