reworked index checking + done some work on links...

Signed-off-by: Alex A. Naanou <alex.nanou@gmail.com>

Viewer/features/core.js

@@ -2855,6 +2855,72 @@ function(title, func){
 		{ __session_task__: true }) }
 
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
+
+// XXX EXPERIMENTAL...
+var LinkContext = 
+module.LinkContext = ImageGridFeatures.Feature({
+	title: '',
+	tag: 'link-context',
+	depends: [
+		'changes',
+	],
+
+	actions: actions.Actions({
+		title: null,
+		// NOTE: we need .__parent to be able to test if we are fully 
+		// 		detached in .type...
+		// NOTE: this is maintained by .detachLink(..)...
+		__parent: null,
+		parent: null,
+
+		get type(){
+			return this.parent ?
+					'link' 
+				: (this.__parent
+						&& (this.data !== this.__parent.data 
+							|| this.images !== this.__parent.images)) ?
+					'link-detached'
+				: 'link-partial' },
+
+		__changes: null, 
+		get changes(){
+			return this.parent ?
+				this.parent.changes 
+				: this.__changes },
+		set changes(value){
+			this.parent ? 
+				(this.parent.changes = value)
+	   			: (this.__changes = value)},
+
+		// NOTE: .detachLink(false) is not intended for direct use as it
+		// 		will create a partial link...
+		detachLink: ['- System/',
+			doc``,
+			function(full=true){
+				// partial detach...
+				if(this.type == 'link'){
+					// copy over .changes
+					this.__changes = this.changes === undefined ?
+						undefined
+						: JSON.parse(JSON.stringify([this.changes]))[0]
+					this.__parent = this.parent
+					delete this.parent }
+				// full detach...
+				if(this.type != 'link-detached' && full){
+					Object.assign(
+						this,
+						this.clone(true)) 
+					// cleanup...
+					// NOTE: we do not need to cleanup things outside of 
+					// 		the full detach as this will be done in .links
+					this.links.current === this
+						&& (delete this.links.current)
+					this.links.previous === this
+						&& (delete this.links.previous) } }],
+	}), })
+
+
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 
 // XXX revise logging and logger passing...
@@ -2877,6 +2943,11 @@ var TaskActions = actions.Actions({
 			'__tasks',
 			'__queues',
 
+			// NOTE: we link the changes directly to the parent so no need to 
+			//		copy them...
+			'changes',
+
+			// keep the local features as they are not the same as .parent.features
 			'features',
 		],
 	},
@@ -3063,7 +3134,7 @@ var TaskActions = actions.Actions({
 	// XXX after this is stabilized, do we need session tasks and its complexities??? 
 	__links: null,
 	get links(){
-		var links = this.__linked = this.__linked || {}
+		var links = this.__links = this.__links || {}
 		// remove 'current' if it does not match the current index...
 		// XXX revise the test...
 		var c = links.current
@@ -3152,9 +3223,6 @@ var TaskActions = actions.Actions({
 						// link metadata...
 						parent: this,
 						title: title,
-						// XXX change this when data/images changes...
-						// 		...a prop in the link feature...
-						type: 'link',
 						// link configuration...
 						logger: that.logger
 							.push(`Linked ${ Object.keys(links).length }`),
@@ -3203,6 +3271,14 @@ module.Tasks = ImageGridFeatures.Feature({
 			// XXX BUG: for some reason calling .abort here does not work...
 			//'sessionTasks.stop'],
 			'sessionTasks.abort'],
+
+		['clear.pre',
+			function(){
+				Object.values(this.links || [])
+					.forEach(function(link){
+						// NOTE: we do a partial detach here as .clear(..) will
+						// 		detach the data for us...
+						link.detachLink(false) }) }],
 	],
 })
 

Viewer/features/filesystem.js

@@ -779,6 +779,7 @@ var FileSystemLoaderActions = actions.Actions({
 				})
 		}],
 
