repository.rb

require 'securerandom'

class Repository
  include Gitlab::ShellAdapter

  attr_accessor :path_with_namespace, :project

  CommitError = Class.new(StandardError)

  # Methods that cache data from the Git repository.
  #
  # Each entry in this Array should have a corresponding method with the exact
  # same name. The cache key used by those methods must also match method's
  # name.
  #
  # For example, for entry `:readme` there's a method called `readme` which
  # stores its data in the `readme` cache key.
  CACHED_METHODS = %i(size commit_count readme version contribution_guide
                      changelog license_blob license_key gitignore koding_yml
                      gitlab_ci_yml branch_names tag_names branch_count
                      tag_count avatar exists? empty? root_ref)

  # Certain method caches should be refreshed when certain types of files are
  # changed. This Hash maps file types (as returned by Gitlab::FileDetector) to
  # the corresponding methods to call for refreshing caches.
  METHOD_CACHES_FOR_FILE_TYPES = {
    readme: :readme,
    changelog: :changelog,
    license: %i(license_blob license_key),
    contributing: :contribution_guide,
    version: :version,
    gitignore: :gitignore,
    koding: :koding_yml,
    gitlab_ci: :gitlab_ci_yml,
    avatar: :avatar
  }

  # Wraps around the given method and caches its output in Redis and an instance
  # variable.
  #
  # This only works for methods that do not take any arguments.
  def self.cache_method(name, fallback: nil)
    original = :"_uncached_#{name}"

    alias_method(original, name)

    define_method(name) do
      cache_method_output(name, fallback: fallback) { __send__(original) }
    end
  end

  def self.storages
    Gitlab.config.repositories.storages
  end

  def initialize(path_with_namespace, project)
    @path_with_namespace = path_with_namespace
    @project = project
  end

  def raw_repository
    return nil unless path_with_namespace

    @raw_repository ||= Gitlab::Git::Repository.new(path_to_repo)
  end

  # Return absolute path to repository
  def path_to_repo
    @path_to_repo ||= File.expand_path(
      File.join(@project.repository_storage_path, path_with_namespace + ".git")
    )
  end

  #
  # Git repository can contains some hidden refs like:
  #   /refs/notes/*
  #   /refs/git-as-svn/*
  #   /refs/pulls/*
  # This refs by default not visible in project page and not cloned to client side.
  #
  # This method return true if repository contains some content visible in project page.
  #
  def has_visible_content?
    branch_count > 0
  end

  def commit(ref = 'HEAD')
    return nil unless exists?

    commit =
      if ref.is_a?(Gitlab::Git::Commit)
        ref
      else
        Gitlab::Git::Commit.find(raw_repository, ref)
      end

    commit = ::Commit.new(commit, @project) if commit
    commit
  rescue Rugged::OdbError, Rugged::TreeError
    nil
  end

  def commits(ref, path: nil, limit: nil, offset: nil, skip_merges: false, after: nil, before: nil)
    options = {
      repo: raw_repository,
      ref: ref,
      path: path,
      limit: limit,
      offset: offset,
      after: after,
      before: before,
      # --follow doesn't play well with --skip. See:
      # https://gitlab.com/gitlab-org/gitlab-ce/issues/3574#note_3040520
      follow: false,
      skip_merges: skip_merges
    }

    commits = Gitlab::Git::Commit.where(options)
    commits = Commit.decorate(commits, @project) if commits.present?
    commits
  end

  def commits_between(from, to)
    commits = Gitlab::Git::Commit.between(raw_repository, from, to)
    commits = Commit.decorate(commits, @project) if commits.present?
    commits
  end

  def find_commits_by_message(query, ref = nil, path = nil, limit = 1000, offset = 0)
    unless exists? && has_visible_content? && query.present?
      return []
    end

    ref ||= root_ref

    args = %W(
      #{Gitlab.config.git.bin_path} log #{ref} --pretty=%H --skip #{offset}
      --max-count #{limit} --grep=#{query} --regexp-ignore-case
    )
    args = args.concat(%W(-- #{path})) if path.present?

