Constrain PostHog consent to one normal category per banner

Add a partial unique index ensuring only one category per banner can
have posthog_consent enabled. Default it to the analytics category on
banner creation, clear the previous mapping before setting a new one,
and restrict the toggle to NORMAL categories in both the service layer
and the console UI.

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/cookiebanner/defaults.go

@@ -25,12 +25,53 @@ var defaultCategories = []struct {
 	Kind            coredata.CookieCategoryKind
 	Rank            int
 	GCMConsentTypes []string
+	PostHogConsent  bool
 }{
-	{"Necessary", "necessary", "Essential cookies required for the website to function properly.", coredata.CookieCategoryKindNecessary, 0, []string{"security_storage"}},
-	{"Analytics", "analytics", "Cookies that help understand how visitors interact with the website.", coredata.CookieCategoryKindNormal, 1, []string{"analytics_storage"}},
-	{"Advertising", "advertising", "Cookies used to deliver relevant advertisements and track campaigns.", coredata.CookieCategoryKindNormal, 2, []string{"ad_storage", "ad_user_data", "ad_personalization"}},
-	{"Functional", "functional", "Cookies that enable enhanced functionality and personalization.", coredata.CookieCategoryKindNormal, 3, []string{"functionality_storage", "personalization_storage"}},
-	{"Uncategorised", "uncategorised", "Cookies that have not been assigned to a category yet.", coredata.CookieCategoryKindUncategorised, 4, nil},
+	{
+		Name:            "Necessary",
+		Slug:            "necessary",
+		Description:     "Essential cookies required for the website to function properly.",
+		Kind:            coredata.CookieCategoryKindNecessary,
+		Rank:            0,
+		GCMConsentTypes: []string{"security_storage"},
+		PostHogConsent:  false,
+	},
+	{
+		Name:            "Analytics",
+		Slug:            "analytics",
+		Description:     "Cookies that help understand how visitors interact with the website.",
+		Kind:            coredata.CookieCategoryKindNormal,
+		Rank:            1,
+		GCMConsentTypes: []string{"analytics_storage"},
+		PostHogConsent:  true,
+	},
+	{
+		Name:            "Advertising",
+		Slug:            "advertising",
+		Description:     "Cookies used to deliver relevant advertisements and track campaigns.",
+		Kind:            coredata.CookieCategoryKindNormal,
+		Rank:            2,
+		GCMConsentTypes: []string{"ad_storage", "ad_user_data", "ad_personalization"},
+		PostHogConsent:  false,
+	},
+	{
+		Name:            "Functional",
+		Slug:            "functional",
+		Description:     "Cookies that enable enhanced functionality and personalization.",
+		Kind:            coredata.CookieCategoryKindNormal,
+		Rank:            3,
+		GCMConsentTypes: []string{"functionality_storage", "personalization_storage"},
+		PostHogConsent:  false,
+	},
+	{
+		Name:            "Uncategorised",
+		Slug:            "uncategorised",
+		Description:     "Cookies that have not been assigned to a category yet.",
+		Kind:            coredata.CookieCategoryKindUncategorised,
+		Rank:            4,
+		GCMConsentTypes: nil,
+		PostHogConsent:  false,
+	},
 }
 
 var defaultCategoryTranslationsByLanguage = map[string]map[string]struct {

pkg/cookiebanner/errors.go

@@ -33,4 +33,5 @@ var (
 	ErrCookieNameAlreadyExists    = errors.New("a cookie with this name already exists in this banner")
 	ErrCategoriesBannerMismatch   = errors.New("source and target categories belong to different banners")
 	ErrSameCategoryMove           = errors.New("source and target cookie categories must be different")
+	ErrPostHogConsentKindInvalid  = errors.New("PostHog consent can only be enabled on normal categories")
 )

pkg/cookiebanner/service.go

@@ -574,6 +574,7 @@ func (s *Service) CreateCookieBanner(
 					Kind:            dc.Kind,
 					Rank:            dc.Rank,
 					GCMConsentTypes: gcmConsentTypes,
+					PostHogConsent:  dc.PostHogConsent,
 					CreatedAt:       now,
 					UpdatedAt:       now,
 				}
@@ -1350,6 +1351,15 @@ func (s *Service) UpdateCookieCategory(
 				category.GCMConsentTypes = *req.GCMConsentTypes
 			}
 			if req.PostHogConsent != nil {
+				if *req.PostHogConsent && category.Kind != coredata.CookieCategoryKindNormal {
+					return ErrPostHogConsentKindInvalid
+				}
+				if *req.PostHogConsent {
+					var categories coredata.CookieCategories
+				if err := categories.ClearPostHogConsentByBannerID(ctx, tx, scope, category.CookieBannerID); err != nil {
+						return fmt.Errorf("cannot clear posthog consent: %w", err)
+					}
+				}
 				category.PostHogConsent = *req.PostHogConsent
 			}
 
@@ -2091,13 +2101,13 @@ func (s *Service) ReportDetectedCookies(
 					UpdatedAt:        now,
 				}
 
-				if err := cookie.Insert(ctx, tx, scope); err != nil {
-					if errors.Is(err, coredata.ErrResourceAlreadyExists) {
-						continue
-					}
+				ok, err := cookie.InsertIfNotExists(ctx, tx, scope)
+				if err != nil {
 					return fmt.Errorf("cannot insert detected cookie: %w", err)
 				}
-				inserted++
+				if ok {
+					inserted++
+				}
 			}
 
 			if inserted > 0 {