"""
Database module for PostgreSQL integration (Neon/Vercel Postgres).

This module provides a clean abstraction layer for database operations,
supporting both in-memory storage (for development/testing) and PostgreSQL
via Neon (for production).

Environment Variables:
    DATABASE_URL or POSTGRES_URL: PostgreSQL connection string
    TESTING: Set to "true" to force in-memory database

Usage:
    from database import db
    
    # Create user
    user = await db.create_user(email, password_hash, full_name)
    
    # Get user
    user = await db.get_user_by_email(email)
"""
import os
import sys
from datetime import datetime, timezone
from typing import Optional
from abc import ABC, abstractmethod
from urllib.parse import urlparse, parse_qs
import asyncio
import threading
import asyncio
import threading
import time
import logging

# Configure logger
logger = logging.getLogger(__name__)

# pg8000 for PostgreSQL - pure Python, lightweight
# Wrap in try/except for safer imports
PG8000_AVAILABLE = False
pg8000 = None
try:
    import pg8000
    import pg8000.native
    PG8000_AVAILABLE = True
    PG8000_AVAILABLE = True
except ImportError as e:
    logger.warning(f"pg8000 not available: {e}")
except Exception as e:
    logger.error(f"Error loading pg8000: {e}")


# ============= Abstract Database Interface =============

class DatabaseInterface(ABC):
    """Abstract interface for database operations"""
    
    @abstractmethod
    async def init_tables(self) -> None:
        """Initialize database tables"""
        pass
    
    # User operations
    @abstractmethod
    async def create_user(self, email: str, password_hash: str, full_name: str, 
                         is_admin: bool = False, totp_secret: Optional[str] = None) -> dict:
        pass
    
    @abstractmethod
    async def get_user_by_email(self, email: str) -> Optional[dict]:
        pass
    
    @abstractmethod
    async def get_user_by_id(self, user_id: int) -> Optional[dict]:
        pass
    
    @abstractmethod
    async def update_user_last_login(self, email: str) -> None:
        pass
    
    @abstractmethod
    async def delete_user(self, user_id: int) -> bool:
        pass
    
    @abstractmethod
    async def list_users(self) -> list[dict]:
        pass
    
    # Hotel operations
    @abstractmethod
    @abstractmethod
    async def create_hotel(self, name: str, owner_id: int, booking_url: Optional[str] = None,
                          website_url: Optional[str] = None) -> dict:
        pass
    
    @abstractmethod
    async def get_hotels(self, owner_id: Optional[int] = None) -> list[dict]:
        pass
    
    @abstractmethod
    async def get_hotel(self, hotel_id: int) -> Optional[dict]:
        pass
    
    @abstractmethod
    async def delete_hotel(self, hotel_id: int, owner_id: Optional[int] = None) -> bool:
        pass


# ============= In-Memory Database (Development/Testing) =============

class InMemoryDatabase(DatabaseInterface):
    """In-memory database for development and testing"""
    
    def __init__(self):
        self._users: dict[str, dict] = {}
        self._hotels: list[dict] = []
        self._user_id_counter = 0
        self._hotel_id_counter = 0
    
    async def init_tables(self) -> None:
        """No-op for in-memory database"""
        pass
    
    async def create_user(self, email: str, password_hash: str, full_name: str,
                         is_admin: bool = False, totp_secret: Optional[str] = None) -> dict:
        self._user_id_counter += 1
        user = {
            "id": self._user_id_counter,
            "email": email,
            "password_hash": password_hash,
            "full_name": full_name,
            "is_admin": is_admin,
            "totp_secret": totp_secret,
            "created_at": datetime.now(timezone.utc).isoformat(),
            "last_login": None
        }
        self._users[email] = user
        return user
    
    async def get_user_by_email(self, email: str) -> Optional[dict]:
        return self._users.get(email)
    
    async def get_user_by_id(self, user_id: int) -> Optional[dict]:
        for user in self._users.values():
            if user["id"] == user_id:
                return user
        return None
    
    async def update_user_last_login(self, email: str) -> None:
        if email in self._users:
            self._users[email]["last_login"] = datetime.now(timezone.utc).isoformat()
    
    async def delete_user(self, user_id: int) -> bool:
        for email, user in list(self._users.items()):
            if user["id"] == user_id:
                del self._users[email]
                return True
        return False
    
    async def list_users(self) -> list[dict]:
        return list(self._users.values())
    