    git_log_results = Gitlab::Popen.popen(args, path_to_repo).first.lines
    git_log_results.map { |c| commit(c.chomp) }.compact
  end

  def find_branch(name, fresh_repo: true)
    # Since the Repository object may have in-memory index changes, invalidating the memoized Repository object may
    # cause unintended side effects. Because finding a branch is a read-only operation, we can safely instantiate
    # a new repo here to ensure a consistent state to avoid a libgit2 bug where concurrent access (e.g. via git gc)
    # may cause the branch to "disappear" erroneously or have the wrong SHA.
    #
    # See: https://github.com/libgit2/libgit2/issues/1534 and https://gitlab.com/gitlab-org/gitlab-ce/issues/15392
    raw_repo =
      if fresh_repo
        Gitlab::Git::Repository.new(path_to_repo)
      else
        raw_repository
      end

    raw_repo.find_branch(name)
  end

  def find_tag(name)
    tags.find { |tag| tag.name == name }
  end

  def add_branch(user, branch_name, ref)
    newrev = commit(ref).try(:sha)

    return false unless newrev

    GitOperationService.new(user, self).add_branch(branch_name, newrev)

    after_create_branch
    find_branch(branch_name)
  end

  def add_tag(user, tag_name, target, message = nil)
    newrev = commit(target).try(:id)
    options = { message: message, tagger: user_to_committer(user) } if message

    return false unless newrev

    GitOperationService.new(user, self).add_tag(tag_name, newrev, options)

    find_tag(tag_name)
  end

  def rm_branch(user, branch_name)
    before_remove_branch
    branch = find_branch(branch_name)

    GitOperationService.new(user, self).rm_branch(branch)

    after_remove_branch
    true
  end

  # TODO: why we don't pass user here?
  def rm_tag(tag_name)
    before_remove_tag

    begin
      rugged.tags.delete(tag_name)
      true
    rescue Rugged::ReferenceError
      false
    end
  end

  def ref_names
    branch_names + tag_names
  end

  def branch_exists?(branch_name)
    branch_names.include?(branch_name)
  end

  def ref_exists?(ref)
    rugged.references.exist?(ref)
  rescue Rugged::ReferenceError
    false
  end

  # Makes sure a commit is kept around when Git garbage collection runs.
  # Git GC will delete commits from the repository that are no longer in any
  # branches or tags, but we want to keep some of these commits around, for
  # example if they have comments or CI builds.
  def keep_around(sha)
    return unless sha && commit(sha)

    return if kept_around?(sha)

    # This will still fail if the file is corrupted (e.g. 0 bytes)
    begin
      rugged.references.create(keep_around_ref_name(sha), sha, force: true)
    rescue Rugged::ReferenceError => ex
      Rails.logger.error "Unable to create keep-around reference for repository #{path}: #{ex}"
    rescue Rugged::OSError => ex
      raise unless ex.message =~ /Failed to create locked file/ && ex.message =~ /File exists/
      Rails.logger.error "Unable to create keep-around reference for repository #{path}: #{ex}"
    end
  end

  def kept_around?(sha)
    ref_exists?(keep_around_ref_name(sha))
  end

  def diverging_commit_counts(branch)
    root_ref_hash = raw_repository.rev_parse_target(root_ref).oid
    cache.fetch(:"diverging_commit_counts_#{branch.name}") do
      # Rugged seems to throw a `ReferenceError` when given branch_names rather
      # than SHA-1 hashes
      number_commits_behind = raw_repository.
        count_commits_between(branch.dereferenced_target.sha, root_ref_hash)

      number_commits_ahead = raw_repository.
        count_commits_between(root_ref_hash, branch.dereferenced_target.sha)

