import type { Message } from 'ai';
import { useChat } from 'ai/react';
import { useAnimate } from 'framer-motion';
import { useEffect, useRef, useState } from 'react';
import { cssTransition, toast, ToastContainer } from 'react-toastify';
import { useMessageParser, usePromptEnhancer, useSnapScroll } from '~/lib/hooks';
import { useChatHistory } from '~/lib/persistence';
import { chatStore } from '~/lib/stores/chat';
import { workbenchStore } from '~/lib/stores/workbench';
import { fileModificationsToHTML } from '~/utils/diff';
import { cubicEasingFn } from '~/utils/easings';
import { createScopedLogger } from '~/utils/logger';
import { BaseChat } from './BaseChat';

const toastAnimation = cssTransition({
  enter: 'animated fadeInRight',
  exit: 'animated fadeOutRight',
});

const logger = createScopedLogger('Chat');

export function Chat() {
  const { ready, initialMessages, storeMessageHistory } = useChatHistory();

  return (
    <>
      {ready && <ChatImpl initialMessages={initialMessages} storeMessageHistory={storeMessageHistory} />}
      <ToastContainer position="bottom-right" stacked pauseOnFocusLoss transition={toastAnimation} />;
    </>
  );
}

interface ChatProps {
  initialMessages: Message[];
  storeMessageHistory: (messages: Message[]) => Promise<void>;
}

export function ChatImpl({ initialMessages, storeMessageHistory }: ChatProps) {
  const textareaRef = useRef<HTMLTextAreaElement>(null);

  const [chatStarted, setChatStarted] = useState(initialMessages.length > 0);

  const [animationScope, animate] = useAnimate();

  const { messages, isLoading, input, handleInputChange, setInput, handleSubmit, stop, append } = useChat({
    api: '/api/chat',
    onError: (error) => {
      logger.error(error);
      toast.error('There was an error processing your request');
    },
    onFinish: () => {
      logger.debug('Finished streaming');
    },
    initialMessages,
  });

  const { enhancingPrompt, promptEnhanced, enhancePrompt, resetEnhancer } = usePromptEnhancer();
  const { parsedMessages, parseMessages } = useMessageParser();

  const TEXTAREA_MAX_HEIGHT = chatStarted ? 400 : 200;

  useEffect(() => {
    parseMessages(messages, isLoading);
    storeMessageHistory(messages).catch((error) => toast.error(error.message));
  }, [messages, isLoading, parseMessages]);

  const scrollTextArea = () => {
    const textarea = textareaRef.current;

    if (textarea) {
      textarea.scrollTop = textarea.scrollHeight;
    }
  };

  const abort = () => {
    stop();
    chatStore.setKey('aborted', true);
    workbenchStore.abortAllActions();
  };

  useEffect(() => {
    const textarea = textareaRef.current;

    if (textarea) {
      textarea.style.height = 'auto';

      const scrollHeight = textarea.scrollHeight;

      textarea.style.height = `${Math.min(scrollHeight, TEXTAREA_MAX_HEIGHT)}px`;
      textarea.style.overflowY = scrollHeight > TEXTAREA_MAX_HEIGHT ? 'auto' : 'hidden';
    }
  }, [input, textareaRef]);

  const runAnimation = async () => {
    if (chatStarted) {
      return;
    }

    await animate('#intro', { opacity: 0, flex: 1 }, { duration: 0.2, ease: cubicEasingFn });

    setChatStarted(true);
  };

  const sendMessage = async (event: React.UIEvent) => {
    if (input.length === 0 || isLoading) {
      return;
    }

    /**
     * @note (delm) Usually saving files shouldn't take long but it may take longer if there
     * many unsaved files. In that case we need to block user input and show an indicator
     * of some kind so the user is aware that something is happening. But I consider the
     * happy case to be no unsaved files and I would expect users to save their changes
     * before they send another message.
     */
    await workbenchStore.saveAllFiles();

    const fileModifications = workbenchStore.getFileModifcations();

    chatStore.setKey('aborted', false);

    runAnimation();

    if (fileModifications !== undefined) {
      const diff = fileModificationsToHTML(fileModifications);

      /**
       * If we have file modifications we append a new user message manually since we have to prefix
       * the user input with the file modifications and we don't want the new user input to appear
       * in the prompt. Using `append` is almost the same as `handleSubmit` except that we have to
       * manually reset the input and we'd have to manually pass in file attachments. However, those
       * aren't relevant here.
       */
      append({ role: 'user', content: `${diff}\n\n${input}` });

      setInput('');

      /**
       * After sending a new message we reset all modifications since the model
       * should now be aware of all the changes.
       */
      workbenchStore.resetAllFileModifications();
    } else {
      handleSubmit(event);
    }

    resetEnhancer();

    textareaRef.current?.blur();
  };

  const [messageRef, scrollRef] = useSnapScroll();

  return (
    <BaseChat
      ref={animationScope}
      textareaRef={textareaRef}
      input={input}
      chatStarted={chatStarted}
      isStreaming={isLoading}
      enhancingPrompt={enhancingPrompt}
      promptEnhanced={promptEnhanced}
      sendMessage={sendMessage}
      messageRef={messageRef}
      scrollRef={scrollRef}
      handleInputChange={handleInputChange}
      handleStop={abort}
      messages={messages.map((message, i) => {
        if (message.role === 'user') {
          return message;
        }

        return {
          ...message,
          content: parsedMessages[i] || '',
        };
      })}
      enhancePrompt={() => {
        enhancePrompt(input, (input) => {
          setInput(input);
          scrollTextArea();
        });
      }}
    />
  );
}