    async def create_hotel(self, name: str, owner_id: int, booking_url: Optional[str] = None,
                          website_url: Optional[str] = None) -> dict:
        self._hotel_id_counter += 1
        hotel = {
            "id": self._hotel_id_counter,
            "name": name,
            "owner_id": owner_id,
            "booking_url": booking_url,
            "website_url": website_url,
            "created_at": datetime.now(timezone.utc).isoformat()
        }
        self._hotels.append(hotel)
        return hotel
    
    async def get_hotels(self, owner_id: Optional[int] = None) -> list[dict]:
        if owner_id:
            return [h for h in self._hotels if h.get("owner_id") == owner_id or h.get("owner_id") is None]
        return self._hotels
    
    async def get_hotel(self, hotel_id: int) -> Optional[dict]:
        for hotel in self._hotels:
            if hotel["id"] == hotel_id:
                return hotel
        return None
    
    async def delete_hotel(self, hotel_id: int, owner_id: Optional[int] = None) -> bool:
        for i, hotel in enumerate(self._hotels):
            if hotel["id"] == hotel_id:
                if owner_id and hotel.get("owner_id") != owner_id:
                    return False
                self._hotels.pop(i)
                return True
        return False
    
    def seed_admin_users(self, admin_configs: list[dict]) -> None:
        """Seed admin users for development"""
        for config in admin_configs:
            self._user_id_counter += 1
            self._users[config["email"]] = {
                "id": self._user_id_counter,
                "email": config["email"],
                "password_hash": config["password_hash"],
                "full_name": config["full_name"],
                "is_admin": True,
                "totp_secret": config.get("totp_secret"),
                "created_at": datetime.now(timezone.utc).isoformat(),
                "last_login": None
            }
    
    def seed_regular_users(self, user_configs: list[dict]) -> None:
        """Seed regular (non-admin) users for development"""
        for config in user_configs:
            self._user_id_counter += 1
            self._users[config["email"]] = {
                "id": self._user_id_counter,
                "email": config["email"],
                "password_hash": config["password_hash"],
                "full_name": config["full_name"],
                "is_admin": False,  # Regular users are NOT admins
                "totp_secret": config.get("totp_secret"),
                "created_at": datetime.now(timezone.utc).isoformat(),
                "last_login": None
            }
    
    def seed_demo_hotels(self, hotels: list[dict]) -> None:
        """Seed demo hotels for development"""
        for hotel in hotels:
            self._hotel_id_counter += 1
            self._hotels.append({
                "id": self._hotel_id_counter,
                "name": hotel["name"],
                "owner_id": None, # Publicly visible demo hotel
                "booking_url": hotel.get("booking_url"),
                "website_url": hotel.get("website_url"),
                "created_at": datetime.now(timezone.utc).isoformat()
            })


# ============= PostgreSQL Database (Production - Neon/Vercel) =============

class PostgresDatabase(DatabaseInterface):
    """PostgreSQL database using pg8000 (pure Python, works with Neon, Vercel Postgres, etc.)"""
    
    def __init__(self, connection_url: str):
        """
        Initialize with a PostgreSQL connection URL.
        
        Format: postgresql://user:password@host:port/database?sslmode=require
        """
        self.connection_url = connection_url
        self._conn = None
        self._parse_connection_url()
    
    def _parse_connection_url(self):
        """Parse the connection URL into components"""
        from urllib.parse import unquote
        parsed = urlparse(self.connection_url)
        self._host = parsed.hostname or 'localhost'
        self._port = parsed.port or 5432
        self._user = unquote(parsed.username or 'postgres')
        self._password = unquote(parsed.password or '')
        self._database = parsed.path.lstrip('/').split('?')[0] or 'postgres'
        
        # Parse query params for SSL
        query_params = parse_qs(parsed.query)
        self._ssl = 'sslmode' in query_params and query_params['sslmode'][0] != 'disable'
        # Neon and Vercel always require SSL
        if 'neon' in (self._host or '') or 'vercel' in (self._host or ''):
            self._ssl = True
    
    def _get_connection(self):
        """Get or create database connection"""
        # Ensure we have a lock
        if not hasattr(self, '_lock'):
            self._lock = threading.Lock()
            
        if self._conn is None:
            try:
                ssl_context = None
                if self._ssl:
                    import ssl
                    ssl_context = ssl.create_default_context()
                
