// Disable prop type checks for test harnesses
/* eslint-disable react/prop-types */

import React from 'react'
import { renderHook, act } from '@testing-library/react-hooks/dom'
import { expect } from 'chai'
import fetchMock from 'fetch-mock'
import EventEmitter from 'events'

import { useChatContext } from '../../../../../frontend/js/features/chat/context/chat-context'
import {
  ChatProviders,
  cleanUpContext,
} from '../../../helpers/render-with-context'
import { stubMathJax, tearDownMathJaxStubs } from '../components/stubs'

describe('ChatContext', function () {
  const user = {
    id: 'fake_user',
    first_name: 'fake_user_first_name',
    email: 'fake@example.com',
  }

  beforeEach(function () {
    fetchMock.reset()
    cleanUpContext()

    stubMathJax()
  })

  afterEach(function () {
    tearDownMathJaxStubs()
  })

  describe('socket connection', function () {
    beforeEach(function () {
      // Mock GET messages to return no messages
      fetchMock.get('express:/project/:projectId/messages', [])

      // Mock POST new message to return 200
      fetchMock.post('express:/project/:projectId/messages', 200)
    })

    it('subscribes when mounted', function () {
      const socket = new EventEmitter()
      renderChatContextHook({ user, socket })

      // Assert that there is 1 listener
      expect(socket.rawListeners('new-chat-message').length).to.equal(1)
    })

    it('unsubscribes when unmounted', function () {
      const socket = new EventEmitter()
      const { unmount } = renderChatContextHook({ user, socket })

      unmount()

      // Assert that there is 0 listeners
      expect(socket.rawListeners('new-chat-message').length).to.equal(0)
    })

    it('adds received messages to the list', async function () {
      // Mock socket: we only need to emit events, not mock actual connections
      const socket = new EventEmitter()
      const { result, waitForNextUpdate } = renderChatContextHook({
        user,
        socket,
      })

      // Wait until initial messages have loaded
      result.current.loadInitialMessages()
      await waitForNextUpdate()

      // No messages shown at first
      expect(result.current.messages).to.deep.equal([])

      // Mock message being received from another user
      socket.emit('new-chat-message', {
        id: 'msg_1',
        content: 'new message',
        timestamp: Date.now(),
        user: {
          id: 'another_fake_user',
          first_name: 'another_fake_user_first_name',
          email: 'another_fake@example.com',
        },
      })

      const message = result.current.messages[0]
      expect(message.id).to.equal('msg_1')
      expect(message.contents).to.deep.equal(['new message'])
    })

    it("doesn't add received messages from the current user if a message was just sent", async function () {
      const socket = new EventEmitter()
      const { result, waitForNextUpdate } = renderChatContextHook({
        user,
        socket,
      })

      // Wait until initial messages have loaded
      result.current.loadInitialMessages()
      await waitForNextUpdate()

      // Send a message from the current user
      result.current.sendMessage('sent message')

      // Receive a message from the current user
      socket.emit('new-chat-message', {
        id: 'msg_1',
        content: 'received message',
        timestamp: Date.now(),
        user,
      })

      // Expect that the sent message is shown, but the new message is not
      const messageContents = result.current.messages.map(
        ({ contents }) => contents[0]
      )
      expect(messageContents).to.include('sent message')
      expect(messageContents).to.not.include('received message')
    })

    it('adds the new message from the current user if another message was received after sending', async function () {
      const socket = new EventEmitter()
      const { result, waitForNextUpdate } = renderChatContextHook({
        user,
        socket,
      })

      // Wait until initial messages have loaded
      result.current.loadInitialMessages()
      await waitForNextUpdate()

      // Send a message from the current user
      result.current.sendMessage('sent message from current user')

      const [sentMessageFromCurrentUser] = result.current.messages
      expect(sentMessageFromCurrentUser.contents).to.deep.equal([
        'sent message from current user',
      ])

      act(() => {
        // Receive a message from another user.
        socket.emit('new-chat-message', {
          id: 'msg_1',
          content: 'new message from other user',
          timestamp: Date.now(),
          user: {
            id: 'another_fake_user',
            first_name: 'another_fake_user_first_name',
            email: 'another_fake@example.com',
          },
        })
      })

      const [, messageFromOtherUser] = result.current.messages
      expect(messageFromOtherUser.contents).to.deep.equal([
        'new message from other user',
      ])

