From 76202f923950737ed4165a89ec711435a24afebb Mon Sep 17 00:00:00 2001
From: danielpeintner <daniel.peintner@gmail.com>
Date: Tue, 19 Aug 2025 14:37:59 +0200
Subject: [PATCH] refactor: add possibility to register ContentCodec with
 scheme

TODO calls for contentToValue and valueToContent need to provide schema
---
 packages/core/src/content-serdes.ts     | 40 ++++++++++++++++++++-----
 packages/core/test/ContentSerdesTest.ts | 24 +++++++++++++++
 2 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/packages/core/src/content-serdes.ts b/packages/core/src/content-serdes.ts
index c56f59830..ee928b744 100644
--- a/packages/core/src/content-serdes.ts
+++ b/packages/core/src/content-serdes.ts
@@ -54,6 +54,7 @@ export class ContentSerdes {
     public static readonly JSON_LD: string = "application/ld+json";
 
     private codecs: Map<string, ContentCodec> = new Map();
+    private codecsBySchemes: Map<string, ContentCodec> = new Map();
     private offered: Set<string> = new Set<string>();
 
     public static get(): ContentSerdes {
@@ -107,8 +108,17 @@ export class ContentSerdes {
         return params;
     }
 
-    public addCodec(codec: ContentCodec, offered = false): void {
-        ContentSerdes.get().codecs.set(codec.getMediaType(), codec);
+    // function to create id for combining internally mediaType and scheme
+    private getMediaTypeScheme(mt: string, scheme: string): string {
+        return mt + "|" + scheme;
+    }
+
+    public addCodec(codec: ContentCodec, offered = false, scheme?: string): void {
+        if (scheme !== undefined) {
+            ContentSerdes.get().codecsBySchemes.set(this.getMediaTypeScheme(codec.getMediaType(), scheme), codec);
+        } else {
+            ContentSerdes.get().codecs.set(codec.getMediaType(), codec);
+        }
         if (offered) ContentSerdes.get().offered.add(codec.getMediaType());
     }
 
@@ -125,7 +135,7 @@ export class ContentSerdes {
         return this.codecs.has(mt);
     }
 
-    public contentToValue(content: ReadContent, schema: DataSchema): DataSchemaValue | undefined {
+    public contentToValue(content: ReadContent, schema: DataSchema, scheme?: string): DataSchemaValue | undefined {
         if (content.type === undefined) {
             if (content.body.byteLength > 0) {
                 // default to application/json
@@ -142,9 +152,16 @@ export class ContentSerdes {
 
         // choose codec based on mediaType
         if (this.codecs.has(mt)) {
-            debug(`ContentSerdes deserializing from ${content.type}`);
-
-            const codec = this.codecs.get(mt);
+            let codec: ContentCodec | undefined;
+            if (scheme !== undefined) {
+                codec = this.codecsBySchemes.get(this.getMediaTypeScheme(mt, scheme));
+            }
+            if (codec === undefined) {
+                debug(`ContentSerdes deserializing from ${content.type}`);
+                codec = this.codecs.get(mt);
+            } else {
+                debug(`ContentSerdes deserializing from combining ${content.type} and ${mt}`);
+            }
 
             // use codec to deserialize
             // eslint-disable-next-line @typescript-eslint/no-non-null-assertion -- this.codecs.has(mt) is true
@@ -160,7 +177,8 @@ export class ContentSerdes {
     public valueToContent(
         value: DataSchemaValue | ReadableStream,
         schema: DataSchema | undefined,
-        contentType = ContentSerdes.DEFAULT
+        contentType = ContentSerdes.DEFAULT,
+        scheme?: string
     ): Content {
         if (value === undefined) warn("ContentSerdes valueToContent got no value");
 
@@ -175,7 +193,13 @@ export class ContentSerdes {
         const par = ContentSerdes.getMediaTypeParameters(contentType);
 
         // choose codec based on mediaType
-        const codec = this.codecs.get(mt);
+        let codec: ContentCodec | undefined;
+        if (scheme !== undefined) {
+            codec = this.codecsBySchemes.get(this.getMediaTypeScheme(mt, scheme));
+        }
+        if (codec === undefined) {
+            codec = this.codecs.get(mt);
+        }
         if (codec) {
             debug(`ContentSerdes serializing to ${contentType}`);
             bytes = codec.valueToBytes(value, schema, par);
diff --git a/packages/core/test/ContentSerdesTest.ts b/packages/core/test/ContentSerdesTest.ts
index d67b460a7..9c4abd468 100644
--- a/packages/core/test/ContentSerdesTest.ts
+++ b/packages/core/test/ContentSerdesTest.ts
@@ -91,6 +91,16 @@ class HodorCodec implements ContentCodec {
     }
 }
 
+class HodorHttpCodec extends HodorCodec {
+    bytesToValue(): string {
+        return "HodorHttp";
+    }
+
+    valueToBytes(): Buffer {
+        return Buffer.from("HodorHttp");
+    }
+}
+
 @suite("testing OctectStream codec")
 class SerdesOctetTests {
     @test "OctetStream to value"() {
@@ -1058,6 +1068,7 @@ class CborSerdesTests {
 class SerdesCodecTests {
     static before() {
         ContentSerdes.addCodec(new HodorCodec());
+        ContentSerdes.addCodec(new HodorHttpCodec(), false, "http");
     }
 
     @test async "new codec should serialize"() {
@@ -1072,4 +1083,17 @@ class SerdesCodecTests {
             "Hodor"
         );
     }
+
+    @test async "new codec based on scheme should serialize"() {
+        const content = ContentSerdes.valueToContent("The meaning of Life", { type: "string" }, "text/hodor", "http");
+        const body = await content.toBuffer();
+        body.toString().should.equal("HodorHttp");
+    }
+
+    @test "new codec based on scheme should deserialize"() {
+        const buffer = Buffer.from("Some actual meaningful stuff");
+        expect(
+            ContentSerdes.contentToValue({ type: "text/hodor", body: buffer }, { type: "string" }, "http")
+        ).to.be.deep.equal("HodorHttp");
+    }
 }