From c07bd1f4caae09a30d222df5f10e3e7514bede8e Mon Sep 17 00:00:00 2001
From: "Garen J. Torikian" <gjtorikian@users.noreply.github.com>
Date: Fri, 4 Jan 2019 17:06:30 -0500
Subject: [PATCH] Support ERB templates for landing pages

---
 README.md                                      |  6 ++++++
 lib/graphql-docs/configuration.rb              |  4 +++-
 lib/graphql-docs/generator.rb                  | 18 +++++++++++++++++-
 lib/graphql-docs/helpers.rb                    |  8 ++++++--
 .../fixtures/landing_pages/object.erb          |  6 ++++++
 test/graphql-docs/generator_test.rb            | 15 +++++++++++++++
 6 files changed, 53 insertions(+), 4 deletions(-)
 create mode 100644 test/graphql-docs/fixtures/landing_pages/object.erb

diff --git a/README.md b/README.md
index 91d0595..61aab0a 100644
--- a/README.md
+++ b/README.md
@@ -96,6 +96,12 @@ GraphQLDocs.build(options)
 
 If your `render` method returns `nil`, the `Generator` will not attempt to write any HTML file.
 
+### Templates
+
+The layouts for the individual GraphQL pages are ERB templates, but you can also use ERB templates for your static landing pages.
+
+If you want to add additional variables for your landing pages, you can add define a `variables` hash within the `landing_pages` option.
+
 ### Helper methods
 
 In your ERB layouts, there are several helper methods you can use. The helper methods are:
diff --git a/lib/graphql-docs/configuration.rb b/lib/graphql-docs/configuration.rb
index 15ec21a..1fd72e4 100644
--- a/lib/graphql-docs/configuration.rb
+++ b/lib/graphql-docs/configuration.rb
@@ -48,7 +48,9 @@ module Configuration
         enum: "#{File.dirname(__FILE__)}/landing_pages/enum.md",
         union: "#{File.dirname(__FILE__)}/landing_pages/union.md",
         input_object: "#{File.dirname(__FILE__)}/landing_pages/input_object.md",
-        scalar: "#{File.dirname(__FILE__)}/landing_pages/scalar.md"
+        scalar: "#{File.dirname(__FILE__)}/landing_pages/scalar.md",
+
+        variables: {} # only used for ERB landing pages
       },
 
       classes: {
diff --git a/lib/graphql-docs/generator.rb b/lib/graphql-docs/generator.rb
index af8cd2c..9864243 100644
--- a/lib/graphql-docs/generator.rb
+++ b/lib/graphql-docs/generator.rb
@@ -27,7 +27,23 @@ def initialize(parsed_schema, options)
         elsif !File.exist?(@options[:landing_pages][sym])
           raise IOError, "`#{sym}` landing page #{@options[:landing_pages][sym]} was not found"
         end
-        instance_variable_set("@graphql_#{sym}_landing_page", File.read(@options[:landing_pages][sym]))
+
+        landing_page_contents = File.read(@options[:landing_pages][sym])
+        metadata = ''
+
+        if File.extname((@options[:landing_pages][sym])) == '.erb'
+          opts = @options.merge(@options[:landing_pages][:variables]).merge(helper_methods)
+          if has_yaml?(landing_page_contents)
+            metadata, landing_page = split_into_metadata_and_contents(landing_page_contents, parse: false)
+            erb_template = ERB.new(landing_page)
+          else
+            erb_template = ERB.new(landing_page_contents)
+          end
+
+          landing_page_contents = erb_template.result(OpenStruct.new(opts).instance_eval { binding })
+        end
+
+        instance_variable_set("@graphql_#{sym}_landing_page", metadata + landing_page_contents)
       end
     end
 
diff --git a/lib/graphql-docs/helpers.rb b/lib/graphql-docs/helpers.rb
index 85edb5b..a69578b 100644
--- a/lib/graphql-docs/helpers.rb
+++ b/lib/graphql-docs/helpers.rb
@@ -62,7 +62,7 @@ def graphql_scalar_types
       @parsed_schema[:scalar_types] || []
     end
 
-    def split_into_metadata_and_contents(contents)
+    def split_into_metadata_and_contents(contents, parse: true)
       opts = {}
       pieces = yaml_split(contents)
       if pieces.size < 4
@@ -72,7 +72,11 @@ def split_into_metadata_and_contents(contents)
       end
       # Parse
       begin
-        meta = YAML.load(pieces[2]) || {}
+        if parse
+          meta = YAML.load(pieces[2]) || {}
+        else
+          meta = pieces[2]
+        end
       rescue Exception => e # rubocop:disable Lint/RescueException
         raise "Could not parse YAML for #{name}: #{e.message}"
       end
diff --git a/test/graphql-docs/fixtures/landing_pages/object.erb b/test/graphql-docs/fixtures/landing_pages/object.erb
new file mode 100644
index 0000000..6dfd5c6
--- /dev/null
+++ b/test/graphql-docs/fixtures/landing_pages/object.erb
@@ -0,0 +1,6 @@
+---
+title: Variable Objects
+---
+# Objects
+
+<%= some_var %> in GraphQL represent the resources that you can access.
diff --git a/test/graphql-docs/generator_test.rb b/test/graphql-docs/generator_test.rb
index 62e8fe0..71439f4 100644
--- a/test/graphql-docs/generator_test.rb
+++ b/test/graphql-docs/generator_test.rb
@@ -155,6 +155,21 @@ def test_that_missing_landing_pages_are_reported
     end
   end
 
+  def test_that_erb_landing_pages_work
+    options = deep_copy(GraphQLDocs::Configuration::GRAPHQLDOCS_DEFAULTS)
+    options[:output_dir] = @output_dir
+    options[:landing_pages][:object] = File.join(fixtures_dir, 'landing_pages', 'object.erb')
+    options[:landing_pages][:variables] = { some_var: 'wowie!!' }
+
+    generator = GraphQLDocs::Generator.new(@tiny_results, options)
+    generator.generate
+
+    object = File.read File.join(@output_dir, 'object', 'index.html')
+
+    assert_match /Variable Objects/, object
+    assert_match /wowie!!/, object
+  end
+
   def test_that_broken_yaml_is_caught
     options = deep_copy(GraphQLDocs::Configuration::GRAPHQLDOCS_DEFAULTS)
     options[:landing_pages][:index] = File.join(fixtures_dir, 'landing_pages', 'broken_yaml.md')