import Cookies from "js-cookie";
import Vue from "vue";

type HTTPMethod = "GET" | "POST" | "PUT" | "PATCH";

export class APIError extends Error {
  constructor(message: string, public readonly errors: unknown) {
    super(message);
  }
}

async function api_request(
  method: HTTPMethod,
  endpoint: string,
  successStatus: number,
  data?: any,
  authToken?: string
) {
  const init = {
    headers: new Headers(),
    method: method,
    body: JSON.stringify(data),
  };
  const csrfToken = Cookies.get("csrftoken");
  if (csrfToken != undefined) {
    init.headers.set("X-CSRFToken", csrfToken);
  }
  if (authToken != undefined) {
    init.headers.set("Authorization", `Token ${authToken}`);
  }
  init.headers.set("Accept", "application/json");
  init.headers.set("Content-Type", "application/json");
  const response = await fetch(`/api/${endpoint}/`, init);
  if (response.status !== 204) {
    if (response.status === successStatus) {
      return await response.json();
    } else {
      throw new APIError(response.statusText, await response.json());
    }
  }
}

export class User {
  pk: number | undefined;
  password: string | undefined;
  username: string | null = null;
  isAuthenticated = false;
  isTrusted = false;

  /**
   * Activate the corresponding LDAP account.
   */
  async activate(): Promise<void> {
    await api_request("POST", `users/${this.pk}/activate`, 204, {
      password: this.password,
    });
  }

  async login(): Promise<void> {
    if (!this.username || !this.password) throw new APIError("", "");

    // logout any existing sessions
    //await logout()
    // fetch the login endpoint we use for authentication
    const loginEndpoint = "/api-auth/login/";
    // fetch the login page, so it sets csrf cookies
    await window.fetch(loginEndpoint);

    // authenticate us
    const body = new window.FormData();
    body.append("username", this.username);
    body.append("password", this.password);
    const csrf_token = Cookies.get("csrftoken");
    if (csrf_token) body.append("csrfmiddlewaretoken", csrf_token);
    const res = await window.fetch(loginEndpoint, { method: "post", body });

    // successful logins are followed by a redirect
    if (res.redirected && res.status === 200) {
      this.isAuthenticated = true;
      await this.retrieve();
    } else {
      throw new APIError("", "");
    }
  }

  async retrieve(): Promise<void> {
    const data = await api_request("GET", "users/me", 200);
    this.pk = data.pk;
    this.isTrusted = data.trust_bridge.is_trusted;
  }

  async signup(): Promise<void> {
    await api_request("POST", "users", 201, {
      username: this.username,
      password: this.password,
    });
  }
}

export const user = Vue.observable(new User());