// @flow

import * as Keychain from 'react-native-keychain';
import type {ApiDataLoginType, ApiGenericDataType} from '../utils/WebData';
import {apiRequest, ERROR_TYPE} from '../utils/WebData';

/**
 * champ: error
 *
 * 0 : SUCCESS -> pas d'erreurs
 * 1 : BAD_CREDENTIALS -> email ou mdp invalide
 * 2 : BAD_TOKEN -> session expirée
 * 3 : NO_CONSENT
 * 403 : FORBIDDEN -> accès a la ressource interdit
 * 500 : SERVER_ERROR -> pb coté serveur
 */

const SERVER_NAME = 'amicale-insat.fr';
const AUTH_PATH = 'password';

export default class ConnectionManager {
  static instance: ConnectionManager | null = null;

  #email: string;

  #token: string | null;

  constructor() {
    this.#token = null;
  }

  /**
   * Gets this class instance or create one if none is found
   *
   * @returns {ConnectionManager}
   */
  static getInstance(): ConnectionManager {
    if (ConnectionManager.instance == null)
      ConnectionManager.instance = new ConnectionManager();
    return ConnectionManager.instance;
  }

  /**
   * Gets the current token
   *
   * @returns {string | null}
   */
  getToken(): string | null {
    return this.#token;
  }

  /**
   * Tries to recover login token from the secure keychain
   *
   * @returns Promise<string>
   */
  async recoverLogin(): Promise<string> {
    return new Promise(
      (resolve: (token: string) => void, reject: () => void) => {
        const token = this.getToken();
        if (token != null) resolve(token);
        else {
          Keychain.getInternetCredentials(SERVER_NAME)
            .then((data: Keychain.UserCredentials | false) => {
              if (
                data != null &&
                data.password != null &&
                typeof data.password === 'string'
              ) {
                this.#token = data.password;
                resolve(this.#token);
              } else reject();
            })
            .catch((): void => reject());
        }
      },
    );
  }

  /**
   * Check if the user has a valid token
   *
   * @returns {boolean}
   */
  isLoggedIn(): boolean {
    return this.getToken() !== null;
  }

  /**
   * Saves the login token in the secure keychain
   *
   * @param email
   * @param token
   * @returns Promise<void>
   */
  async saveLogin(email: string, token: string): Promise<void> {
    return new Promise((resolve: () => void, reject: () => void) => {
      Keychain.setInternetCredentials(SERVER_NAME, 'token', token)
        .then(() => {
          this.#token = token;
          this.#email = email;
          resolve();
        })
        .catch((): void => reject());
    });
  }

  /**
   * Deletes the login token from the keychain
   *
   * @returns Promise<void>
   */
  async disconnect(): Promise<void> {
    return new Promise((resolve: () => void, reject: () => void) => {
      Keychain.resetInternetCredentials(SERVER_NAME)
        .then(() => {
          this.#token = null;
          resolve();
        })
        .catch((): void => reject());
    });
  }

  /**
   * Sends the given login and password to the api.
   * If the combination is valid, the login token is received and saved in the secure keychain.
   * If not, the promise is rejected with the corresponding error code.
   *
   * @param email
   * @param password
   * @returns Promise<void>
   */
  async connect(email: string, password: string): Promise<void> {
    return new Promise(
      (resolve: () => void, reject: (error: number) => void) => {
        const data = {
          email,
          password,
        };
        apiRequest(AUTH_PATH, 'POST', data)
          .then((response: ApiDataLoginType) => {
            if (response.token != null) {
              this.saveLogin(email, response.token)
                .then((): void => resolve())
                .catch((): void => reject(ERROR_TYPE.TOKEN_SAVE));
            } else reject(ERROR_TYPE.SERVER_ERROR);
          })
          .catch((error: number): void => reject(error));
      },
    );
  }

  /**
   * Sends an authenticated request with the login token to the API
   *
   * @param path
   * @param params
   * @returns Promise<ApiGenericDataType>
   */
  async authenticatedRequest(
    path: string,
    params: {...},
  ): Promise<ApiGenericDataType> {
    return new Promise(
      (
        resolve: (response: ApiGenericDataType) => void,
        reject: (error: number) => void,
      ) => {
        if (this.getToken() !== null) {
          const data = {
            ...params,
            token: this.getToken(),
          };
          apiRequest(path, 'POST', data)
            .then((response: ApiGenericDataType): void => resolve(response))
            .catch((error: number): void => reject(error));
        } else reject(ERROR_TYPE.TOKEN_RETRIEVE);
      },
    );
  }
}