/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 */

import { useLexicalComposerContext } from '@lexical/react/LexicalComposerContext';
import {
  QueryMatch,
  TypeaheadOption,
  useBasicTypeaheadTriggerMatch,
} from '@lexical/react/LexicalTypeaheadMenuPlugin';
import { useLexicalTextEntity } from '@lexical/react/useLexicalTextEntity';
import React, { useCallback, useEffect, useMemo, useState } from 'react';
import ReactDOM from 'react-dom';

import { $createMentionNode, MentionNode } from '../nodes/mention-node';

import { TypeaheadMenuPlugin } from './typeahead-menu-plugin';

import type { TextNode } from 'lexical';

const REGEX = new RegExp('(^|$|(?:^|\\s))([@])([a-z\\d_-]+(?:@[^@\\s]+)?)', 'i');

const PUNCTUATION =
  '\\.,\\+\\*\\?\\$\\@\\|#{}\\(\\)\\^\\-\\[\\]\\\\/!%\'"~=<>_:;';
const NAME = '\\b[A-Z][^\\s' + PUNCTUATION + ']';

const DocumentMentionsRegex = {
  NAME,
  PUNCTUATION,
};

const CapitalizedNameMentionsRegex = new RegExp(
  '(^|[^#])((?:' + DocumentMentionsRegex.NAME + '{' + 1 + ',})$)',
);

const PUNC = DocumentMentionsRegex.PUNCTUATION;

const TRIGGERS = ['@'].join('');

// Chars we expect to see in a mention (non-space, non-punctuation).
const VALID_CHARS = '[^' + TRIGGERS + PUNC + '\\s]';

// Non-standard series of chars. Each series must be preceded and followed by
// a valid char.
// const VALID_JOINS =
//   '(?:' +
//   '\\.[ |$]|' + // E.g. "r. " in "Mr. Smith"
//   ' |' + // E.g. " " in "Josh Duck"
//   '[' +
//   PUNC +
//   ']|' + // E.g. "-' in "Salier-Hellendag"
//   ')';

// const LENGTH_LIMIT = 75;

const AtSignMentionsRegex = REGEX; /* new RegExp(
  '(^|\\s|\\()(' +
    '[' +
    TRIGGERS +
    ']' +
    '((?:' +
    VALID_CHARS +
    VALID_JOINS +
    '){0,' +
    LENGTH_LIMIT +
    '})' +
    ')$',
); */

// 50 is the longest alias length limit.
const ALIAS_LENGTH_LIMIT = 50;

// Regex used to match alias.
const AtSignMentionsRegexAliasRegex = new RegExp(
  '(^|\\s|\\()(' +
    '[' +
    TRIGGERS +
    ']' +
    '((?:' +
    VALID_CHARS +
    '){0,' +
    ALIAS_LENGTH_LIMIT +
    '})' +
    ')$',
);

// At most, 5 suggestions are shown in the popup.
const SUGGESTION_LIST_LENGTH_LIMIT = 5;

const mentionsCache = new Map();

const dummyMentionsData = ['Test'];

const dummyLookupService = {
  search(string: string, callback: (results: Array<string>) => void): void {
    setTimeout(() => {
      const results = dummyMentionsData.filter((mention) =>
        mention.toLowerCase().includes(string.toLowerCase()),
      );
      callback(results);
    }, 500);
  },
};

function useMentionLookupService(mentionString: string | null) {
  const [results, setResults] = useState<Array<string>>([]);

  useEffect(() => {
    const cachedResults = mentionsCache.get(mentionString);

    if (mentionString === null) {
      setResults([]);
      return;
    }

    if (cachedResults === null) {
      return;
    } else if (cachedResults !== undefined) {
      setResults(cachedResults);
      return;
    }

    mentionsCache.set(mentionString, null);
    dummyLookupService.search(mentionString, (newResults) => {
      mentionsCache.set(mentionString, newResults);
      setResults(newResults);
    });
  }, [mentionString]);

  return results;
}

function checkForCapitalizedNameMentions(
  text: string,
  minMatchLength: number,
): QueryMatch | null {
  const match = CapitalizedNameMentionsRegex.exec(text);
  if (match !== null) {
    // The strategy ignores leading whitespace but we need to know it's
    // length to add it to the leadOffset
    const maybeLeadingWhitespace = match[1];

    const matchingString = match[2];
    if (matchingString !== null && matchingString.length >= minMatchLength) {
      return {
        leadOffset: match.index + maybeLeadingWhitespace.length,
        matchingString,
        replaceableString: matchingString,
      };
    }
  }
  return null;
}

function checkForAtSignMentions(
  text: string,
  minMatchLength: number,
): QueryMatch | null {
  let match = AtSignMentionsRegex.exec(text);
  if (match === null) {
    match = AtSignMentionsRegexAliasRegex.exec(text);
  }
  if (match !== null) {
    // The strategy ignores leading whitespace but we need to know it's
    // length to add it to the leadOffset
    const maybeLeadingWhitespace = match[1];

