from webapi.config.site_settings import site_settings
from beanie import init_beanie
from motor.motor_asyncio import AsyncIOMotorClient, AsyncIOMotorDatabase
from backend.models.models import MessageTemplateDoc, EmailSenderDoc, EmailSendStatusDoc, EmailTrackingDoc, EmailBounceDoc, UsageLogDoc
from common.config.app_settings import app_settings
from common.log.module_logger import ModuleLogger
import asyncio
from collections import OrderedDict
from typing import Optional, Union
import os


# Global variables for database management
MAIN_CLIENT: Optional[AsyncIOMotorClient] = None
TENANT_CACHE: Optional['TenantDBCache'] = None

# Define document models 
document_models = [
    MessageTemplateDoc,
    EmailSenderDoc,
    EmailSendStatusDoc,
    EmailTrackingDoc,
    EmailBounceDoc,
    UsageLogDoc
]
tenant_document_models = [
    MessageTemplateDoc,
    EmailSenderDoc,
    EmailSendStatusDoc
]

class TenantDBCache:
    """
    Enhanced tenant database cache that includes Beanie initialization.
    product_id -> (AsyncIOMotorClient, AsyncIOMotorDatabase, beanie_initialized: bool)
    Uses main_db.tenant_doc to resolve mongodb_uri; caches clients/dbs with LRU and Beanie state.
    """
    
    def __init__(self, main_db: AsyncIOMotorDatabase, max_size: int = 64):
        self.main_db = main_db
        self.max_size = max_size
        self._cache: "OrderedDict[str, tuple[AsyncIOMotorClient, AsyncIOMotorDatabase, bool]]" = OrderedDict()
        self._locks: dict[str, asyncio.Lock] = {}
        self._global_lock = asyncio.Lock()
        self.module_logger = ModuleLogger(sender_id="TenantDBCache")

    async def get_initialized_db(self, product_id: str) -> AsyncIOMotorDatabase:
        """Get tenant database with Beanie already initialized"""
        await self.module_logger.log_info(f"🔍 Starting database retrieval for product_id: {product_id}")
        
        # fast-path
        cached = self._cache.get(product_id)
        if cached:
            client, db, beanie_initialized = cached
            await self.module_logger.log_info(f"📦 Found cached database for {product_id}, beanie_initialized: {beanie_initialized}")
            self._cache.move_to_end(product_id)
            
            if beanie_initialized:
                await self.module_logger.log_info(f"✅ Returning cached database with Beanie already initialized for {product_id}")
                return db
            else:
                # Initialize Beanie if not done yet
                await self.module_logger.log_info(f"🔧 Initializing Beanie for cached database {product_id}")
                await init_beanie(database=db, document_models=tenant_document_models)
                await self.module_logger.log_info(f"✅ Beanie initialization completed for {product_id}")
                
                # Update cache with beanie_initialized = True
                self._cache[product_id] = (client, db, True)
                return db

        # double-checked under per-tenant lock
        await self.module_logger.log_info(f"🔒 Acquiring lock for product_id: {product_id}")
        lock = self._locks.setdefault(product_id, asyncio.Lock())
        async with lock:
            await self.module_logger.log_info(f"🔓 Lock acquired for product_id: {product_id}")
            
            cached = self._cache.get(product_id)
            if cached:
                client, db, beanie_initialized = cached
                await self.module_logger.log_info(f"📦 Double-check found cached database for {product_id}, beanie_initialized: {beanie_initialized}")
                self._cache.move_to_end(product_id)
                
                if beanie_initialized:
                    await self.module_logger.log_info(f"✅ Returning cached database with Beanie already initialized for {product_id}")
                    return db
                else:
                    # Initialize Beanie if not done yet
                    await self.module_logger.log_info(f"🔧 Initializing Beanie for cached database {product_id} (double-check)")
                    await init_beanie(database=db, document_models=tenant_document_models)
                    await self.module_logger.log_info(f"✅ Beanie initialization completed for {product_id} (double-check)")
                    
                    # Update cache with beanie_initialized = True
                    self._cache[product_id] = (client, db, True)
                    return db

            # Create new tenant connection - use raw MongoDB query since we don't have TenantDoc model
            await self.module_logger.log_info(f"🔍 Creating new tenant connection for product_id: {product_id}")
            tenant = await self.main_db["tenant_doc"].find_one({"product_id": product_id})
            if not tenant:
                await self.module_logger.log_error(f"❌ Tenant {product_id} does not exist in main database")
                raise ValueError(f"Tenant {product_id} does not exist")
            if tenant.get("status") != "active":
                await self.module_logger.log_error(f"❌ Tenant {product_id} is not active, status: {tenant.get('status')}")
                raise ValueError(f"Tenant {product_id} is not active")

            uri = tenant["mongodb_uri"]
            await self.module_logger.log_info(f"🔗 Creating Motor client for tenant {product_id} with URI: {uri[:20]}...")
            client = AsyncIOMotorClient(uri, minPoolSize=3, maxPoolSize=20, serverSelectionTimeoutMS=10000)

            # robust db name resolution (get_default_database handles mongodb+srv and empty paths)
            default_db = client.get_default_database()
            if default_db is not None:
                db = default_db
                await self.module_logger.log_info(f"📊 Using default database for tenant {product_id}: {db.name}")
            else:
                # fallback: if no default, just use 'admin' or a convention; or raise
                # Here we default to 'admin' to avoid surprises. Customize as needed.
                db = client["admin"]
                await self.module_logger.log_info(f"📊 Using fallback database 'admin' for tenant {product_id}")

