From 226fe2f4baecd03316c7df2164d91516c367216d Mon Sep 17 00:00:00 2001
From: Hannes Matuschek <hmatuschek@gmail.com>
Date: Sun, 30 Aug 2020 13:57:33 +0200
Subject: [PATCH] Added 'low stock' statistics.

---
 src/Repository/PartRepository.php         | 28 +++++++++++++++++++++++
 src/Services/StatisticsHelper.php         | 11 +++++++++
 templates/Statistics/statistics.html.twig |  4 ++++
 3 files changed, 43 insertions(+)

diff --git a/src/Repository/PartRepository.php b/src/Repository/PartRepository.php
index 1d5c1a7c..d6432a4c 100644
--- a/src/Repository/PartRepository.php
+++ b/src/Repository/PartRepository.php
@@ -44,6 +44,7 @@ namespace App\Repository;
 
 use App\Entity\Parts\PartLot;
 use Doctrine\ORM\QueryBuilder;
+use Doctrine\ORM\Query\ResultSetMapping;
 
 class PartRepository extends NamedDBElementRepository
 {
@@ -84,4 +85,31 @@ class PartRepository extends NamedDBElementRepository
 
         return (int) ($query->getSingleScalarResult() ?? 0);
     }
+
+   /**
+     * Gets the number of parts that are low in stock.
+     *
+     * That is, it's total amount is smaller than the minimal amount.
+     *
+     * @throws \Doctrine\ORM\NoResultException
+     * @throws \Doctrine\ORM\NonUniqueResultException
+     */
+    public function getPartCountWithLowStock(): int
+    {
+        /* Query to get total amount for every part.
+         * As sub-queries are not supported -> resort to native SQL request.*/
+        $rsm = new ResultSetMapping;
+        $rsm->addScalarResult("cnt", "count", 'integer');
+        $query = $this->getEntityManager()->createNativeQuery('
+            SELECT COUNT(DISTINCT parts.id) as cnt FROM parts
+            INNER JOIN (
+                SELECT parts.id FROM part_lots
+                INNER JOIN parts ON parts.id=part_lots.id_part
+                GROUP BY parts.id
+                HAVING SUM(part_lots.amount)<parts.minamount
+            ) AS low
+            ON low.id=parts.id',$rsm);
+
+        return (int) ($query->getSingleScalarResult() ?? 0);
+    }
 }
diff --git a/src/Services/StatisticsHelper.php b/src/Services/StatisticsHelper.php
index 2afa3068..a22b1c7d 100644
--- a/src/Services/StatisticsHelper.php
+++ b/src/Services/StatisticsHelper.php
@@ -80,6 +80,17 @@ class StatisticsHelper
         return $this->part_repo->getPartsCountWithPrice();
     }
 
+    /**
+     * Returns the number of all parts with low stock.
+     *
+     * @throws \Doctrine\ORM\NoResultException
+     * @throws \Doctrine\ORM\NonUniqueResultException
+     */
+    public function getPartCountWithLowStock(): int
+    {
+        return $this->part_repo->getPartCountWithLowStock();
+    }
+
     /**
      * Returns the number of datastructures for the given type.
      */
diff --git a/templates/Statistics/statistics.html.twig b/templates/Statistics/statistics.html.twig
index 5cc2f259..622856c6 100644
--- a/templates/Statistics/statistics.html.twig
+++ b/templates/Statistics/statistics.html.twig
@@ -48,6 +48,10 @@
                     <td>{% trans %}statistics.parts_with_price{% endtrans %}</td>
                     <td>{{ helper.partsCountWithPrice }}</td>
                 </tr>
+                <tr>
+                    <td>{% trans %}statistics.parts_low_stock{% endtrans %}</td>
+                    <td>{{ helper.partCountWithLowStock }}</td>
+                </tr>
                 </tbody>
             </table>
         </div>