require 'securerandom'
require 'batch-loader'

class Repository
  REF_MERGE_REQUEST = 'merge-requests'.freeze
  REF_KEEP_AROUND = 'keep-around'.freeze
  REF_ENVIRONMENTS = 'environments'.freeze

  RESERVED_REFS_NAMES = %W[
    heads
    tags
    replace
    #{REF_ENVIRONMENTS}
    #{REF_KEEP_AROUND}
    #{REF_ENVIRONMENTS}
  ].freeze

  include Gitlab::ShellAdapter
  include RepositoryMirroring

  attr_accessor :full_path, :disk_path, :project

  delegate :ref_name_for_sha, to: :raw_repository

  CreateTreeError = 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 `:commit_count` there's a method called `commit_count` which
  # stores its data in the `commit_count` cache key.
  CACHED_METHODS = %i(size commit_count rendered_readme 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 has_visible_content?).freeze

  # Methods that use cache_method but only memoize the value
  MEMOIZED_CACHED_METHODS = %i(license empty_repo?).freeze

  # 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: :rendered_readme,
    changelog: :changelog,
    license: %i(license_blob license_key license),
    contributing: :contribution_guide,
    gitignore: :gitignore,
    koding: :koding_yml,
    gitlab_ci: :gitlab_ci_yml,
    avatar: :avatar
  }.freeze

  # 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, memoize_only: false)
    original = :"_uncached_#{name}"

    alias_method(original, name)

    define_method(name) do
      cache_method_output(name, fallback: fallback, memoize_only: memoize_only) do
        __send__(original) # rubocop:disable GitlabSecurity/PublicSend
      end
    end
  end

  def initialize(full_path, project, disk_path: nil)
    @full_path = full_path
    @disk_path = disk_path || full_path
    @project = project
  end

  def ==(other)
    @disk_path == other.disk_path
  end

  def raw_repository
    return nil unless full_path

    @raw_repository ||= initialize_raw_repository
  end

  alias_method :raw, :raw_repository

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

  def inspect
    "#<#{self.class.name}:#{@disk_path}>"
  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: Array(path).length == 1,
      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

  # Gitaly migration: https://gitlab.com/gitlab-org/gitaly/issues/384
  def find_commits_by_message(query, ref = nil, path = nil, limit = 1000, offset = 0)
    unless exists? && has_visible_content? && query.present?
      return []
    end

    raw_repository.gitaly_migrate(:commits_by_message) do |is_enabled|
      if is_enabled
        find_commits_by_message_by_gitaly(query, ref, path, limit, offset)
      else
        find_commits_by_message_by_shelling_out(query, ref, path, limit, offset)
      end
    end
  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 = fresh_repo ? initialize_raw_repository : raw_repository

    raw_repo.find_branch(name)
  end

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

  def add_branch(user, branch_name, ref)
    branch = raw_repository.add_branch(branch_name, user: user, target: ref)

    after_create_branch

    branch
  rescue Gitlab::Git::Repository::InvalidRef
    false
  end

  def add_tag(user, tag_name, target, message = nil)
    raw_repository.add_tag(tag_name, user: user, target: target, message: message)
  rescue Gitlab::Git::Repository::InvalidRef
    false
  end

  def rm_branch(user, branch_name)
    before_remove_branch

    raw_repository.rm_branch(branch_name, user: user)

    after_remove_branch
    true
  end

  def rm_tag(user, tag_name)
    before_remove_tag

    raw_repository.rm_tag(tag_name, user: user)

    after_remove_tag
    true
  end

  def ref_names
    branch_names + tag_names
  end

  def branch_exists?(branch_name)
    return false unless raw_repository

    @branch_exists_memo ||= Hash.new do |hash, key|
      hash[key] = raw_repository.branch_exists?(key)
    end

    @branch_exists_memo[branch_name]
  end

  def ref_exists?(ref)
    !!raw_repository&.ref_exists?(ref)
  rescue ArgumentError
    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
      write_ref(keep_around_ref_name(sha), sha)
    rescue Rugged::ReferenceError => ex
      Rails.logger.error "Unable to create #{REF_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 #{REF_KEEP_AROUND} reference for repository #{path}: #{ex}"
    end
  end