      // Receive a message from the current user
      socket.emit('new-chat-message', {
        id: 'msg_2',
        content: 'received message from current user',
        timestamp: Date.now(),
        user,
      })

      // Since the current user didn't just send a message, it is now shown
      const [, , receivedMessageFromCurrentUser] = result.current.messages
      expect(receivedMessageFromCurrentUser.contents).to.deep.equal([
        'received message from current user',
      ])
    })
  })

  describe('loadInitialMessages', function () {
    beforeEach(function () {
      fetchMock.get('express:/project/:projectId/messages', [
        {
          id: 'msg_1',
          content: 'a message',
          user,
          timestamp: Date.now(),
        },
      ])
    })

    it('adds messages to the list', async function () {
      const { result, waitForNextUpdate } = renderChatContextHook({ user })

      result.current.loadInitialMessages()
      await waitForNextUpdate()

      expect(result.current.messages[0].contents).to.deep.equal(['a message'])
    })

    it("won't load messages a second time", async function () {
      const { result, waitForNextUpdate } = renderChatContextHook({ user })

      result.current.loadInitialMessages()
      await waitForNextUpdate()

      expect(result.current.initialMessagesLoaded).to.equal(true)

      // Calling a second time won't do anything
      result.current.loadInitialMessages()
      expect(fetchMock.calls()).to.have.lengthOf(1)
    })
  })

  describe('loadMoreMessages', function () {
    it('adds messages to the list', async function () {
      // Mock a GET request for an initial message
      fetchMock.getOnce('express:/project/:projectId/messages', [
        {
          id: 'msg_1',
          content: 'first message',
          user,
          timestamp: new Date('2021-03-04T10:00:00').getTime(),
        },
      ])

      const { result, waitForNextUpdate } = renderChatContextHook({ user })

      result.current.loadMoreMessages()
      await waitForNextUpdate()

      expect(result.current.messages[0].contents).to.deep.equal([
        'first message',
      ])

      // The before query param is not set
      expect(getLastFetchMockQueryParam('before')).to.be.null
    })

    it('adds more messages if called a second time', async function () {
      // Mock 2 GET requests, with different content
      fetchMock
        .getOnce(
          'express:/project/:projectId/messages',
          // Resolve a full "page" of messages (50)
          createMessages(50, user, new Date('2021-03-04T10:00:00').getTime())
        )
        .getOnce(
          'express:/project/:projectId/messages',
          [
            {
              id: 'msg_51',
              content: 'message from second page',
              user,
              timestamp: new Date('2021-03-04T11:00:00').getTime(),
            },
          ],
          { overwriteRoutes: false }
        )

      const { result, waitForNextUpdate } = renderChatContextHook({ user })

      result.current.loadMoreMessages()
      await waitForNextUpdate()

      // Call a second time
      result.current.loadMoreMessages()
      await waitForNextUpdate()

      // The second request is added to the list
      // Since both messages from the same user, they are collapsed into the
      // same "message"
      expect(result.current.messages[0].contents).to.include(
        'message from second page'
      )

      // The before query param for the second request matches the timestamp
      // of the first message
      const beforeParam = parseInt(getLastFetchMockQueryParam('before'), 10)
      expect(beforeParam).to.equal(new Date('2021-03-04T10:00:00').getTime())
    })

    it("won't load more messages if there are no more messages", async function () {
      // Mock a GET request for 49 messages. This is less the the full page size
      // (50 messages), meaning that there are no further messages to be loaded
      fetchMock.getOnce(
        'express:/project/:projectId/messages',
        createMessages(49, user)
      )

      const { result, waitForNextUpdate } = renderChatContextHook({ user })

      result.current.loadMoreMessages()
      await waitForNextUpdate()

      expect(result.current.messages[0].contents).to.have.length(49)

      result.current.loadMoreMessages()

      expect(result.current.atEnd).to.be.true
      expect(fetchMock.calls()).to.have.lengthOf(1)
    })

    it('handles socket messages while loading', async function () {
      // Mock GET messages so that we can control when the promise is resolved
      let resolveLoadingMessages
      fetchMock.get(
        'express:/project/:projectId/messages',
        new Promise(resolve => {
          resolveLoadingMessages = resolve
        })
      )

      const socket = new EventEmitter()
      const { result, waitForNextUpdate } = renderChatContextHook({
        user,
        socket,
      })

