feat: allow deletion and creation of files with patches

api/src/unraid-api/unraid-file-modifier/file-modification.ts

@@ -92,11 +92,12 @@ export abstract class FileModification {
         if (!patchContents.trim()) {
             throw new Error('Patch contents are empty');
         }
-        const currentContent = await readFile(this.filePath, 'utf8');
+        const currentContent = await readFile(this.filePath, 'utf8').catch(() => '');
         const parsedPatch = parsePatch(patchContents)[0];
         if (!parsedPatch?.hunks.length) {
             throw new Error('Invalid Patch Format: No hunks found');
         }
+
         const results = applyPatch(currentContent, parsedPatch);
         if (results === false) {
             throw new Error(`Failed to apply patch to ${this.filePath}`);
@@ -178,7 +179,12 @@ export abstract class FileModification {
             throw new Error(`Failed to rollback patch from ${this.filePath}`);
         }
 
-        await writeFile(this.filePath, results);
+        if (results === '') {
+            // Delete the file if the patch results in an empty string
+            await unlink(this.filePath);
+        } else {
+            await writeFile(this.filePath, results);
+        }
 
         // Clean up the patch file after successful rollback
         try {

api/src/unraid-api/unraid-file-modifier/modifications/__test__/generic-modification.spec.ts

@@ -74,7 +74,7 @@ const downloadOrRetrieveOriginalFile = async (filePath: string, fileUrl: string)
             );
         }
     }
-    return await readFile(filePath, 'utf-8');
+    return await readFile(filePath, 'utf-8').catch(() => '');
 };
 
 async function testModification(testCase: ModificationTestCase, patcher: FileModification) {
@@ -101,7 +101,7 @@ async function testModification(testCase: ModificationTestCase, patcher: FileMod
 
     // Rollback and verify original state
     await patcher.rollback();
-    const revertedContent = await readFile(filePath, 'utf-8');
+    const revertedContent = await readFile(filePath, 'utf-8').catch(() => '');
     await expect(revertedContent).toMatch(originalContent);
 }
 

api/src/unraid-api/unraid-file-modifier/modifications/log-rotate.modification.ts

@@ -1,9 +1,6 @@
 import { Logger } from '@nestjs/common';
 import { readFile } from 'node:fs/promises';
 
-import { createPatch } from 'diff';
-import { execa } from 'execa';
-
 import { fileExists } from '@app/core/utils/files/file-exists';
 import {
     FileModification,

api/src/unraid-api/unraid-file-modifier/unraid-file-modifier.spec.ts

@@ -11,6 +11,7 @@ import {
     ShouldApplyWithReason,
 } from '@app/unraid-api/unraid-file-modifier/file-modification';
 import { UnraidFileModificationService } from '@app/unraid-api/unraid-file-modifier/unraid-file-modifier.service';
+import { fileExistsSync } from '@app/core/utils/files/file-exists';
 
 const FIXTURE_PATH = join(__dirname, 'modifications', '__test__', '__fixtures__', 'text-patch-file.txt');
 const ORIGINAL_CONTENT = 'original';
@@ -80,6 +81,25 @@ describe.sequential('FileModificationService', () => {
         await expect(service.applyModification(mod)).resolves.toBe(undefined);
     });
 
+    it('should apply modification if file does not exist', async () => {
+        const mod = new TestFileModification(logger);
+        // @ts-expect-error - This is a protected method, but we need to mock it
+        mod.generatePatch = vi.fn().mockResolvedValue(createPatch(FIXTURE_PATH, '', 'modified'));
+        await fs.unlink(FIXTURE_PATH);
+        await expect(service.applyModification(mod)).resolves.toBe(undefined);
+        expect(mockLogger.warn).toHaveBeenCalledWith('Could not load pregenerated patch for: test');
+        expect(mockLogger.log).toHaveBeenCalledWith(
+            'Applying modification: test - Always Apply this mod'
+        );
+        expect(mockLogger.log).toHaveBeenCalledWith('Modification applied successfully: test');
+        const content = await fs.readFile(FIXTURE_PATH, 'utf-8');
+        expect(content).toBe('modified');
+        await service.rollbackAll();
+        expect(fileExistsSync(FIXTURE_PATH)).toBe(false);
+        expect(mockLogger.log).toHaveBeenCalledWith('Rolling back modification: test');
+        expect(mockLogger.log).toHaveBeenCalledWith('Successfully rolled back modification: test');
+    });
+
     it('should not rollback any mods without loaded', async () => {
         await expect(service.rollbackAll()).resolves.toBe(undefined);
     });