202 improve automatic initial application of custom sorting for obsidian deferred views

src/main.ts

@@ -78,11 +78,16 @@ type MonkeyAroundUninstaller = () => void
 
 type ContextMenuProvider = (item: MenuItem) => void
 
-enum FileExplorerStateError {
-	DoesNotExist,
+enum FileExplorerState {
+	DoesNotExist = 1,
 	DeferredView
 }
 
+interface FileExplorerStateError {
+	state: FileExplorerState
+	fileExplorerInDeferredState?: FileExplorerLeaf
+}
+
 type FileExplorerLeafOrError = ValueOrError<FileExplorerLeaf,FileExplorerStateError>
 
 export default class CustomSortPlugin
@@ -188,20 +193,25 @@ export default class CustomSortPlugin
 
 		if (fileExplorer) {
 			if (fileExplorer.isDeferred) {
-				return fileExplorerOrError.setError(FileExplorerStateError.DeferredView)
+				return fileExplorerOrError.setError({
+					state: FileExplorerState.DeferredView,
+					fileExplorerInDeferredState: fileExplorer
+				})
 			} else {
 				return fileExplorerOrError.setValue(fileExplorer)
 			}
 		} else {
-			return fileExplorerOrError.setError(FileExplorerStateError.DoesNotExist)
+			return fileExplorerOrError.setError({
+				state: FileExplorerState.DoesNotExist
+			})
 		}
 	}
 
 	checkFileExplorerIsAvailableAndPatchable(logWarning: boolean = true): FileExplorerLeafOrError {
 		let fileExplorerOrError = this.getFileExplorer()
-		if (fileExplorerOrError.e === FileExplorerStateError.DeferredView) {
+		if (fileExplorerOrError.e && fileExplorerOrError.e.state === FileExplorerState.DeferredView) {
 			if (logWarning) {
-				this.logWarningFileExplorerDeferred()
+				this.logDeferredFileExplorerInfo()
 			}
 			return fileExplorerOrError
 		}
@@ -269,12 +279,17 @@ export default class CustomSortPlugin
 		}
 	}
 
-	logWarningFileExplorerDeferred() {
-		const msg = `${PLUGIN_ID} v${this.manifest.version}: failed to get active File Explorer view.\n`
+	logDeferredFileExplorerInfo() {
+		const msg = `${PLUGIN_ID} v${this.manifest.version}: File Explorer is not displayed yet (Obsidian deferred view detected).\n`
 			+ `Until the File Explorer is visible, the custom-sort plugin cannot apply the custom order.\n`
 		console.warn(msg)
 	}
 
+	logDeferredFileExplorerWatcherSetupInfo() {
+		const msg = `${PLUGIN_ID} v${this.manifest.version}: A watcher was set up to apply custom sort automatically when the File Explorer is displayed.\n`
+		console.warn(msg)
+	}
+
 	logWarningFileExplorerNotAvailable() {
 		const msg = `${PLUGIN_ID} v${this.manifest.version}: failed to locate File Explorer. The 'Files' core plugin can be disabled.\n`
 			+ `Some community plugins can also disable it.\n`
@@ -583,7 +598,7 @@ export default class CustomSortPlugin
 		const plugin = this
 		this.app.workspace.onLayoutReady(() => {
 			setTimeout(() => {
-				plugin.initialDelayedApplicationOfCustomSorting.apply(this)
+				plugin.delayedApplicationOfCustomSorting.apply(this)
 			},
 			plugin.settings.delayForInitialApplication)
 		})
@@ -682,7 +697,39 @@ export default class CustomSortPlugin
 		return false
 	}
 
-	initialDelayedApplicationOfCustomSorting() {
+	setWatcherForDelayedFileExplorerView(fileExplorerInDeferredState?: FileExplorerLeaf) {
+		const self = this
+
+		let workspaceLeafContentElementParentToObserve: HTMLElement|Element|null|undefined = fileExplorerInDeferredState?.view?.containerEl?.parentElement
+		if (!workspaceLeafContentElementParentToObserve) {
+			// Fallback for the case when DOM is not available for deferred file explorer
+			// (did not happen in practice, but just in case)
+			workspaceLeafContentElementParentToObserve = document.querySelector(".workspace");
+		}
+		if (workspaceLeafContentElementParentToObserve) {
+			const fullyFledgedFileExplorerElementSelector=
+					() => workspaceLeafContentElementParentToObserve.querySelector('[data-type="file-explorer"] .nav-files-container');
+
+			const mutationObserver = new MutationObserver((_, observerInstance) => {
+				const fullyFledgedFileExplorerElement = fullyFledgedFileExplorerElementSelector();
+				if (fullyFledgedFileExplorerElement) {
+					observerInstance.disconnect();
+					self.delayedApplicationOfCustomSorting(self.FROM_DOM_WATCHER)
+				}
+			});
+
+			mutationObserver.observe(workspaceLeafContentElementParentToObserve, {
+				childList: true,
+				subtree: false
+			});
+		}
+	}
+
+	// Entering this method for the first time after initial delay after plugin loaded (via setTimeout()),
+	// and if first attempt is unsuccessful, then entering this method again from DOM watcher, when
+	// the File Explorer view gets transformed from delayed view into fully-fledged active view
+	FROM_DOM_WATCHER: boolean = true
+	delayedApplicationOfCustomSorting(fromDOMwatcher?: boolean) {
 		if (!this?.isThePluginStillInstalledAndEnabled()) {
 			console.log(`${PLUGIN_ID} v${this.manifest.version} - delayed handler skipped, plugin no longer active.`)
 			return
@@ -695,7 +742,25 @@ export default class CustomSortPlugin
 			return
 		}
 
-		this.switchPluginStateTo(true)
+		if (!fromDOMwatcher) {
+			// Only for the first delayed invocation:
+			// If file explorer is delayed, configure the watcher
+			// NOTE: Do not configure the watcher if the file explorer is not available
+			let fileExplorerOrError: FileExplorerLeafOrError = this.checkFileExplorerIsAvailableAndPatchable()
+			if (fileExplorerOrError.e && fileExplorerOrError.e.state === FileExplorerState.DeferredView) {
+				this.logDeferredFileExplorerWatcherSetupInfo()
+				this.setWatcherForDelayedFileExplorerView(fileExplorerOrError.e.fileExplorerInDeferredState)
+			} else if (fileExplorerOrError.e) {
+				// file explorer other error - does not exist
+				// force the plugin switch state to report error and show the error icon
+				this.switchPluginStateTo(true)
+			}
+			else { // file explorer is available
+				this.switchPluginStateTo(true)
+			}
+		} else {
+			this.switchPluginStateTo(true)
+		}
 	}
 
 	setRibbonIconToEnabled() {