data: Artwork.{isMainArtwork,mainArtwork,siblingArtworks}

3 files changed, 113 insertions, 2 deletions

diff --git a/src/data/composite/things/artwork/index.js b/src/data/composite/things/artwork/index.js
index b92bff72..e2661b50 100644
--- a/src/data/composite/things/artwork/index.js
+++ b/src/data/composite/things/artwork/index.js
@@ -1 +1,2 @@
+export {default as withContainingArtworkList} from './withContainingArtworkList.js';
 export {default as withDate} from './withDate.js';
diff --git a/src/data/composite/things/artwork/withContainingArtworkList.js b/src/data/composite/things/artwork/withContainingArtworkList.js
new file mode 100644
index 00000000..9c928ffd
--- /dev/null
+++ b/src/data/composite/things/artwork/withContainingArtworkList.js
@@ -0,0 +1,46 @@
+// Gets the list of artworks which contains this one, which is functionally
+// equivalent to `this.thing[this.thingProperty]`. If the exposed value is not
+// a list at all (i.e. the property holds a single artwork), this composition
+// outputs null.
+
+import {input, templateCompositeFrom} from '#composite';
+
+import {raiseOutputWithoutDependency} from '#composite/control-flow';
+import {withPropertyFromObject} from '#composite/data';
+
+export default templateCompositeFrom({
+  annotation: `withContainingArtworkList`,
+
+  outputs: ['#containingArtworkList'],
+
+  steps: () => [
+    raiseOutputWithoutDependency({
+      dependency: 'thing',
+      output: input.value({'#containingArtworkList': null}),
+    }),
+
+    raiseOutputWithoutDependency({
+      dependency: 'thingProperty',
+      output: input.value({'#containingArtworkList': null}),
+    }),
+
+    withPropertyFromObject({
+      object: 'thing',
+      property: 'thingProperty',
+    }).outputs({
+      '#value': '#containingValue',
+    }),
+
+    {
+      dependencies: ['#containingValue'],
+      compute: (continuation, {
+        ['#containingValue']: containingValue,
+      }) => continuation({
+        ['#containingArtworkList']:
+          (Array.isArray(containingValue)
+            ? containingValue
+            : null),
+      }),
+    },
+  ],
+});
diff --git a/src/data/things/artwork.js b/src/data/things/artwork.js
index 197cd5d4..0ef257fe 100644
--- a/src/data/things/artwork.js
+++ b/src/data/things/artwork.js
@@ -24,7 +24,7 @@ import {
   parseDimensions,
 } from '#yaml';
 
-import {withPropertyFromObject} from '#composite/data';
+import {withIndexInList, withPropertyFromObject} from '#composite/data';
 
 import {
   exitWithoutDependency,
@@ -52,7 +52,7 @@ import {
   wikiData,
 } from '#composite/wiki-properties';
 
-import {withDate} from '#composite/things/artwork';
+import {withContainingArtworkList, withDate} from '#composite/things/artwork';
 
 export class Artwork extends Thing {
   static [Thing.referenceType] = 'artwork';
@@ -303,6 +303,70 @@ export class Artwork extends Thing {
     referencedByArtworks: reverseReferenceList({
       reverse: soupyReverse.input('artworksWhichReference'),
     }),
+
+    isMainArtwork: [
+      withContainingArtworkList(),
+
+      exitWithoutDependency({
+        dependency: '#containingArtworkList',
+        value: input.value(null),
+      }),
+
+      {
+        dependencies: [input.myself(), '#containingArtworkList'],
+        compute: ({
+          [input.myself()]: myself,
+          ['#containingArtworkList']: list,
+        }) =>
+          list[0] === myself,
+      },
+    ],
+
+    mainArtwork: [
+      withContainingArtworkList(),
+
+      exitWithoutDependency({
+        dependency: '#containingArtworkList',
+        value: input.value(null),
+      }),
+
+      {
+        dependencies: ['#containingArtworkList'],
+        compute: ({'#containingArtworkList': list}) =>
+          list[0],
+      },
+    ],
+
+    siblingArtworks: [
+      withContainingArtworkList(),
+
+      exitWithoutDependency({
+        dependency: '#containingArtworkList',
+        value: input.value(null),
+      }),
+
+      withIndexInList({
+        list: '#containingArtworkList',
+        item: input.myself(),
+      }),
+
+      exitWithoutDependency({
+        dependency: '#index',
+        mode: input.value('index'),
+        value: input.value(null),
+      }),
+
+      {
+        dependencies: ['#containingArtworkList', '#index'],
+        compute: ({
+          ['#containingArtworkList']: list,
+          ['#index']: index,
+        }) => [
+          ...list.slice(0, index),
+          ...list.slice(index + 1),
+        ],
+      },
+    ],
   });
 
   static [Thing.yamlDocumentSpec] = {