      { behind: number_commits_behind, ahead: number_commits_ahead }
    end
  end

  def expire_tags_cache
    expire_method_caches(%i(tag_names tag_count))
    @tags = nil
  end

  def expire_branches_cache
    expire_method_caches(%i(branch_names branch_count))
    @local_branches = nil
  end

  def expire_statistics_caches
    expire_method_caches(%i(size commit_count))
  end

  def expire_all_method_caches
    expire_method_caches(CACHED_METHODS)
  end

  # Expires the caches of a specific set of methods
  def expire_method_caches(methods)
    methods.each do |key|
      cache.expire(key)

      ivar = cache_instance_variable_name(key)

      remove_instance_variable(ivar) if instance_variable_defined?(ivar)
    end
  end

  def expire_avatar_cache
    expire_method_caches(%i(avatar))
  end

  # Refreshes the method caches of this repository.
  #
  # types - An Array of file types (e.g. `:readme`) used to refresh extra
  #         caches.
  def refresh_method_caches(types)
    to_refresh = []

    types.each do |type|
      methods = METHOD_CACHES_FOR_FILE_TYPES[type.to_sym]

      to_refresh.concat(Array(methods)) if methods
    end

    expire_method_caches(to_refresh)

    to_refresh.each { |method| send(method) }
  end

  def expire_branch_cache(branch_name = nil)
    # When we push to the root branch we have to flush the cache for all other
    # branches as their statistics are based on the commits relative to the
    # root branch.
    if !branch_name || branch_name == root_ref
      branches.each do |branch|
        cache.expire(:"diverging_commit_counts_#{branch.name}")
      end
    # In case a commit is pushed to a non-root branch we only have to flush the
    # cache for said branch.
    else
      cache.expire(:"diverging_commit_counts_#{branch_name}")
    end
  end

  def expire_root_ref_cache
    expire_method_caches(%i(root_ref))
  end

  # Expires the cache(s) used to determine if a repository is empty or not.
  def expire_emptiness_caches
    return unless empty?

    expire_method_caches(%i(empty?))
  end

  def lookup_cache
    @lookup_cache ||= {}
  end

  def expire_exists_cache
    expire_method_caches(%i(exists?))
  end

  # expire cache that doesn't depend on repository data (when expiring)
  def expire_content_cache
    expire_tags_cache
    expire_branches_cache
    expire_root_ref_cache
    expire_emptiness_caches
    expire_exists_cache
    expire_statistics_caches
  end

  # Runs code after a repository has been created.
  def after_create
    expire_exists_cache
    expire_root_ref_cache
    expire_emptiness_caches

    repository_event(:create_repository)
  end

  # Runs code just before a repository is deleted.
  def before_delete
    expire_exists_cache
    expire_all_method_caches
    expire_branch_cache if exists?
    expire_content_cache

    repository_event(:remove_repository)
  end

  # Runs code just before the HEAD of a repository is changed.
  def before_change_head
    # Cached divergent commit counts are based on repository head
    expire_branch_cache
    expire_root_ref_cache

    repository_event(:change_default_branch)
  end

  # Runs code before pushing (= creating or removing) a tag.
  def before_push_tag
    expire_statistics_caches
    expire_emptiness_caches
    expire_tags_cache

    repository_event(:push_tag)
  end

  # Runs code before removing a tag.
  def before_remove_tag
    expire_tags_cache
    expire_statistics_caches

    repository_event(:remove_tag)
  end

  def before_import
    expire_content_cache
  end

  # Runs code after a repository has been forked/imported.
  def after_import
    expire_content_cache
    expire_tags_cache
    expire_branches_cache
  end

  # Runs code after a new commit has been pushed.
  def after_push_commit(branch_name)
    expire_statistics_caches
    expire_branch_cache(branch_name)

    repository_event(:push_commit, branch: branch_name)
  end

  # Runs code after a new branch has been created.
  def after_create_branch
    expire_branches_cache

    repository_event(:push_branch)
  end

  # Runs code before removing an existing branch.
  def before_remove_branch
    expire_branches_cache

    repository_event(:remove_branch)
  end

  # Runs code after an existing branch has been removed.
  def after_remove_branch
    expire_branches_cache
  end

  def method_missing(m, *args, &block)
    if m == :lookup && !block_given?
      lookup_cache[m] ||= {}
      lookup_cache[m][args.join(":")] ||= raw_repository.send(m, *args, &block)
    else
      raw_repository.send(m, *args, &block)
    end
  end

