00// id3/reader.js
01const jsmediatags = require("jsmediatags")
02    , fs = require('then-fs')
03    , path = require('path')
04    , url = require('url')
05    , { mp3Model } = require('../../tools/db')
06    , qnx = require('../../tools/qnx')
07    , uuid = require('uuid/v1')
08    , mkdir = require('../mkdir')
09
10// 创建临时文件夹 
11mkdir(path.join(__dirname, 'pic')); 
12
13function reader(src){
14    let isCache = false; 
15
16    return mp3Model.findOne({
17        url: src
18    }).then(mp3 => {
19        if (mp3){
20            isCache = true; 
21            console.log('From Cache'); 
22            return Promise.resolve(mp3); 
23        } else {
24            isCache = false; 
25            return readMp3From(src); 
26        }
27    })
28}
29
30function readMp3From(src){
31    let picData, picName, picLocal, _id3; 
32
33    return new Promise((res, rej) => {
34        // Try To Parsing ID3 File Meta Data 
35        new jsmediatags.Reader(src)
36            // Target Fields 
37            .setTagsToRead(["title", "artist", "album", "picture", "track", "genre", "TLE"])
38            .read({
39                onSuccess: function(tag) {
40                    res(tag); 
41                },
42                onError: function(error) {
43                    rej(error)
44                }
45            });
46    }).then(id3 => { // Parse Success 
47        // Basic Value 
48        _id3 = id3; 
49        picData = new Buffer(id3.tags.picture.data); 
50        picName = uuid() + '.jpg'; 
51        picLocal = path.join(__dirname, 'pic', picName);
52
53        // Write File To Local 
54        return fs.writeFile(
55            picLocal,
56            picData
57        ); 
58    }).then(suc => { // After Parsing, And Have Picture Saved To Local 
59        // Try To Upload File To Qiniu 
60        return qnx.upload(picLocal, 'album-pic/' + picName); 
61    }).then(qiniuResponse => {
62        let { hash, key, img } = qiniuResponse; 
63
64        _id3.tags.picture.data = []; 
65
66        return {
67            url: src, 
68            picture: img, 
69            info: _id3
70        }
71    }).catch(err => {
72        console.log(err); 
73        return Promise.reject({
74            err: err, 
75            msg: 'Error When Reading ID3'
76        });
77    })
78}
79
80module.exports = reader;

00const express = require('express')
01    , router = express.Router()
02    , rps = require('../tools/responser')
03    , ID3Reader = require('../tools/id3/reader')
04    , { mp3Model } = require('../tools/db')
05    , wait = require('../tools/wait')
06
07// 队列 
08let Q = []; 
09// 是否忙  
10let pending = false; 
11
12function store(req, res){
13    let src; 
14
15    if (Q.length !== 0) {
16        // 队列非空 
17        if (!pending){
18            // 不忙 出队到 src 并设置为忙 
19            src = Q.pop(); 
20            pending = true; 
21
22            // 走一遍 toRead 
23            return toRead(src, req, res).then(suc => {
24                // 成功的时候，再走一次 store 
25                return store(req, res); 
26            });
27        } else {
28            // 忙 等待 100 毫秒后递归执行本函数 
29            return wait(100).then(suc => {
30                return store(req, res); 
31            })
32        }
33    } else {
34        // 队列空 直接 resolved 并设置为 pending 
35        pending = false; 
36        return Promise.resolved(true); 
37    }
38}
39
40// 读取 src 
41function toRead(src, req, res){
42    // 读取并缓存 并设置 pending 
43    console.log('toRead', src); 
44
45    return ID3Reader(src).then(mp3 => {
46        // Set Who 
47        mp3.who = req.user_id; 
48
49        // New Data And Save It 
50        let data = new mp3Model(mp3); 
51
52        return data.save(); 
53    }).then(mp3 => {
54        rps.send2000(res, mp3); 
55    }).catch(err => {
56        rps.send5006(res, {}, err.toString()); 
57    })
58}
59
60function reload(query){
61    return wait(100).then(suc => {
62        return mp3Model.findOne(query).then(mp3 => {
63            if (mp3){
64                return mp3; 
65            } else {
66                return reload(query); 
67            }
68        })
69    })
70}
71
72router.post('/', function(req, res){
73    // 入队 
74    Q.unshift(req.body.src); 
75
76    if (!pending) {
77        // 空闲才做事
78        console.log('处理中 ... '); 
79        store(req, res);
80    } else {
81        // 否则 轮询 
82        reload({
83            url: req.body.src
84        }).then(mp3 => {
85            rps.send2000(res, mp3); 
86        })
87    }
88});