/**********************************************************
 * This plugin for CKeditor provides live collaborative editing features
 * inside ckeditor.
 * It must be configured with a pollUrl and a saveUrl (also requestParameters and saveData) for shared persistent
 * storage.
 * It was built to work with the cmfive CRM REST module and is hopefully
 * sufficiently configurable to work with other persistence systems.
 * Copyright Steve Ryan <stever@syntithenai.com>
 * Licence https://en.wikipedia.org/wiki/MIT_License
 ****************************************************
 */ 
 
CKEDITOR.plugins.add( 'liveedit', {
    init: function( editor ) {
		/**************************************
		 * VISIBILITY STATE FUNCTIONS 
		 * - support CROSS BROWSER visibilitychange events to disable and restart polling 
		 *************************************/
		 // determine which vendor prefixed property is available
		function getHiddenProp(){
			var prefixes = ['webkit','moz','ms','o'];
			
			// if 'hidden' is natively supported just return it
			if ('hidden' in document) return 'hidden';
			
			// otherwise loop over all the known prefixes until we find one
			for (var i = 0; i < prefixes.length; i++){
				if ((prefixes[i] + 'Hidden') in document) 
					return prefixes[i] + 'Hidden';
			}

			// otherwise it's not supported
			return null;
		}
		// check if the document is currently hidden
		function isHidden() {
			var prop = getHiddenProp();
			if (!prop) return false;
			
			return document[prop];
		} 
		// called on visibility change event
		function visChange() {
			if (isHidden()) {
				 updatePollActive=false;
			} else {
				updatePollActive=true;
				startUpdatePoll(editor);
			}
		}
		// BIND visibility change event
		// use the property name to generate the prefixed event name
		var visProp = getHiddenProp();
		if (visProp) {
		  var evtname = visProp.replace(/[H|h]idden/,'') + 'visibilitychange';
		  document.addEventListener(evtname, visChange);
		}


		/**************************************************
		 * POLLING
		 **************************************************/
		var updatePollActive=true;
		var updateTimer=null;
		var lastModified=editor.config.lastModified;
		// ensure configuration								
		if (!editor.config.pollUrl) alert("Invalid configuration, you must provide configuration option pollUrl to the editor.");
		if (!editor.config.saveUrl) alert("Invalid configuration, you must provide configuration option saveUrl to the editor.");
		if (!editor.config.pollTimeOut) editor.config.pollTimeOut=1000;
		if (!editor.config.saveTimeOut) editor.config.saveTimeOut=3000;
		if (!editor.config.requestParameters) editor.config.requestParameters='';
		// recursive timeout function is called when a request completes
		var callUpdateCallBack=function(record) {
			if (window[editor.config.updateCallBack]) window[editor.config.updateCallBack](record);
		}
		
		function replaceContent(editor,content,record) {
			// save cursor position/selection
			var selection = editor.getSelection();
			var range = selection.getRanges()[0];
			if (range) {
				var startPath=CSSelector(range.startContainer.$);
				var startPathParts=startPath.split('>');
				if (range.startContainer.$.nodeType ==3 ) {
					startPath=startPathParts.slice(0,startPathParts.length-1).join('>');
				}
				var endPath=CSSelector(range.startContainer.$);
				var endPathParts=endPath.split('>');
				if (range.endContainer.$.nodeType ==3 ) {
					endPath=endPathParts.slice(0,endPathParts.length-1).join('>');
				}
				var savedSelection={
					startPath : startPath,
					startOffset : range.startOffset,
					endPath : endPath,
					endOffset : range.endOffset
				
