"""
  Main FastAPI application for the search service.
  
  Usage:

      uvicorn api.app:app --host 0.0.0.0 --port 6002 --reload

  """
  
  import os
  import sys

  import logging
  import time

  import argparse
  import uvicorn

  from logging.handlers import TimedRotatingFileHandler

  from collections import defaultdict, deque

  from typing import Optional

  from fastapi import FastAPI, Request, HTTPException

  from fastapi.responses import JSONResponse, FileResponse
  from fastapi.staticfiles import StaticFiles

  from fastapi.middleware.cors import CORSMiddleware

  from fastapi.middleware.trustedhost import TrustedHostMiddleware
  from fastapi.middleware.httpsredirect import HTTPSRedirectMiddleware
  from slowapi import Limiter, _rate_limit_exceeded_handler
  from slowapi.util import get_remote_address
  from slowapi.errors import RateLimitExceeded

  # Configure backend logging

  import pathlib

  
  
  def configure_backend_logging() -> None:
      log_dir = pathlib.Path("logs")
      log_dir.mkdir(exist_ok=True)
      log_level = os.getenv("LOG_LEVEL", "INFO").upper()
      numeric_level = getattr(logging, log_level, logging.INFO)
  
      default_formatter = logging.Formatter(
          "%(asctime)s - %(name)s - %(levelname)s - %(message)s"
      )
  
      root_logger = logging.getLogger()
      root_logger.setLevel(numeric_level)
      root_logger.handlers.clear()
  
      console_handler = logging.StreamHandler()
      console_handler.setLevel(numeric_level)
      console_handler.setFormatter(default_formatter)
      root_logger.addHandler(console_handler)
  
      backend_handler = TimedRotatingFileHandler(
          filename=log_dir / "api.log",
          when="midnight",
          interval=1,
          backupCount=30,
          encoding="utf-8",
      )
      backend_handler.setLevel(numeric_level)
      backend_handler.setFormatter(default_formatter)
      root_logger.addHandler(backend_handler)
  
      verbose_logger = logging.getLogger("backend.verbose")
      verbose_logger.setLevel(numeric_level)
      verbose_logger.handlers.clear()
      verbose_logger.propagate = False
  
      verbose_handler = TimedRotatingFileHandler(
          filename=log_dir / "backend_verbose.log",
          when="midnight",
          interval=1,
          backupCount=30,
          encoding="utf-8",
      )
      verbose_handler.setLevel(numeric_level)
      verbose_handler.setFormatter(
          logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
      )
      verbose_logger.addHandler(verbose_handler)
  
  
  configure_backend_logging()

  logger = logging.getLogger(__name__)
  
  # Initialize rate limiter
  limiter = Limiter(key_func=get_remote_address)
  

  # Add parent directory to path
  sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
  

  from config.env_config import ES_CONFIG, DB_CONFIG

  from config import ConfigLoader

  from utils import ESClient

  from search import Searcher

  from query import QueryParser

  from suggestion import SuggestionService

  from .service_registry import set_es_client

  
  # Global instances

  _es_client: Optional[ESClient] = None
  _searcher: Optional[Searcher] = None
  _query_parser: Optional[QueryParser] = None

  _suggestion_service: Optional[SuggestionService] = None

  _config = None

  def init_service(es_host: str = "http://localhost:9200"):

      """

      Initialize search service with unified configuration.

  
      Args:

          es_host: Elasticsearch host URL
      """

      global _es_client, _searcher, _query_parser, _suggestion_service, _config

      start_time = time.time()
      logger.info("Initializing search service (multi-tenant)")

      # Load configuration
      logger.info("Loading configuration...")
      config_loader = ConfigLoader("config/config.yaml")
      _config = config_loader.load_config()
      logger.info("Configuration loaded")
  

      # Get ES credentials
      es_username = os.getenv('ES_USERNAME') or ES_CONFIG.get('username')
      es_password = os.getenv('ES_PASSWORD') or ES_CONFIG.get('password')

