feat?: backend: disable field when ENV data is available

Author: Pascal Querner

app/code/core/Mage/Adminhtml/Block/System/Config/Form.php

@@ -372,6 +372,7 @@ public function initFields($fieldset, $group, $section, $fieldPrefix = '', $labe
                     'name'                  => $name,
                     'label'                 => $label,
                     'comment'               => $comment,
+                    'disabled'              => $this->isDisabled($path),
                     'tooltip'               => $tooltip,
                     'hint'                  => $hint,
                     'value'                 => $data,
@@ -622,6 +623,20 @@ public function getScope()
         return $scope;
     }
 
+    /**
+     * Render element as disabled, if overwritten by ENV variable
+     *
+     * @param string $data
+     * @return bool
+     */
+    public function isDisabled($path): bool
+    {
+        /** @var Mage_Core_Helper_EnvironmentConfigLoader $environmentConfigLoaderHelper */
+        $environmentConfigLoaderHelper = Mage::helper('core/environmentConfigLoader');
+        $path = $this->getScope() . '/' . $path;
+        return $environmentConfigLoaderHelper->hasPath($path);
+    }
+
     /**
      * Retrieve label for scope
      *

app/code/core/Mage/Core/Helper/EnvironmentConfigLoader.php

@@ -98,6 +98,39 @@ public function overrideEnvironment(Varien_Simplexml_Config $xmlConfig)
         }
     }
 
+    public function hasPath(string $wantedPath): bool
+    {
+        $env = $this->getEnv();
+        $config = [];
+
+        foreach ($env as $configKey => $value) {
+            if (!$this->isConfigKeyValid($configKey)) {
+                continue;
+            }
+
+            list($configKeyParts, $scope) = $this->getConfigKey($configKey);
+
+            switch ($scope) {
+                case static::CONFIG_KEY_DEFAULT:
+                    list($unused1, $unused2, $section, $group, $field) = $configKeyParts;
+                    $path = $this->buildPath($section, $group, $field);
+                    $nodePath = $this->buildNodePath($scope, $path);
+                    $config[$nodePath] = $value;
+                    break;
+
+                case static::CONFIG_KEY_WEBSITES:
+                case static::CONFIG_KEY_STORES:
+                    list($unused1, $unused2, $storeCode, $section, $group, $field) = $configKeyParts;
+                    $path = $this->buildPath($section, $group, $field);
+                    $nodePath = $this->buildNodePath($scope, $path);
+                    $config[$nodePath] = $value;
+                    break;
+            }
+        }
+        $hasConfig = array_key_exists($wantedPath, $config);
+        return $hasConfig;
+    }
+
     public function getAsArray(string $wantedScope): array
     {
         $env = $this->getEnv();
@@ -124,8 +157,6 @@ public function getAsArray(string $wantedScope): array
                 case static::CONFIG_KEY_STORES:
                     list($unused1, $unused2, $storeCode, $section, $group, $field) = $configKeyParts;
                     $path = $this->buildPath($section, $group, $field);
-                    $storeCode = strtolower($storeCode);
-                    $scope = strtolower($scope);
                     $config[$path] = $value;
                     break;
             }