'use strict';

var _slicedToArray = function () { function sliceIterator(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"]) _i["return"](); } finally { if (_d) throw _e; } } return _arr; } return function (arr, i) { if (Array.isArray(arr)) { return arr; } else if (Symbol.iterator in Object(arr)) { return sliceIterator(arr, i); } else { throw new TypeError("Invalid attempt to destructure non-iterable instance"); } }; }();

var riotQuery = require("riot-query");
var arrayDiff = require("arraydiff");

module.exports = {
	init: function init() {
		var _this = this;

		var knownTags = [];
		var listeners = {};

		function triggerEvent(action, query, item) {
			if (listeners[query] != null && listeners[query][action] != null) {
				listeners[query][action].forEach(function (handler) {
					handler(item);
				});
			}
		}

		this.on("updated", function () {
			Object.keys(listeners).forEach(function (query) {
				var currentTags = riotQuery(_this, query);
				var diff = arrayDiff(knownTags, currentTags);

				diff.forEach(function (item) {
					if (item.type === "remove") {
						for (var i = item.index; i < item.index + item.howMany; i++) {
							triggerEvent("remove", query, knownTags[i]);
						}
					} else if (item.type === "move") {
						for (var _i = item.index; _i < item.from + item.howMany; _i++) {
							triggerEvent("move", query, knownTags[_i]);
						}
					} else if (item.type === "insert") {
						item.values.forEach(function (value) {
							triggerEvent("create", query, value);
						});
					}
				});

				knownTags = currentTags;
			});
		});

		this.onChild = function (eventName, handler) {
			var _eventName$split = eventName.split(":", 2);

			var _eventName$split2 = _slicedToArray(_eventName$split, 2);

			var action = _eventName$split2[0];
			var query = _eventName$split2[1];


			if (listeners[query] == null) {
				listeners[query] = {};
			}

			if (listeners[query][action] == null) {
				listeners[query][action] = [];
			}

			listeners[query][action].push(handler);
		};
	}
};