class GollumWiki

  MARKUPS = {
    "Markdown" => :markdown,
    "RDoc"     => :rdoc
  }

  class CouldNotCreateWikiError < StandardError; end

  # Returns a string describing what went wrong after
  # an operation fails.
  attr_reader :error_message

  def initialize(project, user = nil)
    @project = project
    @user = user
  end

  def path
    @project.path + '.wiki'
  end

  def path_with_namespace
    @project.path_with_namespace + ".wiki"
  end

  def url_to_repo
    gitlab_shell.url_to_repo(path_with_namespace)
  end

  def ssh_url_to_repo
    url_to_repo
  end

  def http_url_to_repo
    [Gitlab.config.gitlab.url, "/", path_with_namespace, ".git"].join('')
  end

  # Returns the Gollum::Wiki object.
  def wiki
    @wiki ||= begin
      Gollum::Wiki.new(path_to_repo)
    rescue Grit::NoSuchPathError
      create_repo!
    end
  end

  def empty?
    pages.empty?
  end

  # Returns an Array of Gitlab WikiPage instances or an
  # empty Array if this Wiki has no pages.
  def pages
    wiki.pages.map { |page| WikiPage.new(self, page, true) }
  end

  # Finds a page within the repository based on a tile
  # or slug.
  #
  # title - The human readable or parameterized title of
  #         the page.
  #
  # Returns an initialized WikiPage instance or nil
  def find_page(title, version = nil)
    if page = wiki.page(title, version)
      WikiPage.new(self, page, true)
    else
      nil
    end
  end

  def create_page(title, content, format = :markdown, message = nil)
    commit = commit_details(:created, message, title)

    wiki.write_page(title, format, content, commit)
  rescue Gollum::DuplicatePageError => e
    @error_message = "Duplicate page: #{e.message}"
    return false
  end

  def update_page(page, content, format = :markdown, message = nil)
    commit = commit_details(:updated, message, page.title)

    wiki.update_page(page, page.name, format, content, commit)
  end

  def delete_page(page, message = nil)
    wiki.delete_page(page, commit_details(:deleted, message, page.title))
  end

  private

  def create_repo!
    if init_repo(path_with_namespace)
      Gollum::Wiki.new(path_to_repo)
    else
      raise CouldNotCreateWikiError
    end
  end

  def init_repo(path_with_namespace)
    gitlab_shell.add_repository(path_with_namespace)
  end

  def commit_details(action, message = nil, title = nil)
    commit_message = message || default_message(action, title)

    {email: @user.email, name: @user.name, message: commit_message}
  end

  def default_message(action, title)
    "#{@user.username} #{action} page: #{title}"
  end

  def gitlab_shell
    @gitlab_shell ||= Gitlab::Shell.new
  end

  def path_to_repo
    @path_to_repo ||= File.join(Gitlab.config.gitlab_shell.repos_path, "#{path_with_namespace}.git")
  end
end