  def respond_to_missing?(method, include_private = false)
    raw_repository.respond_to?(method, include_private) || super
  end

  def blob_at(sha, path)
    unless Gitlab::Git.blank_ref?(sha)
      Blob.decorate(Gitlab::Git::Blob.find(self, sha, path))
    end
  end

  def blob_by_oid(oid)
    Gitlab::Git::Blob.raw(self, oid)
  end

  def root_ref
    if raw_repository
      raw_repository.root_ref
    else
      # When the repo does not exist we raise this error so no data is cached.
      raise Rugged::ReferenceError
    end
  end
  cache_method :root_ref

  def exists?
    refs_directory_exists?
  end
  cache_method :exists?

  def empty?
    raw_repository.empty?
  end
  cache_method :empty?

  # The size of this repository in megabytes.
  def size
    exists? ? raw_repository.size : 0.0
  end
  cache_method :size, fallback: 0.0

  def commit_count
    root_ref ? raw_repository.commit_count(root_ref) : 0
  end
  cache_method :commit_count, fallback: 0

  def branch_names
    branches.map(&:name)
  end
  cache_method :branch_names, fallback: []

  def tag_names
    raw_repository.tag_names
  end
  cache_method :tag_names, fallback: []

  def branch_count
    branches.size
  end
  cache_method :branch_count, fallback: 0

  def tag_count
    raw_repository.rugged.tags.count
  end
  cache_method :tag_count, fallback: 0

  def avatar
    if tree = file_on_head(:avatar)
      tree.path
    end
  end
  cache_method :avatar

  def readme
    if head = tree(:head)
      head.readme
    end
  end
  cache_method :readme

  def version
    file_on_head(:version)
  end
  cache_method :version

  def contribution_guide
    file_on_head(:contributing)
  end
  cache_method :contribution_guide

  def changelog
    file_on_head(:changelog)
  end
  cache_method :changelog

  def license_blob
    file_on_head(:license)
  end
  cache_method :license_blob

  def license_key
    return unless exists?

    Licensee.license(path).try(:key)
  end
  cache_method :license_key

  def gitignore
    file_on_head(:gitignore)
  end
  cache_method :gitignore

  def koding_yml
    file_on_head(:koding)
  end
  cache_method :koding_yml

  def gitlab_ci_yml
    file_on_head(:gitlab_ci)
  end
  cache_method :gitlab_ci_yml

  def head_commit
    @head_commit ||= commit(self.root_ref)
  end

  def head_tree
    if head_commit
      @head_tree ||= Tree.new(self, head_commit.sha, nil)
    end
  end

  def tree(sha = :head, path = nil, recursive: false)
    if sha == :head
      return unless head_commit

      if path.nil?
        return head_tree
      else
        sha = head_commit.sha
      end
    end

    Tree.new(self, sha, path, recursive: recursive)
  end

  def blob_at_branch(branch_name, path)
    last_commit = commit(branch_name)

    if last_commit
      blob_at(last_commit.sha, path)
    else
      nil
    end
  end

  # Returns url for submodule
  #
  # Ex.
  #   @repository.submodule_url_for('master', 'rack')
  #   # => git@localhost:rack.git
  #
  def submodule_url_for(ref, path)
    if submodules(ref).any?
      submodule = submodules(ref)[path]

      if submodule
        submodule['url']
      end
    end
  end

  def last_commit_for_path(sha, path)
    args = %W(#{Gitlab.config.git.bin_path} rev-list --max-count=1 #{sha} -- #{path})
    sha = Gitlab::Popen.popen(args, path_to_repo).first.strip
    commit(sha)
  end

  def next_branch(name, opts = {})
    branch_ids = self.branch_names.map do |n|
      next 1 if n == name
      result = n.match(/\A#{name}-([0-9]+)\z/)
      result[1].to_i if result
    end.compact

