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var http = require('http');
var cheerio = require('cheerio');
var url = 'http://www.imooc.com/learn/348';
var assert = require('assert');

function deleteBlank(string) {
    results = []
    lines = string.split('\r\n');
    lines.forEach(function (line) {
        if(! /^\s*$/.test(line)) {
            line = line.replace(/(^\s*)|(\s*$)/g, '');
            results.push(line);
        }
    });

    return results.join(' ');
}

function filterChapters(html) {
    // [{
    //     chpaterTitle: '',
    //     videos: [{
    //         title: '',
    //         id: ''
    //     }]
    // }]

    var $ = cheerio.load(html);
    var chapters = $('.chapter ');
    var courseData = [];

    chapters.each(function(data) {
        var chapter = $(this);
        var chapterTitle = deleteBlank(chapter.find('strong').text());
        var videos = chapter.find('ul.video').children('li');
        var chapterData = {
            chapterTitle: chapterTitle,
            videos: []
        }

        var video = null;
        var videoTitle = null;
        var id = null;
        videos.each(function(item) {
            video = $(this).find('a.J-media-item');
            button = video.find('button');
            button.remove(); // 删除掉button节点，就没有开始学习的文本节点了。
            videoTitle = deleteBlank(video.text());
            id = video.attr('href').split('video/')[1];

            chapterData.videos.push({
                title: videoTitle,
                id: id
            })
        })

        courseData.push(chapterData)
    });

    return courseData;
}

function printCourseInfo(courseData) {
    courseData.forEach(function(course) {
        var chapterTitle = course.chapterTitle;

        console.log(chapterTitle);

        course.videos.forEach(function(video) {
            console.log('   【' + video.id + '】' + video.title);
        });
    })
}

http.get(url, function(res) {
    var html = ''

    res.on('data', function(data) {
        html += data;
    });

    res.on('end', function() {
        var courseData = filterChapters(html);

        printCourseInfo(courseData);
    })
}).on('error', function() {
    console.log('获取数据课程出错哦！');
});