se-boxer.js

"use strict";

// replaces URL to SO questions, answers and comments with the relevant extract
//   using the StackExchange API.
// The filter parameter passed to SO API can be edited here :
//   https://api.stackexchange.com/docs/questions#order=desc&sort=activity&filter=!9YdnSJrC1&site=stackoverflow&run=true

var	http = require('http'),
	zlib = require("zlib"),
	cache = require('bounded-cache')(300),
	bench = require("../../libs/bench.js"),
	rex = require("../../libs/rex.js"),
	Deque = require("double-ended-queue"),
	apiurl = "http://api.stackexchange.com/2.2/",
	apikey, // necessary to get a bigger quota (10 000 instead of 300)
	TTL = 15*60*1000,
	tasks = new Deque(2000),
	currentTask;

const icons = {
	stackoverflow: "so",
	serverfault: "sf",
	superuser: "su"
};


function logo(task){
	var	icon = (icons[task.site] || "se") + "-icon.png",
		path = "static/plugins/stackoverflow/rsc/" + icon;
	return '<img src="'+path+'" width=40>';
}

var handlers = {
	"questions":{
		filter:"!L_Zm1rmoFy)u)LqgLTvHLi",
		dobox:function(item, task){ // builds the HTML of a question from its JSON element as sent by the SO API
			var side = '', main = '';

			side += '<div class=so-type>Question</div>';
			side += '<div class=so-score>Score: <span class=num>'+item.score+'</span></div>';
			side += '<div class="so-answers'+(item.is_answered?' so-accepted':'')+'">';
			side += '<span class=num>'+item.answer_count+'</span> answers</div>';
			side += '<img class=so-owner-img src="'+item.owner.profile_image+'">';
			side += '<div class=so-owner-name>'+item.owner.display_name+'</div>';
			side = '<div class=so-side>'+side+'</div>';

			main += '<a target=_blank class=so-title href="'+task.line+'">'+logo(task)+item.title+'</a>';
			main += '<div class=so-tags>'+item.tags.map(tag => '<span>'+tag+'</span>').join('')+'</div>';
			main += '<div class=so-body>'+item.body+'</div>';
			main = '<div class=so-main>'+main+'</div>';

			return '<div class=stackexchangebox>'+side+main+'</div>';
		}
	},
	"answers":{
		filter:"!)6EG5Z9Ys.RpJe_vSYewAIdDZ-cm",
		dobox:function(item, task){ // builds the HTML of an answer from its JSON element as sent by the SO API
			var side = '', main = '';

			side += '<div class=so-type>Answer</div>';
			var classes = "so-score'+(item.is_accepted?' so-accepted':'')+'";
			side += '<div class='+classes+'>Score: <span class=num>'+item.score+'</span></div>';
			side += '<img class=so-owner-img src="'+item.owner.profile_image+'">';
			side += '<div class=so-owner-name>'+item.owner.display_name+'</div>';
			side = '<div class=so-side>'+side+'</div>';

			main += '<a target=_blank class=so-title href="'+task.line+'">'+logo(task)+item.title+'</a>';
			main += '<div class=so-tags>'+item.tags.map(tag => '<span>'+tag+'</span>').join('')+'</div>';
			main += '<div class=so-body>'+item.body+'</div>';
			main = '<div class=so-main>'+main+'</div>';

			return '<div class=stackexchangebox>'+side+main+'</div>';
		}
	},
	"comments":{
		filter:"!*K)GSjDWh5D7ZCvl",
		dobox:function(item, task){
			var side = '', main = '';

			side += '<div class=so-type>Comment</div>';
			side += '<div class=so-score>Score: <span class=num>'+item.score+'</span></div>';
			side = '<div class=so-side>'+side+'</div>';

			main += '<span class=so-comment>'+item.body+'</span> - ';
			main += '<a target=_blank class=so-comment-link href='+task.line+'">'+
				item.owner.display_name+' <i>'+
				Date(item.creation_date)+ // todo make the browser compute the date using the locale
				'</i></a>';

			main = '<div class=so-main>'+main+'</div>';

			return '<div class=stackexchangebox>'+side+main+'</div>';