    highest_branch_id = branch_ids.max || 0

    return name if opts[:mild] && 0 == highest_branch_id

    "#{name}-#{highest_branch_id + 1}"
  end

  # Remove archives older than 2 hours
  def branches_sorted_by(value)
    case value
    when 'name'
      branches.sort_by(&:name)
    when 'updated_desc'
      branches.sort do |a, b|
        commit(b.dereferenced_target).committed_date <=> commit(a.dereferenced_target).committed_date
      end
    when 'updated_asc'
      branches.sort do |a, b|
        commit(a.dereferenced_target).committed_date <=> commit(b.dereferenced_target).committed_date
      end
    else
      branches
    end
  end

  def tags_sorted_by(value)
    case value
    when 'name'
      VersionSorter.rsort(tags) { |tag| tag.name }
    when 'updated_desc'
      tags_sorted_by_committed_date.reverse
    when 'updated_asc'
      tags_sorted_by_committed_date
    else
      tags
    end
  end

  def contributors
    commits = self.commits(nil, limit: 2000, offset: 0, skip_merges: true)

    commits.group_by(&:author_email).map do |email, commits|
      contributor = Gitlab::Contributor.new
      contributor.email = email

      commits.each do |commit|
        if contributor.name.blank?
          contributor.name = commit.author_name
        end

        contributor.commits += 1
      end

      contributor
    end
  end

  def ref_name_for_sha(ref_path, sha)
    args = %W(#{Gitlab.config.git.bin_path} for-each-ref --count=1 #{ref_path} --contains #{sha})

    # Not found -> ["", 0]
    # Found -> ["b8d95eb4969eefacb0a58f6a28f6803f8070e7b9 commit\trefs/environments/production/77\n", 0]
    Gitlab::Popen.popen(args, path_to_repo).first.split.last
  end

  def refs_contains_sha(ref_type, sha)
    args = %W(#{Gitlab.config.git.bin_path} #{ref_type} --contains #{sha})
    names = Gitlab::Popen.popen(args, path_to_repo).first

    if names.respond_to?(:split)
      names = names.split("\n").map(&:strip)

      names.each do |name|
        name.slice! '* '
      end

      names
    else
      []
    end
  end

  def branch_names_contains(sha)
    refs_contains_sha('branch', sha)
  end

  def tag_names_contains(sha)
    refs_contains_sha('tag', sha)
  end

  def local_branches
    @local_branches ||= raw_repository.local_branches
  end

  alias_method :branches, :local_branches

  def tags
    @tags ||= raw_repository.tags
  end

  # rubocop:disable Metrics/ParameterLists
  def commit_dir(
    user, path,
    message:, branch_name:,
    author_email: nil, author_name: nil,
    source_branch_name: nil, source_project: project)
    check_tree_entry_for_dir(branch_name, path)

    if source_branch_name
      source_project.repository.
        check_tree_entry_for_dir(source_branch_name, path)
    end

    commit_file(
      user,
      "#{path}/.gitkeep",
      '',
      message: message,
      branch_name: branch_name,
      update: false,
      author_email: author_email,
      author_name: author_name,
      source_branch_name: source_branch_name,
      source_project: source_project)
  end
  # rubocop:enable Metrics/ParameterLists

  # rubocop:disable Metrics/ParameterLists
  def commit_file(
    user, path, content,
    message:, branch_name:, update: true,
    author_email: nil, author_name: nil,
    source_branch_name: nil, source_project: project)
    unless update
      error_message = "Filename already exists; update not allowed"

      if tree_entry_at(branch_name, path)
        raise Gitlab::Git::Repository::InvalidBlobName.new(error_message)
      end

      if source_branch_name &&
         source_project.repository.tree_entry_at(source_branch_name, path)
        raise Gitlab::Git::Repository::InvalidBlobName.new(error_message)
      end
    end

    multi_action(
      user: user,
      message: message,
      branch_name: branch_name,
      author_email: author_email,
      author_name: author_name,
      source_branch_name: source_branch_name,
      source_project: source_project,
      actions: [{ action: :create,
                  file_path: path,
                  content: content }])
  end
  # rubocop:enable Metrics/ParameterLists

