from fastapi import Request, HTTPException, status
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.responses import JSONResponse
from app.core.config.Config import settings

class SecurityHeadersMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request: Request, call_next):
        response = await call_next(request)
        is_docs = request.url.path in ["/docs", "/redoc", "/openapi.json"]
        
        # Enforce HSTS
        if request.url.hostname not in ["localhost", "127.0.0.1"]:
            response.headers["Strict-Transport-Security"] = "max-age=63072000; includeSubDomains; preload"
        
        if not is_docs:
            response.headers["X-Frame-Options"] = "DENY"
            
        response.headers["X-Content-Type-Options"] = "nosniff"
        response.headers["Referrer-Policy"] = "strict-origin-when-cross-origin"
        response.headers["Permissions-Policy"] = "geolocation=(), microphone=(), camera=()"
        
        # CSP policies: only apply to docs or frontend pages, NEVER block API connections
        if is_docs:
            response.headers["Content-Security-Policy"] = "default-src * 'unsafe-inline' 'unsafe-eval' data: blob:;"
        elif not request.url.path.startswith("/api/"):
            response.headers["Content-Security-Policy"] = (
                "default-src 'self'; script-src 'self'; connect-src 'self'; "
                "img-src 'self' data:; style-src 'self' 'unsafe-inline';"
            )
            
        return response

class RequestSizeLimitMiddleware(BaseHTTPMiddleware):
    def __init__(self, app, max_bytes: int = 10 * 1024 * 1024):  # Default 10MB
        super().__init__(app)
        self.max_bytes = max_bytes

    async def dispatch(self, request: Request, call_next):
        # Read content length header
        content_length = request.headers.get("content-length")
        if content_length:
            try:
                length = int(content_length)
                if length > self.max_bytes:
                    max_mb = self.max_bytes // (1024 * 1024)
                    return JSONResponse(
                        status_code=status.HTTP_413_REQUEST_ENTITY_TOO_LARGE,
                        content={"detail": f"Payload too large. Maximum size allowed is {max_mb}MB."}
                    )
            except ValueError:
                pass
                
        # Also limit reading chunks if chunked transfer encoding is used
        return await call_next(request)