import React, { useRef, useEffect, useCallback, MouseEventHandler } from "react";
import ContentEditable, { ContentEditableEvent } from "react-contenteditable";
import "./Editable.scss";
import { EditableProps } from "./Editable.interface";

const Editable: React.FC<EditableProps> = ({
  className,
  placeholder,
  content,
  onContentChange,
  handleClick: handleContentClick,
}) => {
  const editableRef = useRef<HTMLElement>(null);
  const lastCaretPosition = useRef<number>(0);

  const getCaretPosition = (el: HTMLElement): number => {
    let caretPosition = 0;
    const selection = window.getSelection();

    if (selection && selection.rangeCount > 0) {
      const range = selection.getRangeAt(0);
      const preRange = range.cloneRange();
      preRange.selectNodeContents(el);
      preRange.setEnd(range.endContainer, range.endOffset);
      caretPosition = preRange.toString().length;
    }

    return caretPosition;
  };

  const setCaretPosition = useCallback((offset: number) => {
    const selection = window.getSelection();
    const range = document.createRange();
    const el = editableRef.current;
    let localOffset = offset;

    el?.childNodes.forEach((element) => {
      if (!element.textContent?.length) {
        element.textContent = "";
      }
      if (localOffset <= element.textContent?.length && localOffset >= 0) {
        range.setStart(element.childNodes[0] ?? element, localOffset);
        range.collapse(true);
        selection?.removeAllRanges();
        selection?.addRange(range);
        localOffset -= element.textContent?.length;
        return;
      } else if (localOffset >= 0) {
        localOffset -= element.textContent?.length;
      }
    });
  }, []);

  const handleChange = (event: ContentEditableEvent) => {
    const newText = event.currentTarget.innerText;
    const currentCaretPosition = getCaretPosition(editableRef.current!);

    if (newText.length <= 500) {
      onContentChange(newText);
      lastCaretPosition.current = currentCaretPosition;
    } else {
      const trimmedText = newText.substring(0, 500);
      event.currentTarget.innerText = trimmedText;
      onContentChange(trimmedText);
      lastCaretPosition.current = currentCaretPosition;
      setCaretPosition(500);
    }
  };

  const handleClick: MouseEventHandler<HTMLDivElement> = (event) => {
    lastCaretPosition.current = getCaretPosition(editableRef.current!);
    if (handleContentClick) handleContentClick(event);
  };

  useEffect(() => {
    const contentEditable = editableRef.current;

    const observer = new MutationObserver((mutations) => {
      mutations.forEach((mutation) => {
        if (mutation.type === "childList") {
          mutation.removedNodes.forEach((node) => {
            if (node instanceof HTMLElement && node.tagName === "A") {
              setCaretPosition(lastCaretPosition.current);
            }
          });
        }
      });
    });

    if (contentEditable) {
      observer.observe(contentEditable, { childList: true, subtree: true });
    }

    return () => {
      observer.disconnect();
    };
  }, [setCaretPosition]);

  return (
    <ContentEditable
      innerRef={editableRef}
      className={`editable ${className}`}
      onChange={handleChange}
      onBlur={() => {}}
      html={content.replaceAll("@@@", "")}
      data-placeholder={placeholder}
      onClick={handleClick}
    />
  );
};

export default Editable;