  # rubocop:disable Metrics/ParameterLists
  def update_file(
    user, path, content,
    message:, branch_name:, previous_path:,
    author_email: nil, author_name: nil,
    source_branch_name: nil, source_project: project)
    action = if previous_path && previous_path != path
               :move
             else
               :update
             end

    multi_action(
      user: user,
      message: message,
      branch_name: branch_name,
      author_email: author_email,
      author_name: author_name,
      source_branch_name: source_branch_name,
      source_project: source_project,
      actions: [{ action: action,
                  file_path: path,
                  content: content,
                  previous_path: previous_path }])
  end
  # rubocop:enable Metrics/ParameterLists

  # rubocop:disable Metrics/ParameterLists
  def remove_file(
    user, path,
    message:, branch_name:,
    author_email: nil, author_name: nil,
    source_branch_name: nil, source_project: project)
    multi_action(
      user: user,
      message: message,
      branch_name: branch_name,
      author_email: author_email,
      author_name: author_name,
      source_branch_name: source_branch_name,
      source_project: source_project,
      actions: [{ action: :delete,
                  file_path: path }])
  end
  # rubocop:enable Metrics/ParameterLists

  # rubocop:disable Metrics/ParameterLists
  def multi_action(
    user:, branch_name:, message:, actions:,
    author_email: nil, author_name: nil,
    source_branch_name: nil, source_project: project)
    GitOperationService.new(user, self).with_branch(
      branch_name,
      source_branch_name: source_branch_name,
      source_project: source_project) do |source_commit|
      index = rugged.index

      parents = if source_commit
                  index.read_tree(source_commit.raw_commit.tree)
                  [source_commit.sha]
                else
                  []
                end

      actions.each do |act|
        git_action(index, act)
      end

      options = {
        tree: index.write_tree(rugged),
        message: message,
        parents: parents
      }
      options.merge!(get_committer_and_author(user, email: author_email, name: author_name))

      Rugged::Commit.create(rugged, options)
    end
  end
  # rubocop:enable Metrics/ParameterLists

  def get_committer_and_author(user, email: nil, name: nil)
    committer = user_to_committer(user)
    author = Gitlab::Git::committer_hash(email: email, name: name) || committer

    {
      author: author,
      committer: committer
    }
  end

  def user_to_committer(user)
    Gitlab::Git.committer_hash(email: user.email, name: user.name)
  end

  def can_be_merged?(source_sha, target_branch)
    our_commit = rugged.branches[target_branch].target
    their_commit = rugged.lookup(source_sha)

    if our_commit && their_commit
      !rugged.merge_commits(our_commit, their_commit).conflicts?
    else
      false
    end
  end

  def merge(user, merge_request, options = {})
    GitOperationService.new(user, self).with_branch(
      merge_request.target_branch) do |source_commit|
      our_commit = source_commit.sha
      their_commit = merge_request.diff_head_sha

      raise 'Invalid merge target' unless our_commit
      raise 'Invalid merge source' unless their_commit

      merge_index = rugged.merge_commits(our_commit, their_commit)
      break if merge_index.conflicts?

      actual_options = options.merge(
        parents: [our_commit, their_commit],
        tree: merge_index.write_tree(rugged),
      )

      commit_id = Rugged::Commit.create(rugged, actual_options)
      merge_request.update(in_progress_merge_commit_sha: commit_id)
      commit_id
    end
  rescue Repository::CommitError # when merge_index.conflicts?
    false
  end

  def revert(
    user, commit, branch_name, revert_tree_id = nil,
    source_branch_name: nil, source_project: project)
    revert_tree_id ||= check_revert_content(commit, branch_name)

    return false unless revert_tree_id

    GitOperationService.new(user, self).with_branch(
      branch_name,
      source_branch_name: source_branch_name,
      source_project: source_project) do |source_commit|

      committer = user_to_committer(user)

