"""
Subdomain Routing Middleware

Routes requests to different URL configurations based on the subdomain.
This allows clean separation of admin, API, and docs URLs.

Subdomains:
- admin.imamjavad.nwhco.ir → config.urls_admin
- api.imamjavad.nwhco.ir → config.urls_api  
- docs.imamjavad.nwhco.ir → config.urls_docs
- imamjavad.nwhco.ir → config.urls (main/frontend)
"""
from django.utils.deprecation import MiddlewareMixin
from django.conf import settings


class SubdomainRoutingMiddleware(MiddlewareMixin):
    """
    Middleware that sets the ROOT_URLCONF based on the request's subdomain.
    """
    
    # Mapping of subdomain prefixes to URL configurations
    SUBDOMAIN_URLCONFS = {
        'admin': 'config.urls_admin',  # Admin + Swagger/Redoc
    }
    
    # List of main domains (without subdomain routing)
    MAIN_DOMAINS = [
        'imamjavad.nwhco.ir',
        'imamjavad.newhorizonco.uk',
        'dovoodi.nwhco.ir',
        'dovodi.newhorizonco.uk',
        'localhost',
        '127.0.0.1',
    ]

    def process_request(self, request):
        """
        Determine the subdomain and set the appropriate ROOT_URLCONF.
        """
        # Get host from request (handles X-Forwarded-Host for proxied requests)
        host = request.get_host().split(':')[0].lower()
        
        # Check if this is a subdomain request
        subdomain = self._extract_subdomain(host)
        
        if subdomain and subdomain in self.SUBDOMAIN_URLCONFS:
            # Set the URL configuration for this subdomain
            request.urlconf = self.SUBDOMAIN_URLCONFS[subdomain]
            # Store subdomain info for potential use in views
            request.subdomain = subdomain
        else:
            # Use default URL configuration
            request.subdomain = None
        
        return None
    
    def _extract_subdomain(self, host):
        """
        Extract the subdomain from the host.
        
        Examples:
        - admin.imamjavad.nwhco.ir → 'admin'
        - api.imamjavad.nwhco.ir → 'api'
        - imamjavad.nwhco.ir → None
        """
        # Check against main domains
        for main_domain in self.MAIN_DOMAINS:
            if host == main_domain:
                return None
            
            # Check if host is a subdomain of a main domain
            if host.endswith('.' + main_domain):
                # Extract subdomain part
                subdomain = host[:-len('.' + main_domain)]
                # Only return first-level subdomain
                if '.' not in subdomain:
                    return subdomain
        
        # Also check against ALLOWED_HOSTS for flexibility
        for allowed_host in getattr(settings, 'ALLOWED_HOSTS', []):
            if allowed_host.startswith('.'):
                # Wildcard domain like .nwhco.ir
                base_domain = allowed_host[1:]
                if host.endswith(base_domain) and host != base_domain:
                    subdomain = host[:-len(base_domain)].rstrip('.')
                    if '.' not in subdomain:
                        return subdomain
        
        return None


def get_subdomain(request):
    """
    Utility function to get the current subdomain from request.
    Can be used in views or templates.
    """
    return getattr(request, 'subdomain', None)


def is_admin_subdomain(request):
    """Check if current request is on admin subdomain."""
    return get_subdomain(request) == 'admin'