Add filename_mapper config (#110)

Co-authored-by: Ryan Workman <19210117+rdavid1099@users.noreply.github.com>

Author: skryukov

lib/typelizer/config.rb

@@ -41,6 +41,7 @@ module Typelizer
   # Config keys that don't affect file content (runtime behavior, or effects captured via properties).
   CONFIGS_NOT_AFFECTING_OUTPUT = %i[
     serializer_name_mapper
+    filename_mapper
     serializer_model_mapper
     properties_transformer
     model_plugin
@@ -56,6 +57,7 @@ module Typelizer
 
   Config = Struct.new(
     :serializer_name_mapper,
+    :filename_mapper,
     :serializer_model_mapper,
     :properties_transformer,
     :properties_sort_order,
@@ -95,6 +97,8 @@ def self.defaults
           name.sub(/(Serializer|Resource)\z/, "")
         end,
 
+        filename_mapper: nil,
+
         serializer_model_mapper: lambda do |serializer|
           base_class = serializer_name_mapper.call(serializer)
           Object.const_get(base_class) if Object.const_defined?(base_class)

lib/typelizer/interface.rb

@@ -36,7 +36,11 @@ def name
     end
 
     def filename
-      name.gsub("::", "/")
+      if config.filename_mapper
+        config.filename_mapper.call(config.serializer_name_mapper.call(serializer))
+      else
+        name.gsub("::", "/")
+      end
     end
 
     def index_path(index_dir)

spec/typelizer/generator_spec.rb

@@ -88,6 +88,28 @@ def restore_defaults!
       FileUtils.rm_rf(custom_output_dir)
     end
 
+    it "uses filename_mapper to generate nested file paths" do
+      nested_dir = default_output_dir.parent.join("generator_nested")
+
+      configuration.writer(:nested) do |c|
+        c.output_dir = nested_dir
+        c.filename_mapper = ->(name) { name.gsub("::", "/") }
+      end
+
+      generator.call(force: true)
+
+      # Alba::UserSerializer mapped name is "Alba::User", filename becomes "Alba/User"
+      expect(nested_dir.join("Alba/User.ts")).to exist
+      expect(nested_dir.join("AlbaUser.ts")).not_to exist
+
+      # Type name in index.ts is still flat
+      index_content = File.read(nested_dir.join("index.ts"))
+      expect(index_content).to include("AlbaUser")
+      expect(index_content).to include("'./Alba/User'")
+    ensure
+      FileUtils.rm_rf(nested_dir)
+    end
+
     it "generates files for all writers and applies writer-specific transformers" do
       expect { generator.call(force: true) }.not_to raise_error