import { Fragment, ReactNode, useCallback, useEffect, useRef } from 'react'

import {
  ChatCompletionMessage,
  ChatCompletionRole,
  events,
  ThreadMessage,
  ExtensionTypeEnum,
  MessageStatus,
  MessageRequest,
  Model,
  ConversationalExtension,
  MessageEvent,
  MessageRequestType,
  ModelEvent,
  Thread,
  ModelInitFailed,
} from '@janhq/core'
import { useAtomValue, useSetAtom } from 'jotai'
import { ulid } from 'ulidx'

import {
  activeModelAtom,
  loadModelErrorAtom,
  stateModelAtom,
} from '@/hooks/useActiveModel'

import { queuedMessageAtom } from '@/hooks/useSendChatMessage'

import { toaster } from '../Toast'

import { extensionManager } from '@/extension'
import {
  getCurrentChatMessagesAtom,
  addNewMessageAtom,
  updateMessageAtom,
} from '@/helpers/atoms/ChatMessage.atom'
import { downloadedModelsAtom } from '@/helpers/atoms/Model.atom'
import {
  updateThreadWaitingForResponseAtom,
  threadsAtom,
  isGeneratingResponseAtom,
  updateThreadAtom,
} from '@/helpers/atoms/Thread.atom'

export default function EventHandler({ children }: { children: ReactNode }) {
  const messages = useAtomValue(getCurrentChatMessagesAtom)
  const addNewMessage = useSetAtom(addNewMessageAtom)
  const updateMessage = useSetAtom(updateMessageAtom)
  const downloadedModels = useAtomValue(downloadedModelsAtom)
  const activeModel = useAtomValue(activeModelAtom)
  const setActiveModel = useSetAtom(activeModelAtom)
  const setStateModel = useSetAtom(stateModelAtom)
  const setQueuedMessage = useSetAtom(queuedMessageAtom)
  const setLoadModelError = useSetAtom(loadModelErrorAtom)

  const updateThreadWaiting = useSetAtom(updateThreadWaitingForResponseAtom)
  const threads = useAtomValue(threadsAtom)
  const modelsRef = useRef(downloadedModels)
  const threadsRef = useRef(threads)
  const setIsGeneratingResponse = useSetAtom(isGeneratingResponseAtom)
  const updateThread = useSetAtom(updateThreadAtom)
  const messagesRef = useRef(messages)
  const activeModelRef = useRef(activeModel)

  useEffect(() => {
    threadsRef.current = threads
  }, [threads])

  useEffect(() => {
    modelsRef.current = downloadedModels
  }, [downloadedModels])

  useEffect(() => {
    messagesRef.current = messages
  }, [messages])

  useEffect(() => {
    activeModelRef.current = activeModel
  }, [activeModel])

  const onNewMessageResponse = useCallback(
    (message: ThreadMessage) => {
      if (message.type === MessageRequestType.Thread) {
        addNewMessage(message)
      }
    },
    [addNewMessage]
  )

  const onModelReady = useCallback(
    (model: Model) => {
      setActiveModel(model)
      toaster({
        title: 'Success!',
        description: `Model ${model.id} has been started.`,
        type: 'success',
      })
      setStateModel(() => ({
        state: 'stop',
        loading: false,
        model: model.id,
      }))
    },
    [setActiveModel, setStateModel]
  )

  const onModelStopped = useCallback(() => {
    setTimeout(() => {
      setActiveModel(undefined)
      setStateModel({ state: 'start', loading: false, model: '' })
    }, 500)
  }, [setActiveModel, setStateModel])

  const onModelInitFailed = useCallback(
    (res: ModelInitFailed) => {
      console.error('Failed to load model: ', res.error.message)
      setStateModel(() => ({
        state: 'start',
        loading: false,
        model: res.id,
      }))
      setLoadModelError(res.error.message)
      setQueuedMessage(false)
    },
    [setStateModel, setQueuedMessage, setLoadModelError]
  )

  const updateThreadTitle = useCallback(
    (message: ThreadMessage) => {
      // Update only when it's finished
      if (message.status !== MessageStatus.Ready) {
        return
      }

      const thread = threadsRef.current?.find((e) => e.id == message.thread_id)
      const messageContent = message.content[0]?.text?.value

