From a7daa3963a4733e9718f2eb801827c14100a7edf Mon Sep 17 00:00:00 2001
From: Charlotte <charlotte.emms@theguardian.com>
Date: Wed, 8 Jan 2025 16:02:21 +0000
Subject: [PATCH] use second slot as merch high instead of static slot

---
 .../src/components/DecideFrontsAdSlots.tsx    |  9 ++++-
 .../src/lib/getFrontsAdPositions.ts           | 39 ++++++-------------
 .../src/lib/getTagPageAdPositions.ts          |  9 +----
 3 files changed, 20 insertions(+), 37 deletions(-)

diff --git a/dotcom-rendering/src/components/DecideFrontsAdSlots.tsx b/dotcom-rendering/src/components/DecideFrontsAdSlots.tsx
index af16efe188e..e038fbe8ca2 100644
--- a/dotcom-rendering/src/components/DecideFrontsAdSlots.tsx
+++ b/dotcom-rendering/src/components/DecideFrontsAdSlots.tsx
@@ -1,10 +1,14 @@
 import { Hide } from '@guardian/source/react-components';
 import type { ReactNode } from 'react';
-import { getMerchHighPosition } from '../lib/getFrontsAdPositions';
 import { palette as themePalette } from '../palette';
 import { AdSlot } from './AdSlot.web';
 import { Section } from './Section';
 
+/** The merchandising high slot is usually the second ad position on a page.
+ * If there are fewer than 4 collections it is first ad position. */
+const getMerchHighSlot = (collectionCount: number): number =>
+	collectionCount >= 4 ? 1 : 0;
+
 export const decideMerchHighAndMobileAdSlots = (
 	renderAds: boolean,
 	index: number,
@@ -16,10 +20,11 @@ export const decideMerchHighAndMobileAdSlots = (
 	if (!renderAds) return null;
 
 	const minContainers = isPaidContent ? 1 : 2;
+	const merchHighSlot = getMerchHighSlot(collectionCount);
 	const shouldInsertMerchHighSlot =
 		!hasPageSkin &&
 		collectionCount > minContainers &&
-		index === getMerchHighPosition(collectionCount);
+		index === mobileAdPositions[merchHighSlot];
 
 	if (shouldInsertMerchHighSlot) {
 		return (
diff --git a/dotcom-rendering/src/lib/getFrontsAdPositions.ts b/dotcom-rendering/src/lib/getFrontsAdPositions.ts
index 44179f544c9..259af7c0101 100644
--- a/dotcom-rendering/src/lib/getFrontsAdPositions.ts
+++ b/dotcom-rendering/src/lib/getFrontsAdPositions.ts
@@ -17,9 +17,6 @@ type GroupedCounts = {
 
 type AdCandidate = Pick<DCRCollectionType, 'collectionType'>;
 
-const getMerchHighPosition = (collectionCount: number): number =>
-	collectionCount >= 4 ? 2 : 0;
-
 /**
  * This happens on the recipes front, where the first container is a thrasher
  * @see https://github.com/guardian/frontend/pull/20617
@@ -27,26 +24,22 @@ const getMerchHighPosition = (collectionCount: number): number =>
 const isFirstContainerAndThrasher = (collectionType: string, index: number) =>
 	index === 0 && collectionType === 'fixed/thrasher';
 
-const isMerchHighPosition = (
-	collectionIndex: number,
-	merchHighPosition: number,
-): boolean => collectionIndex === merchHighPosition;
-
 const isBeforeThrasher = (index: number, collections: AdCandidate[]) =>
 	collections[index + 1]?.collectionType === 'fixed/thrasher';
 
 const isMostViewedContainer = (collection: AdCandidate) =>
 	collection.collectionType === 'news/most-popular';
 
-const shouldInsertAd =
-	(merchHighPosition: number) =>
-	(collection: AdCandidate, index: number, collections: AdCandidate[]) =>
-		!(
-			isFirstContainerAndThrasher(collection.collectionType, index) ||
-			isMerchHighPosition(index, merchHighPosition) ||
-			isBeforeThrasher(index, collections) ||
-			isMostViewedContainer(collection)
-		);
+const shouldInsertAd = (
+	collection: AdCandidate,
+	index: number,
+	collections: AdCandidate[],
+) =>
+	!(
+		isFirstContainerAndThrasher(collection.collectionType, index) ||
+		isBeforeThrasher(index, collections) ||
+		isMostViewedContainer(collection)
+	);
 
 const isEvenIndex = (_collection: unknown, index: number): boolean =>
 	index % 2 === 0;
@@ -61,10 +54,8 @@ const isEvenIndex = (_collection: unknown, index: number): boolean =>
  * we take every other container, up to a maximum of 10, for targeting MPU insertion.
  */
 const getMobileAdPositions = (collections: AdCandidate[]): number[] => {
-	const merchHighPosition = getMerchHighPosition(collections.length);
-
 	return collections
-		.filter(shouldInsertAd(merchHighPosition))
+		.filter(shouldInsertAd)
 		.filter(isEvenIndex)
 		.map((collection: AdCandidate) => collections.indexOf(collection))
 		.filter((adPosition: number) => adPosition !== -1)
@@ -268,10 +259,4 @@ const getFrontsBannerAdPositions = (
 		{ heightSinceAd: 0, adPositions: [] },
 	).adPositions;
 
-export {
-	isEvenIndex,
-	isMerchHighPosition,
-	getMerchHighPosition,
-	getMobileAdPositions,
-	getFrontsBannerAdPositions,
-};
+export { isEvenIndex, getMobileAdPositions, getFrontsBannerAdPositions };
diff --git a/dotcom-rendering/src/lib/getTagPageAdPositions.ts b/dotcom-rendering/src/lib/getTagPageAdPositions.ts
index 0ea66a4f1fc..5dff6c11b07 100644
--- a/dotcom-rendering/src/lib/getTagPageAdPositions.ts
+++ b/dotcom-rendering/src/lib/getTagPageAdPositions.ts
@@ -3,11 +3,7 @@ import {
 	MAX_FRONTS_BANNER_ADS,
 	MAX_FRONTS_MOBILE_ADS,
 } from './commercial-constants';
-import {
-	getMerchHighPosition,
-	isEvenIndex,
-	isMerchHighPosition,
-} from './getFrontsAdPositions';
+import { isEvenIndex } from './getFrontsAdPositions';
 
 /**
  * Uses a very similar approach to pressed fronts, except we
@@ -20,10 +16,7 @@ import {
 const getTagPageMobileAdPositions = (
 	collections: Array<GroupedTrailsBase>,
 ): number[] => {
-	const merchHighPosition = getMerchHighPosition(collections.length);
-
 	return collections
-		.filter((_, index) => !isMerchHighPosition(index, merchHighPosition))
 		.filter(isEvenIndex)
 		.map((collection) =>
 			collections.findIndex(