'use strict';

module.exports = function(Chart) {

	var helpers = Chart.helpers;

	Chart.defaults.global.plugins = {};

	/**
	 * The plugin service singleton
	 * @namespace Chart.plugins
	 * @since 2.1.0
	 */
	Chart.plugins = {
		/**
		 * Globally registered plugins.
		 * @private
		 */
		_plugins: [],

		/**
		 * This identifier is used to invalidate the descriptors cache attached to each chart
		 * when a global plugin is registered or unregistered. In this case, the cache ID is
		 * incremented and descriptors are regenerated during following API calls.
		 * @private
		 */
		_cacheId: 0,

		/**
		 * Registers the given plugin(s) if not already registered.
		 * @param {Array|Object} plugins plugin instance(s).
		 */
		register: function(plugins) {
			var p = this._plugins;
			([]).concat(plugins).forEach(function(plugin) {
				if (p.indexOf(plugin) === -1) {
					p.push(plugin);
				}
			});

			this._cacheId++;
		},

		/**
		 * Unregisters the given plugin(s) only if registered.
		 * @param {Array|Object} plugins plugin instance(s).
		 */
		unregister: function(plugins) {
			var p = this._plugins;
			([]).concat(plugins).forEach(function(plugin) {
				var idx = p.indexOf(plugin);
				if (idx !== -1) {
					p.splice(idx, 1);
				}
			});

			this._cacheId++;
		},

		/**
		 * Remove all registered plugins.
		 * @since 2.1.5
		 */
		clear: function() {
			this._plugins = [];
			this._cacheId++;
		},

		/**
		 * Returns the number of registered plugins?
		 * @returns {Number}
		 * @since 2.1.5
		 */
		count: function() {
			return this._plugins.length;
		},

		/**
		 * Returns all registered plugin instances.
		 * @returns {Array} array of plugin objects.
		 * @since 2.1.5
		 */
		getAll: function() {
			return this._plugins;
		},

		/**
		 * Calls enabled plugins for `chart` on the specified hook and with the given args.
		 * This method immediately returns as soon as a plugin explicitly returns false. The
		 * returned value can be used, for instance, to interrupt the current action.
		 * @param {Object} chart - The chart instance for which plugins should be called.
		 * @param {String} hook - The name of the plugin method to call (e.g. 'beforeUpdate').
		 * @param {Array} [args] - Extra arguments to apply to the hook call.
		 * @returns {Boolean} false if any of the plugins return false, else returns true.
		 */
		notify: function(chart, hook, args) {
			var descriptors = this.descriptors(chart);
			var ilen = descriptors.length;
			var i, descriptor, plugin, params, method;

			for (i=0; i<ilen; ++i) {
				descriptor = descriptors[i];
				plugin = descriptor.plugin;
				method = plugin[hook];
				if (typeof method === 'function') {
					params = [chart].concat(args || []);
					params.push(descriptor.options);
					if (method.apply(plugin, params) === false) {
						return false;
					}
				}
			}

			return true;
		},

		/**
		 * Returns descriptors of enabled plugins for the given chart.
		 * @returns {Array} [{ plugin, options }]
		 * @private
		 */
		descriptors: function(chart) {
			var cache = chart._plugins || (chart._plugins = {});
			if (cache.id === this._cacheId) {
				return cache.descriptors;
			}

			var plugins = [];
			var descriptors = [];
			var config = (chart && chart.config) || {};
			var defaults = Chart.defaults.global.plugins;
			var options = (config.options && config.options.plugins) || {};

			this._plugins.concat(config.plugins || []).forEach(function(plugin) {
				var idx = plugins.indexOf(plugin);
				if (idx !== -1) {
					return;
				}

				var id = plugin.id;
				var opts = options[id];
				if (opts === false) {
					return;
				}

				if (opts === true) {
					opts = helpers.clone(defaults[id]);
				}

				plugins.push(plugin);
				descriptors.push({
					plugin: plugin,
					options: opts || {}
				});
			});

			cache.descriptors = descriptors;
			cache.id = this._cacheId;
			return descriptors;
		}
	};