+	/* XXX cleanup...
 	// XXX update index for removed images...
 	// 		- remove non-existing previews from index
 	// 		- replace non-existing originals with the largest preview (in index)
@@ -838,7 +839,59 @@ var FileSystemLoaderActions = actions.Actions({
 				.then(function(res){
 					return res.flat() })
 		}],
+	//*/
+
 	// XXX EXPERIMENTAL...
+	// XXX move this to base.js???
+	get indexCheckerActions(){
+		var that = this
+		return this.cache('indexCheckerActions', function(cached){
+			return cached instanceof Array ? 
+				cached.slice() 
+				: this.actions
+					.filter(function(action){
+						return that.getActionAttr(action, 'checkIndex') }) }) },
+	// NOTE: this is not implemented as an overloadable action because it
+	// 		would require collection each action's results for post processing
+	// 		which in turn would necessitate a second wrapper action that would
+	// 		call the first as well as requiring the user not to call the 
+	// 		overloaded action, and if each of the individual checks can be run
+	// 		independently it would require a separate wrapper...
+	// 		...this seems quire a bit more convoluted than the current
+	// 		.indexCheckerActions + .checkIndex(..) pair...
+	// XXX since this by default runs in a .linked context this will update 
+	// 		the current context state if it was not reloaded but .changes if 
+	// 		it was set to false will not reflect the changes made by the
+	// 		checker actions...
+	checkIndex: ['File/Check index consistency',
+		core.doc`
+
+
+		Protocol:
+			- this will call all the actions in .indexCheckerActions 
+			- each of the above actions should comply with:
+				.<index-check-action>()
+					-> promise
+			- actions should set .changes appropriately
+			- the returned promise should yield an array of changes -- empty
+				array indicates that no changes were made.
+
+		`,
+		function(options={}){
+			var context = 
+				options.linked === false ? 
+					this 
+					: this.link()
+			return Promise.all(
+					context.indexCheckerActions
+						.map(function(action){
+							return context[action]() }))
+				.then(function(res){
+					res.flat().length > 0
+						&& context.saveIndex() 
+					// XXX BUG?: this is not returned by the action for some reason...
+					return res }) }],
+
 	// XXX add a context wrapper a-la .makeIndex(..)...
 	// 		...might be a good idea to rename this to .checkIndexPaths(..)
 	// 		and make the .checkIndex(..) a context aggregate actions like
@@ -861,6 +914,7 @@ var FileSystemLoaderActions = actions.Actions({
 		NOTE: currently this is disabled for merged indexes, need to load
 			and check individually...
 		`,
+		{checkIndex: true},
 		core.sessionQueueHandler('checkIndex',
 			function(queue, ...args){
 				// XXX ignore merged index...
@@ -887,25 +941,7 @@ var FileSystemLoaderActions = actions.Actions({
 				return updated ? 
 					gid 
 					: [] })],
-	checkIndex: ['File/Check index consistency',
+
-		core.doc``,
-		function(options={}){
-			var context = 
-				options.linked === false ? 
-					this 
-					: this.link()
-			// XXX we could mark all the index test/recovery actions and 
-			// 		get them here dynamically...
-			return Promise.all([
-				context.checkIndexPaths(),
-				// XXX more checks???
-			]).then(function(res){
-				// XXX either make res format a protocol requirement or 
-				// 		revise this...
-				res.flat().length > 0
-					&& context.saveIndex() 
-				// XXX this is not returned by the action for some reason...
-				return res }) }],
 
 	// XXX should this take a path argument???
 	// XXX not yet sure about this...
@@ -1062,9 +1098,7 @@ module.FileSystemLoader = core.ImageGridFeatures.Feature({
 								.markChanged('data')
 								.markChanged('images', imgs.keys()) },
 					function(){}) }],
-		// XXX
+		['checkIndexPaths',
-		//['checkIndexPaths',
-		['checkIndex',
 			function(res){
 				var that = this
 				res.then(