import CodeMirror from 'codemirror5';

// Disabling eslint on purpose
/* eslint-disable */

var listRE = /^(\s*)(>[> ]*|[*+-] \[[x ]\]\s|[*+-]\s|(\d+)([.)]))(\s*)/,
  emptyListRE = /^(\s*)(>[> ]*|[*+-] \[[x ]\]|[*+-]|(\d+)[.)])(\s*)$/,
  unorderedListRE = /[*+-]\s/;

/*
  functions coming from CodeMirror addons continuelist.js
  ===> https://github.com/codemirror/CodeMirror/blob/master/addon/edit/continuelist.js

  we imported it because the way the addon ask to use markdown mode
  since we have our own markdown preview system we couldn't use it directly
  only thing we changed is removing the part that enabled addon only with markdown mode
*/

function newlineAndIndentContinueMarkdownList(cm) {
  if (cm.getOption('disableInput')) return CodeMirror.Pass;
  var ranges = cm.listSelections(),
    replacements = [];
  for (var i = 0; i < ranges.length; i++) {
    var pos = ranges[i].head;

    var eolState = cm.getStateAfter(pos.line);
    var inList = eolState.list !== false;
    var inQuote = eolState.quote !== 0;

    var line = cm.getLine(pos.line),
      match = listRE.exec(line);
    var cursorBeforeBullet = /^\s*$/.test(line.slice(0, pos.ch));
    if (!ranges[i].empty() || (!inList && !inQuote) || !match || cursorBeforeBullet) {
      cm.execCommand('newlineAndIndent');
      return;
    }
    if (emptyListRE.test(line)) {
      var endOfQuote = inQuote && />\s*$/.test(line);
      var endOfList = !/>\s*$/.test(line);
      if (endOfQuote || endOfList)
        cm.replaceRange(
          '',
          {
            line: pos.line,
            ch: 0,
          },
          {
            line: pos.line,
            ch: pos.ch + 1,
          }
        );
      replacements[i] = '\n';
    } else {
      var indent = match[1],
        after = match[5];
      var numbered = !(unorderedListRE.test(match[2]) || match[2].indexOf('>') >= 0);
      var bullet = numbered ? parseInt(match[3], 10) + 1 + match[4] : match[2].replace('x', ' ');
      replacements[i] = '\n' + indent + bullet + after;

      if (numbered) incrementRemainingMarkdownListNumbers(cm, pos);
    }
  }

  cm.replaceSelections(replacements);
}

function incrementRemainingMarkdownListNumbers(cm, pos) {
  var startLine = pos.line,
    lookAhead = 0,
    skipCount = 0;
  var startItem = listRE.exec(cm.getLine(startLine)),
    startIndent = startItem[1];

  do {
    lookAhead += 1;
    var nextLineNumber = startLine + lookAhead;
    var nextLine = cm.getLine(nextLineNumber);
    var nextItem = listRE.exec(nextLine);

    if (nextItem) {
      var nextIndent = nextItem[1];
      var newNumber = parseInt(startItem[3], 10) + lookAhead - skipCount;
      var nextNumber = parseInt(nextItem[3], 10),
        itemNumber = nextNumber;

      if (startIndent === nextIndent && !isNaN(nextNumber)) {
        if (newNumber === nextNumber) itemNumber = nextNumber + 1;
        if (newNumber > nextNumber) itemNumber = newNumber + 1;
        cm.replaceRange(
          nextLine.replace(listRE, nextIndent + itemNumber + nextItem[4] + nextItem[5]),
          {
            line: nextLineNumber,
            ch: 0,
          },
          {
            line: nextLineNumber,
            ch: nextLine.length,
          }
        );
      } else {
        if (startIndent.length > nextIndent.length) return;
        // This doesn't run if the next line immediately indents, as it is
        // not clear of the users intention (new indented item or same level)
        if (startIndent.length < nextIndent.length && lookAhead === 1) return;
        skipCount += 1;
      }
    }
  } while (nextItem);
}

export default newlineAndIndentContinueMarkdownList;