business: add privacy-aware user projection

(cherry picked from commit a636192ef22ee69d792b0ca7db1c6be963be9cb2)

internal/domain/privacy.go

@@ -0,0 +1,83 @@
+package domain
+
+import "errors"
+
+// PrivacyKey identifies a Telegram account privacy setting without exposing tg.*.
+type PrivacyKey string
+
+const (
+	PrivacyKeyStatusTimestamp   PrivacyKey = "status_timestamp"
+	PrivacyKeyChatInvite        PrivacyKey = "chat_invite"
+	PrivacyKeyPhoneCall         PrivacyKey = "phone_call"
+	PrivacyKeyPhoneP2P          PrivacyKey = "phone_p2p"
+	PrivacyKeyForwards          PrivacyKey = "forwards"
+	PrivacyKeyProfilePhoto      PrivacyKey = "profile_photo"
+	PrivacyKeyPhoneNumber       PrivacyKey = "phone_number"
+	PrivacyKeyAddedByPhone      PrivacyKey = "added_by_phone"
+	PrivacyKeyVoiceMessages     PrivacyKey = "voice_messages"
+	PrivacyKeyAbout             PrivacyKey = "about"
+	PrivacyKeyBirthday          PrivacyKey = "birthday"
+	PrivacyKeyStarGiftsAutoSave PrivacyKey = "star_gifts_auto_save"
+	PrivacyKeyNoPaidMessages    PrivacyKey = "no_paid_messages"
+	PrivacyKeySavedMusic        PrivacyKey = "saved_music"
+)
+
+// PrivacyRuleKind mirrors Layer 225 privacy rule constructors.
+type PrivacyRuleKind string
+
+const (
+	PrivacyRuleAllowContacts            PrivacyRuleKind = "allow_contacts"
+	PrivacyRuleAllowAll                 PrivacyRuleKind = "allow_all"
+	PrivacyRuleAllowUsers               PrivacyRuleKind = "allow_users"
+	PrivacyRuleDisallowContacts         PrivacyRuleKind = "disallow_contacts"
+	PrivacyRuleDisallowAll              PrivacyRuleKind = "disallow_all"
+	PrivacyRuleDisallowUsers            PrivacyRuleKind = "disallow_users"
+	PrivacyRuleAllowChatParticipants    PrivacyRuleKind = "allow_chat_participants"
+	PrivacyRuleDisallowChatParticipants PrivacyRuleKind = "disallow_chat_participants"
+	PrivacyRuleAllowCloseFriends        PrivacyRuleKind = "allow_close_friends"
+	PrivacyRuleAllowPremium             PrivacyRuleKind = "allow_premium"
+	PrivacyRuleAllowBots                PrivacyRuleKind = "allow_bots"
+	PrivacyRuleDisallowBots             PrivacyRuleKind = "disallow_bots"
+)
+
+// PrivacyRule is a protocol-neutral privacy rule.
+type PrivacyRule struct {
+	Kind    PrivacyRuleKind `json:"kind"`
+	UserIDs []int64         `json:"user_ids,omitempty"`
+	ChatIDs []int64         `json:"chat_ids,omitempty"`
+}
+
+// PrivacyRules is one owner/key rule set.
+type PrivacyRules struct {
+	OwnerUserID int64         `json:"owner_user_id,omitempty"`
+	Key         PrivacyKey    `json:"key"`
+	Rules       []PrivacyRule `json:"rules"`
+}
+
+// PrivacyContext describes viewer facts needed for privacy evaluation.
+type PrivacyContext struct {
+	OwnerUserID       int64
+	ViewerUserID      int64
+	ViewerIsContact   bool
+	ViewerIsBot       bool
+	ViewerIsPremium   bool
+	ViewerCloseFriend bool
+	SharedChatIDs     []int64
+}
+
+var (
+	ErrPrivacyKeyInvalid  = errors.New("privacy key invalid")
+	ErrPrivacyRuleInvalid = errors.New("privacy rule invalid")
+)
+
+// DefaultPrivacyRules returns Telegram-like defaults used when no user setting exists.
+func DefaultPrivacyRules(key PrivacyKey) []PrivacyRule {
+	switch key {
+	case PrivacyKeyPhoneNumber:
+		return []PrivacyRule{{Kind: PrivacyRuleDisallowAll}}
+	case PrivacyKeyBirthday:
+		return []PrivacyRule{{Kind: PrivacyRuleAllowContacts}}
+	default:
+		return []PrivacyRule{{Kind: PrivacyRuleAllowAll}}
+	}
+}