feat: hash resources to track modifications

If you run a tool to modify the generated resource files (e.g. prettier
or eslint) before checking in the generated model files there is no way
for Anchor to know whether or not it must write to a file again.

This means that all generated files will be written to _and_
prettier/whatever codemod tool will have to be run on all the generated
files each time a change is made. This can take a while if you have a
lot of resources.

To reduce time spent on codemod we hash the file content _before_
writing it to the file and save that. Then, on the next generation,
we'll check that file and won't write to it. The modified files are
returned so they can be used to run the codemods on relevant files.

```sh
cd spec/example
rails anchor:multigen | xargs prettier --write
```

Author: mattkhan

lib/anchor/type_script/multifile_save_service.rb

@@ -17,19 +17,38 @@ def initialize(generator:, folder_path:, force: false)
     def call
       FileUtils.mkdir_p(@folder_path)
       results = @generator.call
-      results.each { |result| save_result(result) }
+      modified_files = results.filter_map { |result| save_result(result) }
+      save_sha
+      modified_files
     end
 
     private
 
+    def sha_hash_path
+      Rails.root.join(@folder_path, "hash.json")
+    end
+
+    def sha_hash
+      return @sha_hash if defined?(@sha_hash)
+
+      @sha_hash = File.exist?(sha_hash_path) ? JSON.parse(File.read(sha_hash_path)) : {}
+    end
+
+    def save_sha
+      File.open(sha_hash_path, "w") { |f| f.write(@generator.sha_hash.to_json) }
+    end
+
+    # @return [String, nil] file name of file that is written to. nil if not written to
     def save_result(result)
       path = Rails.root.join(@folder_path, result.name)
 
       if @force || !File.exist?(path)
         File.open(path, "w") { |f| f.write(result.text) }
-        return
+        return result.name
       end
 
+      return if sha_hash[result.name] == Digest::SHA256.hexdigest(result.text)
+
       existing_content = File.read(path)
 
       new_content = if manually_editable?(existing_content)
@@ -42,6 +61,7 @@ def save_result(result)
       end
 
       File.open(path, "w") { |f| f.write(new_content) }
+      result.name
     end
 
     def manually_editable?(text)

lib/anchor/type_script/multifile_schema_generator.rb

@@ -24,7 +24,12 @@ def initialize( # rubocop:disable Lint/MissingSuper
     end
 
     def call
-      [shared_file] + resource_files
+      @call ||= [shared_file] + resource_files
+    end
+
+    # { res.name => hash(res.text) }
+    def sha_hash
+      @sha_hash ||= call.map { |res| [res.name, Digest::SHA256.hexdigest(res.text)] }.to_h
     end
 
     private

spec/anchor/example_multifile_schema_snapshot_spec.rb

@@ -2,9 +2,9 @@
 
 # rubocop:disable RSpec/EmptyExampleGroup
 RSpec.describe "Example" do
-  def self.multifile_snapshot_test(filename, generate)
+  def self.multifile_snapshot_test(filename, generator)
     it "generates correct #{filename} schema" do
-      results = generate.call
+      results = generator.call
       results.each do |res|
         filename = res.name
 
@@ -21,14 +21,13 @@ def self.multifile_snapshot_test(filename, generate)
     end
   end
 
-  multifile_snapshot_test "schema.ts", -> {
-    Anchor::TypeScript::MultifileSchemaGenerator.call(
+  multifile_snapshot_test "schema.ts",
+    Anchor::TypeScript::MultifileSchemaGenerator.new(
       register: Schema.register,
       context: {},
       include_all_fields: true,
       exclude_fields: nil,
       manually_editable: true,
     )
-  }
 end
 # rubocop:enable RSpec/EmptyExampleGroup

spec/example/lib/tasks/anchor.rake

@@ -39,4 +39,17 @@ namespace :anchor do
       Anchor::JSONSchema::SchemaGenerator.call(register: Schema.register, include_all_fields: true)
     }
   end
+
+  task multigen: :environment do
+    folder_path = "test/files/multifile"
+    generator = Anchor::TypeScript::MultifileSchemaGenerator.new(
+      register: Schema.register,
+      context: {},
+      include_all_fields: true,
+      exclude_fields: nil,
+      manually_editable: true,
+    )
+    modified_files = Anchor::TypeScript::MultifileSaveService.call(generator:, folder_path:)
+    puts modified_files.join(" ")
+  end
 end

spec/example/test/files/multifile/hash.json

@@ -0,0 +1 @@
+{"shared.ts":"e42275c1453e00f368131821b3e4de915d6c5c789a8fc5c72967ddf8c31ad77b","Comment.ts":"fec6ae5197b65afe3fed510a393b7819e288f33366bc34aca1622833c5030ba6","User.ts":"ce80524eb520622e37af4aa9a2b35e49a50cb80bf4ea9921e818631e8a541738","Post.ts":"74d50a09806ff7496c168f2b9b4d6cea64111f42f38effa12464e5ad933c1303","Exhaustive.ts":"ac90628b54e7278d63839fdd4db3d3cbfae9d9e996fb065e5a5d2b756052fe66"}