let users = JSON.parse(localStorage.getItem('users')) || []

export function configureFakeAPI () {
  let realFetch = window.fetch

  window.fetch = function (url, opts) {
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        if (url.endsWith('/users/authenticate') && opts.method === 'POST') {
          let params = JSON.parse(opts.body)

          let filteredUsers = users.filter(user =>
            user.username === params.username &&
            user.password === params.password
          )

          if (filteredUsers.length) {
            let user = filteredUsers[0]
            let responseJson = {
              id: user.id,
              username: user.username
            }
            resolve({ ok: true, json: () => responseJson })
          } else {
            reject(new Error('Username or password is incorrect'))
          }

          return
        }

        if (url.endsWith('/users/register') && opts.method === 'POST') {
          let newUser = JSON.parse(opts.body)

          let duplicateUser = users.filter(user => user.username === newUser.username).length

          if (duplicateUser) {
            reject(new Error('Username "' + newUser.username + '" is already taken'))
            return
          }

          newUser.id = users.length
            ? Math.max(...users.map(user => user.id)) + 1
            : 1

          users.push(newUser)
          localStorage.setItem('users', JSON.stringify(users))

          resolve({ ok: true, json: () => ({}) })

          return
        }

        realFetch(url, opts)
          .then(response => resolve(response))
      }, 500)
    })
  }
}