Allow suggesting single line changes in diffs

1 files changed, 61 insertions, 0 deletions

diff --git a/app/models/suggestion.rb b/app/models/suggestion.rb
new file mode 100644
index 00000000000..cec5ea30f9d
--- /dev/null
+++ b/app/models/suggestion.rb
@@ -0,0 +1,61 @@
+# frozen_string_literal: true
+
+class Suggestion < ApplicationRecord
+  FEATURE_FLAG = :diff_suggestions
+
+  belongs_to :note, inverse_of: :suggestions
+  validates :note, presence: true
+  validates :commit_id, presence: true, if: :applied?
+
+  delegate :original_position, :position, :diff_file,
+    :noteable, to: :note
+
+  def self.feature_enabled?
+    Feature.enabled?(FEATURE_FLAG)
+  end
+
+  def project
+    noteable.source_project
+  end
+
+  def branch
+    noteable.source_branch
+  end
+
+  # For now, suggestions only serve as a way to send patches that
+  # will change a single line (being able to apply multiple in the same place),
+  # which explains `from_line` and `to_line` being the same line.
+  # We'll iterate on that in https://gitlab.com/gitlab-org/gitlab-ce/issues/53310
+  # when allowing multi-line suggestions.
+  def from_line
+    position.new_line
+  end
+  alias_method :to_line, :from_line
+
+  def from_original_line
+    original_position.new_line
+  end
+  alias_method :to_original_line, :from_original_line
+
+  # `from_line_index` and `to_line_index` represents diff/blob line numbers in
+  # index-like way (N-1).
+  def from_line_index
+    from_line - 1
+  end
+  alias_method :to_line_index, :from_line_index
+
+  def appliable?
+    return false unless note.supports_suggestion?
+
+    !applied? &&
+      noteable.opened? &&
+      different_content? &&
+      note.active?
+  end
+
+  private
+
+  def different_content?
+    from_content != to_content
+  end
+end