"""
Middleware components for the Virtual Board Member AI System.
"""

import time
from typing import Callable
from fastapi import Request, Response
from starlette.middleware.base import BaseHTTPMiddleware
from prometheus_client import Counter, Histogram
import structlog

from app.core.config import settings

logger = structlog.get_logger()

# Prometheus metrics
REQUEST_COUNT = Counter(
    "http_requests_total",
    "Total HTTP requests",
    ["method", "endpoint", "status"]
)
REQUEST_LATENCY = Histogram(
    "http_request_duration_seconds",
    "HTTP request latency",
    ["method", "endpoint"]
)


class RequestLoggingMiddleware(BaseHTTPMiddleware):
    """Middleware for logging HTTP requests."""
    
    async def dispatch(self, request: Request, call_next: Callable) -> Response:
        start_time = time.time()
        
        # Log request
        logger.info(
            "HTTP request started",
            method=request.method,
            url=str(request.url),
            client_ip=request.client.host if request.client else None,
            user_agent=request.headers.get("user-agent"),
        )
        
        # Process request
        response = await call_next(request)
        
        # Calculate duration
        duration = time.time() - start_time
        
        # Log response
        logger.info(
            "HTTP request completed",
            method=request.method,
            url=str(request.url),
            status_code=response.status_code,
            duration=duration,
        )
        
        return response


class PrometheusMiddleware(BaseHTTPMiddleware):
    """Middleware for Prometheus metrics."""
    
    async def dispatch(self, request: Request, call_next: Callable) -> Response:
        start_time = time.time()
        
        # Process request
        response = await call_next(request)
        
        # Calculate duration
        duration = time.time() - start_time
        
        # Extract endpoint (remove query parameters and path parameters)
        endpoint = request.url.path
        
        # Record metrics
        REQUEST_COUNT.labels(
            method=request.method,
            endpoint=endpoint,
            status=response.status_code
        ).inc()
        
        REQUEST_LATENCY.labels(
            method=request.method,
            endpoint=endpoint
        ).observe(duration)
        
        return response


class SecurityHeadersMiddleware(BaseHTTPMiddleware):
    """Middleware for adding security headers."""
    
    async def dispatch(self, request: Request, call_next: Callable) -> Response:
        response = await call_next(request)
        
        # Add security headers
        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"
        response.headers["Permissions-Policy"] = "geolocation=(), microphone=(), camera=()"
        
        # Add CSP header in production
        if settings.is_production:
            response.headers["Content-Security-Policy"] = (
                "default-src 'self'; "
                "script-src 'self' 'unsafe-inline' 'unsafe-eval'; "
                "style-src 'self' 'unsafe-inline'; "
                "img-src 'self' data: https:; "
                "font-src 'self' data:; "
                "connect-src 'self' https:; "
                "frame-ancestors 'none';"
            )
        
        return response


class RateLimitMiddleware(BaseHTTPMiddleware):
    """Middleware for rate limiting."""
    
    def __init__(self, app, requests_per_minute: int = 100):
        super().__init__(app)
        self.requests_per_minute = requests_per_minute
        self.request_counts = {}
    
    async def dispatch(self, request: Request, call_next: Callable) -> Response:
        client_ip = request.client.host if request.client else "unknown"
        current_time = time.time()
        
        # Clean old entries
        self._clean_old_entries(current_time)
        
        # Check rate limit
        if not self._check_rate_limit(client_ip, current_time):
            logger.warning(
                "Rate limit exceeded",
                client_ip=client_ip,
                requests_per_minute=self.requests_per_minute
            )
            return Response(
                content="Rate limit exceeded",
                status_code=429,
                headers={"Retry-After": "60"}
            )
        
        # Process request
        response = await call_next(request)
        
        # Record request
        self._record_request(client_ip, current_time)
        
        return response
    
    def _clean_old_entries(self, current_time: float) -> None:
        """Remove entries older than 1 minute."""
        cutoff_time = current_time - 60
        for client_ip in list(self.request_counts.keys()):
            self.request_counts[client_ip] = [
                timestamp for timestamp in self.request_counts[client_ip]
                if timestamp > cutoff_time
            ]
            if not self.request_counts[client_ip]:
                del self.request_counts[client_ip]
    
    def _check_rate_limit(self, client_ip: str, current_time: float) -> bool:
        """Check if client has exceeded rate limit."""
        if client_ip not in self.request_counts:
            return True
        
        requests_in_window = len([
            timestamp for timestamp in self.request_counts[client_ip]
            if current_time - timestamp < 60
        ])
        
        return requests_in_window < self.requests_per_minute
    
    def _record_request(self, client_ip: str, current_time: float) -> None:
        """Record a request for the client."""
        if client_ip not in self.request_counts:
            self.request_counts[client_ip] = []
        
        self.request_counts[client_ip].append(current_time)


class CORSMiddleware(BaseHTTPMiddleware):
    """Custom CORS middleware."""
    
    async def dispatch(self, request: Request, call_next: Callable) -> Response:
        response = await call_next(request)
        
        # Add CORS headers
        origin = request.headers.get("origin")
        if origin and origin in settings.ALLOWED_HOSTS:
            response.headers["Access-Control-Allow-Origin"] = origin
        else:
            response.headers["Access-Control-Allow-Origin"] = "*"
        
        response.headers["Access-Control-Allow-Methods"] = "GET, POST, PUT, DELETE, OPTIONS"
        response.headers["Access-Control-Allow-Headers"] = "Content-Type, Authorization"
        response.headers["Access-Control-Allow-Credentials"] = "true"
        
        return response