module Rid
  # Holds Application config
  #
  class App
    attr_reader :db_url, :db
    attr_accessor :root

    # Initialize app with an options object,
    # which behaves like an open struct.
    #
    # Options are:
    #   root:     specify app root directory
    #   database: set database name
    #
    def initialize(options = OpenStruct.new)
      @root = options.root
      @root ||= find_root
      @root = Pathname.new(@root)

      @db_url = options.database
      @db_url ||= read_db_url
    end

    # Returns an instance of Rid::Database,
    # configured with db_name.
    #
    def db
      return unless @db_url
      @db ||= Rid::Database.new(@db_url)
    end

    # List application documents.
    # Each entry is a filename.
    #
    def documents
      @documents ||= Dir[root.join("*")].
        select { |f| File.directory?(f) && File.file?(File.join(f, '_id')) }.
        map { |f| Rid::Document.new :path => f }
    end

    private

    def read_db_url
      filename = root.join('_database')
      File.read(filename).strip
    rescue Errno::ENOENT
    end

    # from Rails:
    # Returns application root.
    # traverses the directory to top,
    # until it finds app config file.
    def find_root
      cwd = Dir.pwd
      return cwd if File.exists?(File.join(cwd, '_database'))
      Dir.chdir('..') do
        find_root unless cwd == Dir.pwd
      end
    rescue SystemCallError
      # could not chdir, no problem just return
    end
  end
end