Add logic to snippet statistics

In this commit we introduce the necessary
logic to retrieve and store some information
from the snippet repository.

app/models/snippet.rb

@@ -69,6 +69,7 @@ class Snippet < ApplicationRecord
   validates :visibility_level, inclusion: { in: Gitlab::VisibilityLevel.values }
 
   after_save :store_mentions!, if: :any_mentionable_attributes_changed?
+  after_create :create_statistics
 
   # Scopes
   scope :are_internal, -> { where(visibility_level: Snippet::INTERNAL) }

app/models/snippet_statistics.rb

@@ -4,4 +4,32 @@ class SnippetStatistics < ApplicationRecord
   belongs_to :snippet
 
   validates :snippet, presence: true
+
+  delegate :repository, to: :snippet
+
+  def update_commit_count
+    self.commit_count = repository.commit_count
+  end
+
+  def update_repository_size
+    self.repository_size = repository.size.megabytes
+  end
+
+  def update_file_count
+    count = if snippet.repository_exists?
+              repository.ls_files(repository.root_ref).size
+            else
+              0
+            end
+
+    self.file_count = count
+  end
+
+  def refresh!
+    update_commit_count
+    update_repository_size
+    update_file_count
+
+    save!
+  end
 end

changelogs/unreleased/fj-223700-add-count-logic-to-snippet-statistics.yml

+---
+title: Add snippet statistics logic
+merge_request: 35118
+author:
+type: added

spec/models/snippet_spec.rb

@@ -92,6 +92,17 @@ describe Snippet do
     end
   end
 
+  describe 'callbacks' do
+    it 'creates snippet statistics when the snippet is created' do
+      snippet = build(:snippet)
+      expect(snippet.statistics).to be_nil
+
+      snippet.save
+
+      expect(snippet.statistics).to be_persisted
+    end
+  end
+
   describe '#to_reference' do
     context 'when snippet belongs to a project' do
       let(:project) { build(:project, name: 'sample-project') }

spec/models/snippet_statistics_spec.rb

@@ -3,6 +3,87 @@
 require 'spec_helper'
 
 describe SnippetStatistics do
+  let_it_be(:snippet_without_repo) { create(:snippet) }
+  let_it_be(:snippet_with_repo) { create(:snippet, :repository) }
+
+  let(:statistics) { snippet_with_repo.statistics }
+
   it { is_expected.to belong_to(:snippet) }
   it { is_expected.to validate_presence_of(:snippet) }
+
+  describe '#update_commit_count' do
+    subject { statistics.update_commit_count }
+
+    it 'updates the count of commits' do
+      commit_count = snippet_with_repo.repository.commit_count
+
+      subject
+
+      expect(statistics.commit_count).to eq commit_count
+    end
+
+    context 'when the snippet does not have a repository' do
+      let(:statistics) { snippet_without_repo.statistics }
+
+      it 'returns 0' do
+        expect(subject).to eq 0
+        expect(statistics.commit_count).to eq 0
+      end
+    end
+  end
+
+  describe '#update_file_count' do
+    subject { statistics.update_file_count }
+
+    it 'updates the count of files' do
+      file_count = snippet_with_repo.repository.ls_files(nil).count
+
+      subject
+
+      expect(statistics.file_count).to eq file_count
+    end
+
+    context 'when the snippet does not have a repository' do
+      let(:statistics) { snippet_without_repo.statistics }
+
+      it 'returns 0' do
+        expect(subject).to eq 0
+        expect(statistics.file_count).to eq 0
+      end
+    end
+  end
+
+  describe '#update_repository_size' do
+    subject { statistics.update_repository_size }
+
+    it 'updates the repository_size' do
+      repository_size = snippet_with_repo.repository.size.megabytes.to_i
+
+      subject
+
+      expect(statistics.repository_size).to eq repository_size
+    end
+
+    context 'when the snippet does not have a repository' do
+      let(:statistics) { snippet_without_repo.statistics }
+
+      it 'returns 0' do
+        expect(subject).to eq 0
+        expect(statistics.repository_size).to eq 0
+      end
+    end
+  end
+
+  describe '#refresh!' do
+    subject { statistics.refresh! }
+
+    it 'retrieves and saves statistic data from repository' do
+      expect(statistics).to receive(:update_commit_count)
+      expect(statistics).to receive(:update_file_count)
+      expect(statistics).to receive(:update_repository_size)
+      expect(statistics).to receive(:save!)
+
+      subject
+    end
+  end
 end