Add latest changes from gitlab-org/gitlab@13-9-stable-eev13.9.0-rc42

1 files changed, 59 insertions, 0 deletions

diff --git a/lib/gitlab/changelog/generator.rb b/lib/gitlab/changelog/generator.rb
new file mode 100644
index 00000000000..a80ca0728f9
--- /dev/null
+++ b/lib/gitlab/changelog/generator.rb
@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Changelog
+    # Parsing and generating of Markdown changelogs.
+    class Generator
+      # The regex used to parse a release header.
+      RELEASE_REGEX =
+        /^##\s+(?<version>#{Gitlab::Regex.unbounded_semver_regex})/.freeze
+
+      # The `input` argument must be a `String` containing the existing
+      # changelog Markdown. If no changelog exists, this should be an empty
+      # `String`.
+      def initialize(input = '')
+        @lines = input.lines
+        @locations = {}
+
+        @lines.each_with_index do |line, index|
+          matches = line.match(RELEASE_REGEX)
+
+          next if !matches || !matches[:version]
+
+          @locations[matches[:version]] = index
+        end
+      end
+
+      # Generates the Markdown for the given release and returns the new
+      # changelog Markdown content.
+      #
+      # The `release` argument must be an instance of
+      # `Gitlab::Changelog::Release`.
+      def add(release)
+        versions = [release.version, *@locations.keys]
+
+        VersionSorter.rsort!(versions)
+
+        new_index = versions.index(release.version)
+        new_lines = @lines.dup
+        markdown = release.to_markdown
+
+        if (insert_after = versions[new_index + 1])
+          line_index = @locations[insert_after]
+
+          new_lines.insert(line_index, markdown)
+        else
+          # When adding to the end of the changelog, the previous section only
+          # has a single newline, resulting in the release section title
+          # following it immediately. When this is the case, we insert an extra
+          # empty line to keep the changelog readable in its raw form.
+          new_lines.push("\n") if versions.length > 1
+          new_lines.push(markdown.rstrip)
+          new_lines.push("\n")
+        end
+
+        new_lines.join
+      end
+    end
+  end
+end