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

  def write_ref(ref_path, sha)
    rugged.references.create(ref_path, sha, force: true)
  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 has_visible_content?))
    @local_branches = nil
    @branch_exists_memo = 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) } # rubocop:disable GitlabSecurity/PublicSend
  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}")
        cache.expire(:"commit_count_#{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}")
      cache.expire(:"commit_count_#{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? has_visible_content?))
  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

  # Runs code after removing a tag.
  def after_remove_tag
    expire_tags_cache
  end

  # Runs code after the HEAD of a repository is changed.
  def after_change_head
    expire_method_caches(METHOD_CACHES_FOR_FILE_TYPES.keys)
  end

  # Runs code after a repository has been forked/imported.
  def after_import
    expire_content_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) # rubocop:disable GitlabSecurity/PublicSend
    else
      raw_repository.__send__(m, *args, &block) # rubocop:disable GitlabSecurity/PublicSend
    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), project)
    end
  rescue Gitlab::Git::Repository::NoRepository
    nil
  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

  # Gitaly migration: https://gitlab.com/gitlab-org/gitaly/issues/314
  def exists?
    return false unless full_path

    raw_repository.exists?
  end
  cache_method :exists?

  delegate :empty?, to: :raw_repository
  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 commit_count_for_ref(ref)
    return 0 unless exists?

    begin
      cache.fetch(:"commit_count_#{ref}") { raw_repository.commit_count(ref) }
    rescue Rugged::ReferenceError
      0
    end
  end

  delegate :branch_names, to: :raw_repository
  cache_method :branch_names, fallback: []

  delegate :tag_names, to: :raw_repository
  cache_method :tag_names, fallback: []

  delegate :branch_count, :tag_count, :has_visible_content?, to: :raw_repository
  cache_method :branch_count, fallback: 0
  cache_method :tag_count, fallback: 0
  cache_method :has_visible_content?, fallback: false

  def avatar
    # n+1: https://gitlab.com/gitlab-org/gitlab-ce/issues/38327
    Gitlab::GitalyClient.allow_n_plus_1_calls do
      if tree = file_on_head(:avatar)
        tree.path
      end
    end
  end
  cache_method :avatar

  def readme
    if readme = tree(:head)&.readme
      ReadmeBlob.new(readme, self)
    end
  end

  def rendered_readme
    MarkupHelper.markup_unsafe(readme.name, readme.data, project: project) if readme
  end
  cache_method :rendered_readme

  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 license
    return unless license_key

    Licensee::License.new(license_key)
  end
  cache_method :license, memoize_only: true

  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

  # TODO: Ruby may already offer a function like this
  # otherwise move it somewhere else, ie a collection
  # utils class
  def hash_by_kv(array, key, value)
    array.inject(Hash.new) do |memo, item|
      k = item[key]
      v = item[value]

      array = memo[k]
      if array
        array.push(v)
      else
        memo[k] = [v]
      end

      memo
    end
  end

  def last_commit_for_path_lazy(sha, path)
    BatchLoader.for({ sha: sha, path: path }).batch do |items, loader|
      paths_by_sha = hash_by_kv(items, :sha, :path)
      # Bulk fetch the paths for each SHA
      last_commits_for_items = Hash.new
      paths_by_sha.each do |for_sha, paths|
        last_commits_for_sha = raw_repository.last_commit_for_paths(for_sha, paths)

        last_commits_for_sha.each do |result_path, last_commit|
          last_commits_for_items[{ sha: for_sha, path: result_path }] = last_commit
        end
      end

      # Present the results to the loader
      items.each do |item|
        last_commit = last_commits_for_items[item]
        loader.call(item, last_commit)
      end
    end
  end

  def last_commit_for_path(sha, path)
    raw_repository.gitaly_migrate(:last_commit_for_path) do |is_enabled|
      if is_enabled
        last_commit_for_path_by_gitaly(sha, path)
      else
        last_commit_for_path_by_rugged(sha, path)
      end
    end
  end

  def last_commit_id_for_path(sha, path)
    key = path.blank? ? "last_commit_id_for_path:#{sha}" : "last_commit_id_for_path:#{sha}:#{Digest::SHA1.hexdigest(path)}"

