export interface PaginatedData<T> {
  items: T[];
  hasMore: boolean;
  /** The whole list's size — only where it's shown (search results). */
  total?: number;
}

/**
 * API response envelope — every endpoint returns this shape.
 */
export type APIResponse<T> =
  | { success: true; data: T }
  | { success: false; error: { message: string } };

/**
 * Parses an unknown JSON payload into a typed APIResponse<T>.
 * Performs a minimal runtime check on the `success` discriminant so the
 * single internal `as` cast is safe; throws if the shape is unexpected.
 */
export function parseAPIResponse<T>(raw: unknown): APIResponse<T> {
  if (raw !== null && typeof raw === "object" && "success" in raw) {
    return raw as APIResponse<T>;
  }
  throw new Error("Unexpected response format");
}

/**
 * Wire types — createdAt/updatedAt arrive as ISO strings from API/WS/localStorage.
 * WithStringDate<T> replaces Date fields with string so we can type raw API responses.
 */
type WithStringDate<T extends { createdAt: Date }> =
  & Omit<T, "createdAt" | "updatedAt">
  & { createdAt: string; updatedAt?: string };

/**
 * Dumps
 */

export interface RichContent {
  type: string;
  url: string;
  siteName?: string;
  title?: string;
  description?: string;
  /** A real preview image — never a favicon. Absent means "no artwork". */
  thumbnailUrl?: string;
  /** The page's own icon, used as the placeholder's glyph. */
  faviconUrl?: string;
  /** The page's declared brand color, normalized to `#rrggbb`. */
  accentColor?: string;
  videoId?: string;
  embedUrl?: string;
}

export interface Dump {
  id: string;
  kind: "url" | "file";
  title: string;
  slug?: string;
  comment?: string;
  userId: string;
  createdAt: Date;
  updatedAt?: Date;
  url?: string;
  richContent?: RichContent;
  fileName?: string;
  fileMime?: string;
  fileSize?: number;
  voteCount: number;
  commentCount: number;
  isPrivate: boolean;
  thumbnailMime?: string;
  categoryIds?: string[];
}

export type RawDump = WithStringDate<Dump>;

/**
 * `GET /api/preview`. `reached` is false when the page could not be fetched, in
 * which case `richContent` is a hostname-only stub rather than real metadata.
 */
export interface UrlPreviewResponse {
  reached: boolean;
  richContent: RichContent | null;
}

/** An existing dump on the same URL, as returned by `GET /api/dumps/by-url`. */
export interface DumpUrlMatch {
  id: string;
  slug?: string;
  title: string;
  username: string;
  createdAt: Date;
  voteCount: number;
  commentCount: number;
}

export type RawDumpUrlMatch = WithStringDate<DumpUrlMatch>;

export function deserializeDumpUrlMatch(raw: RawDumpUrlMatch): DumpUrlMatch {
  return { ...raw, createdAt: new Date(raw.createdAt) };
}

export function deserializeDump(raw: RawDump): Dump {
  return {
    ...raw,
    createdAt: new Date(raw.createdAt),
    updatedAt: raw.updatedAt ? new Date(raw.updatedAt) : undefined,
  };
}

export function hydrateDump(raw: unknown): Dump {
  return deserializeDump(raw as RawDump);
}

/**
 * Categories
 */

export interface Category {
  id: string;
  slug: string;
  name: string;
  position: number;
  createdAt: Date;
  updatedAt?: Date;
}

export type RawCategory = WithStringDate<Category>;

export function deserializeCategory(raw: RawCategory): Category {
  return {
    ...raw,
    createdAt: new Date(raw.createdAt),
    updatedAt: raw.updatedAt ? new Date(raw.updatedAt) : undefined,
  };
}

export interface CreateCategoryRequest {
  slug: string;
  name: string;
  position?: number;
}

export interface UpdateCategoryRequest {
  slug?: string;
  name?: string;
  position?: number;
}

/**
 * Users
 */

export type Role = "user" | "moderator" | "admin";

export interface PublicUser {
  id: string;
  username: string;
  role: Role;
  createdAt: Date;
  updatedAt?: Date;
  avatarMime?: string;
  description?: string;
  invitedByUsername?: string;
  email?: string;
}

// User is the same shape as PublicUser in the frontend; they differ only
// semantically (authenticated self vs. any public profile).
export type User = PublicUser;

export type RawPublicUser = WithStringDate<PublicUser>;
// Alias so imports of RawUser continue to work.
export type RawUser = RawPublicUser;

export function deserializePublicUser(raw: RawPublicUser): PublicUser {
  return {
    ...raw,
    createdAt: new Date(raw.createdAt),
    updatedAt: raw.updatedAt ? new Date(raw.updatedAt) : undefined,
  };
}

