chat

type BlocklistReader interface {
	// GetBlocked returns which of candidateIDs the owner has blocked, as a set
	// keyed by string(userID.Value). Candidates the owner has not blocked are
	// absent from the map.
	GetBlocked(ctx context.Context, ownerID *commonpb.UserId, candidateIDs []*commonpb.UserId) (map[string]bool, error)
}

type Chat struct {
	ID            *commonpb.ChatId
	Type          chatpb.ChatType
	Members       []*commonpb.UserId
	Title         string
	LastActivity  time.Time
	LastMessageID *messagingpb.MessageId
}

type DmFeedCursor struct {
	LastActivity time.Time
	ChatID       *commonpb.ChatId
}

type MessageRef struct {
	ChatID    *commonpb.ChatId
	MessageID *messagingpb.MessageId
}

type MessagingReader interface {
	// LastMessages returns the message for each ref that exists, keyed by
	// string(chatID.Value). Refs without a message are absent from the map.
	LastMessages(ctx context.Context, refs []MessageRef) (map[string]*messagingpb.Message, error)

	// Pointers returns the delivered/read pointers for the members named in each
	// ref, keyed by string(chatID.Value). Chats with no matching pointers are
	// absent from the map.
	Pointers(ctx context.Context, refs []PointerRef) (map[string][]*messagingpb.Pointer, error)

	// LatestEventSequences returns the head event sequence of each given chat,
	// keyed by string(chatID.Value). Chats at head 0 (no messages) are absent from
	// the map, so a missing key means 0.
	LatestEventSequences(ctx context.Context, chatIDs []*commonpb.ChatId) (map[string]uint64, error)
}

type PointerRef struct {
	ChatID  *commonpb.ChatId
	Members []*commonpb.UserId
}

type ProfileReader interface {
	// GetPhoneNumbers returns the linked phone number for each of the given
	// users that has one, keyed by string(userID.Value). Users without a linked
	// phone number are absent from the map.
	GetPhoneNumbers(ctx context.Context, userIDs []*commonpb.UserId) (map[string]*commonpb.PhoneNumber, error)

	// GetPublicProfiles returns the public profile of each of the given users the
	// profile domain knows, keyed by string(userID.Value). Unknown users are
	// absent from the map. Every public field a member row shows — display name,
	// profile picture, join timestamp — comes back in this one call.
	//
	// A member who has set neither a name nor a picture still gets an entry,
	// carrying just the join timestamp. Every chat member is a user the profile
	// domain knows, so hydration treats a missing entry as an error rather than
	// standing in a profile of its own.
	//
	// Profile pictures come back with their blob metadata already resolved —
	// including a short-lived download URL — so a client can render member avatars
	// without a follow-up call. The URL expires; to re-mint one the client calls
	// GetBlobs with an AccessContext naming that user's profile, which authorizes
	// it because a profile picture is public.
	//
	// There is one proto per user, so a caller that fills in per-member fields
	// must copy before mutating: the same user can be a member of several chats.
	GetPublicProfiles(ctx context.Context, userIDs []*commonpb.UserId) (map[string]*profilepb.UserProfile, error)
}

type Server struct {
	chatpb.UnimplementedChatServer
	// contains filtered or unexported fields
}

type Store interface {
	// PutChat persists a new chat and its membership. It returns ErrChatExists
	// if a chat with the same ID already exists, ErrNoMembers if the member set
	// is empty, and an error when the chat ID's length does not match the chat's
	// type family.
	//
	// For a group chat (16-byte ID, type GROUP), Members become group membership
	// records, equivalent to AddGroupMembers, and are written atomically with the
	// canonical record: creation either fully succeeds or leaves nothing behind.
	// Duplicate members collapse. A set larger than MaxGroupChatCreationMembers
	// is rejected with ErrTooManyMembers rather than written non-atomically; a
	// caller wanting a larger group creates it at the cap and grows it with
	// AddGroupMembers.
	PutChat(ctx context.Context, chat *Chat) error

