From 8497f37b24e662bc25e25570ce7219108e62ad31 Mon Sep 17 00:00:00 2001
From: Bernd Bestel <bernd@berrnd.de>
Date: Tue, 13 Feb 2024 13:12:56 +0100
Subject: [PATCH] Fixed product's last_price related to empty / 0 stock
 transactions (fixes #2470)

---
 changelog/75_UNRELEASED_xxxx-xx-xx.md |  1 +
 migrations/0236.sql                   | 56 +++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 migrations/0236.sql

diff --git a/changelog/75_UNRELEASED_xxxx-xx-xx.md b/changelog/75_UNRELEASED_xxxx-xx-xx.md
index 12c1770d..e23b844f 100644
--- a/changelog/75_UNRELEASED_xxxx-xx-xx.md
+++ b/changelog/75_UNRELEASED_xxxx-xx-xx.md
@@ -14,6 +14,7 @@
   - This executes the configured barcode lookup plugin with the given barcode
   - If the lookup was successful, the product edit page of the created product is displayed, where the product setup can be completed (if required)
   - After that, the transaction is continued with that product
+- Fixed that for the product's last price stock transactions with an empty or `0` price weren't ignored
 
 ### Shopping list
 
diff --git a/migrations/0236.sql b/migrations/0236.sql
new file mode 100644
index 00000000..fdadd0ee
--- /dev/null
+++ b/migrations/0236.sql
@@ -0,0 +1,56 @@
+DROP VIEW products_last_purchased;
+CREATE VIEW products_last_purchased
+AS
+SELECT
+	1 AS id, -- Dummy, LessQL needs an id column
+	sl.product_id,
+	sl.amount,
+	sl.best_before_date,
+	sl.purchased_date,
+	sl.location_id,
+	sl.shopping_location_id,
+	IFNULL((SELECT price FROM products_price_history WHERE product_id = sl.product_id ORDER BY purchased_date DESC LIMIT 1), 0) AS price
+FROM stock_log sl
+JOIN (
+	/*
+		This subquery gets the ID of the stock_log row (per product) which referes to the last purchase transaction,
+		while taking undone and edited transactions into account
+	*/
+	SELECT
+		sl1.product_id,
+		MAX(sl1.id) stock_log_id_of_last_purchase
+	FROM stock_log sl1
+	JOIN (
+		/*
+			This subquery finds the last purchased date per product,
+			there can be multiple purchase transactions per day, therefore a JOIN by purchased_date
+			for the outer query on this and then take MAX id of stock_log (of that day)
+		*/
+		SELECT
+			sl2.product_id,
+			MAX(sl2.purchased_date) AS last_purchased_date
+		FROM stock_log sl2
+		WHERE sl2.undone = 0
+			AND (
+				(sl2.transaction_type IN ('purchase', 'inventory-correction', 'self-production') AND sl2.stock_id NOT IN (SELECT stock_id FROM stock_edited_entries))
+				OR (sl2.transaction_type = 'stock-edit-new' AND sl2.stock_id IN (SELECT stock_id FROM stock_edited_entries) AND sl2.id IN (SELECT stock_log_id_of_newest_edited_entry FROM stock_edited_entries))
+			)
+		GROUP BY sl2.product_id
+	) x2
+		ON sl1.product_id = x2.product_id
+		AND sl1.purchased_date = x2.last_purchased_date
+	WHERE sl1.undone = 0
+		AND (
+			(sl1.transaction_type IN ('purchase', 'inventory-correction', 'self-production') AND sl1.stock_id NOT IN (SELECT stock_id FROM stock_edited_entries))
+			OR (sl1.transaction_type = 'stock-edit-new' AND sl1.stock_id IN (SELECT stock_id FROM stock_edited_entries) AND sl1.id IN (SELECT stock_log_id_of_newest_edited_entry FROM stock_edited_entries))
+		)
+	GROUP BY sl1.product_id
+) x
+	ON sl.product_id = x.product_id
+	AND sl.id = x.stock_log_id_of_last_purchase;
+
+-- Update products_last_purchased cache
+INSERT OR REPLACE INTO cache__products_last_purchased
+	(product_id, amount, best_before_date, purchased_date, price, location_id, shopping_location_id)
+SELECT product_id, amount, best_before_date, purchased_date, price, location_id, shopping_location_id
+FROM products_last_purchased;