// Alias so call sites using deserializeUser continue to work.
export const deserializeUser = deserializePublicUser;

export interface InviteTreeEntry {
  id: string;
  username: string;
  avatarMime?: string;
  invitedById: string;
  createdAt: Date;
}

export type RawInviteTreeEntry = Omit<InviteTreeEntry, "createdAt"> & {
  createdAt: string;
};

export function deserializeInviteTreeEntry(
  raw: RawInviteTreeEntry,
): InviteTreeEntry {
  return { ...raw, createdAt: new Date(raw.createdAt) };
}

/**
 * Authentication
 */

export interface AuthResponse {
  token: string;
  /** Read-only token for media URLs (`?token=`); absent on older sessions. */
  mediaToken?: string;
  user: User;
}

export type RawAuthResponse = Omit<AuthResponse, "user"> & {
  user: RawPublicUser;
};

export function deserializeAuthResponse(raw: RawAuthResponse): AuthResponse {
  return { ...raw, user: deserializePublicUser(raw.user) };
}

/**
 * Comments
 */

export interface Comment {
  id: string;
  dumpId: string;
  userId: string;
  parentId?: string;
  body: string;
  createdAt: Date;
  updatedAt?: Date;
  deleted: boolean;
  likeCount: number;
  authorUsername: string;
  authorAvatarMime?: string;
}

export type RawComment = WithStringDate<Comment>;

export function deserializeComment(raw: RawComment): Comment {
  return {
    ...raw,
    createdAt: new Date(raw.createdAt),
    updatedAt: raw.updatedAt ? new Date(raw.updatedAt) : undefined,
  };
}

/**
 * Chat
 */

export interface ChatMessage {
  id: string;
  userId: string;
  body: string;
  createdAt: Date;
  updatedAt?: Date;
  authorUsername: string;
  authorAvatarMime?: string;
  /** Id of the message this one replies to, if any. Kept even when the target
   * was deleted (the preview fields below then go undefined). */
  replyToId?: string;
  /** Author/snippet of the replied-to message, for a subtle inline reference.
   * Absent when there's no reply, or the target has since been deleted. */
  replyToAuthor?: string;
  replyToBody?: string;
}

export type RawChatMessage = WithStringDate<ChatMessage>;

export function deserializeChatMessage(raw: RawChatMessage): ChatMessage {
  return {
    ...raw,
    createdAt: new Date(raw.createdAt),
    updatedAt: raw.updatedAt ? new Date(raw.updatedAt) : undefined,
  };
}

/**
 * Playlists
 */

export interface Playlist {
  id: string;
  userId: string;
  title: string;
  slug?: string;
  description?: string;
  isPublic: boolean;
  createdAt: Date;
  updatedAt?: Date;
  imageMime?: string;
  dumpCount?: number;
  ownerUsername?: string;
}

export interface PlaylistWithDumps extends Playlist {
  dumps: Dump[];
}

export interface PlaylistMembership {
  playlist: Playlist;
  hasDump: boolean;
}

export type RawPlaylist = WithStringDate<Playlist>;
export type RawPlaylistWithDumps =
  & Omit<WithStringDate<PlaylistWithDumps>, "dumps">
  & { dumps: RawDump[] };
export type RawPlaylistMembership = { playlist: RawPlaylist; hasDump: boolean };

export function deserializePlaylist(raw: RawPlaylist): Playlist {
  return {
    ...raw,
    createdAt: new Date(raw.createdAt),
    updatedAt: raw.updatedAt ? new Date(raw.updatedAt) : undefined,
  };
}

export function deserializePlaylistWithDumps(
  raw: RawPlaylistWithDumps,
): PlaylistWithDumps {
  return {
    ...raw,
    createdAt: new Date(raw.createdAt),
    updatedAt: raw.updatedAt ? new Date(raw.updatedAt) : undefined,
    dumps: raw.dumps.map(deserializeDump),
  };
}

export function deserializePlaylistMembership(
  raw: RawPlaylistMembership,
): PlaylistMembership {
  return { playlist: deserializePlaylist(raw.playlist), hasDump: raw.hasDump };
}

export function hydratePlaylist(raw: unknown): Playlist {
  return deserializePlaylist(raw as RawPlaylist);
}

