import {
  Conversation,
  ErrorMessage,
  KeyValuePair,
  Message,
  OpenAIModel,
} from '@/types';
import {
  FC,
  memo,
  MutableRefObject,
  useCallback,
  useEffect,
  useRef,
  useState,
} from 'react';
import { useTranslation } from 'next-i18next';
import { ChatInput } from './ChatInput';
import { ChatLoader } from './ChatLoader';
import { ChatMessage } from './ChatMessage';
import { ErrorMessageDiv } from './ErrorMessageDiv';
import { ModelSelect } from './ModelSelect';
import { SystemPrompt } from './SystemPrompt';
import { IconSettings } from '@tabler/icons-react';
import { throttle } from '@/utils';

interface Props {
  conversation: Conversation;
  models: OpenAIModel[];
  apiKey: string;
  serverSideApiKeyIsSet: boolean;
  messageIsStreaming: boolean;
  modelError: ErrorMessage | null;
  messageError: boolean;
  loading: boolean;
  onSend: (message: Message, deleteCount?: number) => void;
  onUpdateConversation: (
    conversation: Conversation,
    data: KeyValuePair,
  ) => void;
  onEditMessage: (message: Message, messageIndex: number) => void;
  stopConversationRef: MutableRefObject<boolean>;
}

export const Chat: FC<Props> = memo(
  ({
    conversation,
    models,
    apiKey,
    serverSideApiKeyIsSet,
    messageIsStreaming,
    modelError,
    messageError,
    loading,
    onSend,
    onUpdateConversation,
    onEditMessage,
    stopConversationRef,
  }) => {
    const { t } = useTranslation('chat');
    const [currentMessage, setCurrentMessage] = useState<Message>();
    const [autoScrollEnabled, setAutoScrollEnabled] = useState(true);
    const [showSettings, setShowSettings] = useState<boolean>(false);

    const messagesEndRef = useRef<HTMLDivElement>(null);
    const chatContainerRef = useRef<HTMLDivElement>(null);
    const textareaRef = useRef<HTMLTextAreaElement>(null);

    const handleSettings = () => {
      setShowSettings(!showSettings);
    };

    const scrollDown = () => {
      if (autoScrollEnabled) {
        messagesEndRef.current?.scrollIntoView(true);
      }
    };
    const throttledScrollDown = throttle(scrollDown, 250);

    useEffect(() => {
      throttledScrollDown();
      setCurrentMessage(
        conversation.messages[conversation.messages.length - 2],
      );
    }, [conversation.messages, throttledScrollDown]);

    useEffect(() => {
      const observer = new IntersectionObserver(
        ([entry]) => {
          setAutoScrollEnabled(entry.isIntersecting);
          if (entry.isIntersecting) {
            textareaRef.current?.focus();
          }
        },
        {
          root: null,
          threshold: 0.5,
        },
      );
      const messagesEndElement = messagesEndRef.current;
      if (messagesEndElement) {
        observer.observe(messagesEndElement);
      }
      return () => {
        if (messagesEndElement) {
          observer.unobserve(messagesEndElement);
        }
      };
    }, [messagesEndRef]);

    return (
      <div className="overflow-none relative flex-1 bg-white dark:bg-[#343541]">
        {!(apiKey || serverSideApiKeyIsSet) ? (
          <div className="mx-auto flex h-full w-[300px] flex-col justify-center space-y-6 sm:w-[500px]">
            <div className="text-center text-2xl font-semibold text-gray-800 dark:text-gray-100">
              {t('OpenAI API Key Required')}
            </div>
            <div className="text-center text-gray-500 dark:text-gray-400">
              {t(
                'Please set your OpenAI API key in the bottom left of the sidebar.',
              )}
            </div>
            <div className="text-center text-gray-500 dark:text-gray-400">
              {t("If you don't have an OpenAI API key, you can get one here: ")}
              <a
                href="https://platform.openai.com/account/api-keys"
                target="_blank"
                rel="noreferrer"
                className="text-blue-500 hover:underline"
              >
                openai.com
              </a>
            </div>
          </div>
        ) : modelError ? (
          <ErrorMessageDiv error={modelError} />
        ) : (
          <>
            <div
              className="max-h-full overflow-x-hidden"
              ref={chatContainerRef}
            >
              {conversation.messages.length === 0 ? (
                <>
                  <div className="mx-auto flex w-[350px] flex-col space-y-10 pt-12 sm:w-[600px]">
                    <div className="text-center text-3xl font-semibold text-gray-800 dark:text-gray-100">
                      {models.length === 0 ? t('Loading...') : 'Chatbot UI'}
                    </div>

                    {models.length > 0 && (
                      <div className="flex h-full flex-col space-y-4 rounded border border-neutral-200 p-4 dark:border-neutral-600">
                        <ModelSelect
                          model={conversation.model}
                          models={models}
                          onModelChange={(model) =>
                            onUpdateConversation(conversation, {
                              key: 'model',
                              value: model,
                            })
                          }
                        />

                        <SystemPrompt
                          conversation={conversation}
                          onChangePrompt={(prompt) =>
                            onUpdateConversation(conversation, {
                              key: 'prompt',
                              value: prompt,
                            })
                          }
                        />
                      </div>
                    )}
                  </div>
                </>
              ) : (
                <>
                  <div className="flex justify-center border border-b-neutral-300 bg-neutral-100 py-2 text-sm text-neutral-500 dark:border-none dark:bg-[#444654] dark:text-neutral-200">
                    {t('Model')}: {conversation.model.name}
                    <IconSettings
                      className="ml-2 cursor-pointer hover:opacity-50"
                      onClick={handleSettings}
                      size={18}
                    />
                  </div>
                  {showSettings && (
                    <div className="mx-auto flex w-[200px] flex-col space-y-10 pt-8 sm:w-[300px]">
                      <div className="flex h-full flex-col space-y-4 rounded border border-neutral-500 p-2">
                        <ModelSelect
                          model={conversation.model}
                          models={models}
                          onModelChange={(model) =>
                            onUpdateConversation(conversation, {
                              key: 'model',
                              value: model,
                            })
                          }
                        />
                      </div>
                    </div>
                  )}

                  {conversation.messages.map((message, index) => (
                    <ChatMessage
                      key={index}
                      message={message}
                      messageIndex={index}
                      onEditMessage={onEditMessage}
                    />
                  ))}

                  {loading && <ChatLoader />}

                  <div
                    className="h-[162px] bg-white dark:bg-[#343541]"
                    ref={messagesEndRef}
                  />
                </>
              )}
            </div>

            <ChatInput
              stopConversationRef={stopConversationRef}
              textareaRef={textareaRef}
              messageIsStreaming={messageIsStreaming}
              conversationIsEmpty={conversation.messages.length > 0}
              model={conversation.model}
              onSend={(message) => {
                setCurrentMessage(message);
                onSend(message);
              }}
              onRegenerate={() => {
                if (currentMessage) {
                  onSend(currentMessage, 2);
                }
              }}
            />
          </>
        )}
      </div>
    );
  },
);
Chat.displayName = 'Chat';