import { createHmac } from 'crypto'
import min from 'min'
import { EventEmitter } from 'events'

const secret = 'foobar'

const store = {
  data: new Map(),
  set(key, value) {
    store.data.set(key, value)
  },

  get(key) {
    if (store.data.has(key)) {
      return store.data.get(key)
    } else {
      throw new Error('no such key')
    }
  },

  remove(key) {
    store.data.delete(key)
  }
}

min.store = store

class User extends EventEmitter {
  async construtor(username, nickname, password = null, salt = secret) {
    if (await User.checkUsername(username)) {
      throw new Error('User was already exists.')
    }

    this.username = username
    this.nickname = nickname

    if (password) {
      this.secretHash = User.createHash(password)
      await this.save()
    }
  }

  async save() {
    await min.hmset(`user:${this.username}`, {
      username: this.username,
      nickname: this.nickname,
      secretHash: this.secretHash
    })
    await min.sadd('users', this.username)
  }

  static fetch(username) {
    const nickname = await min.hget(`user:${username}`, 'nickname')

    return new User(username, nickname)
  }

  static checkPassword(username, password, salt = secret) {
    const secretHash = await min.hget(`user:${username}`, 'secretHash')

    return User.createHash(salt + password.toUpperCase() + salt, salt) === secretHash
  }

  static createHash(str, salt = secret) {
    return createHmac(salt + str.toUpperCase() + salt, salt)
  }

  static checkUsername(username) {
    return min.sismember('users', username)
  }
}