		}
	}
};

// unzip and parse the response from a request to the SO API.
// SO API always answers with gzipped content (even if your headers forbid it, it seems)
// callback is given an error and a js object
function getFromSO(url, callback){
	var buffer = [];
	http.get(url, function(res){
		var gunzip = zlib.createGunzip();
		res.pipe(gunzip);
		gunzip.on('data', function(data){
			buffer.push(data.toString())
		}).on("end", function(){
			try {
				callback(null, JSON.parse(buffer.join('')));
			} catch (e) {
				callback(e);
			}
		}).on("error", function(e){
			callback(e);
		});
	}).on('error', function(e){
		callback(e)
	});
}

function dequeue(){
	if (currentTask) return;
	var task = tasks.shift();
	if (!task) return;
	currentTask = task;
	var	benchOperation = bench.start("Stack Exchange / Box Page"),
		box = cache.get(task.key);
	if (box !== undefined) {
		return setTimeout(function(){
			currentTask = null;
			if (box) task.send('box', {mid:task.mid, from:task.line, to:box});
			dequeue();
		}, 50);
	}
	var	handler = handlers[task.type],
		url = apiurl+task.type+"/"+task.num+"?site="+(task.meta?'meta.':'')+task.site+"&filter="+handler.filter;
	if (apikey) url += "&key="+apikey;
	getFromSO(url, function(error, data){
		currentTask = null;
		setTimeout(dequeue, 50);
		if (error) {
			console.log("ERROR:", error);
			cache.set(task.key, null, TTL);
			return;
		}
		if (!data.items || !data.items.length) {
			console.log("invalid answer (or bad SO url)");
			cache.set(task.key, null, TTL);
			return;
		}
		var box = handler.dobox(data.items[0], task);
		cache.set(task.key, box, TTL);
		benchOperation.end();
		task.send('box', {mid:task.mid, from:task.line, to:box});
	});
}

// task is an object whose properties are
//  - line : the line of text (URL to SO)
//  - type : "questions" | "answers" | "comments"
//  - site : "stackoverflow" | "askubuntu" | ...
//  - meta : false | true
//  - num  : id of the thing
//  - mid  : the id of the message
//  - send : box sending function
exports.addTask = function(task){
	task.key = task.type+'.'+task.num;
	tasks.push(task);
	dequeue();
}

exports.init = function(miaou){
	try {
		apikey = miaou.config.oauth2.stackexchange.key;
	} catch (e) {
		console.log("No API key for Stack Overflow boxing - reduced quota");
	}
}

const	urlRegex = rex`
	(?:^|\n)\s*https?:\/\/
	(meta\.)?(stackoverflow|askubuntu|([^.]+\.)?stackexchange|superuser|serverfault).com\/
	(a|q|questions)\/(\d+)(\/[^\s#]*)?(#\S+)?\s*(?:$|\n)
	/gm`;

// read the text to find and analyze SE URL
exports.rawTasks = function(text){
	urlRegex.lastIndex = 0;
	var	tasks = [],
		match;
	while ((match=urlRegex.exec(text))) {
		var	path = match[6], submatch,
			hash = match[7],
			task = { line:match[0], meta:!!match[1], site:match[2] };
		if ( hash && (submatch=hash.match(/^#comment(\d+)_\d+$/)) ) {
			task.type = "comments";
			task.num = +submatch[1];
		} else if ( match[4]==='a' ) {
			task.type = "answers";
			task.num = +match[5];
		} else if ( path && (submatch=path.match(/^\/[^\/]+\/(\d+)$/)) ) {
			task.type = "answers";
			task.num = +submatch[1];
		} else {
			task.type = "questions";
			task.num = +match[5];
		}
		if (match[3] !== 'chat.') tasks.push(task);
	}
	return tasks;
}