/**
 * Backend
 */

// ── Validation constants (shared with frontend via src/config/api.ts) ──────────
export const VALIDATION = {
  USERNAME_MIN: 1,
  USERNAME_MAX: 32,
  PASSWORD_MIN: 8,
  PASSWORD_MAX: 128,
  DUMP_TITLE_MAX: 200,
  DUMP_COMMENT_MAX: 5000,
  PLAYLIST_TITLE_MAX: 100,
  PLAYLIST_DESCRIPTION_MAX: 2000,
  COMMENT_BODY_MAX: 5000,
  USER_DESCRIPTION_MAX: 2000,
} as const;

export interface RichContent {
  type: string;
  url: string;
  siteName?: string;
  title?: string;
  description?: string;
  thumbnailUrl?: 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;
}

/**
 * Authentication
 */

export interface User {
  id: string;
  username: string;
  passwordHash: string;
  isAdmin: boolean;
  createdAt: Date;
  updatedAt?: Date;
  avatarMime?: string;
  description?: string;
  invitedByUsername?: string;
}

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

export interface RegisterUserRequest {
  username: string;
  password: string;
  inviteToken: string;
}

export interface UpdateUserRequest {
  username?: string;
  password?: string;
  isAdmin?: boolean;
  description?: string | null;
}

export function isLoginUserRequest(obj: unknown): obj is LoginUserRequest {
  return !!obj && typeof obj === "object" &&
    "username" in obj && typeof obj.username === "string" &&
    "password" in obj && typeof obj.password === "string";
}

export function isRegisterUserRequest(
  obj: unknown,
): obj is RegisterUserRequest {
  if (
    !obj || typeof obj !== "object" ||
    !("username" in obj) || typeof obj.username !== "string" ||
    !("password" in obj) || typeof obj.password !== "string" ||
    !("inviteToken" in obj) || typeof obj.inviteToken !== "string"
  ) return false;
  const { username, password } = obj as RegisterUserRequest;
  return /^[a-zA-Z0-9_]{1,32}$/.test(username) &&
    password.length >= VALIDATION.PASSWORD_MIN &&
    password.length <= VALIDATION.PASSWORD_MAX;
}

export function isUpdateUserRequest(obj: unknown): obj is UpdateUserRequest {
  if (!obj || typeof obj !== "object") return false;
  const o = obj as Record<string, unknown>;
  if ("username" in o) {
    if (typeof o.username !== "string") return false;
    if (!/^[a-zA-Z0-9_]{1,32}$/.test(o.username as string)) return false;
  }
  if ("password" in o) {
    if (typeof o.password !== "string") return false;
    const len = (o.password as string).length;
    if (len < VALIDATION.PASSWORD_MIN || len > VALIDATION.PASSWORD_MAX) {
      return false;
    }
  }
  if ("isAdmin" in o && typeof o.isAdmin !== "boolean") return false;
  if (
    "description" in o && typeof o.description !== "string" &&
    o.description !== null
  ) return false;
  if (
    typeof o.description === "string" &&
    (o.description as string).length > VALIDATION.USER_DESCRIPTION_MAX
  ) return false;
  return true;
}

export interface AuthResponse {
  token: string;
  user: User;
}

export interface AuthPayload {
  userId: string;
  username: string;
  isAdmin: boolean;
  exp: number;
}

export function isAuthPayload(obj: unknown): obj is AuthPayload {
  return !!obj &&
    typeof obj === "object" &&
    "userId" in obj && typeof obj.userId === "string" &&
    "username" in obj && typeof obj.username === "string" &&
    "isAdmin" in obj && typeof obj.isAdmin === "boolean" &&
    "exp" in obj && typeof obj.exp === "number";
}

export interface InvitePayload {
  purpose: "invite";
  inviterId: string;
  exp: number;
}

export function isInvitePayload(obj: unknown): obj is InvitePayload {
  return !!obj && typeof obj === "object" &&
    "purpose" in obj && (obj as Record<string, unknown>).purpose === "invite" &&
    "inviterId" in obj &&
    typeof (obj as Record<string, unknown>).inviterId === "string";
}

/**
 * API
 */

export enum APIErrorCode {
  BAD_REQUEST = "BAD_REQUEST",
  NOT_FOUND = "NOT_FOUND",
  SERVER_ERROR = "SERVER_ERROR",
  TIMEOUT = "TIMEOUT",
  UNAUTHORIZED = "UNAUTHORIZED",
  VALIDATION_ERROR = "VALIDATION_ERROR",
}

export interface APIError {
  code: APIErrorCode;
  message: string;
}

export interface APISuccess<T> {
  success: true;
  data: T;
  error?: never;
}

export interface APIFailure {
  success: false;
  data?: never;
  error: APIError;
}

export type APIResponse<T> = APISuccess<T> | APIFailure;

export interface PaginatedData<T> {
  items: T[];
  total: number;
  hasMore: boolean;
}

export class APIException extends Error {
  readonly code: APIErrorCode;
  readonly status: number;

  constructor(code: APIErrorCode, status: number, message: string) {
    super(message);
    this.code = code;
    this.status = status;
  }
}

