feat: add utility service for handling file types

src/app/services/filetype-utils.spec.ts

@@ -0,0 +1,52 @@
+import { TestBed } from '@angular/core/testing';
+
+import { FiletypeUtils } from './filetype-utils';
+
+describe('Filetype', () => {
+  let service: FiletypeUtils;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({});
+    service = TestBed.inject(FiletypeUtils);
+  });
+
+  it('should be created', () => {
+    expect(service).toBeTruthy();
+  });
+
+  it('should validate image mimetypes', () => {
+    expect(service.isValidImageMimeType('image/png')).toBe(true);
+    expect(service.isValidImageMimeType('text/lua')).toBe(false);
+  });
+
+  describe('getImageMimeTypeFromFilename', () => {
+    it('should return appropriate MimeType for valid file extension', () => {
+      const FILENAME_MOCK = 'mock.png';
+      const mimeType = service.getImageMimeTypeFromFilename(FILENAME_MOCK);
+      expect(mimeType).toEqual('image/png');
+    });
+
+    it('should throw error for files without extension', async () => {
+      const FILENAME_MOCK = 'mock';
+      expect(() => service.getImageMimeTypeFromFilename(FILENAME_MOCK)).toThrow();
+    });
+
+    it('should throw error for unknown file extensions', () => {
+      const FILENAME_MOCK = 'mock.txt';
+      expect(() => service.getImageMimeTypeFromFilename(FILENAME_MOCK)).toThrow();
+    });
+  });
+
+  describe('getImageExtensionFromMimeType', () => {
+    it('should return appropriate file extension for valid MimeType', () => {
+      const MIMETYPE_MOCK = 'image/jpeg';
+      const fileExt = service.getImageExtensionFromMimeType(MIMETYPE_MOCK);
+      expect(fileExt).toEqual('jpeg');
+    });
+
+    it('should throw error for uknown mimetypes', () => {
+      const MIMETYPE_MOCK = 'text/lua';
+      expect(() => service.getImageExtensionFromMimeType(MIMETYPE_MOCK)).toThrow();
+    });
+  });
+});

src/app/services/filetype-utils.ts

@@ -0,0 +1,44 @@
+import { Injectable } from '@angular/core';
+
+@Injectable({
+  providedIn: 'root',
+})
+export class FiletypeUtils {
+  
+  isValidImageMimeType(mimeType: string) {
+    try {
+      this.getImageExtensionFromMimeType(mimeType);
+      return true;
+    }catch(e) {
+      console.error(e);
+      return false;
+    }
+  }
+
+  getImageMimeTypeFromFilename(filename: string): string {
+    const ext = filename.split('.')[1]?.toLowerCase();
+    if (!ext) throw new Error('File has no extension!');
+    const mimeMap: Record<string, string> = {
+      jpg: 'image/jpeg',
+      jpeg: 'image/jpeg',
+      png: 'image/png',
+      webp: 'image/webp',
+      gif: 'image/gif',
+    };
+    if (!mimeMap[ext]) throw new Error('Invalid file extension!');
+    return mimeMap[ext];
+  }
+
+  getImageExtensionFromMimeType(mimeType: string) {
+    const extMap: Record<string, string> = {
+      'image/jpeg': 'jpeg',
+      'image/png': 'png',
+      'image/webp': 'webp',
+      'image/gif': 'gif',
+    };
+    if (!extMap[mimeType]) throw new Error('Invalid mimetype!');
+    return extMap[mimeType];
+  }
+
+  
+}