/**
 * Notifications
 */

export type NotificationType =
  | "playlist_followed"
  | "user_followed"
  | "user_dump_posted"
  | "playlist_dump_added"
  | "dump_upvoted"
  | "user_mentioned"
  | "dump_commented"
  | "comment_liked";

export interface PlaylistFollowedData {
  followerId: string;
  followerUsername: string;
  playlistId: string;
  playlistTitle: string;
}

export interface UserFollowedData {
  followerId: string;
  followerUsername: string;
}

export interface UserDumpPostedData {
  dumperId: string;
  dumperUsername: string;
  dumpId: string;
  dumpTitle: string;
}

export interface PlaylistDumpAddedData {
  dumpId: string;
  dumpTitle: string;
  playlistId: string;
  playlistTitle: string;
}

export interface DumpUpvotedData {
  voterId: string;
  voterUsername: string;
  dumpId: string;
  dumpTitle: string;
}

export interface UserMentionedData {
  mentionerId: string;
  mentionerUsername: string;
  contextType: "comment" | "dump" | "playlist" | "chat";
  contextId: string;
  contextTitle: string;
  dumpId?: string;
}

export interface DumpCommentedData {
  commenterId: string;
  commenterUsername: string;
  commentId: string;
  dumpId: string;
  dumpTitle: string;
}

export interface CommentLikedData {
  likerId: string;
  likerUsername: string;
  commentId: string;
  dumpId: string;
  dumpTitle: string;
}

export type NotificationData =
  | PlaylistFollowedData
  | UserFollowedData
  | UserDumpPostedData
  | PlaylistDumpAddedData
  | DumpUpvotedData
  | UserMentionedData
  | DumpCommentedData
  | CommentLikedData;

export interface Notification {
  id: string;
  userId: string;
  type: NotificationType;
  data: NotificationData;
  read: boolean;
  createdAt: Date;
}

export type RawNotification = WithStringDate<Notification>;

export function deserializeNotification(raw: RawNotification): Notification {
  return { ...raw, createdAt: new Date(raw.createdAt) };
}

/**
 * WebSockets — online presence
 */

export interface OnlineUser {
  userId: string;
  username: string;
  hasAvatar: boolean;
  avatarVersion?: number;
}

/**
 * WebSocket messages — server → client (incoming)
 *
 * All messages share a `type` discriminant so the full union can be narrowed
 * with a switch/case in WSProvider without additional type guards.
 */

export interface WSPingMessage {
  type: "ping";
}
export interface WSWelcomeMessage {
  type: "welcome";
  users: OnlineUser[];
  myVotes: string[];
  myCommentLikes: string[];
  unreadNotificationCount: number;
  chatReadAt?: string;
  unreadChatCount: number;
}
export interface WSPresenceUpdateMessage {
  type: "presence_update";
  users: OnlineUser[];
}
export interface WSVotesUpdateMessage {
  type: "votes_update";
  dumpId: string;
  voteCount: number;
  voterId: string;
  action: "cast" | "remove";
}
export interface WSVoteAckMessage {
  type: "vote_ack";
  dumpId: string;
  action: "cast" | "remove";
  voteCount: number;
}
export interface WSCommentLikesUpdateMessage {
  type: "comment_likes_update";
  commentId: string;
  likeCount: number;
  likerId: string;
  action: "cast" | "remove";
}
export interface WSCommentLikeAckMessage {
  type: "comment_like_ack";
  commentId: string;
  action: "cast" | "remove";
  likeCount: number;
}
export interface WSDumpCreatedMessage {
  type: "dump_created";
  dump: RawDump;
}
export interface WSDumpUpdatedMessage {
  type: "dump_updated";
  dump: RawDump;
}
export interface WSDumpDeletedMessage {
  type: "dump_deleted";
  dumpId: string;
}
export interface WSPlaylistCreatedMessage {
  type: "playlist_created";
  playlist: RawPlaylist;
}
export interface WSPlaylistUpdatedMessage {
  type: "playlist_updated";
  playlist: RawPlaylist;
}
export interface WSPlaylistDeletedMessage {
  type: "playlist_deleted";
  playlistId: string;
  userId: string;
}
export interface WSPlaylistDumpsUpdatedMessage {
  type: "playlist_dumps_updated";
  playlistId: string;
  /** The members this recipient can see, in order. */
  dumpIds: string[];
  /** Every member, as Playlist.dumpCount counts them. */
  dumpCount: number;
}
export interface WSUserUpdatedMessage {
  type: "user_updated";
  user: RawPublicUser;
}
export interface WSCommentCreatedMessage {
  type: "comment_created";
  comment: RawComment;
}
export interface WSCommentUpdatedMessage {
  type: "comment_updated";
  comment: RawComment;
}
export interface WSCommentDeletedMessage {
  type: "comment_deleted";
  commentId: string;
  dumpId: string;
}
export interface WSNotificationCreatedMessage {
  type: "notification_created";
  notification: RawNotification;
}
export interface WSErrorMessage {
  type: "error";
  message?: string;
  // Context for optimistic-action failures so the client can revert the exact
  // pending vote/like immediately instead of waiting for its ACK timeout.
  dumpId?: string;
  commentId?: string;
  action?: "cast" | "remove";
  /** Set when a chat action failed, so it can be surfaced in the chat. */
  scope?: "chat";
  /** Echo of the failed chat_send's nonce. */
  nonce?: string;
}

