let plugins = [];

const defaults = {
	initializeByDefault: true
};

export default {
	mount(plugin) {
		// Set default static properties
		for (let option in defaults) {
			if (defaults.hasOwnProperty(option) && !(option in plugin)) {
				plugin[option] = defaults[option];
			}
		}

		plugins.forEach(p => {
			if (p.pluginName === plugin.pluginName) {
				throw (`Sortable: Cannot mount plugin ${ plugin.pluginName } more than once`);
			}
		});

		plugins.push(plugin);
	},
	pluginEvent(eventName, sortable, evt) {
		this.eventCanceled = false;
		evt.cancel = () => {
			this.eventCanceled = true;
		};
		const eventNameGlobal = eventName + 'Global';
		plugins.forEach(plugin => {
			if (!sortable[plugin.pluginName]) return;
			// Fire global events if it exists in this sortable
			if (
				sortable[plugin.pluginName][eventNameGlobal]
			) {
				sortable[plugin.pluginName][eventNameGlobal]({ sortable, ...evt });
			}

			// Only fire plugin event if plugin is enabled in this sortable,
			// and plugin has event defined
			if (
				sortable.options[plugin.pluginName] &&
				sortable[plugin.pluginName][eventName]
			) {
				sortable[plugin.pluginName][eventName]({ sortable, ...evt });
			}
		});
	},
	initializePlugins(sortable, el, defaults, options) {
		plugins.forEach(plugin => {
			const pluginName = plugin.pluginName;
			if (!sortable.options[pluginName] && !plugin.initializeByDefault) return;

			let initialized = new plugin(sortable, el, sortable.options);
			initialized.sortable = sortable;
			initialized.options = sortable.options;
			sortable[pluginName] = initialized;

			// Add default options from plugin
			Object.assign(defaults, initialized.defaults);
		});

		for (let option in sortable.options) {
			if (!sortable.options.hasOwnProperty(option)) continue;
			let modified = this.modifyOption(sortable, option, sortable.options[option]);
			if (typeof(modified) !== 'undefined') {
				sortable.options[option] = modified;
			}
		}
	},
	getEventProperties(name, sortable) {
		let eventProperties = {};
		plugins.forEach(plugin => {
			if (typeof(plugin.eventProperties) !== 'function') return;
			Object.assign(eventProperties, plugin.eventProperties.call(sortable[plugin.pluginName], name));
		});

		return eventProperties;
	},
	modifyOption(sortable, name, value) {
		let modifiedValue;
		plugins.forEach(plugin => {
			// Plugin must exist on the Sortable
			if (!sortable[plugin.pluginName]) return;

			// If static option listener exists for this option, call in the context of the Sortable's instance of this plugin
			if (plugin.optionListeners && typeof(plugin.optionListeners[name]) === 'function') {
				modifiedValue = plugin.optionListeners[name].call(sortable[plugin.pluginName], value);
			}
		});

		return modifiedValue;
	}
};