    const matchingString = match[3];
    if (matchingString.length >= minMatchLength) {
      return {
        leadOffset: match.index + maybeLeadingWhitespace.length,
        matchingString,
        replaceableString: match[2],
      };
    }
  }
  return null;
}

function getPossibleQueryMatch(text: string): QueryMatch | null {
  const match = checkForAtSignMentions(text, 1);
  return match === null ? checkForCapitalizedNameMentions(text, 3) : match;
}

class MentionTypeaheadOption extends TypeaheadOption {

  name: string;
  picture: JSX.Element;

  constructor(name: string, picture: JSX.Element) {
    super(name);
    this.name = name;
    this.picture = picture;
  }

}

function MentionsTypeaheadMenuItem({
  index,
  isSelected,
  onClick,
  onMouseEnter,
  option,
}: {
  index: number
  isSelected: boolean
  onClick: () => void
  onMouseEnter: () => void
  option: MentionTypeaheadOption
}) {
  let className = 'item';
  if (isSelected) {
    className += ' selected';
  }
  return (
    <li
      key={option.key}
      tabIndex={-1}
      className={className}
      ref={option.setRefElement}
      role='option'
      aria-selected={isSelected}
      id={'typeahead-item-' + index}
      onMouseEnter={onMouseEnter}
      onClick={onClick}
    >
      {option.picture}
      <span className='text'>{option.name}</span>
    </li>
  );
}

export function MentionPlugin(): JSX.Element | null {
  const [editor] = useLexicalComposerContext();

  const [queryString, setQueryString] = useState<string | null>(null);

  const results = useMentionLookupService(queryString);

  const checkForSlashTriggerMatch = useBasicTypeaheadTriggerMatch('/', {
    minLength: 0,
  });

  const options = useMemo(
    () =>
      results
        .map(
          (result) =>
            new MentionTypeaheadOption(result, <i className='icon user' />),
        )
        .slice(0, SUGGESTION_LIST_LENGTH_LIMIT),
    [results],
  );

  const onSelectOption = useCallback(
    (
      selectedOption: MentionTypeaheadOption,
      nodeToReplace: TextNode | null,
      closeMenu: () => void,
    ) => {
      editor.update(() => {
        const mentionNode = $createMentionNode(selectedOption.name);
        if (nodeToReplace) {
          nodeToReplace.replace(mentionNode);
        }
        mentionNode.select();
        closeMenu();
      });
    },
    [editor],
  );

  const checkForMentionMatch = useCallback(
    (text: string) => {
      const mentionMatch = getPossibleQueryMatch(text);
      const slashMatch = checkForSlashTriggerMatch(text, editor);
      return !slashMatch && mentionMatch ? mentionMatch : null;
    },
    [checkForSlashTriggerMatch, editor],
  );

  useEffect(() => {
    if (!editor.hasNodes([MentionNode])) {
      throw new Error('MentionPlugin: MentionNode not registered on editor');
    }
  }, [editor]);

  const createMentionNode = useCallback((textNode: TextNode): MentionNode => {
    return $createMentionNode(textNode.getTextContent());
  }, []);

  const getMentionMatch = useCallback((text: string) => {
    const matchArr = REGEX.exec(text);

    if (matchArr === null) {
      return null;
    }

    const mentionLength = matchArr[3].length + 1;
    const startOffset = matchArr.index + matchArr[1].length;
    const endOffset = startOffset + mentionLength;
    return {
      end: endOffset,
      start: startOffset,
    };
  }, []);

  useLexicalTextEntity<MentionNode>(
    getMentionMatch,
    MentionNode,
    createMentionNode,
  );

  return (
    <TypeaheadMenuPlugin<MentionTypeaheadOption>
      onQueryChange={setQueryString}
      onSelectOption={onSelectOption}
      triggerFn={checkForMentionMatch}
      options={options}
      menuRenderFn={(
        anchorElementRef,
        { selectedIndex, selectOptionAndCleanUp, setHighlightedIndex },
      ) =>
        anchorElementRef.current && results.length
          ? ReactDOM.createPortal(
            <div className='typeahead-popover mentions-menu'>
              <ul>
                {options.map((option, i: number) => (
                  <MentionsTypeaheadMenuItem
                    index={i}
                    isSelected={selectedIndex === i}
                    onClick={() => {
                      setHighlightedIndex(i);
                      selectOptionAndCleanUp(option);
                    }}
                    onMouseEnter={() => {
                      setHighlightedIndex(i);
                    }}
                    key={option.key}
                    option={option}
                  />
                ))}
              </ul>
            </div>,
            anchorElementRef.current,
          )
          : null
      }
    />
  );
}