export interface WSForceLogoutMessage {
  type: "force_logout";
}

export interface WSChatMessageMessage {
  type: "chat_message";
  message: RawChatMessage;
  nonce?: string;
}

export interface WSChatMessageUpdatedMessage {
  type: "chat_message_updated";
  message: RawChatMessage;
}

export interface WSChatMessageDeletedMessage {
  type: "chat_message_deleted";
  id: string;
}

export interface WSChatTypingUpdateMessage {
  type: "chat_typing_update";
  users: OnlineUser[];
}

export interface WSChatReadUpdateMessage {
  type: "chat_read_update";
  readAt: string;
  unread: number;
}

export type IncomingWSMessage =
  | WSPingMessage
  | WSWelcomeMessage
  | WSPresenceUpdateMessage
  | WSVotesUpdateMessage
  | WSVoteAckMessage
  | WSCommentLikesUpdateMessage
  | WSCommentLikeAckMessage
  | WSDumpCreatedMessage
  | WSDumpUpdatedMessage
  | WSDumpDeletedMessage
  | WSPlaylistCreatedMessage
  | WSPlaylistUpdatedMessage
  | WSPlaylistDeletedMessage
  | WSPlaylistDumpsUpdatedMessage
  | WSUserUpdatedMessage
  | WSCommentCreatedMessage
  | WSCommentUpdatedMessage
  | WSCommentDeletedMessage
  | WSNotificationCreatedMessage
  | WSErrorMessage
  | WSForceLogoutMessage
  | WSChatMessageMessage
  | WSChatMessageUpdatedMessage
  | WSChatMessageDeletedMessage
  | WSChatTypingUpdateMessage
  | WSChatReadUpdateMessage;

/**
 * WebSocket messages — client → server (outgoing)
 */

export interface WSPongMessage {
  type: "pong";
}
export interface WSVoteCastMessage {
  type: "vote_cast";
  dumpId: string;
}
export interface WSVoteRemoveMessage {
  type: "vote_remove";
  dumpId: string;
}
export interface WSCommentLikeCastMessage {
  type: "comment_like_cast";
  commentId: string;
}
export interface WSCommentLikeRemoveMessage {
  type: "comment_like_remove";
  commentId: string;
}

export interface WSChatSendMessage {
  type: "chat_send";
  body: string;
  replyToId?: string;
  nonce?: string;
}

export interface WSChatTypingMessage {
  type: "chat_typing";
  typing: boolean;
}

export interface WSChatFocusMessage {
  type: "chat_focus";
  open: boolean;
}

export interface WSChatEditMessage {
  type: "chat_edit";
  id: string;
  body: string;
}

export interface WSChatDeleteMessage {
  type: "chat_delete";
  id: string;
}

export interface WSChatReadMessage {
  type: "chat_read";
  at: string;
}

export type OutgoingWSMessage =
  | WSPongMessage
  | WSVoteCastMessage
  | WSVoteRemoveMessage
  | WSCommentLikeCastMessage
  | WSCommentLikeRemoveMessage
  | WSChatSendMessage
  | WSChatTypingMessage
  | WSChatFocusMessage
  | WSChatEditMessage
  | WSChatDeleteMessage
  | WSChatReadMessage;

/**
 * Follows
 */

export interface FollowStatus {
  followedUserIds: string[];
  followedPlaylistIds: string[];
}

/**
 * Request DTOs
 */

export interface LoginRequest {
  username: string;
  password: string;
}

export interface RegisterRequest {
  username: string;
  password: string;
  inviteToken: string;
  email: string;
}

export interface CreateUrlDumpRequest {
  url: string;
  /** Overrides the title scraped from the page — the poster edited the preview. */
  title?: string;
  comment?: string;
  isPrivate?: boolean;
  categoryIds?: string[];
}

export interface UpdateDumpRequest {
  url?: string;
  title?: string;
  /** `null` removes the note; leaving it out keeps it. */
  comment?: string | null;
  isPrivate?: boolean;
  categoryIds?: string[];
}

export interface CreateCommentRequest {
  body: string;
  parentId?: string;
}

export interface UpdateCommentRequest {
  body: string;
}

export interface CreatePlaylistRequest {
  title: string;
  description?: string;
  isPublic: boolean;
}

export interface UpdatePlaylistRequest {
  title?: string;
  description?: string | null;
  isPublic?: boolean;
}

export interface ReorderPlaylistRequest {
  dumpIds: string[];
}

export interface UpdateUserRequest {
  description?: string;
  email?: string;
}