const assert = require('assert');
const establishedDatabase = require('src/database/database');

class UserRepository {

  constructor(database) {
    this.database = database || establishedDatabase;
    this.queries = {
      read: 'select * from user where lower(user_name) = lower(?)',
      create: 'insert into user (user_name, email) values(?, ?)',
      change: 'update user set password = ? where user_name = ?',
      retrieveHash: 'select * from user where user_name = ?',
    };
  }

  /**
   * Create a user in a database.
   * @param {User} user the user you want to create
   * @returns {Promise}
   */
  create(user) {
    return Promise.resolve()
    .then(() => this.database.get(this.queries.read, user.username))
    .then(row => assert.equal(row, undefined))
    .then(() => this.database.run(this.queries.create, [user.username, user.email]))
    .catch((error) => {
      if (error.message.endsWith('email')) {
        throw new Error('That email is already taken');
      } else if (error.name === 'AssertionError' || error.message.endsWith('user_name')) {
        throw new Error('That username is already taken');
      }
    });
  }

  /**
   * Retrieve a password from a database.
   * @param {User} user the user you want to retrieve the password
   * @returns {Promise}
   */
  retrieveHash(user) {
    return this.database.get(this.queries.retrieveHash, user.username).then((row) => {
      assert(row, 'The user does not exist.');
      return row.password;
    });
  }

  /**
   * Change a user's password in a database.
   * @param {User} user the user you want to create
   * @param {String} password the new password you want to change
   * @returns {Promise}
   */
  changePassword(user, password) {
    return this.database.run(this.queries.change, [password, user.username]);
  }

}

module.exports = UserRepository;