module SubmoduleHelper
  extend self

  VALID_SUBMODULE_PROTOCOLS = %w[http https git ssh].freeze

  # links to files listing for submodule if submodule is a project on this server
  def submodule_links(submodule_item, ref = nil, repository = @repository)
    url = repository.submodule_url_for(ref, submodule_item.path)

    if url == '.' || url == './'
      url = File.join(Gitlab.config.gitlab.url, @project.full_path)
    end

    if url =~ %r{([^/:]+)/([^/]+(?:\.git)?)\Z}
      namespace, project = $1, $2
      gitlab_hosts = [Gitlab.config.gitlab.url,
                      Gitlab.config.gitlab_shell.ssh_path_prefix]

      gitlab_hosts.each do |host|
        if url.start_with?(host)
          namespace, _, project = url.sub(host, '').rpartition('/')
          break
        end
      end

      namespace.sub!(%r{\A/}, '')
      project.rstrip!
      project.sub!(/\.git\z/, '')

      if self_url?(url, namespace, project)
        [namespace_project_path(namespace, project),
         namespace_project_tree_path(namespace, project, submodule_item.id)]
      elsif relative_self_url?(url)
        relative_self_links(url, submodule_item.id)
      elsif github_dot_com_url?(url)
        standard_links('github.com', namespace, project, submodule_item.id)
      elsif gitlab_dot_com_url?(url)
        standard_links('gitlab.com', namespace, project, submodule_item.id)
      else
        [sanitize_submodule_url(url), nil]
      end
    else
      [sanitize_submodule_url(url), nil]
    end
  end

  protected

  def github_dot_com_url?(url)
    url =~ %r{github\.com[/:][^/]+/[^/]+\Z}
  end

  def gitlab_dot_com_url?(url)
    url =~ %r{gitlab\.com[/:][^/]+/[^/]+\Z}
  end

  def self_url?(url, namespace, project)
    url_no_dotgit = url.chomp('.git')
    return true if url_no_dotgit == [Gitlab.config.gitlab.url, '/', namespace, '/',
                                     project].join('')

    url_with_dotgit = url_no_dotgit + '.git'
    url_with_dotgit == Gitlab::Shell.new.url_to_repo([namespace, '/', project].join(''))
  end

  def relative_self_url?(url)
    # (./)?(../repo.git) || (./)?(../../project/repo.git) )
    url =~ %r{\A((\./)?(\.\./))(?!(\.\.)|(.*/)).*(\.git)?\z} || url =~ %r{\A((\./)?(\.\./){2})(?!(\.\.))([^/]*)/(?!(\.\.)|(.*/)).*(\.git)?\z}
  end

  def standard_links(host, namespace, project, commit)
    base = ['https://', host, '/', namespace, '/', project].join('')
    [base, [base, '/tree/', commit].join('')]
  end

  def relative_self_links(url, commit)
    url.rstrip!
    # Map relative links to a namespace and project
    # For example:
    # ../bar.git -> same namespace, repo bar
    # ../foo/bar.git -> namespace foo, repo bar
    # ../../foo/bar/baz.git -> namespace bar, repo baz
    components = url.split('/')
    base = components.pop.gsub(/.git$/, '')
    namespace = components.pop.gsub(/^\.\.$/, '')

    if namespace.empty?
      namespace = @project.namespace.full_path
    end

    begin
      [
        namespace_project_path(namespace, base),
        namespace_project_tree_path(namespace, base, commit)
      ]
    rescue ActionController::UrlGenerationError
      [nil, nil]
    end
  end

  def sanitize_submodule_url(url)
    uri = URI.parse(url)

    if uri.scheme.in?(VALID_SUBMODULE_PROTOCOLS)
      uri.to_s
    else
      nil
    end
  rescue URI::InvalidURIError
    nil
  end
end