package httpauth

import (
	"context"
	"net/http"

	"code.nochebuena.dev/go/rbac"
)

// PermissionProvider resolves the permission mask for a given uid on a resource.
type PermissionProvider interface {
	ResolveMask(ctx context.Context, uid, resource string) (rbac.PermissionMask, error)
}

// AuthzMiddleware reads the rbac.Identity from context (set by EnrichmentMiddleware)
// and gates the request against the required permission on resource.
// Returns 401 if no identity is in the context.
// Returns 403 if the identity lacks the required permission or if the provider errors.
func AuthzMiddleware(provider PermissionProvider, resource string, required rbac.Permission) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			identity, ok := rbac.FromContext(r.Context())
			if !ok {
				http.Error(w, "unauthorized", http.StatusUnauthorized)
				return
			}

			mask, err := provider.ResolveMask(r.Context(), identity.UID, resource)
			if err != nil || !mask.Has(required) {
				http.Error(w, "forbidden", http.StatusForbidden)
				return
			}

			next.ServeHTTP(w, r)
		})
	}
}