				};
				// modify texts
				editor.setData(record.body);
				lastModified=record.dt_modified;
				callUpdateCallBack(record);
				// restore selection
				editor.focus();
				var startElement=editor.document.findOne(savedSelection.startPath ).getFirst();
				var endElement=editor.document.findOne(savedSelection.endPath ).getFirst();
				// replace full selection
				if (startElement && endElement) { 
					var range = editor.createRange();
					try {
						range.setStart( startElement,savedSelection.startOffset );
						range.setEnd( startElement,savedSelection.endOffset );
						selection.selectRanges( [ range ] );
					} catch (e) {
						console.log(['FAIL REPLACE RANGE',e]);
					}
				}
			} else {
				// no selection exists so just modify text
				editor.setData(record.body);
				lastModified=record.dt_modified;
				callUpdateCallBack(record);
			}
		}
		
		var startUpdatePoll = function(editor) {
			pollUrl=editor.config.pollUrl;
			if (updateTimer) clearTimeout(updateTimer);
			updateTimer=setTimeout(function() {
				if (updatePollActive) {  
					$.ajax(
						pollUrl +  lastModified + "?" + editor.config.requestParameters,
						{
							cache: false,
							dataType:"json"
						}
					).done(function(content) {
						console.log(JSON.stringify(content));
						if (content && content.success ) {
							if (content.success.length>0 && content.success[0].body) {
								replaceContent(editor,content,content.success[0]);
							}
						}	
					}).always(function() {
						startUpdatePoll(editor);											
					});										
				}// else {
				//	startUpdatePoll(editor);
				//}
			},editor.config.pollTimeOut);
		}
		/**************************************************
		 * SAVE ON KEYUP
		 **************************************************/
		function bindKeyUp(editor) {
			var saveUrl=editor.config.saveUrl;
			editor.on('contentDom', function() {
				var saveTimer=null;
				var editable = editor.editable();
				var callChangeCallBack=function() {
					if (window[editor.config.changeCallBack]) window[editor.config.changeCallBack]();
				}
				var callSaveCallBack=function(record) {
					if (window[editor.config.saveCallBack]) window[editor.config.saveCallBack](record);
				}
				editable.attachListener( editor.document, 'keyup', function() {
					updatePollActive=false;
					callChangeCallBack();
					if (saveTimer) clearTimeout(saveTimer);
					saveTimer=setTimeout(function() {
						var doSave=function() {
							var val=editor.getData();
							var data=editor.config.saveData;
							// first check if there are any recent saves we might overwrite
							$.ajax(
								editor.config.pollUrl + lastModified + "?" + editor.config.requestParameters,
								{data:data,dataType:'json',cache:false}
							).done(
								function(response) {
									var requestSave = function(body) {
										data.body=body;
										$.ajax(
											editor.config.saveUrl  + "?" + editor.config.requestParameters,
											{data:data,dataType:'json',cache:false,method:'POST'}
										).done(
											function(response) {
												if (response.success && response.success.id) {
													replaceContent(editor,response,response.success); 
													callSaveCallBack(response.success);
													updatePollActive=true;
													lastModified=response.success.dt_modified;
												}
												startUpdatePoll(editor);
											}
										).fail(function() {alert('Failed to save.')}) ;
									}
									// no results means we can just save
									if (response.success) {
										if (response.success.length==0)  {
												requestSave(editor.getData());
										// existing changes - ask the user to reload or force overwrite	
										} else if (response.success && response.success.length > 0) {
											// reload with other changes
											if (confirm('Your changes conflict with those made by another user. Click OK to reload with their changes or Cancel to force your changes?')) {
												replaceContent(editor,response,response.success[0]); 
												lastModified=response.success[0].dt_modified;
												callUpdateCallBack(response.success[0]);
												startUpdatePoll(editor);
											// force these changes
											} else {
												requestSave(editor.getData());
											}
										}
									} else {
										alert('Failed to poll on save');
									}
								}
							) // end done
						}
						doSave();
					},editor.config.saveTimeOut);
				})
			});
		}
		 
		
		/***********************************
		 * INIT
		 ***********************************/
		startUpdatePoll(editor);
		bindKeyUp(editor);

    }
});