    cache.fetch(key) do
      raw_repository.gitaly_migrate(:last_commit_for_path) do |is_enabled|
        if is_enabled
          last_commit_for_path_by_gitaly(sha, path).id
        else
          last_commit_id_for_path_by_shelling_out(sha, path)
        end
      end
    end
  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

  def branches_sorted_by(value)
    raw_repository.local_branches(sort_by: value)
  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 refs_contains_sha(ref_type, sha)
    args = %W(#{ref_type} --contains #{sha})
    names = run_git(args).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

  def create_dir(user, path, **options)
    options[:user] = user
    options[:actions] = [{ action: :create_dir, file_path: path }]

    multi_action(**options)
  end

  def create_file(user, path, content, **options)
    options[:user] = user
    options[:actions] = [{ action: :create, file_path: path, content: content }]

    multi_action(**options)
  end

  def update_file(user, path, content, **options)
    previous_path = options.delete(:previous_path)
    action = previous_path && previous_path != path ? :move : :update

    options[:user] = user
    options[:actions] = [{ action: action, file_path: path, previous_path: previous_path, content: content }]

    multi_action(**options)
  end

  def delete_file(user, path, **options)
    options[:user] = user
    options[:actions] = [{ action: :delete, file_path: path }]

    multi_action(**options)
  end

  def with_cache_hooks
    result = yield

    return unless result

    after_create if result.repo_created?
    after_create_branch if result.branch_created?

    result.newrev
  end

  def with_branch(user, *args)
    with_cache_hooks do
      Gitlab::Git::OperationService.new(user, raw_repository).with_branch(*args) do |start_commit|
        yield start_commit
      end
    end
  end

  # rubocop:disable Metrics/ParameterLists
  def multi_action(
    user:, branch_name:, message:, actions:,
    author_email: nil, author_name: nil,
    start_branch_name: nil, start_project: project)

    with_branch(
      user,
      branch_name,
      start_branch_name: start_branch_name,
      start_repository: start_project.repository.raw_repository) do |start_commit|

      index = Gitlab::Git::Index.new(raw_repository)

      if start_commit
        index.read_tree(start_commit.rugged_commit.tree)
        parents = [start_commit.sha]
      else
        parents = []
      end

      actions.each do |options|
        index.public_send(options.delete(:action), options) # rubocop:disable GitlabSecurity/PublicSend
      end

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

      create_commit(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 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, source_sha, merge_request, message)
    with_cache_hooks do
      raw_repository.merge(user, source_sha, merge_request.target_branch, message) do |commit_id|
        merge_request.update(in_progress_merge_commit_sha: commit_id)
        nil # Return value does not matter.
      end
    end
  end

  def ff_merge(user, source, target_branch, merge_request: nil)
    our_commit = rugged.branches[target_branch].target
    their_commit =
      if source.is_a?(Gitlab::Git::Commit)
        source.raw_commit
      else
        rugged.lookup(source)
      end

    raise 'Invalid merge target' if our_commit.nil?
    raise 'Invalid merge source' if their_commit.nil?

    with_branch(user, target_branch) do |start_commit|
      merge_request&.update(in_progress_merge_commit_sha: their_commit.oid)

      their_commit.oid
    end
  end

  def revert(
    user, commit, branch_name, message,
    start_branch_name: nil, start_project: project)

    with_cache_hooks do
      raw_repository.revert(
        user: user,
        commit: commit.raw,
        branch_name: branch_name,
        message: message,
        start_branch_name: start_branch_name,
        start_repository: start_project.repository.raw_repository
      )
    end
  end

  def cherry_pick(
    user, commit, branch_name, message,
    start_branch_name: nil, start_project: project)

    with_cache_hooks do
      raw_repository.cherry_pick(
        user: user,
        commit: commit.raw,
        branch_name: branch_name,
        message: message,
        start_branch_name: start_branch_name,
        start_repository: start_project.repository.raw_repository
      )
    end
  end

  def resolve_conflicts(user, branch_name, params)
    with_branch(user, branch_name) do
      committer = user_to_committer(user)

      create_commit(params.merge(author: committer, committer: committer))
    end
  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 && 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 ancestor?(ancestor_id, descendant_id)
    return false if ancestor_id.nil? || descendant_id.nil?

