/**
 * Unobtrusive scripting adapter for jQuery
 *
 * Requires jQuery 1.4.3 or later.
 * https://github.com/rails/jquery-ujs

 * Uploading file using rails.js
 * =============================
 *
 * By default, browsers do not allow files to be uploaded via AJAX. As a result, if there are any non-blank file fields
 * in the remote form, this adapter aborts the AJAX submission and allows the form to submit through standard means.
 *
 * The `ajax:aborted:file` event allows you to bind your own handler to process the form submission however you wish.
 *
 * Ex:
 *     $('form').live('ajax:aborted:file', function(){
 *       // Implement own remote file-transfer handler here.
 *       // Returning false in this handler tells rails.js to disallow standard form submission
 *       return false;
 *     });
 *
 * The `ajax:aborted:file` event is fired when a file-type input is detected with a non-blank value.
 *
 * Third-party tools can use this hook to detect when an AJAX file upload is attempted, and then use
 * techniques like the iframe method to upload the file instead.
 *
 * Required fields in rails.js
 * ===========================
 *
 * This adapter aborts AJAX form submissions if any non-blank input[required] fields are detected.
 * Unlike file uploads, however, blank required input fields cancel the whole form submission, by default.
 *
 * The `ajax:aborted:required` event allows you to bind your own handler to inform the user of blank required inputs.
 *
 * !! Note that Opera does not fire the form's submit event if there are blank required inputs,
 *    so this event may never get fired in Opera.
 *
 * Ex:
 *     $('form').live('ajax:aborted:required', function(){
 *       // Returning false in this handler tells rails.js to submit the form anyway
 *       return ! confirm("Would you like to submit the form with missing info?");
 *     });
 */

(function($) {

	// Shorthand to make it a little easier to call public rails functions from within rails.js
	var rails;

	$.rails = rails = {

		// Link elements bound by jquery-ujs
		linkClickSelector: 'a[data-confirm], a[data-method], a[data-remote]',

		// Form elements bound by jquery-ujs
		formSubmitSelector: 'form',

		// Form input elements bound by jquery-ujs
		formInputClickSelector: 'form input[type=submit], form input[type=image], form button[type=submit], form button:not([type])',

		// Make sure that every Ajax request sends the CSRF token
		CSRFProtection: function(xhr) {
			var token = $('meta[name="csrf-token"]').attr('content');
			if (token) xhr.setRequestHeader('X-CSRF-Token', token);
		},

		// Triggers an event on an element and returns false if the event result is false
		fire: function(obj, name, data) {
			var event = $.Event(name);
			obj.trigger(event, data);
			return event.result !== false;
		},

		// Submits "remote" forms and links with ajax
		handleRemote: function(element) {
			var method, url, data,
				dataType = element.data('type') || ($.ajaxSettings && $.ajaxSettings.dataType);

			if (rails.fire(element, 'ajax:before')) {

				if (element.is('form')) {
					method = element.attr('method');
					url = element.attr('action');
					data = element.serializeArray();
					// memoized value from clicked submit button
					var button = element.data('ujs:submit-button');
					if (button) {
						data.push(button);
						element.data('ujs:submit-button', null);
					}
				} else {
					method = element.data('method');
					url = element.attr('href');
					data = null;
				}

				$.ajax({
					url: url, type: method || 'GET', data: data, dataType: dataType,
					// stopping the "ajax:beforeSend" event will cancel the ajax request
					beforeSend: function(xhr, settings) {
						if (settings.dataType === undefined) {
							xhr.setRequestHeader('accept', '*/*;q=0.5, ' + settings.accepts.script);
						}
						return rails.fire(element, 'ajax:beforeSend', [xhr, settings]);
					},
					success: function(data, status, xhr) {
						element.trigger('ajax:success', [data, status, xhr]);
					},
					complete: function(xhr, status) {
						element.trigger('ajax:complete', [xhr, status]);
					},
					error: function(xhr, status, error) {
						element.trigger('ajax:error', [xhr, status, error]);
					}
				});
			}
		},

		// Handles "data-method" on links such as:
		// <a href="/users/5" data-method="delete" rel="nofollow" data-confirm="Are you sure?">Delete</a>
		handleMethod: function(link) {
			var href = link.attr('href'),
				method = link.data('method'),
				csrf_token = $('meta[name=csrf-token]').attr('content'),
				csrf_param = $('meta[name=csrf-param]').attr('content'),
				form = $('<form method="post" action="' + href + '"></form>'),
				metadata_input = '<input name="_method" value="' + method + '" type="hidden" />';

			if (csrf_param !== undefined && csrf_token !== undefined) {
				metadata_input += '<input name="' + csrf_param + '" value="' + csrf_token + '" type="hidden" />';
			}

			form.hide().append(metadata_input).appendTo('body');
			form.submit();
		},

		/* Disables form elements:
			- Caches element value in 'ujs:enable-with' data store
			- Replaces element text with value of 'data-disable-with' attribute
			- Adds disabled=disabled attribute
		*/
		disableFormElements: function(form) {
			form.find('input[data-disable-with], button[data-disable-with]').each(function() {
				var element = $(this), method = element.is('button') ? 'html' : 'val';
				element.data('ujs:enable-with', element[method]());
				element[method](element.data('disable-with'));
				element.attr('disabled', 'disabled');
			});
		},

