/**
 * Live updates, votes, likes and the chat travel over one WebSocket between
 * `WSProvider` in the client and `routes/ws.ts` in the server. This module
 * types its messages, JSON objects told apart by `type`.
 *
 * The server's messages go out from `services/ws-service.ts`, and `WSProvider`
 * handles them. Their Dates arrive as strings, so the client reads them as
 * `Wire<ServerToClientMessage>` and deserializes what it keeps.
 *
 * @module
 */

import type { ChatMessage } from "./chat.ts";
import type { Comment } from "./comment.ts";
import type { Dump } from "./dump.ts";
import type { Notification } from "./notification.ts";
import type { Playlist } from "./playlist.ts";
import type { PublicUser } from "./user.ts";

/**
 * Sent by the server to every socket every 30 s. `WSProvider` answers
 * {@link PongMessage}, and a socket that missed the previous ping is closed.
 * The server also answers a client's ping, though the client never sends one.
 */
export interface PingMessage {
  type: "ping";
}

/**
 * Sent in answer to a {@link PingMessage}. The server records the client's to
 * keep its socket open, and the client ignores the server's.
 */
export interface PongMessage {
  type: "pong";
}

/**
 * Sent by `WSProvider` when the user upvotes a dump, after it has shown the
 * vote. The server answers {@link VoteAckMessage}, or an {@link ErrorMessage}
 * naming the dump, on which the client undoes the vote, as it does when
 * neither comes within 5 s.
 */
export interface VoteCastMessage {
  type: "vote_cast";
  dumpId: string;
}

/** Sent by `WSProvider` to withdraw an upvote, as {@link VoteCastMessage}. */
export interface VoteRemoveMessage {
  type: "vote_remove";
  dumpId: string;
}

/**
 * Sent by `WSProvider` when the user likes a comment, and handled as
 * {@link VoteCastMessage} is, with {@link CommentLikeAckMessage} for the ack.
 */
export interface CommentLikeCastMessage {
  type: "comment_like_cast";
  commentId: string;
}

/**
 * Sent by `WSProvider` to withdraw a like, as {@link CommentLikeCastMessage}.
 */
export interface CommentLikeRemoveMessage {
  type: "comment_like_remove";
  commentId: string;
}

/**
 * Sent by `WSProvider` when the user posts in the chatbox, which shows the
 * message as pending meanwhile. The server broadcasts it as
 * {@link ChatMessageMessage}, or answers a chat {@link ErrorMessage}.
 */
export interface ChatSendMessage {
  type: "chat_send";
  body: string;
  /** Ignored if longer than 64 characters or naming no message. */
  replyToId?: string;
  /**
   * Chosen by the client, and echoed on the broadcast or the error, so that
   * it can match the outcome to its pending message. Ignored if longer than
   * 64 characters.
   */
  nonce?: string;
}

/**
 * Sent by the chatbox while the user types, every 3 s, and once they pause.
 * The server answers every signed-in socket with
 * {@link ChatTypingUpdateMessage} when the user starts or stops, and forgets a
 * typer it hasn't heard from in 6 s.
 */
export interface ChatTypingMessage {
  type: "chat_typing";
  typing: boolean;
}

/**
 * Sent by `WSProvider` when the chatbox opens or closes, when the tab is
 * hidden or shown, and after each `welcome`. The server notifies no one of a
 * chat mention while one of their sockets says `open`.
 */
export interface ChatFocusMessage {
  type: "chat_focus";
  /** True only while the chatbox is open in a visible tab. */
  open: boolean;
}

/**
 * Sent by `WSProvider` when the user edits a chat message, their own or, with
 * `chat:moderate`, anyone's. The server broadcasts
 * {@link ChatMessageUpdatedMessage}, or answers a chat {@link ErrorMessage}.
 */
export interface ChatEditMessage {
  type: "chat_edit";
  id: string;
  body: string;
}

/**
 * Sent by `WSProvider` when the user deletes a chat message, as
 * {@link ChatEditMessage}. The server broadcasts
 * {@link ChatMessageDeletedMessage}.
 */
export interface ChatDeleteMessage {
  type: "chat_delete";
  id: string;
}

