1 files changed, 106 insertions, 0 deletions
diff --git a/app/models/commit_range.rb b/app/models/commit_range.rb
new file mode 100644
index 00000000000..e6456198264
--- /dev/null
+++ b/app/models/commit_range.rb
@@ -0,0 +1,106 @@
+# CommitRange makes it easier to work with commit ranges
+#
+# Examples:
+#
+#   range = CommitRange.new('f3f85602...e86e1013')
+#   range.exclude_start?  # => false
+#   range.reference_title # => "Commits f3f85602 through e86e1013"
+#   range.to_s            # => "f3f85602...e86e1013"
+#
+#   range = CommitRange.new('f3f856029bc5f966c5a7ee24cf7efefdd20e6019..e86e1013709735be5bb767e2b228930c543f25ae')
+#   range.exclude_start?  # => true
+#   range.reference_title # => "Commits f3f85602^ through e86e1013"
+#   range.to_param        # => {from: "f3f856029bc5f966c5a7ee24cf7efefdd20e6019^", to: "e86e1013709735be5bb767e2b228930c543f25ae"}
+#   range.to_s            # => "f3f85602..e86e1013"
+#
+#   # Assuming `project` is a Project with a repository containing both commits:
+#   range.project = project
+#   range.valid_commits? # => true
+#
+class CommitRange
+  include ActiveModel::Conversion
+
+  attr_reader :sha_from, :notation, :sha_to
+
+  # Optional Project model
+  attr_accessor :project
+
+  # See `exclude_start?`
+  attr_reader :exclude_start
+
+  # The beginning and ending SHA sums can be between 6 and 40 hex characters,
+  # and the range selection can be double- or triple-dot.
+  PATTERN = /\h{6,40}\.{2,3}\h{6,40}/
+
+  # Initialize a CommitRange
+  #
+  # range_string - The String commit range.
+  # project      - An optional Project model.
+  #
+  # Raises ArgumentError if `range_string` does not match `PATTERN`.
+  def initialize(range_string, project = nil)
+    range_string.strip!
+
+    unless range_string.match(/\A#{PATTERN}\z/)
+      raise ArgumentError, "invalid CommitRange string format: #{range_string}"
+    end
+
+    @exclude_start = !range_string.include?('...')
+    @sha_from, @notation, @sha_to = range_string.split(/(\.{2,3})/, 2)
+
+    @project = project
+  end
+
+  def inspect
+    %(#<#{self.class}:#{object_id} #{to_s}>)
+  end
+
+  def to_s
+    "#{sha_from[0..7]}#{notation}#{sha_to[0..7]}"
+  end
+
+  # Returns a String for use in a link's title attribute
+  def reference_title
+    "Commits #{suffixed_sha_from} through #{sha_to}"
+  end
+
+  # Return a Hash of parameters for passing to a URL helper
+  #
+  # See `namespace_project_compare_url`
+  def to_param
+    { from: suffixed_sha_from, to: sha_to }
+  end
+
+  def exclude_start?
+    exclude_start
+  end
+
+  # Check if both the starting and ending commit IDs exist in a project's
+  # repository
+  #
+  # project - An optional Project to check (default: `project`)
+  def valid_commits?(project = project)
+    return nil   unless project.present?
+    return false unless project.valid_repo?
+
+    commit_from.present? && commit_to.present?
+  end
+
+  def persisted?
+    true
+  end
+
+  def commit_from
+    @commit_from ||= project.repository.commit(suffixed_sha_from)
+  end
+
+  def commit_to
+    @commit_to ||= project.repository.commit(sha_to)
+  end
+
+  private
+
+  def suffixed_sha_from
+    sha_from + (exclude_start? ? '^' : '')
+  end
+end