package httpapi

import (
	"errors"
	"net/http"

	"github.com/descrybe/descrybe-v2/apps/api/internal/billing"
)

// writePlanGate writes a 402 plan_gate payload when err is a known billing gate.
// Returns true when the response was written.
func writePlanGate(w http.ResponseWriter, err error) bool {
	if err == nil {
		return false
	}
	if !(errors.Is(err, billing.ErrInsufficientCredits) ||
		errors.Is(err, billing.ErrProductLimitExceeded) ||
		errors.Is(err, billing.ErrAIRequiresUpgrade) ||
		errors.Is(err, billing.ErrEPRELRequiresUpgrade) ||
		errors.Is(err, billing.ErrFeatureDisabled)) {
		return false
	}
	body := map[string]any{
		"error":       err.Error(),
		"code":        planGateCode(err),
		"upgrade_url": "/pricing",
	}
	if errors.Is(err, billing.ErrFeatureDisabled) {
		body["error"] = "feature_disabled"
		if key := billing.FeatureKeyFromError(err); key != "" {
			body["feature"] = key
		}
	}
	JSON(w, http.StatusPaymentRequired, body)
	return true
}

// requireFeatures rejects with 402 when any key is not effective for the company.
// Billing nil: pass-through only outside production; production fails closed with 503.
// Returns false when the response was already written.
func (s *Server) requireFeatures(w http.ResponseWriter, r *http.Request, keys ...string) bool {
	if len(keys) == 0 {
		return true
	}
	if s.testAssertFeatures != nil {
		if err := s.testAssertFeatures(r.Context(), keys...); err != nil {
			if writePlanGate(w, err) {
				return false
			}
			Error(w, http.StatusInternalServerError, "feature check failed")
			return false
		}
		return true
	}
	if s.Billing == nil {
		if s.Config.IsProduction() {
			Error(w, http.StatusServiceUnavailable, "billing unavailable")
			return false
		}
		return true
	}
	cid, ok := CompanyIDFromContext(r.Context())
	if !ok {
		Error(w, http.StatusUnauthorized, "company required")
		return false
	}
	if err := s.Billing.AssertFeatures(r.Context(), cid, keys...); err != nil {
		if writePlanGate(w, err) {
			return false
		}
		Error(w, http.StatusInternalServerError, "feature check failed")
		return false
	}
	return true
}

// RequireFeature rejects the request with 402 when the company's effective
// features do not include key. Billing nil: pass-through only outside production;
// production fails closed with 503 (never silently allow all features).
func (s *Server) RequireFeature(key string) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			if !s.requireFeatures(w, r, key) {
				return
			}
			next.ServeHTTP(w, r)
		})
	}
}