	/**
	 * Plugin extension hooks.
	 * @interface IPlugin
	 * @since 2.1.0
	 */
	/**
	 * @method IPlugin#beforeInit
	 * @desc Called before initializing `chart`.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#afterInit
	 * @desc Called after `chart` has been initialized and before the first update.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#beforeUpdate
	 * @desc Called before updating `chart`. If any plugin returns `false`, the update
	 * is cancelled (and thus subsequent render(s)) until another `update` is triggered.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 * @returns {Boolean} `false` to cancel the chart update.
	 */
	/**
	 * @method IPlugin#afterUpdate
	 * @desc Called after `chart` has been updated and before rendering. Note that this
	 * hook will not be called if the chart update has been previously cancelled.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#beforeDatasetsUpdate
 	 * @desc Called before updating the `chart` datasets. If any plugin returns `false`,
	 * the datasets update is cancelled until another `update` is triggered.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 * @returns {Boolean} false to cancel the datasets update.
	 * @since version 2.1.5
	 */
	/**
	 * @method IPlugin#afterDatasetsUpdate
	 * @desc Called after the `chart` datasets have been updated. Note that this hook
	 * will not be called if the datasets update has been previously cancelled.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 * @since version 2.1.5
	 */
	/**
	 * @method IPlugin#beforeDatasetUpdate
 	 * @desc Called before updating the `chart` dataset at the given `args.index`. If any plugin
	 * returns `false`, the datasets update is cancelled until another `update` is triggered.
	 * @param {Chart} chart - The chart instance.
	 * @param {Object} args - The call arguments.
	 * @param {Object} args.index - The dataset index.
	 * @param {Number} args.meta - The dataset metadata.
	 * @param {Object} options - The plugin options.
	 * @returns {Boolean} `false` to cancel the chart datasets drawing.
	 */
	/**
	 * @method IPlugin#afterDatasetUpdate
 	 * @desc Called after the `chart` datasets at the given `args.index` has been updated. Note
	 * that this hook will not be called if the datasets update has been previously cancelled.
	 * @param {Chart} chart - The chart instance.
	 * @param {Object} args - The call arguments.
	 * @param {Object} args.index - The dataset index.
	 * @param {Number} args.meta - The dataset metadata.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#beforeLayout
	 * @desc Called before laying out `chart`. If any plugin returns `false`,
	 * the layout update is cancelled until another `update` is triggered.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 * @returns {Boolean} `false` to cancel the chart layout.
	 */
	/**
	 * @method IPlugin#afterLayout
	 * @desc Called after the `chart` has been layed out. Note that this hook will not
	 * be called if the layout update has been previously cancelled.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#beforeRender
	 * @desc Called before rendering `chart`. If any plugin returns `false`,
	 * the rendering is cancelled until another `render` is triggered.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 * @returns {Boolean} `false` to cancel the chart rendering.
	 */
	/**
	 * @method IPlugin#afterRender
	 * @desc Called after the `chart` has been fully rendered (and animation completed). Note
	 * that this hook will not be called if the rendering has been previously cancelled.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#beforeDraw
	 * @desc Called before drawing `chart` at every animation frame specified by the given
	 * easing value. If any plugin returns `false`, the frame drawing is cancelled until
	 * another `render` is triggered.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Number} easingValue - The current animation value, between 0.0 and 1.0.
	 * @param {Object} options - The plugin options.
	 * @returns {Boolean} `false` to cancel the chart drawing.
	 */
	/**
	 * @method IPlugin#afterDraw
	 * @desc Called after the `chart` has been drawn for the specific easing value. Note
	 * that this hook will not be called if the drawing has been previously cancelled.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Number} easingValue - The current animation value, between 0.0 and 1.0.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#beforeDatasetsDraw
 	 * @desc Called before drawing the `chart` datasets. If any plugin returns `false`,
	 * the datasets drawing is cancelled until another `render` is triggered.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Number} easingValue - The current animation value, between 0.0 and 1.0.
	 * @param {Object} options - The plugin options.
	 * @returns {Boolean} `false` to cancel the chart datasets drawing.
	 */
	/**
	 * @method IPlugin#afterDatasetsDraw
	 * @desc Called after the `chart` datasets have been drawn. Note that this hook
	 * will not be called if the datasets drawing has been previously cancelled.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Number} easingValue - The current animation value, between 0.0 and 1.0.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#beforeDatasetDraw
 	 * @desc Called before drawing the `chart` dataset at the given `args.index` (datasets
	 * are drawn in the reverse order). If any plugin returns `false`, the datasets drawing
	 * is cancelled until another `render` is triggered.
	 * @param {Chart} chart - The chart instance.
	 * @param {Object} args - The call arguments.
	 * @param {Object} args.index - The dataset index.
	 * @param {Number} args.meta - The dataset metadata.
	 * @param {Number} args.easingValue - The current animation value, between 0.0 and 1.0.
	 * @param {Object} options - The plugin options.
	 * @returns {Boolean} `false` to cancel the chart datasets drawing.
	 */
	/**
	 * @method IPlugin#afterDatasetDraw
 	 * @desc Called after the `chart` datasets at the given `args.index` have been drawn
	 * (datasets are drawn in the reverse order). Note that this hook will not be called
	 * if the datasets drawing has been previously cancelled.
	 * @param {Chart} chart - The chart instance.
	 * @param {Object} args - The call arguments.
	 * @param {Object} args.index - The dataset index.
	 * @param {Number} args.meta - The dataset metadata.
	 * @param {Number} args.easingValue - The current animation value, between 0.0 and 1.0.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#beforeEvent
 	 * @desc Called before processing the specified `event`. If any plugin returns `false`,
	 * the event will be discarded.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {IEvent} event - The event object.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#afterEvent
	 * @desc Called after the `event` has been consumed. Note that this hook
	 * will not be called if the `event` has been previously discarded.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {IEvent} event - The event object.
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#resize
	 * @desc Called after the chart as been resized.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Number} size - The new canvas display size (eq. canvas.style width & height).
	 * @param {Object} options - The plugin options.
	 */
	/**
	 * @method IPlugin#destroy
	 * @desc Called after the chart as been destroyed.
	 * @param {Chart.Controller} chart - The chart instance.
	 * @param {Object} options - The plugin options.
	 */

	/**
	 * Provided for backward compatibility, use Chart.plugins instead
	 * @namespace Chart.pluginService
	 * @deprecated since version 2.1.5
	 * @todo remove at version 3
	 * @private
	 */
	Chart.pluginService = Chart.plugins;

	/**
	 * Provided for backward compatibility, inheriting from Chart.PlugingBase has no
	 * effect, instead simply create/register plugins via plain JavaScript objects.
	 * @interface Chart.PluginBase
	 * @deprecated since version 2.5.0
	 * @todo remove at version 3
	 * @private
	 */
	Chart.PluginBase = Chart.Element.extend({});
};
