From 7cd5ba82029aea5acfd39d6aa47518fc96852d62 Mon Sep 17 00:00:00 2001
From: tpluscode <tpluscode@users.noreply.github.com>
Date: Thu, 22 Sep 2022 20:13:47 +0200
Subject: [PATCH] feat: 'header-first' api documentation discovery

---
 .changeset/bright-sheep-raise.md          |  5 +++
 src/Resources/CoreMixins/HydraResource.ts |  7 +++--
 src/alcaeus.ts                            |  3 ++
 tests/Resources/HydraResource-spec.ts     | 37 ++++++++++++++++++++---
 4 files changed, 45 insertions(+), 7 deletions(-)
 create mode 100644 .changeset/bright-sheep-raise.md

diff --git a/.changeset/bright-sheep-raise.md b/.changeset/bright-sheep-raise.md
new file mode 100644
index 00000000..d30e0904
--- /dev/null
+++ b/.changeset/bright-sheep-raise.md
@@ -0,0 +1,5 @@
+---
+"alcaeus": patch
+---
+
+Option to control where to look for the api documentation link
diff --git a/src/Resources/CoreMixins/HydraResource.ts b/src/Resources/CoreMixins/HydraResource.ts
index 357e792e..056237a0 100644
--- a/src/Resources/CoreMixins/HydraResource.ts
+++ b/src/Resources/CoreMixins/HydraResource.ts
@@ -110,8 +110,11 @@ export function createHydraResourceMixin(alcaeus: () => HydraClient<any>) {
 
             public get apiDocumentation(): ApiDocumentation | undefined {
                 const client = alcaeus()
-                const id = this.pointer.out(hydra.apiDocumentation).value ||
-                  client.resources.get(this.pointer)?.response.apiDocumentationLink
+                const representationLink = this.pointer.out(hydra.apiDocumentation).value
+                const headerLink = client.resources.get(this.pointer)?.response.apiDocumentationLink
+                const id = client.apiDocumentationDiscovery === 'header-first'
+                    ? headerLink || representationLink
+                    : representationLink || headerLink
 
                 if (id) {
                     const idNode = namedNode(id)
diff --git a/src/alcaeus.ts b/src/alcaeus.ts
index 655eb249..ff6b8edb 100644
--- a/src/alcaeus.ts
+++ b/src/alcaeus.ts
@@ -51,6 +51,7 @@ export interface HydraClient<D extends DatasetCore = DatasetCore> {
     resources: ResourceStore<D>
     apiDocumentations: ResourceRepresentation<D, ApiDocumentation<D>>[]
     cacheStrategy: ResourceCacheStrategy
+    apiDocumentationDiscovery: 'header-first' | 'representation-first'
 }
 
 interface AlcaeusInit<D extends DatasetCore> {
@@ -78,6 +79,8 @@ export class Alcaeus<D extends DatasetCore> implements HydraClient<D> {
 
     public cacheStrategy: ResourceCacheStrategy = { ...DefaultCacheStrategy }
 
+    public apiDocumentationDiscovery = 'representation-first' as const
+
     public readonly resources: ResourceStore<D>
 
     private readonly __apiDocumentations: Map<NamedNode, ResourceRepresentation<D, ApiDocumentation<D>>> = new TermMap()
diff --git a/tests/Resources/HydraResource-spec.ts b/tests/Resources/HydraResource-spec.ts
index 0f0dd03d..a65d8af2 100644
--- a/tests/Resources/HydraResource-spec.ts
+++ b/tests/Resources/HydraResource-spec.ts
@@ -15,6 +15,7 @@ import { hydra, rdf, schema } from '@tpluscode/rdf-ns-builders'
 import * as mixins from '../../src/Resources/Mixins'
 import { ResourceRepresentation } from '../../src/ResourceRepresentation'
 import { createHydraResourceMixin } from '../../src/Resources/CoreMixins'
+import { HydraClient } from '../../src/alcaeus'
 
 const parser = new Parser()
 const ex = namespace('http://example.com/vocab#')
@@ -23,11 +24,9 @@ const apiDocumentations: ResourceRepresentation<DatasetCore, Hydra.ApiDocumentat
 const resources = {
     get: jest.fn(),
 }
-const client = () => ({
-    apiDocumentations,
-    resources,
-} as any)
-const HydraResource: Constructor<Resource> = createHydraResourceMixin(client)(Hydra.ResourceMixin(RdfResourceImpl as any))
+let client: HydraClient
+const getClient = () => client
+const HydraResource: Constructor<Resource> = createHydraResourceMixin(getClient)(Hydra.ResourceMixin(RdfResourceImpl as any))
 
 HydraResource.factory = new ResourceFactory(HydraResource)
 HydraResource.factory.addMixin(...Object.values(mixins))
@@ -50,6 +49,10 @@ async function pushApiDocumentation(apiGraph: Stream, term = ex.api) {
 describe('HydraResource', () => {
     beforeEach(() => {
         apiDocumentations.splice(0, apiDocumentations.length)
+        client = {
+            apiDocumentations,
+            resources,
+        } as any
     })
 
     describe('get operations', () => {
@@ -550,5 +553,29 @@ describe('HydraResource', () => {
             // then
             expect(apiDocumentation?.id).toEqual(ex.api1)
         })
+
+        it('ignores link within representation when set to "header-first"', async () => {
+            // given
+            client.apiDocumentationDiscovery = 'header-first'
+            resources.get.mockReturnValue({
+                response: {
+                    apiDocumentationLink: ex.api1.value,
+                },
+            })
+            const resourceGraph = parse(
+                turtle`
+                    <http://example.com/> ${hydra.apiDocumentation} ${ex.api2} .
+                `)
+            const resource = new HydraResource(cf({
+                dataset: await $rdf.dataset().import(resourceGraph),
+                term: namedNode('http://example.com/'),
+            }))
+
+            // when
+            const { apiDocumentation } = resource
+
+            // then
+            expect(apiDocumentation?.id).toEqual(ex.api1)
+        })
     })
 })