add utility function mergeEnvVarsWithDefaults

lib/validator.js

@@ -3,7 +3,7 @@ const addFormats = require('ajv-formats');
 const fs = require('fs');
 const path = require('path');
 
-const schemaPath = path.join(__dirname, 'schema/app-schema.json');
+const schemaPath = path.join(__dirname, './schema/app-schema.json');
 const schema = JSON.parse(fs.readFileSync(schemaPath, 'utf8'));
 
 /**
@@ -149,8 +149,38 @@ function validateAppConfig(config) {
   }
 }
 
+const mergeEnvVarsWithDefaults = (env_vars, route, schema) => {
+  env_vars = env_vars || {};
+  const merged = {...env_vars};
+
+  // First handle global properties (those not starting with /)
+  Object.entries(schema).forEach(([propName, propSchema]) => {
+    if (!propName.startsWith('/')) {
+      if (!(propName in merged) && 'default' in propSchema) {
+        merged[propName] = propSchema.default;
+      }
+    }
+  });
+
+  // Then handle route-specific properties
+  const routeSchema = schema[route];
+  if (!routeSchema) {
+    return merged;
+  }
+
+  Object.entries(routeSchema).forEach(([propName, propSchema]) => {
+    if (!(propName in merged) && 'default' in propSchema) {
+      merged[propName] = propSchema.default;
+    }
+  });
+
+  return merged;
+};
+
+
 module.exports = {
   validateAppConfig,
   getAppConfig,
+  mergeEnvVarsWithDefaults,
   schema
 };