package middleware

// Reference: P2E §2.8 — Feature flag middleware
// Feature gating middleware. In GoChat (self-hosted), all features are available
// by default. This middleware exists for API compatibility with Chatwoot's
// enterprise feature gating, but defaults to allow when no flags are configured.

import (
	"encoding/json"
	"net/http"

	"github.com/gin-gonic/gin"

	"github.com/gochat/gochat/pkg/response"
)

// Known feature flags from Chatwoot enterprise features:
// Reference: Chatwoot app/models/account.rb — FEATURE_FLAGS constant
const (
	FeatureAutoAssignment      = "auto_assignment"
	FeatureCustomRoles         = "custom_roles"
	FeatureAutomation          = "automation"
	FeatureKnowledgeBase       = "knowledge_base"
	FeatureReporting           = "reporting"
	FeatureCSAT                = "csat"
	FeatureHelpCenter          = "help_center"
	FeatureAgentBots           = "agent_bots"
	FeatureMFA                 = "mfa"
	FeatureChannelFacebook     = "channel_facebook"
	FeatureChannelTwilio       = "channel_twilio"
	FeatureChannelWhatsApp     = "channel_whatsapp"
	FeatureChannelEmail        = "channel_email"
	FeatureChannelTelegram     = "channel_telegram"
	FeatureChannelLine         = "channel_line"
	FeatureEnterpriseReporting = "enterprise_reporting"
	FeatureMacro               = "macro"
	FeatureCampaign            = "campaign"
	FeatureTeamInboxes         = "team_inboxes"
)

// FeatureFlagCheck creates a middleware that verifies the current account
// has the specified feature flag enabled.
//
// In GoChat (self-hosted), all features are available by default.
// If feature flags are present in the context, they are checked.
// If no flags are present, the request is allowed (self-hosted = all features enabled).
func FeatureFlagCheck(flag string) gin.HandlerFunc {
	return func(c *gin.Context) {
		featureFlags, exists := c.Get("feature_flags")
		if !exists {
			// Try to load from account if it was set
			accountFlags, accExists := c.Get("account_feature_flags")
			if accExists {
				featureFlags = accountFlags
				exists = true
			}
		}

		if !exists {
			// No feature flags in context — allow in self-hosted mode.
			// GoChat is not a SaaS; all features are available.
			c.Next()
			return
		}

		if hasFeatureFlag(featureFlags, flag) {
			c.Next()
			return
		}

		response.AbortWithStatusError(c, http.StatusForbidden, response.ErrForbidden,
			"Feature '"+flag+"' is not enabled on this account")
	}
}

// hasFeatureFlag checks if a flag is enabled in the feature flags.
// Feature flags can be stored as:
//   - JSON object: {"help_center": true, "csat": false}
//   - JSON array: ["help_center", "csat"]
//   - Comma-separated string: "help_center,csat"
//   - []string: {"help_center", "csat"}
func hasFeatureFlag(raw interface{}, flag string) bool {
	switch v := raw.(type) {
	case []string:
		for _, f := range v {
			if f == flag {
				return true
			}
		}
		return false
	case string:
		if v == "" {
			return false
		}
		// Try JSON object first: {"flag": true}
		var obj map[string]interface{}
		if err := json.Unmarshal([]byte(v), &obj); err == nil {
			if val, ok := obj[flag]; ok {
				if b, ok := val.(bool); ok {
					return b
				}
				return true // non-bool value = present = enabled
			}
			return false
		}
		// Try JSON array: ["flag"]
		var arr []string
		if err := json.Unmarshal([]byte(v), &arr); err == nil {
			for _, f := range arr {
				if f == flag {
					return true
				}
			}
			return false
		}
		return false
	case map[string]interface{}:
		if val, ok := v[flag]; ok {
			if b, ok := val.(bool); ok {
				return b
			}
			return true
		}
		return false
	case []interface{}:
		for _, item := range v {
			if s, ok := item.(string); ok && s == flag {
				return true
			}
		}
		return false
	default:
		return false
	}
}