syntax = "proto3";

package chatto.api.v1;

import "buf/validate/validate.proto";
import "chatto/api/v1/message_types.proto";
import "chatto/api/v1/pagination.proto";
import "chatto/api/v1/read_state.proto";
import "chatto/api/v1/room_timeline.proto";
import "chatto/api/v1/rooms.proto";

// Selects threads by the author of their root message, not their replies.
enum ThreadRootAuthorFilter {
  // Include all root authors.
  THREAD_ROOT_AUTHOR_FILTER_UNSPECIFIED = 0;
  // Include only roots authored by the authenticated viewer.
  THREAD_ROOT_AUTHOR_FILTER_VIEWER = 1;
  // Include only roots authored by other users.
  THREAD_ROOT_AUTHOR_FILTER_OTHERS = 2;
}

// Current follow state for one thread and viewer.
message ThreadFollowState {
  // Room containing the thread.
  string room_id = 1;
  // Event ID of the root message for the thread.
  string thread_root_event_id = 2;
  // True when the current user follows the thread.
  bool following = 3;
}

// Request to follow one message thread.
message FollowThreadRequest {
  // Required. Room containing the thread.
  string room_id = 1 [(buf.validate.field).string.min_len = 1];
  // Required. Event ID of the root message for the thread.
  string thread_root_event_id = 2 [(buf.validate.field).string.min_len = 1];
}

// Result of following a thread.
message FollowThreadResponse {
  reserved 1;
  reserved "following";
  // Current follow state after the operation.
  ThreadFollowState state = 2;
}

// Request to stop following one message thread.
message UnfollowThreadRequest {
  // Required. Room containing the thread.
  string room_id = 1 [(buf.validate.field).string.min_len = 1];
  // Required. Event ID of the root message for the thread.
  string thread_root_event_id = 2 [(buf.validate.field).string.min_len = 1];
}

// Result of unfollowing a thread.
message UnfollowThreadResponse {
  reserved 1;
  reserved "following";
  // Current follow state after the operation.
  ThreadFollowState state = 2;
}

// One followed thread for the current user.
message FollowedThread {
  reserved 1 to 3, 5 to 7;
  reserved "room_id", "room_name", "thread_root_event_id", "reply_count", "last_reply_at", "has_unread";

  // Renderable root message, when the root is still visible.
  Message root_message = 4;
  // Room containing the thread.
  RoomSummary room = 8;
  // Aggregated thread state.
  ThreadSummary thread = 9;
  // Most recent visible reply, when the thread has one.
  Message latest_reply = 10;
  // User IDs used to derive a direct-message conversation label. Empty for
  // channel rooms.
  repeated string direct_message_participant_user_ids = 11;
}

// Request for a page of followed threads for the current user.
message ListFollowedThreadsRequest {
  reserved 1, 2;
  reserved "limit", "offset";

  // Defaults to 20 results when absent or limit is zero. Maximum: 100.
  PageRequest page = 3;
  // Include followed direct-message threads. Defaults to false so older
  // clients retain the channel-only result shape.
  bool include_direct_message_threads = 4;
  // Return only threads with replies that the viewer has not read. The page
  // total then counts only these threads. Older servers ignore this field and
  // return all followed threads.
  bool unread_only = 5;
  // Filter root authors before pagination and total counts. Threads whose
  // root author is unavailable are omitted when a filter is selected.
  ThreadRootAuthorFilter root_author_filter = 6 [(buf.validate.field).enum.defined_only = true];
}

// Response containing one followed-thread page.
message ListFollowedThreadsResponse {
  reserved 2, 3;
  reserved "total_count", "has_more";

  // Followed threads in newest-activity-first order.
  repeated FollowedThread threads = 1;
  // Hot-path related entities needed to render this feed page without
  // per-thread hydration.
  RoomTimelineIncludes includes = 4;
  // Page metadata.
  PageInfo page = 5;
}

// Manages thread follow state for the current user.
service ThreadService {
  // Reads the current viewer's stored marker without changing it. Requires the
  // same membership and read access as MarkThreadAsRead. Missing resources
  // return NOT_FOUND; inaccessible resources return PERMISSION_DENIED.
  rpc GetThreadReadState(GetThreadReadStateRequest) returns (GetThreadReadStateResponse);
  // Reads up to 100 states under the same authorization as GetThreadReadState.
  // Missing and inaccessible resources are omitted; duplicates use first-seen order.
  rpc BatchGetThreadReadStates(BatchGetThreadReadStatesRequest) returns (BatchGetThreadReadStatesResponse);

  // Lists distinct authors of non-retracted replies, excluding erased users.
  // The root author is included only if they also replied. Requires the same
  // membership and message-read access as GetThreadEvents.
  rpc ListThreadParticipants(ListThreadParticipantsRequest) returns (ListThreadParticipantsResponse);

  // Returns followed threads in rooms where the current user is a member.
  // All threads also require message.read or an active relationship with
  // message.read-interactions. Direct-message threads are returned only when
  // include_direct_message_threads is true.
  // The result includes enough root and latest-reply data for clients to render
  // the list without extra per-thread fetches.
  // Activity can reorder the live result between offset pages. After a thread
  // activity update, clients must restart paging at offset zero.
  rpc ListFollowedThreads(ListFollowedThreadsRequest) returns (ListFollowedThreadsResponse);
  // Follows a thread for the current user. Room membership plus message.read or
  // an active relationship with message.read-interactions are required.
  // Followed threads can be surfaced in clients and can participate in thread
  // notification behavior.
  rpc FollowThread(FollowThreadRequest) returns (FollowThreadResponse);
  // Stops following a thread for the current user. Room membership plus
  // message.read or an active relationship with message.read-interactions are
  // required. The response reports
  // the resulting follow state so clients can update local UI immediately.
  rpc UnfollowThread(UnfollowThreadRequest) returns (UnfollowThreadResponse);
  // Returns one page of events in a message thread. Room membership is
  // required. Reads also require message.read or an active relationship with
  // message.read-interactions. Initial pages include the thread root message; cursor pages
  // return replies in the requested direction.
  rpc GetThreadEvents(GetThreadEventsRequest) returns (GetThreadEventsResponse);
  // Returns a thread timeline window centered around a specific event. Use this
  // to open a reply from a notification or search result in context. Returns
  // NOT_FOUND when the thread root or anchor event is missing or hidden.
  // Returns PERMISSION_DENIED when room membership is missing, both read modes
  // are missing, or an interaction-scoped account has no relationship with the
  // thread.
  rpc GetThreadEventsAround(GetThreadEventsAroundRequest) returns (GetThreadEventsAroundResponse);
  // Marks a thread timeline as read through the supplied event without changing
  // the room-level read marker. Room membership plus message.read or an active
  // relationship with message.read-interactions are required.
  rpc MarkThreadAsRead(MarkThreadAsReadRequest) returns (MarkThreadAsReadResponse);
}

// Request a complete thread participant collection, ordered by user ID ascending.
message ListThreadParticipantsRequest {
  // Room containing the thread.
  string room_id = 1 [(buf.validate.field).string.min_len = 1];
  // Root message ID.
  string thread_root_event_id = 2 [(buf.validate.field).string.min_len = 1];
  // Defaults to 50 results. Maximum: 100. Zero uses the default.
  PageRequest page = 3;
}

// A page of distinct reply authors. An empty thread returns an empty page.
message ListThreadParticipantsResponse {
  // User IDs in this page. Use UserService.BatchGetUsers for profiles.
  repeated string user_ids = 1;
  // Count and continuation for all current participants.
  PageInfo page = 2;
}