                # pg8000.connect is the correct API
                self._conn = pg8000.connect(
                    host=self._host,
                    port=self._port,
                    user=self._user,
                    password=self._password,
                    database=self._database,
                    ssl_context=ssl_context
                )
                self._conn.autocommit = True
            except Exception as e:
                logger.error(f"Failed to connect to database: {e}")
                raise
        return self._conn
    
    def _run_query_in_thread(self, query: str, params: Optional[tuple] = None) -> list[dict]:
        """Run query in a separate thread with locking and retry logic"""
        if not hasattr(self, '_lock'):
             self._lock = threading.Lock()
             
        with self._lock:
            # Simple retry mechanism for lost connections
            max_retries = 2
            for attempt in range(max_retries):
                try:
                    conn = self._get_connection()
                    cursor = conn.cursor()
                    try:
                        # pg8000 uses %s style parameters just like psycopg2
                        if params is not None:
                            cursor.execute(query, params)
                        else:
                            cursor.execute(query)
                        
                        # Check if this is a SELECT-like query that returns rows
                        try:
                            if cursor.description and len(cursor.description) > 0:
                                columns = [desc[0] for desc in cursor.description]
                                rows = cursor.fetchall()
                                return [dict(zip(columns, row)) for row in rows]
                        except (TypeError, AttributeError):
                            # DDL statements don't return rows
                            pass
                        return []
                    finally:
                        cursor.close()
                except (pg8000.InterfaceError, pg8000.DatabaseError, AttributeError) as e:
                    # Connection might be dead, close and retry
                    logger.warning(f"Database error (attempt {attempt+1}/{max_retries}): {e}")
                    if self._conn:
                        try:
                            self._conn.close()
                        except:
                            pass
                        self._conn = None
                    
                    if attempt == max_retries - 1:
                        raise e
                    # Wait a bit before retry
                    time.sleep(0.5)
            # Should not be reached due to raise above
            return []

    async def _execute_query(self, query: str, params: Optional[tuple] = None) -> list[dict]:
        """Execute a SQL query asynchronously using a thread pool"""
        loop = asyncio.get_running_loop()
        return await loop.run_in_executor(None, self._run_query_in_thread, query, params)
    
    async def init_tables(self) -> None:
        """Initialize database tables"""
        # Users table
        await self._execute_query("""
            CREATE TABLE IF NOT EXISTS users (
                id SERIAL PRIMARY KEY,
                email VARCHAR(255) UNIQUE NOT NULL,
                password_hash VARCHAR(512) NOT NULL,
                full_name VARCHAR(255) NOT NULL,
                is_admin BOOLEAN DEFAULT FALSE,
                totp_secret VARCHAR(64),
                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
                last_login TIMESTAMP
            )
        """)
        
        # Hotels table
        await self._execute_query("""
            CREATE TABLE IF NOT EXISTS hotels (
                id SERIAL PRIMARY KEY,
                name VARCHAR(255) NOT NULL,
                booking_url TEXT,
                website_url TEXT,
                owner_id INTEGER REFERENCES users(id) ON DELETE CASCADE,
                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
            )
        """)
        # Add owner_id column if it doesn't exist (for migration)
        await self._execute_query("""
            ALTER TABLE hotels ADD COLUMN IF NOT EXISTS owner_id INTEGER REFERENCES users(id) ON DELETE CASCADE
        """)
        
        # Price comparisons table (for history)
        await self._execute_query("""
            CREATE TABLE IF NOT EXISTS price_comparisons (
                id SERIAL PRIMARY KEY,
                user_id INTEGER REFERENCES users(id) ON DELETE CASCADE,
                hotel_ids INTEGER[] NOT NULL,
                check_in DATE NOT NULL,
                check_out DATE NOT NULL,
                occupancy VARCHAR(50),
                results JSONB,
                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
            )
        """)
        
        # Create index for faster email lookups
        await self._execute_query("""
            CREATE INDEX IF NOT EXISTS idx_users_email ON users(email)
        """)
    
    async def create_user(self, email: str, password_hash: str, full_name: str,
                         is_admin: bool = False, totp_secret: Optional[str] = None) -> dict:
        rows = await self._execute_query(
            """
            INSERT INTO users (email, password_hash, full_name, is_admin, totp_secret)
            VALUES (%s, %s, %s, %s, %s)
            RETURNING id, email, password_hash, full_name, is_admin, totp_secret, 
                      created_at::text, last_login::text
            """,
            (email, password_hash, full_name, is_admin, totp_secret)
        )
        return rows[0] if rows else {}
    
