From d03f1ca7008bb8928de0ec8538d8c110516b68f7 Mon Sep 17 00:00:00 2001
From: Gabriel Arazas <foodogsquared@foodogsquared.one>
Date: Sun, 5 Mar 2023 13:48:40 +0800
Subject: [PATCH] Add GitLab raw content include processor

---
 lib/asciidoctor/foodogsquared-extensions.rb   |  2 +
 .../README.adoc                               | 40 +++++++++++
 .../extension.rb                              | 70 +++++++++++++++++++
 3 files changed, 112 insertions(+)
 create mode 100644 lib/asciidoctor/gitlab-raw-content-include-processor/README.adoc
 create mode 100644 lib/asciidoctor/gitlab-raw-content-include-processor/extension.rb

diff --git a/lib/asciidoctor/foodogsquared-extensions.rb b/lib/asciidoctor/foodogsquared-extensions.rb
index ed9c274..d98ce3d 100644
--- a/lib/asciidoctor/foodogsquared-extensions.rb
+++ b/lib/asciidoctor/foodogsquared-extensions.rb
@@ -3,9 +3,11 @@ require 'asciidoctor/extensions'
 require_relative 'man-inline-macro/extension'
 require_relative 'swhid-inline-macro/extension'
 require_relative 'github-raw-content-include-processor/extension'
+require_relative 'gitlab-raw-content-include-processor/extension'
 
 Asciidoctor::Extensions.register do
   inline_macro ManInlineMacro
   inline_macro SWHInlineMacro
   include_processor GitHubRawIncludeProcessor
+  include_processor GitLabRawIncludeProcessor
 end
diff --git a/lib/asciidoctor/gitlab-raw-content-include-processor/README.adoc b/lib/asciidoctor/gitlab-raw-content-include-processor/README.adoc
new file mode 100644
index 0000000..8f84a26
--- /dev/null
+++ b/lib/asciidoctor/gitlab-raw-content-include-processor/README.adoc
@@ -0,0 +1,40 @@
+= GitLab raw content include processor
+:toc:
+
+
+It's a link:https://docs.asciidoctor.org/asciidoctor/latest/extensions/include-processor/[include processor] for easily including raw content from GitLab repositories.
+
+
+== Synopsis
+
+[source, asciidoc]
+----
+include::gitlab/$OWNER/$REPO[rev=$COMMIT, path=$FILEPATH]
+----
+
+
+== Extra notes
+
+A link:https://docs.gitlab.com/ee/user/profile/personal_access_tokens.html#personal-access-tokens[personal access token] is most likely required.
+Get one and place the value in an environment variable `GITLAB_API_PERSONAL_ACCESS_TOKEN`.
+
+
+== Attributes
+
+There are some attributes required to be passed.
+
+- `rev` is the commit to be checked out.
+- `path` is the file path to be included.
+
+Aside from the required attributes, there are optional attributes to configured further.
+
+- `domain` is the domain of the GitLab instance.
+By default, it points to the `gitlab.com` official instance.
+
+- `version` is the version string of the API to be used.
+By default, it uses version `v4`.
+
+
+== Example usage
+
+- `include::gitlab:gitlab-org/gitlab[rev=master, path=README.md]` should
diff --git a/lib/asciidoctor/gitlab-raw-content-include-processor/extension.rb b/lib/asciidoctor/gitlab-raw-content-include-processor/extension.rb
new file mode 100644
index 0000000..d6422b9
--- /dev/null
+++ b/lib/asciidoctor/gitlab-raw-content-include-processor/extension.rb
@@ -0,0 +1,70 @@
+require 'base64'
+require 'json'
+require 'open-uri'
+require 'uri'
+
+class GitLabRawIncludeProcessor < Asciidoctor::Extensions::IncludeProcessor
+  @@prefix = 'gitlab:'
+
+  def handles? target
+    target.start_with? @@prefix
+  end
+
+  def warn_or_raise doc, warning
+    if (doc.safe > Asciidoctor::SafeMode::SERVER) && !(doc.attr? 'allow-uri-read')
+      raise warning
+    else
+      warn warning
+    end
+  end
+
+  def process doc, reader, target, attrs
+    src = target.delete_prefix(@@prefix).split('/', 2)
+    owner = src.at 0
+    repo = src.at 1
+    namespaced_repo = "#{owner}/#{repo}"
+
+    raise %(there is no 'path' attribute given for GitLab repo '#{namespaced_repo}') unless (attrs.key? 'path')
+    raise %(no given ref for getting file in '#{namespaced_repo}') unless (attrs.key? 'rev')
+
+    path = attrs['path']
+    rev = attrs['rev']
+
+    domain = attrs['domain'] || 'gitlab.com'
+    version = attrs['version'] || 'v4'
+
+    uri = URI.parse %(https://#{domain}/api/#{version})
+
+    # Set the project.
+    uri += %(/projects/#{URI.encode_www_form_component namespaced_repo})
+
+    # Then the filename.
+    uri += %(/repository/files/#{URI.encode_www_form_component path})
+
+    # Then the revision.
+    query = { :ref => rev }
+    uri.query = URI.encode_www_form query
+
+    begin
+      OpenURI.open_uri(
+        uri,
+        'Content-Type' => 'application/json',
+        'PRIVATE-TOKEN' => ENV['GITLAB_API_PERSONAL_ACCESS_TOKEN'],
+      ) do |f|
+        response = JSON.parse(f.read)
+
+        if response['content'] && response['encoding'] == 'base64'
+          Base64.decode64 response['content']
+        end
+
+        reader.push_include content, target, target, 1, attrs
+      end
+    rescue OpenURI::HTTPError => e
+      warning = %(error while getting '#{path}' in GitLab repo '#{repo}': #{e})
+      warn_or_raise doc, warning
+      reader.push_include warning, target, target, 1, attrs
+    end
+
+    reader
+  end
+end