      # Connect to Elasticsearch
      logger.info(f"Connecting to Elasticsearch at {es_host}...")

      if es_username and es_password:

          _es_client = ESClient(hosts=[es_host], username=es_username, password=es_password)
      else:

          _es_client = ESClient(hosts=[es_host])
      

      if not _es_client.ping():
          raise ConnectionError(f"Failed to connect to Elasticsearch at {es_host}")

      logger.info("Elasticsearch connected")

      # expose ES client for any shared components (e.g. searcher)
      set_es_client(_es_client)

      # Initialize components
      logger.info("Initializing query parser...")

      _query_parser = QueryParser(_config)

      
      logger.info("Initializing searcher...")

      _searcher = Searcher(_es_client, _config, _query_parser)

      logger.info("Initializing suggestion service...")
      _suggestion_service = SuggestionService(_es_client)

      elapsed = time.time() - start_time

      logger.info(f"Search service ready! (took {elapsed:.2f}s) | Index: {_config.es_index_name}")

  
  
  def get_es_client() -> ESClient:
      """Get Elasticsearch client."""
      if _es_client is None:
          raise RuntimeError("Service not initialized")
      return _es_client
  
  
  def get_searcher() -> Searcher:
      """Get searcher instance."""
      if _searcher is None:
          raise RuntimeError("Service not initialized")
      return _searcher
  
  
  def get_query_parser() -> QueryParser:
      """Get query parser instance."""
      if _query_parser is None:
          raise RuntimeError("Service not initialized")
      return _query_parser
  
  

  def get_suggestion_service() -> SuggestionService:
      """Get suggestion service instance."""
      if _suggestion_service is None:
          raise RuntimeError("Service not initialized")
      return _suggestion_service
  
  

  def get_config():
      """Get global config instance."""
      if _config is None:
          raise RuntimeError("Service not initialized")
      return _config
  
  

  # Create FastAPI app with enhanced configuration

  app = FastAPI(
      title="E-Commerce Search API",
      description="Configurable search engine for cross-border e-commerce",

      version="1.0.0",
      docs_url="/docs",
      redoc_url="/redoc",
      openapi_url="/openapi.json"
  )
  
  # Add rate limiting middleware
  app.state.limiter = limiter
  app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)
  
  # Add trusted host middleware (restrict to localhost and trusted domains)
  app.add_middleware(
      TrustedHostMiddleware,
      allowed_hosts=["*"]  # Allow all hosts for development, restrict in production

  )
  

  # Add security headers middleware
  @app.middleware("http")
  async def add_security_headers(request: Request, call_next):
      response = await call_next(request)
      response.headers["X-Content-Type-Options"] = "nosniff"
      response.headers["X-Frame-Options"] = "DENY"
      response.headers["X-XSS-Protection"] = "1; mode=block"
      response.headers["Referrer-Policy"] = "strict-origin-when-cross-origin"
      return response
  
  # Add CORS middleware with more restrictive settings

  app.add_middleware(
      CORSMiddleware,

      allow_origins=["*"],  # Restrict in production to specific domains

      allow_credentials=True,

      allow_methods=["GET", "POST", "PUT", "DELETE", "OPTIONS"],

      allow_headers=["*"],

      expose_headers=["X-Total-Count"]

  )
  
  
  @app.on_event("startup")
  async def startup_event():
      """Initialize service on startup."""

      # Configure thread pool size for uvicorn (default is 40, set to 48)
      try:
          import anyio.to_thread
          limiter = anyio.to_thread.current_default_thread_limiter()
          limiter.total_tokens = 48
          logger.info(f"Thread pool size set to {limiter.total_tokens}")
      except Exception as e:
          logger.warning(f"Failed to set thread pool size: {e}, using default")
      

      es_host = os.getenv("ES_HOST", "http://localhost:9200")

      logger.info("Starting E-Commerce Search API (Multi-Tenant)")

      logger.info(f"Elasticsearch Host: {es_host}")

      try:

          init_service(es_host=es_host)

          logger.info("Service initialized successfully")

      except Exception as e:

          logger.error(f"Failed to initialize service: {e}", exc_info=True)

          raise

  
  
