const debug = require('debug')('crowi:service:PassportService');
const passport = require('passport');
const LocalStrategy = require('passport-local').Strategy;
const LdapStrategy = require('passport-ldapauth');

/**
 * the service class of Passport
 */
class PassportService {

  // see '/lib/form/login.js'
  static get USERNAME_FIELD() { return 'loginForm[username]' }
  static get PASSWORD_FIELD() { return 'loginForm[password]' }

  constructor(crowi) {
    this.crowi = crowi;

    /**
     * the flag whether LocalStrategy is set up successfully
     */
    this.isLocalStrategySetup = false;

    /**
     * the flag whether LdapStrategy is set up successfully
     */
    this.isLdapStrategySetup = false;

    /**
     * the flag whether serializer/deserializer are set up successfully
     */
    this.isSerializerSetup = false;
  }

  /**
   * reset LocalStrategy
   *
   * @memberof PassportService
   */
  resetLocalStrategy() {
    debug('LocalStrategy: reset');
    passport.unuse('local');
    this.isLocalStrategySetup = false;
  }

  /**
   * setup LocalStrategy
   *
   * @memberof PassportService
   */
  setupLocalStrategy() {
    // check whether the strategy has already been set up
    if (this.isLocalStrategySetup) {
      throw new Error('LocalStrategy has already been set up');
    }

    debug('LocalStrategy: setting up..');

    const User = this.crowi.model('User');

    passport.use(new LocalStrategy(
      {
        usernameField: PassportService.USERNAME_FIELD,
        passwordField: PassportService.PASSWORD_FIELD,
      },
      (username, password, done) => {
        // find user
        User.findUserByUsernameOrEmail(username, password, (err, user) => {
          if (err) { return done(err); }
          // check existence and password
          if (!user || !user.isPasswordValid(password)) {
            return done(null, false, { message: 'Incorrect credentials.' });
          }
          return done(null, user);
        });
      }
    ));

    this.isLocalStrategySetup = true;
    debug('LocalStrategy: setup is done');
  }

  /**
   * reset LdapStrategy
   *
   * @memberof PassportService
   */
  resetLdapStrategy() {
    debug('LdapStrategy: reset');
    passport.unuse('ldapauth');
    this.isLdapStrategySetup = false;
  }

  /**
   * Asynchronous configuration retrieval
   *
   * @memberof PassportService
   */
  setupLdapStrategy() {
    // check whether the strategy has already been set up
    if (this.isLdapStrategySetup) {
      throw new Error('LdapStrategy has already been set up');
    }

    const config = this.crowi.config;
    const Config = this.crowi.model('Config');
    const isLdapEnabled = Config.isEnabledPassportLdap(config);

    // when disabled
    if (!isLdapEnabled) {
      return;
    }

    debug('LdapStrategy: setting up..');

    const attrMapUsername = config.crowi['security:passport-ldap:attrMapUsername'] || 'uid';
    debug(`LdapStrategy: attrMapUsername=${attrMapUsername}`);

    passport.use(new LdapStrategy(this.getLdapConfigurationFunc(config, {passReqToCallback: true}),
      (req, ldapAccountInfo, done) => {
        debug("LDAP authentication has succeeded", ldapAccountInfo);

        const ExternalAccount = this.crowi.model('ExternalAccount');

        // it is guaranteed that username that is input from form can be acquired
        // because this processes after authentication
        const ldapAccountId = this.getLdapAccountIdFromReq(req);

        const usernameToBeRegistered = ldapAccountInfo[attrMapUsername];

        // find or register(create) user
        ExternalAccount.findOrRegister('ldap', ldapAccountId, usernameToBeRegistered)
          .then((externalAccount) => {
            return externalAccount.getPopulatedUser();
          })
          .then((user) => {
            done(null, user);
          })
          .catch((err) => {
            done(null, false, err);
          });
      }
    ));

    this.isLdapStrategySetup = true;
    debug('LdapStrategy: setup is done');
  }

  /**
   * CAUTION: this method is capable to use only when `req.body.loginForm` is not null
   *
   * @param {any} req
   * @returns
   * @memberof PassportService
   */
  getLdapAccountIdFromReq(req) {
    return req.body.loginForm.username;
  }

  /**
   * Asynchronous configuration retrieval
   * @see https://github.com/vesse/passport-ldapauth#asynchronous-configuration-retrieval
   *
   * @param {object} config
   * @param {object} opts
   * @returns
   * @memberof PassportService
   */
  getLdapConfigurationFunc(config, opts) {
    // get configurations
    const isUserBind      = config.crowi['security:passport-ldap:isUserBind'];
    const serverUrl       = config.crowi['security:passport-ldap:serverUrl'];
    let   bindDN          = config.crowi['security:passport-ldap:bindDN'];
    let   bindCredentials = config.crowi['security:passport-ldap:bindDNPassword'];
    const searchFilter    = config.crowi['security:passport-ldap:searchFilter'] || '(uid={{username}})';

    // parse serverUrl
    // see: https://regex101.com/r/0tuYBB/1
    const match = serverUrl.match(/(ldaps?:\/\/[^\/]+)\/(.*)?/);
    if (match == null || match.length < 1) {
      debug('LdapStrategy: serverUrl is invalid');
      return;
    }
    const url = match[1];
    const searchBase = match[2] || '';

    debug(`LdapStrategy: url=${url}`);
    debug(`LdapStrategy: searchBase=${searchBase}`);
    debug(`LdapStrategy: isUserBind=${isUserBind}`);
    if (!isUserBind) {
      debug(`LdapStrategy: bindDN=${bindDN}`);
      debug(`LdapStrategy: bindCredentials=${bindCredentials}`);
    }
    debug(`LdapStrategy: searchFilter=${searchFilter}`);

    return (req, callback) => {
      // get credentials from form data
      const loginForm = req.body.loginForm;
      if (!req.form.isValid) {
        return callback({ message: 'Incorrect credentials.' });
      }

      // user bind
      if (isUserBind) {
        bindDN = bindDN.replace(/{{username}}/, loginForm.username);
        bindCredentials = loginForm.password;
      }

      process.nextTick(() => {
        const mergedOpts = Object.assign({
          usernameField: PassportService.USERNAME_FIELD,
          passwordField: PassportService.PASSWORD_FIELD,
          server: { url, bindDN, bindCredentials, searchBase, searchFilter },
        }, opts);
        debug('ldap configuration: ', mergedOpts);
        callback(null, mergedOpts);
      });
    };
  }

  /**
   * setup serializer and deserializer
   *
   * @memberof PassportService
   */
  setupSerializer() {
    // check whether the serializer/deserializer have already been set up
    if (this.isSerializerSetup) {
      throw new Error('serializer/deserializer have already been set up');
    }

    debug('setting up serializer and deserializer');

    const User = this.crowi.model('User');

    passport.serializeUser(function(user, done) {
      done(null, user.id);
    });
    passport.deserializeUser(function(id, done) {
      User.findById(id, function(err, user) {
        done(err, user);
      });
    });

    this.isSerializerSetup = true;
  }

}

module.exports = PassportService;