module VkontakteApi
  # A class representing a connection to VK. It holds the access token.
  class Client
    include Resolver
    
    # Access rights and their respective number representation.
    SCOPE = {
      :notify         => 1,
      :friends        => 2,
      :photos         => 4,
      :audio          => 8,
      :video          => 16,
      :offers         => 32,
      :questions      => 64,
      :pages          => 128,
      :status         => 1024,
      :notes          => 2048,
      :messages       => 4096,
      :wall           => 8192,
      :ads            => 32768,
      :docs           => 131072,
      :groups         => 262144,
      :notifications  => 524288,
      :stats          => 1048576
    }
    
    # An access token needed by authorized requests.
    # @return [String]
    attr_reader :token
    # Current user id.
    # @return [Integer]
    attr_reader :user_id
    # Token expiration time
    # @return [Time]
    attr_reader :expires_at
    
    # A new API client.
    # If given an `OAuth2::AccessToken` instance, it extracts and keeps
    # the token string, the user id and the expiration time;
    # otherwise it just stores the given token.
    # @param [String, OAuth2::AccessToken] token An access token.
    def initialize(token = nil)
      if token.respond_to?(:token) && token.respond_to?(:params)
        # token is an OAuth2::AccessToken
        @token      = token.token
        @user_id    = token.params['user_id']
        @expires_at = Time.at(token.expires_at) unless token.expires_at.nil?
      else
        # token is a String or nil
        @token = token
      end
    end
    
    # Is a `VkontakteApi::Client` instance authorized.
    def authorized?
      !@token.nil?
    end
    
    # Did the token already expire.
    def expired?
      @expires_at && @expires_at < Time.now
    end
    
    # Access rights of this token.
    # @return [Array] An array of symbols representing the access rights.
    def scope
      SCOPE.reject do |access_scope, mask|
        (settings & mask).zero?
      end.keys
    end
    
  private
    def settings
      @settings ||= self.get_user_settings
    end
  end
end