"""
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

from request_log_context import LOG_LINE_FORMAT, RequestLogContextFilter


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(LOG_LINE_FORMAT)
    request_filter = RequestLogContextFilter()

    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)
    console_handler.addFilter(request_filter)
    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)
    backend_handler.addFilter(request_filter)
    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(LOG_LINE_FORMAT))
    verbose_handler.addFilter(request_filter)
    verbose_logger.addHandler(verbose_handler)

    for logger_name in ("uvicorn", "uvicorn.error", "uvicorn.access"):
        uvicorn_logger = logging.getLogger(logger_name)
        uvicorn_logger.handlers.clear()
        uvicorn_logger.setLevel(numeric_level)
        uvicorn_logger.propagate = True


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 import get_app_config
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
_app_config = None


def _request_log_extra_from_http(request: Request) -> dict:
    reqid = getattr(getattr(request, "state", None), "reqid", None) or request.headers.get("X-Request-ID")
    uid = (
        getattr(getattr(request, "state", None), "uid", None)
        or request.headers.get("X-User-ID")
        or request.headers.get("User-ID")
    )
    return {"reqid": reqid or "-1", "uid": uid or "-1"}


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, _app_config

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

    # Load configuration
    logger.info("Loading configuration...")
    _app_config = get_app_config()
    search_config = _app_config.search
    logger.info("Configuration loaded")

    # Get ES credentials
    es_username = _app_config.infrastructure.elasticsearch.username
    es_password = _app_config.infrastructure.elasticsearch.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(search_config)
    
    logger.info("Initializing searcher...")
    _searcher = Searcher(_es_client, search_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: {search_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 _app_config is None:
        raise RuntimeError("Service not initialized")
    return _app_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 = get_app_config().infrastructure.elasticsearch.host
    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,
        extra=_request_log_extra_from_http(request),
    )

    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}",
        extra=_request_log_extra_from_http(request),
    )

    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
    )