	// AddGroupMembers adds users as joined members of a group chat. It is
	// idempotent: adding an already-joined member is a no-op that preserves
	// their original join time, and re-adding a departed member rejoins them
	// fresh. It returns ErrChatNotFound if the chat does not exist, and an
	// error if chatID is not a group chat ID.
	AddGroupMembers(ctx context.Context, chatID *commonpb.ChatId, userIDs []*commonpb.UserId) error

	// RemoveGroupMember ends a user's membership in a group chat. Departure is
	// a tombstone, not a deletion: the user stops being a member (IsMember
	// false, excluded from GetMembers) but the record of their former
	// membership is kept, and they can be re-added later. Removing a non-member
	// or unknown user is a no-op. It returns an error if chatID is not a group
	// chat ID.
	RemoveGroupMember(ctx context.Context, chatID *commonpb.ChatId, userID *commonpb.UserId) error

	// GetChatByID returns the canonical record for the chat with the given ID,
	// or ErrChatNotFound. It reads only that record: Members carries a DM's
	// inline participants and is always empty for a group chat, whose mutable
	// membership lives in its own records. A caller that needs a group's members
	// reads them explicitly via GetMembers, so the cost of enumerating a large
	// group is never paid implicitly by a metadata read.
	GetChatByID(ctx context.Context, chatID *commonpb.ChatId) (*Chat, error)

	// GetDmFeedPage returns one page of userID's DM feed for a single chat type,
	// pinned to a snapshot: the DMs of chatType userID is a member of whose
	// last_activity is at or before snapshot, ordered by (last_activity, chat_id)
	// descending (most recent first), at most limit chats (limit <= 0 means
	// unbounded). When cursor is nil the page starts at the most recent chat in
	// the snapshot; otherwise it resumes strictly after cursor. An empty result
	// (no error) is returned when no chats remain.
	//
	// Pinning to a fixed watermark makes a multi-page read internally consistent.
	// last_activity only ever advances to a wall-clock send time, so any chat that
	// becomes active after the snapshot moves strictly above the watermark and
	// leaves the window — it can be neither duplicated onto nor skipped within a
	// later page. Those freshly-active chats are surfaced through the live
	// MetadataUpdate event stream instead (see the Chat service's GetDmChatFeed).
	//
	// It is scoped to a single DM type because each type is its own feed (see
	// GetDmChatFeedRequest.dm_chat_type). Group chats will have a parallel
	// accessor, and the server merges the descending streams into one feed.
	GetDmFeedPage(ctx context.Context, userID *commonpb.UserId, chatType chatpb.ChatType, snapshot time.Time, cursor *DmFeedCursor, limit int) ([]*Chat, error)

	// GetMembers returns the member user IDs of a chat, or ErrChatNotFound. For
	// a DM this is the canonical inline member list; for a group chat it is the
	// currently joined members.
	GetMembers(ctx context.Context, chatID *commonpb.ChatId) ([]*commonpb.UserId, error)

	// IsMember reports whether userID is a member of chatID. It returns false
	// (no error) when the chat does not exist, or when a group member has been
	// removed.
	IsMember(ctx context.Context, chatID *commonpb.ChatId, userID *commonpb.UserId) (bool, error)

	// AdvanceLastMessage records messageID as the chat's most recent message,
	// moving last_activity forward to ts and last_message_id to messageID, and
	// reports whether it advanced. The two fields are two views of the same event
	// (the newest message) and are updated together. If the stored last_activity
	// is already at or after ts, it is a no-op and reports advanced=false. It
	// returns ErrChatNotFound if the chat does not exist.
	//
	// For a DM it also returns the chat's members — the set the new activity is
	// fanned out to, which rides on the canonical record it must load regardless.
	// A caller that goes on to broadcast the same activity can reuse this set
	// instead of issuing a separate GetMembers. Members are returned on both the
	// advanced and no-op paths; they are nil on error (including
	// ErrChatNotFound). A group chat's membership lives in its own records, so
	// members is empty and the caller reads GetMembers itself.
	AdvanceLastMessage(ctx context.Context, chatID *commonpb.ChatId, messageID *messagingpb.MessageId, ts time.Time) (advanced bool, members []*commonpb.UserId, err error)
}