support for case insensitive search

src/app.module.spec.ts

@@ -90,4 +90,16 @@ describe('AppController (e2e)', () => {
                 expect(response.body).toMatchObject([]);
             });
     });
+
+    it('/api/movies?writers=gEoRgE lUcAs (GET)', () => {
+        return request(app.getHttpServer())
+            .get('/api/movies?writers=gEoRgE lUcAs')
+            .expect(200)
+            .expect((response) => {
+                expect(response.body).toMatchObject([
+                    { title: 'Indiana Jones and the Last Crusade' },
+                    { title: 'Star Wars: Episode IV - A New Hope' },
+                ]);
+            });
+    });
 });

src/services/omdbEnrichedDataService.spec.ts

@@ -304,4 +304,17 @@ describe('createOmdbEnrichedDataService', () => {
 
         expect(result).toMatchObject([]);
     });
+
+    it('returns correct search results for writer = gEoRgE lUcAs and actor = hArRiSoN fOrD', async () => {
+        const service = await servicePromise;
+        const result = service.getSearchResults({
+            actors: 'hArRiSoN fOrD',
+            writers: 'gEoRgE lUcAs',
+        });
+
+        expect(result).toMatchObject([
+            { title: 'Indiana Jones and the Last Crusade' },
+            { title: 'Star Wars: Episode IV - A New Hope' },
+        ]);
+    });
 });

src/services/omdbEnrichedDataService.ts

@@ -5,6 +5,7 @@ import type {
     OmdbProvider,
     SearchFilters,
 } from '../types';
+import { areStringsEqual } from '../utils/stringHelpers';
 
 export const createOmdbEnrichedDataService = async (
     internalProvider: InternalProvider,
@@ -48,11 +49,27 @@ export const createOmdbEnrichedDataService = async (
                     const metadataValue =
                         metadata[fieldName as keyof SearchFilters];
                     if (Array.isArray(metadataValue)) {
-                        // filterValue here is filters[fieldName], and is not undefined (because it comes from nonEmptyFilters),
-                        // so it's guaranteed to have a matching type because of SearchFilters / GenericSearchFilters definition,
-                        // but this logic is too complicated for TS to prove it automatically.
-                        // eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-argument
-                        return metadataValue.includes(filterValue as any);
+                        return metadataValue.some((singularValue) => {
+                            if (typeof singularValue === 'string') {
+                                return areStringsEqual(
+                                    singularValue,
+                                    // filterValue here is filters[fieldName], and is not undefined (because it comes from nonEmptyFilters),
+                                    // so it's guaranteed to have a matching type because of SearchFilters / GenericSearchFilters definition,
+                                    // but this logic is too complicated for TS to prove it automatically.
+                                    // eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-argument
+                                    filterValue as any,
+                                );
+                            } else {
+                                return singularValue === filterValue;
+                            }
+                        });
+                    } else if (typeof metadataValue === 'string') {
+                        return areStringsEqual(
+                            metadataValue,
+                            // see comment above
+                            // eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-argument
+                            filterValue as any,
+                        );
                     } else {
                         return metadataValue === filterValue;
                     }

src/utils/stringHelpers.spec.ts

@@ -0,0 +1,24 @@
+import { describe, it, expect } from '@jest/globals';
+import { areStringsEqual } from './stringHelpers';
+
+describe('areStringsEqual', () => {
+    it('returns true for identical strings', () => {
+        expect(areStringsEqual('abc', 'abc')).toBe(true);
+    });
+
+    it('returns false for different strings', () => {
+        expect(areStringsEqual('abc', 'def')).toBe(false);
+    });
+
+    it('returns true for strings with different casing', () => {
+        expect(areStringsEqual('abc', 'ABC')).toBe(true);
+    });
+
+    it('returns true for strings with different variants', () => {
+        expect(areStringsEqual('Nürnberg', 'Nurnberg')).toBe(true);
+    });
+
+    it('returns true for strings with different casing (turkish I)', () => {
+        expect(areStringsEqual('İSMİNİZ.GIF', 'isminiz.gif')).toBe(true);
+    });
+});

src/utils/stringHelpers.ts

@@ -0,0 +1,8 @@
+export const areStringsEqual = (a: string, b: string) => {
+    return (
+        a.localeCompare(b, undefined, {
+            usage: 'search',
+            sensitivity: 'base',
+        }) === 0
+    );
+};