      // The thread title should not be updated if the message is less than 10 words
      // And no new line character is present
      // And non-alphanumeric characters should be removed
      if (thread && messageContent && !messageContent.includes('\n')) {
        // Remove non-alphanumeric characters
        const cleanedMessageContent = messageContent
          .replace(/[^a-z0-9\s]/gi, '')
          .trim()
        // Split the message into words
        const words = cleanedMessageContent.split(' ')
        // Check if the message is less than 10 words
        if (words.length < 10) {
          // Update the Thread title with the response of the inference on the 1st prompt
          updateThread({
            ...thread,
            title: cleanedMessageContent,
            metadata: thread.metadata,
          })

          extensionManager
            .get<ConversationalExtension>(ExtensionTypeEnum.Conversational)
            ?.saveThread({
              ...thread,
            })
        }
      }
    },
    [updateThread]
  )

  const updateThreadMessage = useCallback(
    (message: ThreadMessage) => {
      updateMessage(
        message.id,
        message.thread_id,
        message.content,
        message.status
      )
      if (message.status === MessageStatus.Pending) {
        if (message.content.length) {
          setIsGeneratingResponse(false)
        }
        return
      }
      // Mark the thread as not waiting for response
      updateThreadWaiting(message.thread_id, false)

      setIsGeneratingResponse(false)

      const thread = threadsRef.current?.find((e) => e.id == message.thread_id)
      if (thread) {
        const messageContent = message.content[0]?.text?.value
        const metadata = {
          ...thread.metadata,
          ...(messageContent && { lastMessage: messageContent }),
        }

        updateThread({
          ...thread,
          metadata,
        })

        extensionManager
          .get<ConversationalExtension>(ExtensionTypeEnum.Conversational)
          ?.saveThread({
            ...thread,
            metadata,
          })

        // If this is not the summary of the Thread, don't need to add it to the Thread
        extensionManager
          .get<ConversationalExtension>(ExtensionTypeEnum.Conversational)
          ?.addNewMessage(message)

        // Attempt to generate the title of the Thread when needed
        generateThreadTitle(message, thread)
      }
    },
    [setIsGeneratingResponse, updateMessage, updateThread, updateThreadWaiting]
  )

  const onMessageResponseUpdate = useCallback(
    (message: ThreadMessage) => {
      switch (message.type) {
        case MessageRequestType.Summary:
          updateThreadTitle(message)
          break
        default:
          updateThreadMessage(message)
      }
    },
    [updateThreadMessage, updateThreadTitle]
  )

  const generateThreadTitle = (message: ThreadMessage, thread: Thread) => {
    // If this is the first ever prompt in the thread
    if (
      thread &&
      thread.title?.trim() === 'New Thread' &&
      activeModelRef.current
    ) {
      // This is the first time message comes in on a new thread
      //  Summarize the first message, and make that the title of the Thread
      // 1. Get the summary of the first prompt using whatever engine user is currently using
      const threadMessages = messagesRef?.current

      if (!threadMessages || threadMessages.length === 0) return

      const summarizeFirstPrompt = `Summarize in a 5-word Title. Give the title only. "${threadMessages[0].content[0].text.value}"`
      // Prompt: Given this query from user {query}, return to me the summary in 5 words as the title
      const msgId = ulid()
      const messages: ChatCompletionMessage[] = [
        {
          role: ChatCompletionRole.System,
          content:
            'The conversation below is for a text summarization, user asks assistant to summarize a text and assistant should response in just less than 10 words',
        },
        {
          role: ChatCompletionRole.User,
          content: summarizeFirstPrompt,
        },
      ]

      const messageRequest: MessageRequest = {
        id: msgId,
        threadId: message.thread_id,
        type: MessageRequestType.Summary,
        messages,
        model: {
          ...activeModelRef.current,
          parameters: {
            stream: false,
          },
        },
      }

      // 2. Update the title with the result of the inference
      setTimeout(() => {
        events.emit(MessageEvent.OnMessageSent, messageRequest)
      }, 1000)
    }
  }

  useEffect(() => {
    if (window.core?.events) {
      events.on(MessageEvent.OnMessageResponse, onNewMessageResponse)
      events.on(MessageEvent.OnMessageUpdate, onMessageResponseUpdate)
      events.on(ModelEvent.OnModelReady, onModelReady)
      events.on(ModelEvent.OnModelFail, onModelInitFailed)
      events.on(ModelEvent.OnModelStopped, onModelStopped)
    }
  }, [
    onNewMessageResponse,
    onMessageResponseUpdate,
    onModelReady,
    onModelInitFailed,
    onModelStopped,
  ])

  useEffect(() => {
    return () => {
      events.off(MessageEvent.OnMessageResponse, onNewMessageResponse)
      events.off(MessageEvent.OnMessageUpdate, onMessageResponseUpdate)
    }
  }, [onNewMessageResponse, onMessageResponseUpdate])
  return <Fragment>{children}</Fragment>
}