const xhr = require("xmlhttprequest").XMLHttpRequest;

const API_URL = "https://lolibooru.moe/post/index.json";

/*function nodes_of(page, path) {

	const document = parse5.parse(page);
	const xhtml = xmlser.serializeToString(document);
	const doc = new dom().parseFromString(xhtml);
	const select = xpath.useNamespace({"x": "http://www.w3.org/1999/xhtml"});
	return select(path, doc);
}

function nodes(url, path, cb) {

	const x = new xhr();

	x.onreadystatechange = function() {
		if(this.readyState===4) {
			cb(nodes_of(this.responseText, path));
		}
	};

	x.open("GET", url);
	x.send();
}*/

function query(limit, page, _tags) {
	if(_tags)
	{
		var tags = _tags.join(" ");
	}
	return API_URL + "?limit="+limit+"&page="+page+(tags?"&tags="+encodeURIComponent(tags):"");
}

function rin(range) {
	return Math.floor(Math.random() * (range-1));
}

function getLoli(puts, number, range, page, tags, cb) {
	var x = new xhr();

	if(number==0) {
		puts("Number was 0, returning");
		cb([]);
		return;
	}

	x.onreadystatechange = function() {
		if(this.readyState===4) {
			let response = JSON.parse(this.responseText);
			if(response) {
				puts("Response okay");
				if(number==1) {
					let r = rin(range);
					puts("Running on single (index "+r+")");
					cb([response[r]]);
				}
				else {
					let resp = Array.from({length: number}, (value,key) => key);
					puts("Proto resp "+number+ " ar "+ JSON.stringify(resp));
					for(let i = (number-1);i>=1;i--)
					{
						let v = resp[i];
						let j = rin(i);
						resp[i] = resp[j];
						resp[j] = v;
					}
					puts("Running on multiple (indecies "+ resp.join(", ")+")");
					cb(resp.map(v => response[v]));
				}
			} else {
				puts("Invalid response");
				cb.error = "Invalid JSON from server";
				cb();
			}
		}
	};

	x.open("GET", query(range, page, tags));
	x.send();
}

function randomiseWith(puts, number, range, maxPage, tags, cb) {
	let page = Math.floor(Math.random() * (range-1));
	puts("Using page "+page);
	if(number > range || number<0) {
		cb.error = "Invalid range";
		cb();
	}
	else
		getLoli(puts, number,range, page, tags, cb);
}

function Config() {
	this.range = 5;
	this.page = 150;
	this.tags = undefined;
	this.number = 1;
	this.debug = function(){};
}

var cfg = new Config();
exports.defaultConfig = cfg;
exports.Config = Config;

function randomise(cb, conf) {
	if(!conf)
		return randomise(cb, cfg);
	conf.debug("Calling with params "+JSON.stringify(conf));
	randomiseWith(conf.debug, conf.number, conf.range, conf.page, conf.tags, cb);
}
exports.randomise = randomise;