const fs = require('fs');

// --------------- 读取源文件 ---------------
const originData = require('./vuxArea3.json');

// --------------- 常量 ---------------
const constant = {
  ARRAY_TYPE: 'Array',
  JSON_TYPE: 'Json',
};

// --------------- 转换的配置 ---------------

const config = {
  originKey: {
    children: null,
    parent: 'parent',
    value: 'value',
    label: 'name'
  },
  originType: constant.ARRAY_TYPE,
  targetKey: {
    children: 'children',
    parent: null,
    value: 'value',
    label: 'label'
  },
  targetType: constant.JSON_TYPE
};

// --------------- 转换函数 ---------------
function convertArrayToJson(initData, { originKey, targetKey }) {
  if (!initData || initData.length === 0) return [];
  if (!initData.length === 1) return initData;
  if (!(initData instanceof Array)) return [initData];

  const result = [];
  const tempMap = [];

  const key = originKey.value;
  const parentKey = originKey.parent;
  const l = initData.length;
  let i;

  // key转换
  const data = initData.map(item => ({
    [originKey.parent]: item[originKey.parent],
    [targetKey.value]: item[originKey.value],
    [targetKey.label]: item[originKey.label]
  }));

  // 临时引用
  for (i = 0; i < l; i += 1) {
    tempMap[data[i][key]] = data[i];
  }

  // 叶子通过临时引用挂载，利用所有的节点都是单例，才可以通过临时引用去挂载叶子
  // 根元素直接push到根节点
  for (i = 0; i < l; i += 1) {
    const parentValue = data[i][parentKey];
    // 当前元素存在父元素，并且子不等于父
    if (tempMap[parentValue] && data[i][key] !== parentValue) {
      // 父元素上在children上加上当前元素
      tempMap[parentValue][targetKey.children] =
        tempMap[parentValue][targetKey.children] || [];
      tempMap[parentValue][targetKey.children].push(data[i]);
    } else {
      // 当前元素是根元素
      result.push(data[i]);
    }
  }
  return result;
}

function convert(data, { originKey, originType, targetKey, targetType }) {
  if (originType === constant.ARRAY_TYPE && targetType === constant.JSON_TYPE) {
    return convertArrayToJson(data, { originKey, targetKey });
  }
  return [];
}

// --------------- 执行 ---------------
const result = convert(originData, config);
let resultStr = '';
try {
  resultStr = JSON.stringify(result);
} catch (e) {
  console.log(e);
}
resultStr = resultStr.replace(/"parent":"[a-zA-Z\d]+",/g, '');

// --------------- 写入 ---------------
fs.writeFile('./result.json', resultStr, 'utf-8', (err) => {
  if (err) {
    console.log(err);
  } else {
    console.log(`### conver ${config.originType} to ${config.targetType} success! `);
  }
});