1 files changed, 75 insertions, 0 deletions
diff --git a/shared/components/src/utils/shelfAspectRatio.ts b/shared/components/src/utils/shelfAspectRatio.ts
new file mode 100644
index 0000000..eeb977d
--- /dev/null
+++ b/shared/components/src/utils/shelfAspectRatio.ts
@@ -0,0 +1,75 @@
+import { getAspectRatio } from '@amp/web-app-components/src/components/Artwork/utils/artProfile';
+import { setContext, getContext, hasContext } from 'svelte';
+import { derived, writable } from 'svelte/store';
+import type { Readable } from 'svelte/store';
+import type { Profile } from '@amp/web-app-components/src/components/Artwork/types';
+import type { AspectRatioOverrideConfig } from '@amp/web-app-components/src/components/Shelf/types';
+
+const SHELF_ASPECT_RATIO_KEY = 'shelf-aspect-ratio';
+
+export const getShelfAspectRatioContext = (): {
+    shelfAspectRatio: Readable<string>;
+    addProfile: (profile: string | Profile) => void;
+} => {
+    return getContext(SHELF_ASPECT_RATIO_KEY);
+};
+
+export const hasShelfAspectRatioContext = () =>
+    hasContext(SHELF_ASPECT_RATIO_KEY);
+
+const createShelfAspectRatioStore = (config: AspectRatioOverrideConfig) => {
+    const { subscribe, update } = writable(new Map() as Map<string, number>);
+
+    const addProfile = (profile: string) => {
+        const ratio = getAspectRatio(profile).toFixed(2);
+
+        update((ratiosCount) => {
+            const currentCount = ratiosCount.get(ratio);
+            const newCount = ratiosCount.has(ratio) ? currentCount + 1 : 0;
+            ratiosCount.set(ratio, newCount);
+            return ratiosCount;
+        });
+    };
+
+    const aspectRatioStore = {
+        subscribe,
+        addProfile,
+    };
+
+    const shelfAspectRatio = derived(aspectRatioStore, ($store) => {
+        let aspectRatio: string = null;
+
+        // Don't set shelf aspect ratio when only 1 ratio is found
+        //
+        // This allows e.g. a shelf with only tall artwork Powerswooshes to use
+        // their native 3:4 aspect ratio, even when the shelf is set to use the
+        // fixed 1:1 aspect ratio or a dominant aspect ratio.
+        if ($store.size > 1) {
+            if (config.type === 'fixed') {
+                aspectRatio = config.aspectRatio;
+            } else if (config.type === 'dominant') {
+                let highestCount = 0;
+                for (const [ratio, count] of $store.entries()) {
+                    if (highestCount < count) {
+                        aspectRatio = ratio;
+                        highestCount = count;
+                    }
+                }
+            }
+        }
+
+        return aspectRatio;
+    });
+
+    return {
+        shelfAspectRatio,
+        addProfile,
+    };
+};
+
+export const createShelfAspectRatioContext = (
+    config: AspectRatioOverrideConfig,
+) => {
+    setContext(SHELF_ASPECT_RATIO_KEY, createShelfAspectRatioStore(config));
+    return getShelfAspectRatioContext();
+};