//该文件用于解析HTML，输出为Object对象

const htmlparser2 = require("htmlparser2");

function getNodeContent(node) {
  return node[Object.keys(node)[0]];
}

/**每个节点的表示方法为:
{
  tagname: {
    key1: value1,
    key2: value2,
    __children: [
      {

      }
    ]
  }
}*/
function generateNewNode(tagName, attributes = {}) {
  // 构建新节点
  const newNode = {};
  newNode[tagName] = attributes;
  attributes.__children = [];
  return newNode;
}

function parseHtml(htmlData) {
  return new Promise((resolve, reject) => {
    // 根节点
    const root = generateNewNode('root');
    // 当前访问的节点
    let currentAccessObject = root;
    // 之前访问的节点数组
    let lastAccessStack = [root];

    // options docment: https://github.com/fb55/htmlparser2/wiki/Parser-options
    const parser = new htmlparser2.Parser({
      onopentag(tagname, attributes) {
        const newNode = generateNewNode(tagname, attributes);
        lastAccessStack.push(newNode);
        getNodeContent(currentAccessObject).__children.push(newNode);
        currentAccessObject = newNode;
      },
      ontext(text) {
        if (text.trim()) {
          getNodeContent(currentAccessObject).__text__ = text.trim();
        }
      },
      onclosetag(tagname) {
        lastAccessStack.pop();
        currentAccessObject = lastAccessStack[lastAccessStack.length - 1];
      },
      onend(){
        resolve(root);
      },

      onerror(error) {
        reject(error);
      }
    });
    parser.write(
      htmlData
    );
    parser.end();
  })
}

async function html2Json(htmlData) {
  return await parseHtml(htmlData);
}

export { html2Json };