  @app.on_event("shutdown")
  async def shutdown_event():
      """Cleanup on shutdown."""
      logger.info("Shutting down E-Commerce Search API")

  
  
  @app.exception_handler(Exception)
  async def global_exception_handler(request: Request, exc: Exception):

      """Global exception handler with detailed logging."""
      client_ip = request.client.host if request.client else "unknown"
      logger.error(f"Unhandled exception from {client_ip}: {exc}", exc_info=True)
  

      return JSONResponse(
          status_code=500,
          content={
              "error": "Internal server error",

              "detail": "An unexpected error occurred. Please try again later.",
              "timestamp": int(time.time())
          }
      )
  
  
  @app.exception_handler(HTTPException)
  async def http_exception_handler(request: Request, exc: HTTPException):
      """HTTP exception handler."""
      logger.warning(f"HTTP exception from {request.client.host if request.client else 'unknown'}: {exc.status_code} - {exc.detail}")
  
      return JSONResponse(
          status_code=exc.status_code,
          content={
              "error": exc.detail,
              "status_code": exc.status_code,
              "timestamp": int(time.time())

          }
      )
  
  

  @app.get("/api")

  @limiter.limit("60/minute")
  async def root(request: Request):
      """Root endpoint with rate limiting."""
      client_ip = request.client.host if request.client else "unknown"
      logger.info(f"Root endpoint accessed from {client_ip}")
  

      return {
          "service": "E-Commerce Search API",
          "version": "1.0.0",

          "status": "running",
          "timestamp": int(time.time())

      }
  
  

  @app.get("/health")
  @limiter.limit("120/minute")
  async def health_check(request: Request):
      """Health check endpoint."""
      try:
          # Check if services are initialized

          get_es_client()

          get_searcher()

  
          return {
              "status": "healthy",
              "services": {
                  "config": "initialized",
                  "elasticsearch": "connected",
                  "searcher": "initialized"
              },
              "timestamp": int(time.time())
          }
      except Exception as e:
          logger.error(f"Health check failed: {e}")
          return JSONResponse(
              status_code=503,
              content={
                  "status": "unhealthy",
                  "error": str(e),
                  "timestamp": int(time.time())
              }
          )
  
  

  # Include routers (search app should NOT mount indexer routes)
  from .routes import search, admin

  
  app.include_router(search.router)
  app.include_router(admin.router)

  # Mount static files and serve frontend
  frontend_path = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "frontend")
  if os.path.exists(frontend_path):
      # Serve frontend HTML at root
      @app.get("/")
      async def serve_frontend():
          """Serve the frontend HTML."""
          index_path = os.path.join(frontend_path, "index.html")
          if os.path.exists(index_path):
              return FileResponse(index_path)
          return {"service": "E-Commerce Search API", "version": "1.0.0", "status": "running"}
      
      # Mount static files (CSS, JS, images)
      app.mount("/static", StaticFiles(directory=os.path.join(frontend_path, "static")), name="static")
      
      logger.info(f"Frontend static files mounted from: {frontend_path}")
  else:
      logger.warning(f"Frontend directory not found: {frontend_path}")
  

  
  if __name__ == "__main__":

      parser = argparse.ArgumentParser(description='Start search API service (multi-tenant)')

      parser.add_argument('--host', default='0.0.0.0', help='Host to bind to')

      parser.add_argument('--port', type=int, default=6002, help='Port to bind to')

      parser.add_argument('--es-host', default='http://localhost:9200', help='Elasticsearch host')
      parser.add_argument('--reload', action='store_true', help='Enable auto-reload')
      args = parser.parse_args()
  

      # Set environment variable

      os.environ['ES_HOST'] = args.es_host
  
      # Run server
      uvicorn.run(
          "api.app:app",
          host=args.host,
          port=args.port,
          reload=args.reload
      )