import {
  forwardRef,
  ReactNode,
  useCallback,
  useImperativeHandle,
  useMemo,
  useState,
} from 'react';

import MessageBox, { Message, MessageBoxProps } from './MessageBox';

type Messages = {
  [messageKey: string]: Message;
};

type MessageGroupOptionalProps = {
  count?: number;
  defaultMessageType?: MessageBoxProps['type'];
  messages?: Messages;
  onSet?: (length: number) => void;
  usePlaceholder?: boolean;
};

type MessageGroupProps = MessageGroupOptionalProps;

type MessageGroupForwardedRefContent = {
  exists?: (key: string) => boolean;
  setMessage?: (key: string, message?: Message) => void;
  setMessageRe?: (re: RegExp, message?: Message) => void;
};

const MESSAGE_GROUP_DEFAULT_PROPS: Required<
  Omit<MessageGroupOptionalProps, 'messages' | 'onSet'>
> &
  Pick<MessageGroupOptionalProps, 'messages' | 'onSet'> = {
  count: 0,
  defaultMessageType: 'info',
  messages: undefined,
  onSet: undefined,
  usePlaceholder: true,
};

const MessageGroup = forwardRef<
  MessageGroupForwardedRefContent,
  MessageGroupProps
>(
  (
    {
      count = MESSAGE_GROUP_DEFAULT_PROPS.count,
      defaultMessageType = MESSAGE_GROUP_DEFAULT_PROPS.defaultMessageType,
      messages: externalMessages,
      onSet,
      usePlaceholder:
        isUsePlaceholder = MESSAGE_GROUP_DEFAULT_PROPS.usePlaceholder,
    },
    ref,
  ) => {
    const [internalMessages, setInternalMessages] = useState<Messages>({});

    const messages = useMemo<Messages>(
      () => ({
        ...externalMessages,
        ...internalMessages,
      }),
      [externalMessages, internalMessages],
    );

    const exists = useCallback(
      (key: string) => messages[key] !== undefined,
      [messages],
    );
    const setMessage = useCallback(
      (key: string, message?: Message) => {
        let length = 0;

        setInternalMessages((previous) => {
          const { [key]: unused, ...rest } = previous;
          const result: Messages = rest;

          if (message) {
            result[key] = message;
          }

          length = Object.keys(result).length;

          return result;
        });

        onSet?.call(null, length);
      },
      [onSet],
    );
    const setMessageRe = useCallback(
      (re: RegExp, message?: Message) => {
        let length = 0;

        const assignMessage = message
          ? (container: Messages, key: string) => {
              container[key] = message;
              length += 1;
            }
          : undefined;

        setInternalMessages((previous) => {
          const result: Messages = {};

          Object.keys(previous).forEach((key: string) => {
            if (re.test(key)) {
              assignMessage?.call(null, result, key);
            } else {
              result[key] = previous[key];
              length += 1;
            }
          });

          return result;
        });

        onSet?.call(null, length);
      },
      [onSet],
    );

    const messageElements = useMemo(() => {
      const pairs = Object.entries(messages);
      const isValidCount = count > 0;
      const limit = isValidCount ? count : pairs.length;
      const result: ReactNode[] = [];

      pairs.every(([messageKey, message]) => {
        const { children: messageChildren, type = defaultMessageType } =
          message;

        result.push(
          <MessageBox key={`message-${messageKey}`} type={type}>
            {messageChildren}
          </MessageBox>,
        );

        return result.length < limit;
      });

      if (isUsePlaceholder && isValidCount && result.length === 0) {
        const placeholderCount = count - result.length;

        for (let i = 0; i < placeholderCount; i += 1) {
          result.push(
            <MessageBox
              key={`message-placeholder-${i}`}
              sx={{ visibility: 'hidden' }}
              text="Placeholder"
            />,
          );
        }
      }

      return result;
    }, [count, defaultMessageType, isUsePlaceholder, messages]);

    useImperativeHandle(ref, () => ({ exists, setMessage, setMessageRe }), [
      exists,
      setMessage,
      setMessageRe,
    ]);

    return <>{messageElements}</>;
  },
);

MessageGroup.defaultProps = MESSAGE_GROUP_DEFAULT_PROPS;
MessageGroup.displayName = 'MessageGroup';

export type { MessageGroupForwardedRefContent };

export default MessageGroup;