/**
 * Sent by `WSProvider`, at most once a second, as the user reads the chat. The
 * server moves their read marker to `at`, a message's ISO `createdAt`, and
 * answers {@link ChatReadUpdateMessage}. It drops the message silently when it
 * is malformed or over its rate limit.
 */
export interface ChatReadMessage {
  type: "chat_read";
  at: string;
}

/**
 * Sent by `WSProvider`, and dispatched by the route's `handleMessage`, which
 * checks each field's type before using it.
 */
export type ClientToServerMessage =
  | PingMessage
  | PongMessage
  | VoteCastMessage
  | VoteRemoveMessage
  | CommentLikeCastMessage
  | CommentLikeRemoveMessage
  | ChatSendMessage
  | ChatTypingMessage
  | ChatFocusMessage
  | ChatEditMessage
  | ChatDeleteMessage
  | ChatReadMessage;

/**
 * Sent by the server in {@link WelcomeMessage},
 * {@link PresenceUpdateMessage} and {@link ChatTypingUpdateMessage}, once per
 * signed-in user whatever their number of sockets.
 */
export interface OnlineUser {
  userId: string;
  username: string;
  hasAvatar: boolean;
  /**
   * Set when the avatar changed while the user was connected, for the client
   * to append to the avatar's URL so it doesn't show the cached one.
   */
  avatarVersion?: number;
}

/**
 * Sent by the server to a socket once it opens, just after the
 * {@link PresenceUpdateMessage} that announces it. `WSProvider` replaces its
 * state with this one, dropping its pending votes and likes. After a
 * reconnect, it also bumps `connectionEpoch`, so that pages refetch what they
 * missed. The per-user fields are empty or zero on an anonymous socket.
 */
export interface WelcomeMessage {
  type: "welcome";
  users: OnlineUser[];
  myVotes: string[];
  myCommentLikes: string[];
  unreadNotificationCount: number;
  /** Absent on an anonymous socket. */
  chatReadAt?: string;
  unreadChatCount: number;
}

/**
 * Sent by the server to every socket when a socket opens or closes, and when
 * a connected user's avatar changes.
 */
export interface PresenceUpdateMessage {
  type: "presence_update";
  users: OnlineUser[];
}

/**
 * Sent by the server after a vote, to every socket, or to the poster's alone
 * for a private dump. `WSProvider` updates the count, and when `voterId` is
 * the user, it updates their votes too, so their other tabs follow.
 */
export interface VotesUpdateMessage {
  type: "votes_update";
  dumpId: string;
  voteCount: number;
  voterId: string;
  action: "cast" | "remove";
}

/**
 * Sent by the server to the socket that sent a {@link VoteCastMessage} or
 * {@link VoteRemoveMessage}, once the vote is stored. `WSProvider` confirms
 * its optimistic vote with it.
 */
export interface VoteAckMessage {
  type: "vote_ack";
  dumpId: string;
  action: "cast" | "remove";
  voteCount: number;
}

/**
 * Sent by the server after a like, as {@link VotesUpdateMessage} is after a
 * vote: to the dump's poster alone when the comment is on a private dump.
 */
export interface CommentLikesUpdateMessage {
  type: "comment_likes_update";
  commentId: string;
  likeCount: number;
  likerId: string;
  action: "cast" | "remove";
}

/**
 * Sent by the server to the socket that liked or unliked a comment, as
 * {@link VoteAckMessage} is for a vote.
 */
export interface CommentLikeAckMessage {
  type: "comment_like_ack";
  commentId: string;
  action: "cast" | "remove";
  likeCount: number;
}

/**
 * Sent by the server when a dump is posted, to every socket if it is public
 * and to its poster's alone if it is private. It also goes to everyone but the
 * poster when a private dump goes public, since to them it is new.
 * `WSProvider` puts it at the top of its recent dumps.
 */
export interface DumpCreatedMessage {
  type: "dump_created";
  dump: Dump;
}

