摘要：源碼獲取中光標坐標獲取中光標位置獲取光標位置獲取焦點前坐標中插入文本輸入元素獲取焦點獲取光標位置在光標位置插入值輸入元素獲取焦點獲取焦點前坐標獲取焦點后坐標插入文字設置中光標位置設置話題顏色例如部分為紅色暫未用到獲取所有話題中文本

// 獲取 textarea 中光標坐標
const textareaCaret = require("textarea-caret");

function getCaretCoordinates($el) {
    let caret = textareaCaret($el, $el.selectionEnd);

    return {
        top: caret.top, 
        left: caret.left, 
        height: caret.height
    }
}

// 獲取 textarea 中光標位置
function getCursorPosition($el) {
    var cursorPos = 0;
    if (document.selection) {
        // IE
        var fus = document.selection.createRange(); //獲取光標位置 
        fus.moveStart("character", -$el.value.length);
        cursorPos = fus.text.length;

    } 
    if ($el.selectionStart || $el.selectionStart == 0) {
        var start = $el.selectionStart;　　 //獲取焦點前坐標 
        cursorPos = start;
    }
    return cursorPos;
}

// textarea 中插入文本
function insertCursorText($el, text) {
  var cursorPos = 0;

  if (document.selection) {
      // IE
      $el.focus(); //輸入元素textara獲取焦點 
      var fus = document.selection.createRange(); //獲取光標位置 

      fus.moveStart("character", -$el.value.length);
      cursorPos = fus.text.length;

      fus.text = text; //在光標位置插入值 
      $el.focus(); ///輸入元素textara獲取焦點 
  } else if ($el.selectionStart || $el.selectionStart == 0) {
      var start = $el.selectionStart;　　 //獲取焦點前坐標 
      var end = $el.selectionEnd;　　 //獲取焦點后坐標 

      cursorPos = start;

      // 插入文字
      $el.value = $el.value.substring(0, start) + text + $el.value.substring(end, $el.value.length);
  } else {
      $el.value += text;
  }

  return {
      value: $el.value,
      cursorPos: cursorPos
  }
}

// 設置 textarea 中光標位置
function setCursorPosition($el, pos) {
    if($el.setSelectionRange) {
        $el.focus();
        $el.setSelectionRange(pos, pos);
    } else if ($el.createTextRange) {
        var range = $el.createTextRange();
        range.collapse(true);
        range.moveEnd("character", pos);
        range.moveStart("character", pos);
        range.select();
    }
}

// 設置 “話題” 顏色 (例如："#123#" 部分為紅色) 【暫未用到】
function setTopicStyle(value) {
    var exp = /(#|＃)((?!#).)*(#|＃)/g
    value = value.replace(/<[^>]*?>(.*?)/gi, "").replace(/(.*?)]*?>/gi, "").replace(exp, (item) => {
        let newVal = "" + item + ""
        return newVal
    })
    return value
}

// 獲取所有話題, src ： textarea 中文本
function parse(src) {

    return src.split(/(#[^#]+#)/).reduce((res, v, i, a) => {

        if (v.length > 1 && v.startsWith("#") && v.endsWith("#")) {
            res.list.push({
                tag: v.substring(1, v.length-1),
                index: res.index,
                completed: true
            });
            
        } else {
          if (i === a.length -1) {

              const parts = v.split("#");
              if (parts.length > 1) {
                  res.list.push({
                      tag: parts.pop(),
                      index: parts[0].length + res.index,
                      completed: false
                  });
              }
          }
        }

        res.index += v.length;

        return res;

    }, {list: [], index: 0});

}

// 獲取當前話題 res: parse(src); caretPos： getCursorPosition($el)
function getCurrent(res, caretPos) {

    let current = null;

    res.list.some((v, i) => {
        if (v.index < caretPos && v.index + v.tag.length + 2 > caretPos) {
            current = v;
            return true;
        }

        return false;
    });

    return current;
}

export default {
    getCaretCoordinates,
    getCursorPosition,
    setCursorPosition,
    insertCursorText,
    setTopicStyle,
    parse, 
    getCurrent
}