      Rugged::Commit.create(rugged,
        message: commit.revert_message(user),
        author: committer,
        committer: committer,
        tree: revert_tree_id,
        parents: [source_commit.sha])
    end
  end

  def cherry_pick(
    user, commit, branch_name, cherry_pick_tree_id = nil,
    source_branch_name: nil, source_project: project)
    cherry_pick_tree_id ||= check_cherry_pick_content(commit, branch_name)

    return false unless cherry_pick_tree_id

    GitOperationService.new(user, self).with_branch(
      branch_name,
      source_branch_name: source_branch_name,
      source_project: source_project) do |source_commit|

      committer = user_to_committer(user)

      Rugged::Commit.create(rugged,
        message: commit.message,
        author: {
          email: commit.author_email,
          name: commit.author_name,
          time: commit.authored_date
        },
        committer: committer,
        tree: cherry_pick_tree_id,
        parents: [source_commit.sha])
    end
  end

  def resolve_conflicts(user, branch_name, params)
    GitOperationService.new(user, self).with_branch(branch_name) do
      committer = user_to_committer(user)

      Rugged::Commit.create(rugged, params.merge(author: committer, committer: committer))
    end
  end

  def check_revert_content(commit, branch_name)
    source_sha = find_branch(branch_name).dereferenced_target.sha
    args       = [commit.id, source_sha]
    args << { mainline: 1 } if commit.merge_commit?

    revert_index = rugged.revert_commit(*args)
    return false if revert_index.conflicts?

    tree_id = revert_index.write_tree(rugged)
    return false unless diff_exists?(source_sha, tree_id)

    tree_id
  end

  def check_cherry_pick_content(commit, branch_name)
    source_sha = find_branch(branch_name).dereferenced_target.sha
    args       = [commit.id, source_sha]
    args << 1 if commit.merge_commit?

    cherry_pick_index = rugged.cherrypick_commit(*args)
    return false if cherry_pick_index.conflicts?

    tree_id = cherry_pick_index.write_tree(rugged)
    return false unless diff_exists?(source_sha, tree_id)

    tree_id
  end

  def diff_exists?(sha1, sha2)
    rugged.diff(sha1, sha2).size > 0
  end

  def merged_to_root_ref?(branch_name)
    branch_commit = commit(branch_name)
    root_ref_commit = commit(root_ref)

    if branch_commit
      same_head = branch_commit.id == root_ref_commit.id
      !same_head && is_ancestor?(branch_commit.id, root_ref_commit.id)
    else
      nil
    end
  end

  def merge_base(first_commit_id, second_commit_id)
    first_commit_id = commit(first_commit_id).try(:id) || first_commit_id
    second_commit_id = commit(second_commit_id).try(:id) || second_commit_id
    rugged.merge_base(first_commit_id, second_commit_id)
  rescue Rugged::ReferenceError
    nil
  end

  def is_ancestor?(ancestor_id, descendant_id)
    merge_base(ancestor_id, descendant_id) == ancestor_id
  end

  def empty_repo?
    !exists? || !has_visible_content?
  end

  def search_files_by_content(query, ref)
    return [] if empty_repo? || query.blank?

    offset = 2
    args = %W(#{Gitlab.config.git.bin_path} grep -i -I -n --before-context #{offset} --after-context #{offset} -E -e #{Regexp.escape(query)} #{ref || root_ref})
    Gitlab::Popen.popen(args, path_to_repo).first.scrub.split(/^--$/)
  end

  def search_files_by_name(query, ref)
    return [] if empty_repo? || query.blank?

    args = %W(#{Gitlab.config.git.bin_path} ls-tree --full-tree -r #{ref || root_ref} --name-status | #{Regexp.escape(query)})
    Gitlab::Popen.popen(args, path_to_repo).first.lines.map(&:strip)
  end

  def with_tmp_ref(source_repository, source_branch_name)
    tmp_ref = "refs/tmp/#{SecureRandom.hex}/head"

    fetch_ref(
      source_repository.path_to_repo,
      "#{Gitlab::Git::BRANCH_REF_PREFIX}#{source_branch_name}",
      tmp_ref
    )

    yield

  ensure
    rugged.references.delete(tmp_ref)
  end

  def fetch_ref(source_path, source_ref, target_ref)
    args = %W(#{Gitlab.config.git.bin_path} fetch --no-tags -f #{source_path} #{source_ref}:#{target_ref})
    Gitlab::Popen.popen(args, path_to_repo)
  end

