Allow lookup by serial number

lib/Machine.lib.php

@@ -35,6 +35,31 @@ class Machine {
         return $database->has('machines', ['machineid' => $id]);
     }
 
+    /**
+     * Check if a given serial number can identify exactly one machine.
+     * @global $database $database
+     * @param type $serial
+     * @return bool
+     */
+    public static function serialExists(string $serial): bool {
+        global $database;
+        return $database->has('machines', ['serial' => $serial]) && $database->count('machines', ['serial' => $serial]) == 1;
+    }
+
+    /**
+     * Convert a serial into a machine ID.
+     * @global $database $database
+     * @param string $serial
+     * @return string|bool machine ID if found, otherwise false.
+     */
+    public static function getIDFromSerial(string $serial) {
+        global $database;
+        if (Machine::serialExists($serial)) {
+            return $database->get('machines', 'machineid', ['serial' => $serial]) . "";
+        }
+        return false;
+    }
+
     public function save() {
         global $database;
         if ($this->exists) {

public/index.php

@@ -23,7 +23,7 @@ require_once __DIR__ . "/../lib/required_public.php";
     <div class="row justify-content-center">
         <div class="col-12 col-md-8">
             <?php
-            if (empty($_GET["id"]) || !Machine::exists($_GET["id"])) {
+            if (empty($_GET["id"]) || (!Machine::exists($_GET["id"]) && !Machine::serialExists($_GET["id"]))) {
                 ?>
                 <div class="card">
                     <h3 class="card-header d-flex">
@@ -33,7 +33,7 @@ require_once __DIR__ . "/../lib/required_public.php";
                     </h3>
                     <div class="card-body">
                         <?php
-                        if (!empty($_GET["id"]) && !Machine::exists($_GET["id"])) {
+                        if (!empty($_GET["id"])) {
                             ?>
                             <p class="text-danger">No machine with ID <code><?php echo htmlspecialchars($_GET['id']); ?></code> could be found.</p>
                             <?php
@@ -50,7 +50,11 @@ require_once __DIR__ . "/../lib/required_public.php";
                 </div>
                 <?php
             } else {
+                if (Machine::exists($_GET["id"])) {
                 $machine = new Machine($_GET['id']);
+                } else {
+                    $machine = new Machine(Machine::getIDFromSerial($_GET['id']));
+                }
                 ?>
                 <div class="card">
                     <h3 class="card-header d-flex">