Introduces event queue processor to create a consistent UI (#11780)

extensions/sql-migration/src/models/migrationWizardPage.ts

@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import * as azdata from 'azdata';
-import { MigrationStateModel } from './stateMachine';
+import { MigrationStateModel, StateChangeEvent } from './stateMachine';
 export abstract class MigrationWizardPage {
 	constructor(protected readonly wizardPage: azdata.window.WizardPage, protected readonly migrationStateModel: MigrationStateModel) { }
 
@@ -16,5 +16,37 @@ export abstract class MigrationWizardPage {
 
 	public abstract async onPageEnter(): Promise<void>;
 	public abstract async onPageLeave(): Promise<void>;
+
+	private readonly stateChanges: (() => Promise<void>)[] = [];
+	protected async onStateChangeEvent(e: StateChangeEvent) {
+
+		this.stateChanges.push((): Promise<void> => {
+			return this.handleStateChange(e);
+		});
+
+		this.enableQueueProcessor();
+	}
+
+	private queueActive = false;
+	private async enableQueueProcessor(): Promise<void> {
+		if (this.queueActive) {
+			return;
+		}
+		this.queueActive = true;
+		while (true) {
+			const stateChangeFunction = this.stateChanges.shift();
+			if (!stateChangeFunction) {
+				break;
+			}
+			try {
+				await stateChangeFunction();
+			} catch (ex) {
+				console.error(ex);
+			}
+		}
+		this.queueActive = false;
+	}
+
+	protected abstract async handleStateChange(e: StateChangeEvent): Promise<void>;
 }
 

extensions/sql-migration/src/models/stateMachine.ts

@@ -27,6 +27,7 @@ export enum State {
 export interface Model {
 	readonly sourceConnection: azdata.connection.Connection;
 	readonly currentState: State;
+	gatheringInformationError: string | undefined;
 }
 
 export interface StateChangeEvent {
@@ -37,6 +38,7 @@ export interface StateChangeEvent {
 export class MigrationStateModel implements Model, vscode.Disposable {
 	private _stateChangeEventEmitter = new vscode.EventEmitter<StateChangeEvent>();
 	private _currentState: State;
+	private _gatheringInformationError: string | undefined;
 
 	constructor(private readonly _sourceConnection: azdata.connection.Connection) {
 		this._currentState = State.INIT;
@@ -58,6 +60,14 @@ export class MigrationStateModel implements Model, vscode.Disposable {
 		this._stateChangeEventEmitter.fire({ oldState, newState: this.currentState });
 	}
 
+	public get gatheringInformationError(): string | undefined {
+		return this._gatheringInformationError;
+	}
+
+	public set gatheringInformationError(error: string | undefined) {
+		this._gatheringInformationError = error;
+	}
+
 	public get stateChangeEvent(): vscode.Event<StateChangeEvent> {
 		return this._stateChangeEventEmitter.event;
 	}

extensions/sql-migration/src/wizard/sourceConfigurationPage.ts

@@ -6,7 +6,8 @@
 import * as azdata from 'azdata';
 import { MigrationWizardPage } from '../models/migrationWizardPage';
 import { SOURCE_CONFIGURATION_PAGE_TITLE, COLLECTING_SOURCE_CONFIGURATIONS, COLLECTING_SOURCE_CONFIGURATIONS_INFO, COLLECTING_SOURCE_CONFIGURATIONS_ERROR } from '../models/strings';
-import { MigrationStateModel } from '../models/stateMachine';
+import { MigrationStateModel, StateChangeEvent, State } from '../models/stateMachine';
+import { Disposable } from 'vscode';
 
 export class SourceConfigurationPage extends MigrationWizardPage {
 	constructor(migrationStateModel: MigrationStateModel) {
@@ -29,19 +30,11 @@ export class SourceConfigurationPage extends MigrationWizardPage {
 	}
 
 	private async registerContent(view: azdata.ModelView) {
-		await this.createGatheringInformationPage(view);
+		await this.initialState(view);
-		setTimeout(async () => {
-			console.log('doing it');
-			try {
-				await this.createErrorInInformationGatheringPage(view);
-			} catch (ex) {
-				console.log(ex);
-			}
-		}, 5000);
 	}
 
 	private gatheringInfoComponent!: azdata.FormComponent;
-	private async createGatheringInformationPage(view: azdata.ModelView) {
+	private async initialState(view: azdata.ModelView) {
 		this.gatheringInfoComponent = this.createGatheringInfoComponent(view);
 		const form = view.modelBuilder.formContainer().withFormItems(
 			[
@@ -59,9 +52,13 @@ export class SourceConfigurationPage extends MigrationWizardPage {
 
 	// }
 
-	private async createErrorInInformationGatheringPage(view: azdata.ModelView) {
+	private async enterErrorState() {
 		const component = this.gatheringInfoComponent.component as azdata.TextComponent;
-		component.value = COLLECTING_SOURCE_CONFIGURATIONS_ERROR('Some error');
+		component.value = COLLECTING_SOURCE_CONFIGURATIONS_ERROR(this.migrationStateModel.gatheringInformationError);
+	}
+
+	private async enterTargetSelectionState() {
+
 	}
 
 	//#region component builders
@@ -79,11 +76,22 @@ export class SourceConfigurationPage extends MigrationWizardPage {
 		};
 	}
 	//#endregion
-	public async onPageEnter(): Promise<void> {
 
+	private eventListener: Disposable | undefined;
+	public async onPageEnter(): Promise<void> {
+		this.eventListener = this.migrationStateModel.stateChangeEvent(async (e) => this.onStateChangeEvent(e));
 	}
 
 	public async onPageLeave(): Promise<void> {
+		this.eventListener?.dispose();
+	}
 
+	protected async handleStateChange(e: StateChangeEvent): Promise<void> {
+		switch (e.newState) {
+			case State.COLLECTION_SOURCE_INFO_ERROR:
+				return this.enterErrorState();
+			case State.TARGET_SELECTION:
+				return this.enterTargetSelectionState();
+		}
 	}
 }