"""
Tenant middleware for handling multi-tenant requests
"""
from typing import Optional
from fastapi import Request, HTTPException, status
from starlette.middleware.base import BaseHTTPMiddleware
from sqlalchemy.orm import Session

from .config.settings import settings
from .models import Tenant
from .database import SessionLocal


class TenantMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request: Request, call_next):
        # Get tenant ID from header
        tenant_id = request.headers.get(settings.TENANT_ID_HEADER)
        
        # If not in header, try to extract from subdomain
        if not tenant_id:
            host = request.headers.get("host", "")
            tenant_id = self.extract_tenant_from_host(host)
        
        # Look up tenant in database
        tenant = None
        if tenant_id:
            db: Session = SessionLocal()
            try:
                tenant = db.query(Tenant).filter(Tenant.subdomain == tenant_id).first()
            finally:
                db.close()
        
        if settings.MULTI_TENANT_ENABLED and not tenant:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="Valid tenant ID is required"
            )
        
        # Attach tenant info to request
        request.state.tenant = tenant
        request.state.tenant_id = tenant.id if tenant else None
        
        response = await call_next(request)
        return response

    def extract_tenant_from_host(self, host: str) -> Optional[str]:
        """
        Extract tenant from host (subdomain.tenant.com)
        """
        import re
        # Match subdomain from host (e.g., "tenant1.example.com" -> "tenant1")
        match = re.match(r'^([^.]+)\.', host)
        if match:
            return match.group(1)
        return None