window.onload = function(){
    createlist();
    setInterval(checkplay, 3000);
}

// 搜索音乐
function getsongs(){
    document.getElementById("reslist").innerHTML = "";
    var search = document.getElementById("search-song");
    var reslist = document.getElementById("reslist");
    var urls = `http://150.158.7.169:3000/search?keywords=${search.value}`
    var xhr = new XMLHttpRequest();
    xhr.open("GET", urls);
    xhr.send();
    xhr.onreadystatechange = function(){
        if(xhr.readyState == 4 && xhr.status == 200){
           //console.log(xhr.responseText);
           var obj = JSON.parse(xhr.responseText);
           //console.log(obj.result.songs);
           console.log(obj);
           var list = obj.result.songs;
           //for(i = 0; i < obj.result.songs.length; i++){
           for(var i = 0; i < list.length; i++){
               artiststr = getArtist(list[i]);
               console.log({"songid":list[i].id, "songname":list[i].name, "artist":artiststr});
               if(list[i].fee == 0 || list[i].fee == 8){
                    reslist.innerHTML += `<li id="listitem"><a href="javascript:void(0)" onclick="playmusic(${list[i].id}, '${list[i].name}', '${artiststr}')">${list[i].name} - ${getArtist(list[i])}</a>`+
                    `<button type="button" id="playbtn" onclick="addlist(${list[i].id}, '${list[i].name}', '${artiststr}')">加入播放列表</button></li>`;
               }else{
                    reslist.innerHTML += `<li>[不支持播放]${list[i].name} - ${getArtist(list[i])}</li>`
               }
           }
        }else{
            //alert(xhr.statusText);
        }
    }
    document.getElementById("keyword").innerHTML = search.value;
}

// 获取艺术家
function getArtist(obj){
    var artiststr = "";
    var artistd = obj.artists;
    for(var i = 0; i < artistd.length; i++){
        if(i != artistd.length - 1){
            artiststr += artistd[i].name + "/";
        }else{
            artiststr += artistd[i].name;
        }
    }
    return artiststr;
}

// 播放音乐
function playmusic(playid, songname, artist){
    document.getElementById("nowplay").innerHTML = `${songname} - ${artist}`
    url = `https://music.163.com/song/media/outer/url?id=${playid}.mp3`;
    document.getElementById("Player").setAttribute('src',url);
    // 选中后自动播放
    document.getElementById("Player").play();
    // 插入到历史记录
    inserthistory(playid, songname, artist);
}

// 队列 -- Writtrn By Copilot & Web
function Queue(){
    this.items = [];

    Queue.prototype.nqueue = (element) => {
        this.items.push(element);
    }

    Queue.prototype.dequeue = () => {
        return this.items.shift();
    }

    Queue.prototype.front = () => {
        return this.items[0];
    }

    Queue.prototype.isEmpty = () => {
        return this.items.length == 0;
    }

    Queue.prototype.clear = () => {
        this.items = [];
    }

    Queue.prototype.size = () => {
        return this.items.length;
    }

    Queue.prototype.toString = () => {
        var str = "";
        for(var i = 0; i < this.items.length; i++){
            str += this.items[i] + " ";
        }
        return str;
    }
}

// 创建播放列表
function createlist(){
    // 构造队列
    list = new Queue();
}

// 添加到播放列表
function addlist(songid, songname, artist){
    list.nqueue({"songid":songid, "songname":songname, "artist":artist});
    console.log(`${songname} - ${artist} 已被加入播放列表`);
}

// 播放下一首
function playnext(){
    if(list.isEmpty()){
        console.log("音乐列表已经播放完毕了哦，快加入新的音乐吧~");
        alert("音乐列表已经播放完毕了哦，快加入新的音乐吧~");
        return;
    }
    var next = list.dequeue();
    playmusic(next.songid, next.songname, next.artist);
}

// 检测是否播放完毕
function checkplay(){
    // 为了防止播放列表结束以后一直调用playnext产生过多的alart，所以需要检测播放列表是否为空
    if(!list.isEmpty()){
        if(document.getElementById("Player").ended){
            // 播放完毕后自动播放下一首
            playnext();
        }
    }else{
        //clearInterval(checkplay);
    }
}