      // Start loading messages
      result.current.loadMoreMessages()

      // Mock message being received from the socket while the request is in
      // flight
      socket.emit('new-chat-message', {
        id: 'socket_msg',
        content: 'socket message',
        timestamp: Date.now(),
        user: {
          id: 'another_fake_user',
          first_name: 'another_fake_user_first_name',
          email: 'another_fake@example.com',
        },
      })

      // Resolve messages being loaded
      resolveLoadingMessages([
        {
          id: 'fetched_msg',
          content: 'loaded message',
          user,
          timestamp: Date.now(),
        },
      ])
      await waitForNextUpdate()

      // Although the loaded message was resolved last, it appears first (since
      // requested messages must have come first)
      const messageContents = result.current.messages.map(
        ({ contents }) => contents[0]
      )
      expect(messageContents).to.deep.equal([
        'loaded message',
        'socket message',
      ])
    })
  })

  describe('sendMessage', function () {
    beforeEach(function () {
      // Mock GET messages to return no messages and POST new message to be
      // successful
      fetchMock
        .get('express:/project/:projectId/messages', [])
        .postOnce('express:/project/:projectId/messages', 200)
    })

    it('optimistically adds the message to the list', function () {
      const { result } = renderChatContextHook({ user })

      result.current.sendMessage('sent message')

      expect(result.current.messages[0].contents).to.deep.equal([
        'sent message',
      ])
    })

    it('POSTs the message to the backend', function () {
      const { result } = renderChatContextHook({ user })

      result.current.sendMessage('sent message')

      const [, { body }] = fetchMock.lastCall(
        'express:/project/:projectId/messages',
        'POST'
      )
      expect(JSON.parse(body)).to.deep.equal({ content: 'sent message' })
    })

    it("doesn't send if the content is empty", function () {
      const { result } = renderChatContextHook({ user })

      result.current.sendMessage('')

      expect(result.current.messages).to.be.empty
      expect(
        fetchMock.called('express:/project/:projectId/messages', {
          method: 'post',
        })
      ).to.be.false
    })
  })

  describe('unread messages', function () {
    beforeEach(function () {
      // Mock GET messages to return no messages
      fetchMock.get('express:/project/:projectId/messages', [])
    })

    it('increments unreadMessageCount when a new message is received', function () {
      const socket = new EventEmitter()
      const { result } = renderChatContextHook({ user, socket })

      // Receive a new message from the socket
      socket.emit('new-chat-message', {
        id: 'msg_1',
        content: 'new message',
        timestamp: Date.now(),
        user,
      })

      expect(result.current.unreadMessageCount).to.equal(1)
    })

    it('resets unreadMessageCount when markMessagesAsRead is called', function () {
      const socket = new EventEmitter()
      const { result } = renderChatContextHook({ user, socket })

      // Receive a new message from the socket, incrementing unreadMessageCount
      // by 1
      socket.emit('new-chat-message', {
        id: 'msg_1',
        content: 'new message',
        timestamp: Date.now(),
        user,
      })

      result.current.markMessagesAsRead()

      expect(result.current.unreadMessageCount).to.equal(0)
    })
  })
})

function renderChatContextHook(props) {
  return renderHook(() => useChatContext(), {
    // Wrap with ChatContext.Provider (and the other editor context providers)
    wrapper: ({ children }) => (
      <ChatProviders {...props}>{children}</ChatProviders>
    ),
  })
}

function createMessages(number, user, timestamp = Date.now()) {
  return Array.from({ length: number }, (_m, idx) => ({
    id: `msg_${idx + 1}`,
    content: `message ${idx + 1}`,
    user,
    timestamp,
  }))
}

/*
 * Get query param by key from the last fetchMock response
 */
function getLastFetchMockQueryParam(key) {
  const { url } = fetchMock.lastResponse()
  const { searchParams } = new URL(url, 'https://www.overleaf.com')
  return searchParams.get(key)
}