From 0cae825c86f23bf889f5c67c7e54b3e62538088a Mon Sep 17 00:00:00 2001
From: Jonathan Niles <jonathanwniles@gmail.com>
Date: Wed, 23 Mar 2022 07:26:13 +0100
Subject: [PATCH] feat(invoice): add invoice balance function

This commit adds a MySQL function for computing the balance of an
invoice.  It is for analysis purposes currently.
---
 server/models/admin.sql | 43 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/server/models/admin.sql b/server/models/admin.sql
index ea437fb473..07de5be23d 100644
--- a/server/models/admin.sql
+++ b/server/models/admin.sql
@@ -296,4 +296,47 @@ BEGIN
   UPDATE lot SET barcode = CONCAT('LT', LEFT(HEX(lot.uuid), 8));
 END $$
 
+/**
+ zGetInvoiceBalance()
+
+ Gets the balance on an invoice due to a debtor.
+*/
+CREATE FUNCTION zGetInvoiceBalance(invoiceUuid BINARY(16))
+RETURNS DOUBLE DETERMINISTIC
+BEGIN
+  DECLARE entityUuid BINARY(16);
+
+  -- get the debtorUuid
+  SELECT debtor_uuid INTO entityUuid FROM invoice WHERE invoice.uuid = invoiceUuid;
+
+  --  return the balance
+  RETURN (
+    SELECT SUM(debit - credit) AS balance
+    FROM (
+      SELECT record_uuid AS uuid, debit_equiv as debit, credit_equiv as credit, entity_uuid
+      FROM posting_journal
+      WHERE posting_journal.record_uuid = invoiceUuid AND entity_uuid = entityUuid
+
+      UNION ALL
+
+      SELECT record_uuid AS uuid, debit_equiv as debit, credit_equiv as credit, entity_uuid
+       FROM  general_ledger
+       WHERE general_ledger.record_uuid = invoiceUuid AND entity_uuid = entityUuid
+
+       UNION ALL
+
+      SELECT reference_uuid AS uuid, debit_equiv as debit, credit_equiv as credit, entity_uuid
+      FROM posting_journal
+      WHERE posting_journal.reference_uuid = invoiceUuid AND entity_uuid = entityUuid
+
+      UNION ALL
+
+      SELECT reference_uuid AS uuid, debit_equiv as debit, credit_equiv as credit, entity_uuid
+      FROM general_ledger
+      WHERE general_ledger.reference_uuid = invoiceUuid AND entity_uuid = entityUuid
+    ) AS ledger
+    GROUP BY ledger.uuid
+  );
+END $$
+
 DELIMITER ;