[SQL Migration] Add state check to target MI resource on target selection page (#18673)

* Add MI ready state check and error message

* Fix a typo

* Update error message logic

* Update '(Unavailable)' prefix to be localized string

* Show error messsage when non-Ready MI is initially selected (not just on Next button)

* Update error message with appropriate casing and actionable step

extensions/sql-migration/src/constants/strings.ts

@@ -249,6 +249,10 @@ export function AZURE_SQL_TARGET_PAGE_DESCRIPTION(targetInstance: string = 'inst
 export const AZURE_SQL_DATABASE_MANAGED_INSTANCE = localize('sql.migration.azure.sql.database.managed.instance', "Azure SQL Managed Instance");
 export const NO_MANAGED_INSTANCE_FOUND = localize('sql.migration.no.managedInstance.found', "No managed instance found.");
 export const INVALID_MANAGED_INSTANCE_ERROR = localize('sql.migration.invalid.managedInstance.error', "To continue, select a valid managed instance.");
+export function UNAVAILABLE_MANAGED_INSTANCE_PREFIX(miName: string): string {
+	return localize('sql.migration.unavailable.managedInstance', "(Unavailable) {0}", miName);
+}
+
 
 // Virtual Machine
 export const AZURE_SQL_DATABASE_VIRTUAL_MACHINE = localize('sql.migration.azure.sql.database.virtual.machine', "SQL Server on Azure Virtual Machines");
@@ -291,6 +295,9 @@ export function ACCOUNT_ACCESS_ERROR(account: AzureAccount, error: Error) {
 		`${account?.properties?.tenants[0]?.displayName} (${account?.properties?.tenants[0]?.userId})`,
 		error.message);
 }
+export function MI_NOT_READY_ERROR(miName: string, state: string): string {
+	return localize('sql.migration.mi.not.ready', "The managed instance '{0}' is unavailable for migration because it is currently in the '{1}' state. To continue, select an available managed instance.", miName, state);
+}
 
 // database backup page
 export const DATABASE_BACKUP_PAGE_TITLE = localize('sql.migration.database.page.title', "Database backup");

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

@@ -1008,10 +1008,21 @@ export class MigrationStateModel implements Model, vscode.Disposable {
 			}
 
 			this._targetManagedInstances.forEach((managedInstance) => {
-				managedInstanceValues.push({
+				let managedInstanceValue: azdata.CategoryValue;
+
+				if (managedInstance.properties.state === 'Ready') {
+					managedInstanceValue = {
 						name: managedInstance.id,
 						displayName: `${managedInstance.name}`
-				});
+					};
+				} else {
+					managedInstanceValue = {
+						name: managedInstance.id,
+						displayName: constants.UNAVAILABLE_MANAGED_INSTANCE_PREFIX(managedInstance.name)
+					};
+				}
+
+				managedInstanceValues.push(managedInstanceValue);
 			});
 
 			if (managedInstanceValues.length === 0) {

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

@@ -12,6 +12,7 @@ import * as constants from '../constants/strings';
 import * as styles from '../constants/styles';
 import { WIZARD_INPUT_COMPONENT_WIDTH } from './wizardController';
 import { deepClone, findDropDownItemIndex, selectDropDownIndex, selectDefaultDropdownValue } from '../api/utils';
+import { azureResource } from 'azureResource';
 
 export class TargetSelectionPage extends MigrationWizardPage {
 	private _view!: azdata.ModelView;
@@ -120,9 +121,14 @@ export class TargetSelectionPage extends MigrationWizardPage {
 			const resourceDropdownValue = (<azdata.CategoryValue>this._azureResourceDropdown.value)?.displayName;
 			switch (this.migrationStateModel._targetType) {
 				case MigrationTargetType.SQLMI: {
-					if (!this.migrationStateModel._targetServerInstance ||
+					let targetMi = this.migrationStateModel._targetServerInstance as azureResource.AzureSqlManagedInstance;
-						resourceDropdownValue === constants.NO_MANAGED_INSTANCE_FOUND) {
+					if (!targetMi || resourceDropdownValue === constants.NO_MANAGED_INSTANCE_FOUND) {
 						errors.push(constants.INVALID_MANAGED_INSTANCE_ERROR);
+						break;
+					}
+					if (targetMi.properties.state !== 'Ready') {
+						errors.push(constants.MI_NOT_READY_ERROR(targetMi.name, targetMi.properties.state));
+						break;
 					}
 					break;
 				}
@@ -403,6 +409,17 @@ export class TargetSelectionPage extends MigrationWizardPage {
 
 					case MigrationTargetType.SQLMI:
 						this.migrationStateModel._targetServerInstance = this.migrationStateModel.getManagedInstance(selectedIndex);
+						if (this.migrationStateModel._targetServerInstance.properties.state !== 'Ready') {
+							this.wizard.message = {
+								text: constants.MI_NOT_READY_ERROR(this.migrationStateModel._targetServerInstance.name, this.migrationStateModel._targetServerInstance.properties.state),
+								level: azdata.window.MessageLevel.Error
+							};
+						} else {
+							this.wizard.message = {
+								text: '',
+								level: azdata.window.MessageLevel.Error
+							};
+						}
 						break;
 				}
 			} else {