1 files changed, 78 insertions, 0 deletions
diff --git a/src/data/composite/things/track/withOriginalRelease.js b/src/data/composite/things/track/withOriginalRelease.js
new file mode 100644
index 0000000..c7f4965
--- /dev/null
+++ b/src/data/composite/things/track/withOriginalRelease.js
@@ -0,0 +1,78 @@
+// Just includes the original release of this track as a dependency.
+// If this track isn't a rerelease, then it'll provide null, unless the
+// {selfIfOriginal} option is set, in which case it'll provide this track
+// itself. This will early exit (with notFoundValue) if the original release
+// is specified by reference and that reference doesn't resolve to anything.
+
+import {input, templateCompositeFrom} from '#composite';
+import find from '#find';
+import {validateWikiData} from '#validators';
+
+import {exitWithoutDependency, withResultOfAvailabilityCheck}
+  from '#composite/control-flow';
+import {withResolvedReference} from '#composite/wiki-data';
+
+export default templateCompositeFrom({
+  annotation: `withOriginalRelease`,
+
+  inputs: {
+    selfIfOriginal: input({type: 'boolean', defaultValue: false}),
+
+    data: input({
+      validate: validateWikiData({referenceType: 'track'}),
+      defaultDependency: 'trackData',
+    }),
+
+    notFoundValue: input({defaultValue: null}),
+  },
+
+  outputs: ['#originalRelease'],
+
+  steps: () => [
+    withResultOfAvailabilityCheck({
+      from: 'originalReleaseTrack',
+    }),
+
+    {
+      dependencies: [
+        input.myself(),
+        input('selfIfOriginal'),
+        '#availability',
+      ],
+
+      compute: (continuation, {
+        [input.myself()]: track,
+        [input('selfIfOriginal')]: selfIfOriginal,
+        '#availability': availability,
+      }) =>
+        (availability
+          ? continuation()
+          : continuation.raiseOutput({
+              ['#originalRelease']:
+                (selfIfOriginal ? track : null),
+            })),
+    },
+
+    withResolvedReference({
+      ref: 'originalReleaseTrack',
+      data: input('data'),
+      find: input.value(find.track),
+    }),
+
+    exitWithoutDependency({
+      dependency: '#resolvedReference',
+      value: input('notFoundValue'),
+    }),
+
+    {
+      dependencies: ['#resolvedReference'],
+
+      compute: (continuation, {
+        ['#resolvedReference']: resolvedReference,
+      }) =>
+        continuation({
+          ['#originalRelease']: resolvedReference,
+        }),
+    },
+  ],
+});