    Gitlab::GitalyClient.migrate(:is_ancestor) do |is_enabled|
      if is_enabled
        raw_repository.ancestor?(ancestor_id, descendant_id)
      else
        rugged_is_ancestor?(ancestor_id, descendant_id)
      end
    end
  end

  def empty_repo?
    !exists? || !has_visible_content?
  end
  cache_method :empty_repo?, memoize_only: true

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

    offset = 2
    args = %W(grep -i -I -n --before-context #{offset} --after-context #{offset} -E -e #{Regexp.escape(query)} #{ref || root_ref})

    run_git(args).first.scrub.split(/^--$/)
  end

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

    args = %W(ls-tree --full-tree -r #{ref || root_ref} --name-status | #{Regexp.escape(query)})

    run_git(args).first.lines.map(&:strip)
  end

  def add_remote(name, url)
    raw_repository.remote_add(name, url)
  rescue Rugged::ConfigError
    raw_repository.remote_update(name, url: url)
  end

  def remove_remote(name)
    raw_repository.remote_delete(name)
    true
  rescue Rugged::ConfigError
    false
  end

  def fetch_remote(remote, forced: false, no_tags: false)
    gitlab_shell.fetch_remote(raw_repository, remote, forced: forced, no_tags: no_tags)
  end

  def fetch_source_branch(source_repository, source_branch, local_ref)
    raw_repository.fetch_source_branch(source_repository.raw_repository, source_branch, local_ref)
  end

  def compare_source_branch(target_branch_name, source_repository, source_branch_name, straight:)
    raw_repository.compare_source_branch(target_branch_name, source_repository.raw_repository, source_branch_name, straight: straight)
  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, memoize_only: false, &block)
    ivar = cache_instance_variable_name(key)

    if instance_variable_defined?(ivar)
      instance_variable_get(ivar)
    else
      begin
        value =
          if memoize_only
            yield
          else
            cache.fetch(key, &block)
          end
        instance_variable_set(ivar, value)
      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 |blob|
        Gitlab::FileDetector.type_of(blob.path) == type
      end
    end
  end

  def route_map_for(sha)
    blob_data_at(sha, '.gitlab/route-map.yml')
  end

  def gitlab_ci_yml_for(sha, path = '.gitlab-ci.yml')
    blob_data_at(sha, path)
  end

  private

  def blob_data_at(sha, path)
    blob = blob_at(sha, path)
    return unless blob

    blob.load_all_data!
    blob.data
  end

  def cache
    # TODO: should we use UUIDs here? We could move repositories without clearing this cache
    @cache ||= RepositoryCache.new(full_path, @project.id)
  end

  def tags_sorted_by_committed_date
    tags.sort_by do |tag|
      # Annotated tags can point to any object (e.g. a blob), but generally
      # tags point to a commit. If we don't have a commit, then just default
      # to putting the tag at the end of the list.
      target = tag.dereferenced_target

      if target
        target.committed_date
      else
        Time.now
      end
    end
  end

  def keep_around_ref_name(sha)
    "refs/#{REF_KEEP_AROUND}/#{sha}"
  end

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

  def last_commit_for_path_by_gitaly(sha, path)
    c = raw_repository.gitaly_commit_client.last_commit_for_path(sha, path)
    commit(c)
  end

  def last_commit_for_path_by_rugged(sha, path)
    sha = last_commit_id_for_path_by_shelling_out(sha, path)
    commit(sha)
  end

  def last_commit_id_for_path_by_shelling_out(sha, path)
    args = %W(rev-list --max-count=1 #{sha} -- #{path})
    run_git(args).first.strip
  end

  def repository_storage_path
    @project.repository_storage_path
  end

  def initialize_raw_repository
    Gitlab::Git::Repository.new(project.repository_storage, disk_path + '.git', Gitlab::GlRepository.gl_repository(project, false))
  end

  def find_commits_by_message_by_shelling_out(query, ref, path, limit, offset)
    ref ||= root_ref

    args = %W(
      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 = run_git(args).first.lines

    git_log_results.map { |c| commit(c.chomp) }.compact
  end

  def find_commits_by_message_by_gitaly(query, ref, path, limit, offset)
    raw_repository
      .gitaly_commit_client
      .commits_by_message(query, revision: ref, path: path, limit: limit, offset: offset)
      .map { |c| commit(c) }
  end
end