    async def get_user_by_email(self, email: str) -> Optional[dict]:
        rows = await self._execute_query(
            """SELECT id, email, password_hash, full_name, is_admin, totp_secret,
                      created_at::text, last_login::text 
               FROM users WHERE email = %s""",
            (email,)
        )
        return rows[0] if rows else None
    
    async def get_user_by_id(self, user_id: int) -> Optional[dict]:
        rows = await self._execute_query(
            """SELECT id, email, password_hash, full_name, is_admin, totp_secret,
                      created_at::text, last_login::text 
               FROM users WHERE id = %s""",
            (user_id,)
        )
        return rows[0] if rows else None
    
    async def update_user_last_login(self, email: str) -> None:
        await self._execute_query(
            "UPDATE users SET last_login = CURRENT_TIMESTAMP WHERE email = %s",
            (email,)
        )
    
    async def delete_user(self, user_id: int) -> bool:
        rows = await self._execute_query(
            "DELETE FROM users WHERE id = %s RETURNING id",
            (user_id,)
        )
        return len(rows) > 0
    
    async def list_users(self) -> list[dict]:
        return await self._execute_query(
            """SELECT id, email, password_hash, full_name, is_admin, totp_secret,
                      created_at::text, last_login::text 
               FROM users ORDER BY created_at DESC"""
        )
    
    async def create_hotel(self, name: str, owner_id: int, booking_url: Optional[str] = None,
                          website_url: Optional[str] = None) -> dict:
        rows = await self._execute_query(
            """
            INSERT INTO hotels (name, owner_id, booking_url, website_url)
            VALUES (%s, %s, %s, %s)
            RETURNING id, name, owner_id, booking_url, website_url, created_at::text
            """,
            (name, owner_id, booking_url, website_url)
        )
        return rows[0] if rows else {}
    
    async def get_hotels(self, owner_id: Optional[int] = None) -> list[dict]:
        if owner_id:
            return await self._execute_query(
                """SELECT id, name, owner_id, booking_url, website_url, created_at::text 
                   FROM hotels WHERE owner_id = %s OR owner_id IS NULL ORDER BY name""",
                (owner_id,)
            )
        return await self._execute_query(
            "SELECT id, name, owner_id, booking_url, website_url, created_at::text FROM hotels ORDER BY name"
        )
    
    async def get_hotel(self, hotel_id: int) -> Optional[dict]:
        """Get a single hotel by ID"""
        rows = await self._execute_query(
            """SELECT id, name, owner_id, booking_url, website_url, created_at::text 
               FROM hotels WHERE id = %s""",
            (hotel_id,)
        )
        return rows[0] if rows else None

    async def delete_hotel(self, hotel_id: int, owner_id: Optional[int] = None) -> bool:
        """Delete hotel, optionally verifying ownership"""
        if owner_id:
            rows = await self._execute_query(
                "DELETE FROM hotels WHERE id = %s AND owner_id = %s RETURNING id",
                (hotel_id, owner_id)
            )
        else:
            rows = await self._execute_query(
                "DELETE FROM hotels WHERE id = %s RETURNING id",
                (hotel_id,)
            )
        return len(rows) > 0
        rows = await self._execute_query(
            "DELETE FROM hotels WHERE id = %s RETURNING id",
            (hotel_id,)
        )
        return len(rows) > 0
    
    def close(self):
        """Close database connection"""
        if self._conn:
            self._conn.close()
            self._conn = None


# ============= Database Factory =============

def create_database() -> DatabaseInterface:
    """
    Create the appropriate database instance based on environment.
    
    Environment variables checked (in order):
    - DATABASE_URL: Standard PostgreSQL connection string
    - POSTGRES_URL: Vercel/Neon Postgres connection string
    
    Returns InMemoryDatabase for development/testing.
    Returns PostgresDatabase when a connection URL is configured.
    """
    # Check for database URL (multiple common env var names)
    postgres_url = (
        os.environ.get("DATABASE_URL") or 
        os.environ.get("POSTGRES_URL") or
        os.environ.get("POSTGRES_URL_NON_POOLING") or
        ""
    )
    testing = os.environ.get("TESTING", "false").lower() == "true"
    
    # Use in-memory database for testing or when no database URL is configured
    if testing or not postgres_url:
        return InMemoryDatabase()
    
    # Check if pg8000 is available
    if not PG8000_AVAILABLE:
        logger.warning("pg8000 not available, falling back to in-memory database")
        return InMemoryDatabase()
    
    return PostgresDatabase(postgres_url)


# Singleton database instance
db: DatabaseInterface = create_database()