		/* Re-enables disabled form elements:
			- Replaces element text with cached value from 'ujs:enable-with' data store (created in `disableFormElements`)
			- Removes disabled attribute
		*/
		enableFormElements: function(form) {
			form.find('input[data-disable-with]:disabled, button[data-disable-with]:disabled').each(function() {
				var element = $(this), method = element.is('button') ? 'html' : 'val';
				if (element.data('ujs:enable-with')) element[method](element.data('ujs:enable-with'));
				element.removeAttr('disabled');
			});
		},

		// If message provided in 'data-confirm' attribute, fires `confirm` event and returns result of confirm dialog.
		// Attaching a handler to the element's `confirm` event that returns false cancels the confirm dialog.
		allowAction: function(element) {
			var message = element.data('confirm');
			return !message || (rails.fire(element, 'confirm') && confirm(message));
		},

		// Helper function which checks for blank inputs in a form that match the specified CSS selector
		blankInputs: function(form, specifiedSelector, nonBlank) {
			var inputs = $(), input,
				selector = specifiedSelector || 'input,textarea';
			form.find(selector).each(function() {
				input = $(this);
				// Collect non-blank inputs if nonBlank option is true, otherwise, collect blank inputs
				if (nonBlank ? input.val() : !input.val()) {
					inputs = inputs.add(input);
				}
			});
			return inputs.length ? inputs : false;
		},

		// Helper function which checks for non-blank inputs in a form that match the specified CSS selector
		nonBlankInputs: function(form, specifiedSelector) {
			return rails.blankInputs(form, specifiedSelector, true); // true specifies nonBlank
		},

		// Helper function, needed to provide consistent behavior in IE
		stopEverything: function(e) {
			e.stopImmediatePropagation();
			return false;
		},

		// find all the submit events directly bound to the form and
		// manually invoke them. If anyone returns false then stop the loop
		callFormSubmitBindings: function(form) {
			var events = form.data('events'), continuePropagation = true;
			if (events !== undefined && events['submit'] !== undefined) {
				$.each(events['submit'], function(i, obj){
					if (typeof obj.handler === 'function') return continuePropagation = obj.handler(obj.data);
				});
			}
			return continuePropagation;
		}
	};

	// ajaxPrefilter is a jQuery 1.5 feature
	if ('ajaxPrefilter' in $) {
		$.ajaxPrefilter(function(options, originalOptions, xhr){ rails.CSRFProtection(xhr); });
	} else {
		$(document).ajaxSend(function(e, xhr){ rails.CSRFProtection(xhr); });
	}

	$(rails.linkClickSelector).live('click.rails', function(e) {
		var link = $(this);
		if (!rails.allowAction(link)) return rails.stopEverything(e);

		if (link.data('remote') !== undefined) {
			rails.handleRemote(link);
			return false;
		} else if (link.data('method')) {
			rails.handleMethod(link);
			return false;
		}
	});

	$(rails.formSubmitSelector).live('submit.rails', function(e) {
		var form = $(this),
			remote = form.data('remote') !== undefined,
			blankRequiredInputs = rails.blankInputs(form, 'input[name][required],textarea[name][required]'),
			nonBlankFileInputs = rails.nonBlankInputs(form, 'input:file');

		if (!rails.allowAction(form)) return rails.stopEverything(e);

		// skip other logic when required values are missing or file upload is present
		if (blankRequiredInputs && rails.fire(form, 'ajax:aborted:required', [blankRequiredInputs])) {
			return !remote;
		}

		if (remote) {
			if (nonBlankFileInputs) {
				return rails.fire(form, 'ajax:aborted:file', [nonBlankFileInputs]);
			}

			// If browser does not support submit bubbling, then this live-binding will be called before direct
			// bindings. Therefore, we should directly call any direct bindings before remotely submitting form.
			if (!$.support.submitBubbles && rails.callFormSubmitBindings(form) === false) return rails.stopEverything(e);

			rails.handleRemote(form);
			return false;
		} else {
			// slight timeout so that the submit button gets properly serialized
			setTimeout(function(){ rails.disableFormElements(form); }, 13);
		}
	});

	$(rails.formInputClickSelector).live('click.rails', function(event) {
		var button = $(this);

		if (!rails.allowAction(button)) return rails.stopEverything(event);

		// register the pressed submit button
		var name = button.attr('name'),
			data = name ? {name:name, value:button.val()} : null;

		button.closest('form').data('ujs:submit-button', data);
	});

	$(rails.formSubmitSelector).live('ajax:beforeSend.rails', function(event) {
		if (this == event.target) rails.disableFormElements($(this));
	});

	$(rails.formSubmitSelector).live('ajax:complete.rails', function(event) {
		if (this == event.target) rails.enableFormElements($(this));
	});

})( jQuery );
