export class ApiError extends Error {
  constructor(status, message, requestId = "") {
    super(message);
    this.status = status;
    this.requestId = requestId;
  }

  get isNetworkError() {
    return this.status === 0;
  }
}

export function describeError(error) {
  const message = error && error.message ? error.message : "Something went wrong.";
  const alreadyReferenced = message.includes("reference");
  if (error instanceof ApiError && error.requestId && error.status >= 500 && !alreadyReferenced) {
    return `${message} (reference ${error.requestId})`;
  }
  return message;
}

const unauthorizedListeners = new Set();

export function onUnauthorized(listener) {
  unauthorizedListeners.add(listener);
}

function parseBody(text) {
  if (!text) return null;
  try {
    return JSON.parse(text);
  } catch {
    return null;
  }
}

function fallbackMessage(status) {
  if (status === 502 || status === 503 || status === 504) {
    return `The server is not responding right now (${status}). Try again in a moment.`;
  }
  if (status === 413) return "The request was too large.";
  return `Request failed (${status}).`;
}

async function send(path, options) {
  try {
    return await fetch(path, options);
  } catch {
    throw new ApiError(0, "Cannot reach the server. Check your connection.");
  }
}

async function request(method, path, body) {
  const options = { method, credentials: "same-origin", headers: {} };
  if (body !== undefined) {
    options.headers["Content-Type"] = "application/json";
    options.body = JSON.stringify(body);
  }

  const response = await send(path, options);
  let text = "";
  try {
    text = await response.text();
  } catch {
    throw new ApiError(0, "The connection dropped while reading the server response.");
  }
  const data = parseBody(text);

  if (!response.ok) {
    if (response.status === 401 && path !== "/api/login") {
      unauthorizedListeners.forEach((listener) => listener());
    }
    const message = data && data.error ? data.error : fallbackMessage(response.status);
    const requestId = (data && data.requestId) || response.headers.get("X-Request-ID") || "";
    throw new ApiError(response.status, message, requestId);
  }
  return data;
}

function jobPath(id, suffix = "") {
  return `/api/jobs/${encodeURIComponent(id)}${suffix}`;
}

export const api = {
  session: () => request("GET", "/api/session"),
  login: (username, password) => request("POST", "/api/login", { username, password }),
  logout: () => request("POST", "/api/logout", {}),
  libraries: () => request("GET", "/api/libraries"),
  disk: () => request("GET", "/api/disk"),
  settings: () => request("GET", "/api/settings"),
  saveSettings: (settings) => request("POST", "/api/settings", settings),
  jobs: () => request("GET", "/api/jobs"),
  createJob: (payload) => request("POST", "/api/jobs", payload),
  files: (id) => request("GET", jobPath(id, "/files")),
  extract: (id, path) => request("POST", jobPath(id, "/extract"), { path }),
  move: (id, payload) => request("POST", jobPath(id, "/move"), payload),
  pause: (id) => request("POST", jobPath(id, "/pause"), {}),
  resume: (id) => request("POST", jobPath(id, "/resume"), {}),
  reorder: (id, direction) => request("POST", jobPath(id, "/queue"), { direction }),
  remove: (id) => request("DELETE", jobPath(id)),
  history: () => request("GET", "/api/history"),
  clearHistory: () => request("DELETE", "/api/history"),
};