Implemented plugin for swaping defined build-time constants

.vite/plugins/swap-defined-variables.js

@@ -0,0 +1,28 @@
+/**
+ * @param {SwapDefinedVariablesSettings} settings
+ * @return {import('vite').Plugin}
+ */
+export function SwapDefinedVariablesPlugin(settings) {
+  return {
+    name: 'koloml:swap-defined-variables',
+    enforce: 'post',
+    configResolved: (config) => {
+      if (
+        config.define
+        && process.env.hasOwnProperty(settings.envVariable)
+        && process.env[settings.envVariable] === settings.expectedValue
+      ) {
+        for (const [key, value] of Object.entries(settings.define)) {
+          config.define[key] = value;
+        }
+      }
+    }
+  }
+}
+
+/**
+ * @typedef {Object} SwapDefinedVariablesSettings
+ * @property {string} envVariable
+ * @property {string} expectedValue
+ * @property {Record<string, string>} define
+ */