fix(migrations): Fixes issue with multiple if elses with same template (#52863)

This should fix the issue where if the same ng-template is used with multiple if / else statements, it replaces all usages properly.
fixes: #52854

PR Close #52863

packages/core/schematics/ng-generate/control-flow-migration/util.ts

@@ -283,16 +283,18 @@ export function processNgTemplates(template: string): string {
 
   // swap placeholders and remove
   for (const [name, t] of templates) {
-    const placeholder = `${name}|`;
-
-    if (template.indexOf(placeholder) > -1) {
+    const replaceRegex = new RegExp(`${name}\\|`, 'g');
+    const matches = [...template.matchAll(replaceRegex)];
+    if (matches.length > 0) {
       if (t.i18n !== null) {
         const container = wrapIntoI18nContainer(t.i18n, t.children);
-        template = template.replace(placeholder, container);
+        template = template.replace(replaceRegex, container);
       } else {
-        template = template.replace(placeholder, t.children);
+        template = template.replace(replaceRegex, t.children);
       }
-      if (t.count <= 2) {
+
+      // the +1 accounts for the t.count's counting of the original template
+      if (t.count === matches.length + 1) {
         template = template.replace(t.contents, '');
       }
     }

packages/core/schematics/test/control_flow_migration_spec.ts

@@ -2730,6 +2730,49 @@ describe('control flow migration', () => {
 
       expect(actual).toBe(expected);
     });
+
+    it('should migrate multiple if/else using the same ng-template', async () => {
+      writeFile('/comp.ts', `
+        import {Component} from '@angular/core';
+        import {NgIf} from '@angular/common';
+
+        @Component({
+          selector: 'declare-comp',
+          templateUrl: 'comp.html',
+        })
+        class DeclareComp {}
+      `);
+
+      writeFile('/comp.html', [
+        `<div>`,
+        `  <div *ngIf="hasPermission; else noPermission">presentation</div>`,
+        `  <div *ngIf="someOtherPermission; else noPermission">presentation</div>`,
+        `</div>`,
+        `<ng-template #noPermission>`,
+        `  <p>No Permissions</p>`,
+        `</ng-template>`,
+      ].join('\n'));
+
+      await runMigration();
+      const actual = tree.readContent('/comp.html');
+
+      const expected = [
+        `<div>`,
+        `  @if (hasPermission) {`,
+        `<div>presentation</div>`,
+        `} @else {\n`,
+        `  <p>No Permissions</p>\n`,
+        `}`,
+        `  @if (someOtherPermission) {`,
+        `<div>presentation</div>`,
+        `} @else {\n`,
+        `  <p>No Permissions</p>\n`,
+        `}`,
+        `</div>\n`,
+      ].join('\n');
+
+      expect(actual).toBe(expected);
+    });
   });
 
   describe('imports', () => {