  def create_ref(ref, ref_path)
    fetch_ref(path_to_repo, ref, ref_path)
  end

  def ls_files(ref)
    actual_ref = ref || root_ref
    raw_repository.ls_files(actual_ref)
  end

  def gitattribute(path, name)
    raw_repository.attributes(path)[name]
  end

  def copy_gitattributes(ref)
    actual_ref = ref || root_ref
    begin
      raw_repository.copy_gitattributes(actual_ref)
      true
    rescue Gitlab::Git::Repository::InvalidRef
      false
    end
  end

  # Caches the supplied block both in a cache and in an instance variable.
  #
  # The cache key and instance variable are named the same way as the value of
  # the `key` argument.
  #
  # This method will return `nil` if the corresponding instance variable is also
  # set to `nil`. This ensures we don't keep yielding the block when it returns
  # `nil`.
  #
  # key - The name of the key to cache the data in.
  # fallback - A value to fall back to in the event of a Git error.
  def cache_method_output(key, fallback: nil, &block)
    ivar = cache_instance_variable_name(key)

    if instance_variable_defined?(ivar)
      instance_variable_get(ivar)
    else
      begin
        instance_variable_set(ivar, cache.fetch(key, &block))
      rescue Rugged::ReferenceError, Gitlab::Git::Repository::NoRepository
        # if e.g. HEAD or the entire repository doesn't exist we want to
        # gracefully handle this and not cache anything.
        fallback
      end
    end
  end

  def cache_instance_variable_name(key)
    :"@#{key.to_s.tr('?!', '')}"
  end

  def file_on_head(type)
    if head = tree(:head)
      head.blobs.find do |file|
        Gitlab::FileDetector.type_of(file.name) == type
      end
    end
  end

  protected

  def tree_entry_at(branch_name, path)
    branch_exists?(branch_name) &&
      # tree_entry is private
      raw_repository.send(:tree_entry, commit(branch_name), path)
  end

  def check_tree_entry_for_dir(branch_name, path)
    return unless branch_exists?(branch_name)

    entry = tree_entry_at(branch_name, path)

    return unless entry

    if entry[:type] == :blob
      raise Gitlab::Git::Repository::InvalidBlobName.new(
        "Directory already exists as a file")
    else
      raise Gitlab::Git::Repository::InvalidBlobName.new(
        "Directory already exists")
    end
  end

  private

  def git_action(index, action)
    path = normalize_path(action[:file_path])

    if action[:action] == :move
      previous_path = normalize_path(action[:previous_path])
    end

    case action[:action]
    when :create, :update, :move
      mode =
        case action[:action]
        when :update
          index.get(path)[:mode]
        when :move
          index.get(previous_path)[:mode]
        end
      mode ||= 0o100644

      index.remove(previous_path) if action[:action] == :move

      content = if action[:encoding] == 'base64'
                  Base64.decode64(action[:content])
                else
                  action[:content]
                end

      oid = rugged.write(content, :blob)

      index.add(path: path, oid: oid, mode: mode)
    when :delete
      index.remove(path)
    end
  end

  def normalize_path(path)
    pathname = Gitlab::Git::PathHelper.normalize_path(path)

    if pathname.each_filename.include?('..')
      raise Gitlab::Git::Repository::InvalidBlobName.new('Invalid path')
    end

    pathname.to_s
  end

  def refs_directory_exists?
    return false unless path_with_namespace

    File.exist?(File.join(path_to_repo, 'refs'))
  end

  def cache
    @cache ||= RepositoryCache.new(path_with_namespace, @project.id)
  end

  def tags_sorted_by_committed_date
    tags.sort_by { |tag| tag.dereferenced_target.committed_date }
  end

  def keep_around_ref_name(sha)
    "refs/keep-around/#{sha}"
  end

  def repository_event(event, tags = {})
    Gitlab::Metrics.add_event(event, { path: path_with_namespace }.merge(tags))
  end
end