            # Initialize Beanie for this tenant database
            await self.module_logger.log_info(f"🔧 Initializing Beanie for new tenant database {product_id}")
            await init_beanie(database=db, document_models=tenant_document_models)
            await self.module_logger.log_info(f"✅ Beanie initialization completed for new tenant database {product_id}")

            # LRU put with beanie_initialized = True
            await self._lru_put(product_id, (client, db, True))
            await self.module_logger.log_info(f"💾 Tenant database {product_id} cached successfully with Beanie initialized")
            return db

    async def get_main_db_initialized(self) -> AsyncIOMotorDatabase:
        """Get main database with Beanie initialized for tenant models"""
        await self.module_logger.log_info("🔧 Initializing Beanie for main database with business models")
        # Re-initialize Beanie for main database with business models
        await init_beanie(database=self.main_db, document_models=document_models)
        await self.module_logger.log_info("✅ Beanie initialization completed for main database")
        return self.main_db

    async def get_db(self, product_id: str) -> AsyncIOMotorDatabase:
        """Legacy method for compatibility - just returns database without Beanie initialization"""
        cached = self._cache.get(product_id)
        if cached:
            self._cache.move_to_end(product_id)
            return cached[1]

        # Use get_initialized_db and return the database part
        db = await self.get_initialized_db(product_id)
        return db

    async def _lru_put(self, key: str, value: tuple[AsyncIOMotorClient, AsyncIOMotorDatabase, bool]):
        async with self._global_lock:
            await self.module_logger.log_info(f"📝 Adding {key} to cache, current cache size: {len(self._cache)}")
            self._cache[key] = value
            self._cache.move_to_end(key)
            if len(self._cache) > self.max_size:
                old_key, (old_client, _, _) = self._cache.popitem(last=False)
                await self.module_logger.log_info(f"🗑️ Cache full, removing LRU tenant: {old_key}")
                try:
                    old_client.close()
                    await self.module_logger.log_info(f"🔌 Closed connection for evicted tenant: {old_key}")
                except Exception as e:
                    await self.module_logger.log_error(f"❌ Error closing connection for {old_key}: {str(e)}")
                self._locks.pop(old_key, None)

    async def aclose(self):
        async with self._global_lock:
            await self.module_logger.log_info(f"🔌 Closing all cached connections, count: {len(self._cache)}")
            for key, (client, _, _) in self._cache.items():
                try:
                    client.close()
                    await self.module_logger.log_info(f"✅ Closed connection for tenant: {key}")
                except Exception as e:
                    await self.module_logger.log_error(f"❌ Error closing connection for {key}: {str(e)}")
            self._cache.clear()
            self._locks.clear()
            await self.module_logger.log_info("🧹 Tenant cache cleared successfully")


def register(app):
    """Register database-related configurations and setup"""
    app.debug = site_settings.DEBUG
    app.title = site_settings.NAME

    @app.on_event("startup")
    async def start_database():
        await initiate_database(app)
    
    @app.on_event("shutdown")
    async def shutdown_database():
        await cleanup_database()


async def initiate_database(app):
    """Initialize main database and tenant cache"""
    global MAIN_CLIENT, TENANT_CACHE
    
    module_logger = ModuleLogger(sender_id="DatabaseInit")
    
    await module_logger.log_info("🚀 Starting database initialization")
    
    # 1) Create main/catalog client + DB
    await module_logger.log_info(f"🔗 Creating main MongoDB client with URI: {app_settings.MONGODB_URI[:20]}...")
    MAIN_CLIENT = AsyncIOMotorClient(app_settings.MONGODB_URI)
    main_db = MAIN_CLIENT[app_settings.MONGODB_NAME]
    await module_logger.log_info(f"📊 Main database created: {app_settings.MONGODB_NAME}")

    # 2) Initialize Beanie for main DB with business document models
    await module_logger.log_info(f"🔧 Initializing Beanie for main database with {len(document_models)} document models")
    await init_beanie(database=main_db, document_models=document_models)
    await module_logger.log_info("✅ Beanie initialization completed for main database")

    # 3) Create tenant cache that uses main_db lookups to resolve product_id -> tenant db
    max_cache_size = getattr(app_settings, 'TENANT_CACHE_MAX', 64)
    await module_logger.log_info(f"📦 Creating tenant cache with max size: {max_cache_size}")
    TENANT_CACHE = TenantDBCache(main_db, max_size=max_cache_size)

    # 4) Store on app state for middleware to access
    app.state.main_db = main_db
    app.state.tenant_cache = TENANT_CACHE
    
    await module_logger.log_info("✅ Database and tenant cache initialized successfully")
    print("Database and tenant cache initialized successfully")


async def cleanup_database():
    """Cleanup database connections and cache"""
    global MAIN_CLIENT, TENANT_CACHE
    
    module_logger = ModuleLogger(sender_id="DatabaseCleanup")
    await module_logger.log_info("🧹 Starting database cleanup")
    
    if TENANT_CACHE:
        await module_logger.log_info("📦 Closing tenant cache")
        await TENANT_CACHE.aclose()
    
    if MAIN_CLIENT:
        await module_logger.log_info("🔌 Closing main database client")
        MAIN_CLIENT.close()
    
    await module_logger.log_info("✅ Database connections closed successfully")
    print("Database connections closed successfully")