// 播放列表
function playthelist(){
    if(list.isEmpty()){
        console.log("音乐列表没有歌曲哦，快加入新的音乐吧~");
        alert("音乐列表没有歌曲哦，快加入新的音乐吧~");
        return;
    }
    var next = list.dequeue();
    playmusic(next.songid, next.songname, next.artist);
}

// 获取播放列表
function getplaylist(){
    //var playlist = document.getElementById("playlist");
    //playlist.innerHTML = "";
    var reslist = document.getElementById("reslist");
    reslist.innerHTML = "";
    for(var i = 0; i < list.size(); i++){
        reslist.innerHTML += `<li>${list.items[i].songname} - ${list.items[i].artist}<button type="button" id="delbtn" onclick="RemoveItemFromListByID(${i})">删除</button></li>`;
        //console.log(`${list.items[i].songname} - ${list.items[i].artist}`);
    }
    document.getElementById('keyword').innerHTML = "当前播放列表";
}

/* // -- Writtrn By Copilot
function RemoveItemFromList(songid){
    for(var i = 0; i < list.size(); i++){
        if(list.items[i].songid == songid){
            list.items.splice(i, 1);
            break;
        }
    }
    getplaylist();
}
*/

// 删除指定序号的音乐 -- Writtrn By Copilot
function RemoveItemFromListByID(uid){
    list.items.splice(uid, 1);
    getplaylist();
}

// 插入音乐到历史记录 -- Writtrn By Copilot
function inserthistory(songid, songname, artist){
    // 从本地获取历史记录
    var historyList = JSON.parse(localStorage.getItem("historyList"));
    // 判断是否有历史记录
    if(historyList == null){
        historyList = [];   // 创建一个空数组
    }
    var flag = false;       // 标记是否已经存在
    // 判断是否已经存在
    for(var i = 0; i < historyList.length; i++){
        // 如果已经存在，则更新播放时间
        if(historyList[i].songid == songid){
            flag = true;
            break;
        }
    }
    // 如果不存在，则插入
    if(!flag){
        // historyList.push({"songid":songid, "songname":songname, "artist":artist, "playtime":new Date().getTime()});
        historyList.push({"songid":songid, "songname":songname, "artist":artist});
    }
    // 存储到本地
    localStorage.setItem("historyList", JSON.stringify(historyList));
}

// 获取历史记录 -- Writtrn By Copilot
function gethistory(){
    var historyList = JSON.parse(localStorage.getItem("historyList"));
    if(historyList == null){
        historyList = [];
    }
    var reslist = document.getElementById("reslist");
    reslist.innerHTML = "";
    for(var i = 0; i < historyList.length; i++){
        reslist.innerHTML += `<li>${historyList[i].songname} - ${historyList[i].artist}` + 
        `<button type="button" id="playbtn" onclick="addlist(${historyList[i].songid}, '${historyList[i].songname}', '${historyList[i].artist}')">加入播放列表</button></li>`;
    }
    document.getElementById('keyword').innerHTML = "历史记录";
}

// 清空历史记录 -- Writtrn By Copilot
function removehistory(){
    localStorage.removeItem("historyList");
    gethistory();
}

// 当点击清空列表的时候进行一次确认，如果确认之后再进行删除操作。
function ClearList(){
    var Choose = confirm("确定清空歌单吗？(此操作不可逆！)")
    if(Choose == true){
        removehistory();
        console.log("The History List Has been cleared.");
        return true;
    }else{
        console.log("List Clear Canceled!");
        return false;
    }
}

// 添加所有歌曲到播放列表
function addAllHistorytoPlayList(){
    var historyList = JSON.parse(localStorage.getItem("historyList"));
    if(historyList == null){
        historyList = [];
    }
    var reslist = document.getElementById("reslist");
    reslist.innerHTML = "";
    for(var i = 0; i < historyList.length; i++){
        addlist(historyList[i].songid, historyList[i].songname, historyList[i].artist);
        console.log(`${historyList[i].songname} - ${historyList[i].artist} is add to list.`);
    }
    alert("已把历史记录插入到了播放列表");
    // Planning to Code...
}

// 清空播放列表
function ClearthePlaylist(){
    if(!list.isEmpty()){
        list.clear();
        console.log("List Cleared!");
    }else{
        console.log("List is empty, not need to clear.")
    }
}

// 推送到云播放列表
function PushToCloud(){
    // Cloud Prepareing...
}

// 拉取云播放列表
function PullToCloud(){
    // Cloud Prepareing...
}