/**
 * 
 * ## Manage application **context**
 * 
 * The application context is mainly (but not only) driven by the client router, which observes the url hash and converts it to a context.
 * It can also be used as a global variable to store application states.
 * 
 * With KissJS, the url hash **must** contain the following parameter:
 * - ui: it stands for "user interface" and is used to display the main view
 * 
 * The url hash **may** contain other informations depending on your application.
 * For example:
 * - applicationId: the active application id
 * - modelId: the active model id
 * - viewType: the active view type (datatable|calendar|kanban|gallery|...)
 * - viewId: the active view id
 * - recordId: the active record id (when displayed in a form)
 * - themeColor: the current application CSS theme color
 * - themeGeometry: the current application CSS theme geometry
 * - etc...
 * 
 * @namespace
 */
kiss.context = {

	/**
	 * Context history
	 * 
	 * Keep the history of visited routes
	 * 
	 * @example
	 * console.log(kiss.context.history)
	 * 
	 * // Output:
	 * [
	 *  {ui: "tutorial", chapterId: "1", sectionId: "2"},
	 *  {ui: "tutorial", chapterId: "1", sectionId: "7"},
	 *  {ui: "tutorial", chapterId: "2", sectionId: "3"}
	 * // ...
	 * ]
	 */
	history: [],

	/**
	 * Last context
	 * 
	 * @example
	 * console.log(kiss.context.lastContext)
	 * 
	 * // Output:
	 * {ui: "tutorial", chapterId: "2", sectionId: "3"}
	 */
	lastContext: {},

	/**
	 * Last context changes
	 * 
	 * @example
	 * console.log(kiss.context.changes)
	 * 
	 * // Output:
	 * {ui: false, chapterId: false, sectionId: true}
	 */
	changes: {},

	/**
	 * Update the application context:
	 * - you can use this as a global way to save some of your application states
	 * - the whole context history is saved in kiss.context.history
	 * 
	 * @param {object} newContext
	 * 
	 * @example
	 * kiss.context.update({
	 *  applicationId: "c393b159-2dd2-41e0-9d68-17c40f7088ab",
	 *  viewId: "56b64b39-e932-49ae-86f2-30058345d9c8",
	 *  language: "fr"
	 * })
	 */
	update(newContext) {
		let {
			history,
			...currentContext
		} = kiss.tools.snapshot(kiss.context)

		kiss.context.lastContext = currentContext
		kiss.context.history.push(currentContext)
		Object.assign(kiss.context, newContext)
	},

	/**
	 * Allow to check how the context has changed during the last routing event
	 * 
	 * @param {string} [propertyName] - The property to check. If not provided, it returns all the property changes.
	 * @param contextName
	 * @returns {object} Where each property value is a boolean (true means "has changed")
	 * 
	 * @example
	 * console.log(kiss.context.hasChanged())
	 * // Output:
	 * {
	 *  ui: false,
	 *  viewId: true,
	 *  themeColor: false
	 * }
	 * 
	 * console.log(kiss.context.hasChanged("ui")) // Output: false
	 */
	hasChanged(contextName) {
		let isNew = (this.history.length <= 1)
		let propertiesToCheck = Object.keys(kiss.tools.snapshot(this))
		let lastContext = kiss.context.history[kiss.context.history.length - 1]

		propertiesToCheck.forEach(property => {
			if (property != "history") this.changes[property] = (isNew) ? false : (kiss.context[property] != lastContext[property])
		})

		if (contextName) return this.changes[contextName]
		return this.changes
	}
}