const Koa = require('koa');
const app = new Koa();


app.use(async (ctx)=>{
    // console.log(ctx.request);//经过封装的请求对象
    // console.log(ctx.req); //node.js原生HTTP请求对象
    //当请求时GET请求时，显示表单让用户填写
    if (ctx.url === '/' && ctx.method === 'GET') {
        let html = `
            <h1>Koa2 request post demo</h1>
            <form method="POST"  action="/">
                <p>userName</p>
                <input name="userName" /> <br/>
                <p>age</p>
                <input name="age" /> <br/>
                <p>webSite</p>
                <input name='webSite' /><br/>
                <button type="submit">submit</button>
            </form>
        `;
        ctx.body = html;
    }
    //当请求时POST请求时
    else if(ctx.url==='/'&&ctx.method==='POST'){
        console.log(ctx.request);
        let pastData = await parsePostData(ctx);
        ctx.body='接收到请求';
    }else{
        //其他页面请求显示404页面
        ctx.body='<h1>404!</h1>'
    }
});

//获取post传递过来的参数，并解析成json形式
function parsePostData(ctx){
    return new Promise((resolve,reject)=>{
        try{
            let postdata = "";
            ctx.req.on("data",(data)=>{
                postdata+=data;
            });
            ctx.req.addListener("end",()=>{
                let parseData = parseQueryStr(postdata);
                resolve(parseData);
            })
        }catch(err){
            reject(error);
        }
    })
};

function parseQueryStr(queryStr){
    let queryData = {};
    let queryStrList = queryStr.split('&');
    for(let [index,queryStr] of queryStrList.entries()){//{['userName=wang','age=18','webSite=jspang.com']}
        let itemList = queryStr.split('=');
        console.log(itemList);
        queryData[itemList[0]] = decodeURIComponent(itemList[1]);
    }
    return queryData;
}
app.listen(3000,()=>{
    console.log('server is starting at port 3000')
})