/**
 * Comments
 */

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

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

export function isCreateCommentRequest(
  obj: unknown,
): obj is CreateCommentRequest {
  if (!obj || typeof obj !== "object") return false;
  const o = obj as Record<string, unknown>;
  return typeof o.body === "string" &&
    (o.body as string).trim().length > 0 &&
    (o.body as string).length <= VALIDATION.COMMENT_BODY_MAX &&
    (!("parentId" in o) || typeof o.parentId === "string" ||
      o.parentId === null);
}

export interface UpdateCommentRequest {
  body: string;
}

export function isUpdateCommentRequest(
  obj: unknown,
): obj is UpdateCommentRequest {
  if (!obj || typeof obj !== "object") return false;
  const o = obj as Record<string, unknown>;
  return typeof o.body === "string" &&
    (o.body as string).trim().length > 0 &&
    (o.body as string).length <= VALIDATION.COMMENT_BODY_MAX;
}

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

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

export interface ReorderPlaylistRequest {
  dumpIds: string[];
}

export function isCreatePlaylistRequest(
  obj: unknown,
): obj is CreatePlaylistRequest {
  if (
    !obj || typeof obj !== "object" ||
    !("title" in obj) || typeof obj.title !== "string" ||
    !("isPublic" in obj) || typeof obj.isPublic !== "boolean"
  ) return false;
  const o = obj as Record<string, unknown>;
  if ((o.title as string).length === 0 || (o.title as string).length > VALIDATION.PLAYLIST_TITLE_MAX) return false;
  if (
    "description" in o && typeof o.description !== "string" &&
    o.description !== null
  ) return false;
  if (
    typeof o.description === "string" &&
    (o.description as string).length > VALIDATION.PLAYLIST_DESCRIPTION_MAX
  ) return false;
  return true;
}

export function isUpdatePlaylistRequest(
  obj: unknown,
): obj is UpdatePlaylistRequest {
  if (!obj || typeof obj !== "object") return false;
  const o = obj as Record<string, unknown>;
  if ("title" in o) {
    if (typeof o.title !== "string") return false;
    if ((o.title as string).length === 0 || (o.title as string).length > VALIDATION.PLAYLIST_TITLE_MAX) return false;
  }
  if (
    "description" in o && typeof o.description !== "string" &&
    o.description !== null
  ) return false;
  if (
    typeof o.description === "string" &&
    (o.description as string).length > VALIDATION.PLAYLIST_DESCRIPTION_MAX
  ) return false;
  if ("isPublic" in o && typeof o.isPublic !== "boolean") return false;
  return true;
}

export function isReorderPlaylistRequest(
  obj: unknown,
): obj is ReorderPlaylistRequest {
  return !!obj && typeof obj === "object" &&
    "dumpIds" in obj && Array.isArray(obj.dumpIds) &&
    (obj.dumpIds as unknown[]).every((id) => typeof id === "string");
}

/**
 * Request DTOs
 */

export interface CreateUrlDumpRequest {
  url: string;
  comment?: string;
  isPrivate?: boolean;
}

export function isCreateUrlDumpRequest(
  obj: unknown,
): obj is CreateUrlDumpRequest {
  if (
    !obj || typeof obj !== "object" ||
    !("url" in obj) || typeof obj.url !== "string"
  ) return false;
  const o = obj as Record<string, unknown>;
  if (
    "comment" in o && typeof o.comment !== "string" && o.comment !== null
  ) return false;
  if (
    typeof o.comment === "string" &&
    (o.comment as string).length > VALIDATION.DUMP_COMMENT_MAX
  ) return false;
  if ("isPrivate" in o && typeof o.isPrivate !== "boolean") return false;
  return true;
}

export interface UpdateDumpRequest {
  url?: string;
  comment?: string;
  isPrivate?: boolean;
}

export function isUpdateDumpRequest(obj: unknown): obj is UpdateDumpRequest {
  if (!obj || typeof obj !== "object") return false;
  const o = obj as Record<string, unknown>;
  if ("url" in o && typeof o.url !== "string" && o.url !== null) return false;
  if (
    "comment" in o && typeof o.comment !== "string" && o.comment !== null
  ) return false;
  if (
    typeof o.comment === "string" &&
    (o.comment as string).length > VALIDATION.DUMP_COMMENT_MAX
  ) return false;
  if ("isPrivate" in o && typeof o.isPrivate !== "boolean") return false;
  return true;
}

/**
 * WebSockets
 */

export interface VoteCastMessage {
  type: "vote_cast";
  dumpId: string;
  userId: string;
}

export interface VoteAckMessageFailure {
  type: "vote_ack";
  dumpId: string;
  success: false;
  error: APIError;
}

export interface VoteAckMessageSuccess {
  type: "vote_ack";
  dumpId: string;
  action: "cast" | "remove";
  success: true;
  voteCount: number;
  error?: never;
}

export type VoteAckMessage = VoteAckMessageSuccess | VoteAckMessageFailure;

export interface VoteRemoveMessage {
  type: "vote_remove";
  dumpId: string;
}

export interface VotesUpdateMessage {
  type: "votes_update";
  dumpId: string;
  voteCount: number;
}

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

export interface WelcomeMessage {
  type: "welcome";
  users: OnlineUser[];
  myVotes: string[];
}

export interface PresenceUpdateMessage {
  type: "presence_update";
  users: OnlineUser[];
}

export interface PingMessage {
  type: "ping";
}

export interface PongMessage {
  type: "pong";
}

/**
 * Follows
 */

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

/**
 * Notifications
 */

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

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";
  contextId: string;
  contextTitle: string;
  dumpId?: string;
}

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

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