/**
 * Sent by the server when a dump changes, to every socket if it is public and
 * to its poster's alone if it is private, as when it has just gone private.
 * `WSProvider` refreshes it in place, without moving it up the feeds.
 */
export interface DumpUpdatedMessage {
  type: "dump_updated";
  dump: Dump;
}

/**
 * Sent by the server when a dump is deleted, to every socket if it was public
 * and to its poster's alone if it was private. It also goes to everyone but
 * the poster when a public dump goes private. `WSProvider` drops it from every
 * list.
 */
export interface DumpDeletedMessage {
  type: "dump_deleted";
  dumpId: string;
}

/**
 * Sent by the server when the dumps related to some dumps changed: a note or
 * a comment gained or lost a link to a dump, or a dump that has such links
 * turned public. It goes to the sockets whose user may see both ends of a
 * link. The `Dump` page showing one of `dumpIds` fetches its related dumps
 * again.
 */
export interface DumpRelatedChangedMessage {
  type: "dump_related_changed";
  /**
   * The dump whose links changed, then the dumps at their other end, without
   * those this socket's user may not see.
   */
  dumpIds: string[];
}

/**
 * Sent by the server when a playlist is created, to every socket if it is
 * public, else to its owner's. It also goes to everyone but the owner when a
 * private playlist goes public, since to them it is new. `WSProvider` passes
 * it on to the playlist pages as a `playlist` event, as it does the three
 * messages below.
 */
export interface PlaylistCreatedMessage {
  type: "playlist_created";
  playlist: Playlist;
}

/**
 * Sent by the server when a playlist changes, to every socket if it is public,
 * else to its owner's, as when it has just gone private. Its `dumpCount` and
 * `lastDumpAt` are the socket's user's, as in `playlist_created`.
 */
export interface PlaylistUpdatedMessage {
  type: "playlist_updated";
  playlist: Playlist;
}

/**
 * Sent by the server when a playlist is deleted, to those who could see it. It
 * also goes to everyone but the owner when a public playlist goes private.
 */
export interface PlaylistDeletedMessage {
  type: "playlist_deleted";
  playlistId: string;
  userId: string;
}

/**
 * Sent by the server when dumps are added to, removed from or reordered in a
 * playlist, to those who can see it, and when one of its dumps is deleted or
 * changes visibility, which changes what its viewers see of it.
 */
export interface PlaylistDumpsUpdatedMessage {
  type: "playlist_dumps_updated";
  playlistId: string;
  /**
   * Only the dumps this socket's user may see, in order: another user's
   * private dump is left out.
   */
  dumpIds: string[];
  /**
   * When the latest of them was added, the playlist's `lastDumpAt` for this
   * socket's user. It is missing when `dumpIds` is empty.
   */
  lastDumpAt?: Date;
}

/**
 * Sent by the server to every socket after a profile edit, a rename, a role
 * change or an avatar upload. `WSProvider` refreshes the user's avatar
 * wherever it shows, and passes it on as a `user` event, which updates their
 * profile and their name on the lists.
 */
export interface UserUpdatedMessage {
  type: "user_updated";
  user: PublicUser;
}

/**
 * Sent by the server when a comment is posted, to every socket if its dump is
 * public, else to the dump's poster's. `WSProvider` passes it on to the dump's
 * page and the dump lists as a `comment` event, as it does the two messages
 * below.
 */
export interface CommentCreatedMessage {
  type: "comment_created";
  comment: Comment;
}

/** Sent by the server when a comment is edited, as when one is posted. */
export interface CommentUpdatedMessage {
  type: "comment_updated";
  comment: Comment;
}

/** Sent by the server when a comment is deleted, as when one is posted. */
export interface CommentDeletedMessage {
  type: "comment_deleted";
  commentId: string;
  /** Lets a dump's page ignore the comments of other dumps. */
  dumpId: string;
}

/**
 * Sent by the notification service to every socket of the notified user.
 * `WSProvider` bumps the unread count and chimes.
 */
export interface NotificationCreatedMessage {
  type: "notification_created";
  notification: Notification;
}

