From ab06dd30f3f8b0538b693fe50dd3d1f70c035b25 Mon Sep 17 00:00:00 2001
From: Joachim Van Herwegen <joachimvh@gmail.com>
Date: Fri, 20 Aug 2021 16:46:32 +0200
Subject: [PATCH] feat: Allow filtering in ConstantConverter based on type

---
 src/storage/conversion/ConstantConverter.ts   | 21 ++++++++++++++++-
 .../conversion/ConstantConverter.test.ts      | 23 ++++++++++++++++++-
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/src/storage/conversion/ConstantConverter.ts b/src/storage/conversion/ConstantConverter.ts
index 040d5279a..37c8042ef 100644
--- a/src/storage/conversion/ConstantConverter.ts
+++ b/src/storage/conversion/ConstantConverter.ts
@@ -23,6 +23,14 @@ export interface ConstantConverterOptions {
    * The minimum requested quality/preference before this should trigger.
    */
   minQuality?: number;
+  /**
+   * Media ranges for which the conversion should happen.
+   */
+  enabledMediaRanges?: string[];
+  /**
+   * Media ranges for which the conversion should not happen.
+   */
+  disabledMediaRanges?: string[];
 }
 
 /**
@@ -57,6 +65,8 @@ export class ConstantConverter extends RepresentationConverter {
       container: options.container ?? true,
       document: options.document ?? true,
       minQuality: options.minQuality ?? 0,
+      enabledMediaRanges: options.enabledMediaRanges ?? [ '*/*' ],
+      disabledMediaRanges: options.disabledMediaRanges ?? [],
     };
   }
 
@@ -83,10 +93,19 @@ export class ConstantConverter extends RepresentationConverter {
       throw new NotImplementedHttpError(`Preference is lower than the specified minimum quality`);
     }
 
+    const sourceContentType = representation.metadata.contentType ?? '';
     // Do not replace the representation if it already has our content type
-    if (matchesMediaType(representation.metadata.contentType ?? '', this.contentType)) {
+    if (matchesMediaType(sourceContentType, this.contentType)) {
       throw new NotImplementedHttpError(`Representation is already ${this.contentType}`);
     }
+
+    // Only replace the representation if it matches the media range settings
+    if (!this.options.enabledMediaRanges.some((type): boolean => matchesMediaType(sourceContentType, type))) {
+      throw new NotImplementedHttpError(`${sourceContentType} is not one of the enabled media types.`);
+    }
+    if (this.options.disabledMediaRanges.some((type): boolean => matchesMediaType(sourceContentType, type))) {
+      throw new NotImplementedHttpError(`${sourceContentType} is one of the disabled media types.`);
+    }
   }
 
   public async handle({ representation }: RepresentationConverterArgs): Promise<Representation> {
diff --git a/test/unit/storage/conversion/ConstantConverter.test.ts b/test/unit/storage/conversion/ConstantConverter.test.ts
index 27e81ff78..964dc359d 100644
--- a/test/unit/storage/conversion/ConstantConverter.test.ts
+++ b/test/unit/storage/conversion/ConstantConverter.test.ts
@@ -3,6 +3,7 @@ import arrayifyStream from 'arrayify-stream';
 import { RepresentationMetadata } from '../../../../src/ldp/representation/RepresentationMetadata';
 import type { ConstantConverterOptions } from '../../../../src/storage/conversion/ConstantConverter';
 import { ConstantConverter } from '../../../../src/storage/conversion/ConstantConverter';
+import { CONTENT_TYPE } from '../../../../src/util/Vocabularies';
 
 const createReadStream = jest.spyOn(fs, 'createReadStream').mockReturnValue('file contents' as any);
 
@@ -12,7 +13,7 @@ describe('A ConstantConverter', (): void => {
   let converter: ConstantConverter;
 
   beforeEach(async(): Promise<void> => {
-    options = { container: true, document: true, minQuality: 1 };
+    options = { container: true, document: true, minQuality: 1, enabledMediaRanges: [ '*/*' ], disabledMediaRanges: []};
     converter = new ConstantConverter('abc/def/index.html', 'text/html', options);
   });
 
@@ -69,6 +70,26 @@ describe('A ConstantConverter', (): void => {
     await expect(converter.canHandle(args)).rejects.toThrow('Representation is already text/html');
   });
 
+  it('does not support representations if their content-type is not enabled.', async(): Promise<void> => {
+    const preferences = { type: { 'text/html': 1 }};
+    const representation = { metadata: new RepresentationMetadata({ [CONTENT_TYPE]: 'text/plain' }) } as any;
+    const args = { identifier: { path: 'container/' }, representation, preferences };
+
+    converter = new ConstantConverter('abc/def/index.html', 'text/html', { enabledMediaRanges: [ 'text/turtle' ]});
+
+    await expect(converter.canHandle(args)).rejects.toThrow('text/plain is not one of the enabled media types.');
+  });
+
+  it('does not support representations if their content-type is disabled.', async(): Promise<void> => {
+    const preferences = { type: { 'text/html': 1 }};
+    const representation = { metadata: new RepresentationMetadata({ [CONTENT_TYPE]: 'text/plain' }) } as any;
+    const args = { identifier: { path: 'container/' }, representation, preferences };
+
+    converter = new ConstantConverter('abc/def/index.html', 'text/html', { disabledMediaRanges: [ 'text/*' ]});
+
+    await expect(converter.canHandle(args)).rejects.toThrow('text/plain is one of the disabled media types.');
+  });
+
   it('supports representations with an unknown content type.', async(): Promise<void> => {
     const preferences = { type: { 'text/html': 1 }};
     const metadata = new RepresentationMetadata();