#!/usr/bin/env node

var URL = require('url');
var HTTP = require('http');
var FS = require('fs');
var EXPAT = require('node-expat');
var El = require('node-xmpp').Element;


if (process.argv.length !== 5) {
    console.error('Usage: <user> <pass> <conference_id>');
    process.exit(1);
}
var user = process.argv[2];
var pass = process.argv[3];
var conference_id = process.argv[4];
var outputDir = '.';
var baseDir = '/fahrplan';

var clients = [];
for(var i = 0; i < 8; i++)
    clients.push(HTTP.createClient(443, 'cccv.pentabarf.org', true));

function get(path, cb) {
    var client = clients[Math.floor(Math.random() * clients.length)];

    console.log("GET " + path);
    var req = client.request('GET', path + '?preview=1',
			     { 'Host': 'cccv.pentabarf.org',
			       'Authorization': 'Basic ' + base64(user + ':' + pass) });
    req.end();

    req.on('response', function(res) {
	if (res.statusCode === 200)
	    cb(res);
	else
	    console.warn(res.statusCode + ': ' + path);
    });
}

function base64(s) {
    return new Buffer(s).toString('base64');
}

function ensureDirs(path) {
    var paths = path.split('/');
    paths.pop();
    var path1 = '';
    paths.forEach(function(dir) {
	if (path1 !== '')
	    path1 += '/';
	path1 += dir;
	try {
	    FS.mkdirSync(path1, 0755);
	} catch (e) { }
    });
}

function downloadTo(path) {
    return function(res) {
	ensureDirs(path);
	var f = FS.createWriteStream(path);
	console.log('>> ' + path);
	res.on('data', function(data) {
	    f.write(data, 'binary');
	});
	res.on('end', function() {
	    f.end();
	});
    };
}

function downloadXml(path, attrMapper) {
    return function(res) {
	ensureDirs(path);
	var f = FS.createWriteStream(path);
	console.log('<> ' + path);
	var p = new EXPAT.Parser();
	var el;
	p.addListener('startElement', function(name, attrs) {
	    var attrs2 = {};
	    for(var k in attrs) {
		if (attrs.hasOwnProperty(k))
		    attrs2[k] = attrMapper(k, attrs[k]);
	    }

	    var child = new El(name, attrs2);
	    if (el) {
		el = el.cnode(child);
	    } else
		el = child;
	});
	p.addListener('endElement', function(name) {
	    if (!el.parent) {
		f.write(el.toString());
		el = undefined;
	    } else
		el = el.parent;
	});
	p.addListener('text', function(s) {
	    if (el)
		el.t(s);
	});
	p.addListener('xmlDecl', function(version, encoding, standalone) {
	    f.write('<?xml');
	    if (version)
		f.write(' version="' + version + '"');
	    if (encoding)
		f.write(' encoding="' + encoding + '"');
	    if (standalone)
		f.write(' standalone="' + (standalone ? 'yes' : 'no') + '"');
	    f.write("?>\n");
	});

	res.on('data', function(data) {
	    p.parse(data);
	});
	res.on('end', function() {
	    p.parse('', true);
	    f.end();
	});
    };
}

function Spider() {
    this.seen = {};
    this.see('/schedule/' + conference_id + '/index.de.html');
}

var normalizePath = function(path, from) {
    from = from || 'https://cccv.pentabarf.org/';
    var uri = URL.parse(URL.resolve('https://cccv.pentabarf.org/', path));
    if (uri.hostname !== 'cccv.pentabarf.org')
	return null;
    return uri.pathname;
};

var manglePath = function(path) {
    var m;
    if ((m = path.match(/^\/schedule\/\d+\/(.+)$/)))
	return baseDir + '/' + m[1];
    else if ((m = path.match(/^\/(xml|ical|xcal)\/(schedule|conference)\/\d+/))) {
	var ext;
	switch(m[1]) {
	    case 'ical':
		ext = 'ics';
		break;
	    case 'xcal':
		ext = 'xcs';
		break;
	    default:
		ext = m[1];
	}
	return baseDir + '/schedule.' + ext;
    } else
	return baseDir + path;
};

Spider.prototype.see = function(path, from) {
    path = normalizePath(path, from);
    if (!path)
	return;
    var outPath = outputDir + manglePath(path);

    if (this.seen.hasOwnProperty(path))
	return;
    this.seen[path] = true;

    if (/\.html$/.test(path)) {
	var that = this;
	function rewriteAttr(k, v) {
	    switch(k) {
	    case 'href':
	    case 'src':
		that.see(v);
		return manglePath(v);
	    default:
		return v;
	    }
	}
	get(path, downloadXml(outPath, rewriteAttr));
    } else
	get(path, downloadTo(outPath));
};

new Spider();