/**
 * Sent by the notification service to every socket of a user who opened their
 * notifications, which marks them all read. `WSProvider` zeroes the bell's
 * count, in the other tabs and devices too.
 */
export interface NotificationsReadMessage {
  type: "notifications_read";
}

/**
 * Sent by the category service to every socket after a category is created,
 * edited or deleted. `CategoriesProvider` fetches the categories again.
 */
export interface CategoriesChangedMessage {
  type: "categories_changed";
}

/**
 * Sent by the server to the socket whose message failed. With `dumpId` or
 * `commentId`, `WSProvider` undoes that optimistic vote or like at once rather
 * than after its 5 s timeout. With `scope`, the chatbox shows it, on the
 * pending message `nonce` names or as a notice. Any other error is ignored.
 */
export interface ErrorMessage {
  type: "error";
  /** In English: the chatbox shows it untranslated. */
  message?: string;
  dumpId?: string;
  commentId?: string;
  action?: "cast" | "remove";
  scope?: "chat";
  /** Set only on the failure of a {@link ChatSendMessage} that had one. */
  nonce?: string;
}

/**
 * Sent by the server to every signed-in socket, the sender's included, when a
 * chat message is posted. `WSProvider` adds it to the live chat, counts it
 * unread unless the user is reading the chat, and may chime.
 */
export interface ChatMessageMessage {
  type: "chat_message";
  message: ChatMessage;
  /**
   * The sender's {@link ChatSendMessage} nonce, by which its client swaps the
   * pending copy for this one.
   */
  nonce?: string;
}

/**
 * Sent by the server to every signed-in socket when a chat message is edited.
 */
export interface ChatMessageUpdatedMessage {
  type: "chat_message_updated";
  message: ChatMessage;
}

/**
 * Sent by the server to every signed-in socket when a chat message is deleted.
 * The client also keeps the id, to show the replies to it as replies to a
 * deleted message.
 */
export interface ChatMessageDeletedMessage {
  type: "chat_message_deleted";
  id: string;
}

/**
 * Sent by the server to every signed-in socket when a user starts or stops
 * typing in the chat, with everyone typing. The chatbox shows their avatars.
 */
export interface ChatTypingUpdateMessage {
  type: "chat_typing_update";
  users: OnlineUser[];
}

/**
 * Sent by the server to every socket of a user after their
 * {@link ChatReadMessage}, so that all their tabs and devices update the chat's
 * badge.
 */
export interface ChatReadUpdateMessage {
  type: "chat_read_update";
  readAt: string;
  /** Counts only the messages of other users after `readAt`. */
  unread: number;
}

/**
 * Sent by the server to every socket of a user who followed or unfollowed a
 * user or a playlist, so that `FollowProvider` in their other tabs refetches
 * the follow status.
 */
export interface FollowsChangedMessage {
  type: "follows_changed";
}

/**
 * Sent by `services/ws-service.ts` and the WebSocket route, and handled by
 * `WSProvider`'s `onmessage`.
 */
export type ServerToClientMessage =
  | PingMessage
  | PongMessage
  | WelcomeMessage
  | PresenceUpdateMessage
  | VotesUpdateMessage
  | VoteAckMessage
  | CommentLikesUpdateMessage
  | CommentLikeAckMessage
  | DumpCreatedMessage
  | DumpUpdatedMessage
  | DumpDeletedMessage
  | DumpRelatedChangedMessage
  | PlaylistCreatedMessage
  | PlaylistUpdatedMessage
  | PlaylistDeletedMessage
  | PlaylistDumpsUpdatedMessage
  | UserUpdatedMessage
  | CommentCreatedMessage
  | CommentUpdatedMessage
  | CommentDeletedMessage
  | NotificationCreatedMessage
  | NotificationsReadMessage
  | CategoriesChangedMessage
  | ErrorMessage
  | ChatMessageMessage
  | ChatMessageUpdatedMessage
  | ChatMessageDeletedMessage
  | ChatTypingUpdateMessage
  | ChatReadUpdateMessage
  | FollowsChangedMessage;