require 'oauth2'

module YammerOAuth2
  class Client < OAuth2::Client

    DEFAULT_URL = 'https://www.yammer.com'

    def initialize(client_id, client_secret, opts={})
      site_url = opts.delete(:site_url) || DEFAULT_URL
      super(site_url, client_id, client_secret, opts)
      @token_path     = '/oauth2/token'
      @authorize_path = '/dialog/oauth/authorize'
      yield self if block_given?
      self
    end

    # Generates the Yammer URL that the user will be redirected to in order to
    # authorize your application
    #
    # @see https://developer.yammer.com/api/oauth2.html#client-side
    #
    # @opts [Hash] additional parameters to be include in URL eg. scope, state, etc
    #
    # client = YammerClient.new(config)
    # client.clientside_authorization_url({
    #      :redirect_uri => 'https://localhost/oauth/cb',
    #    })
    # >> https://www.yammer.com/dialog/oauth/?client_id={client_id}&
    #    redirect_uri=http%3A%2F%2Flocalhost%2Foauth%2Fcb&response_type=token
    #
    def clientside_authorization_url(opts={})
      implicit.token_url(opts)
    end

    # Generates the Yammer URL that the user will be redirected to in order to
    # authorize your application
    #
    # @see https://developer.yammer.com/api/oauth2.html#server-side
    #
    # @opts [Hash] additional parameters to be include in URL eg. scope, state, etc
    #
    # >> client = YammerClient.new(config)
    # >> client.webserver_authorization_url({
    #      :redirect_uri => 'https://localhost/oauth/cb',
    #    })
    # >> https://www.yammer.com/dialog/oauth/?client_id={client_id}&
    #    redirect_uri=http%3A%2F%2Flocalhost%2Foauth%2Fcb&response_type=code
    #
    def webserver_authorization_url(opts={})
      opts[:scope] = normalize_scope(opts[:scope]) if opts[:scope]
      authorization_code.authorization_url(opts)
    end

    # Generates the Yammer URL that the user will be redirected to in order to
    # authorize your application
    #
    # @see https://developer.yammer.com/api/oauth2.html#server-side
    #
    # @opts [Hash] additional parameters to be include in URL eg. scope, state, etc
    #
    # >> client = YammerClient.new(config)
    # >> client.webserver_authorization_url({
    #      :client_secret => @client_secret
    #      :code => 'G3Y6jU3a',
    #      :redirect_uri => 'https://localhost/oauth/cb',
    #    })
    # >> https://www.yammer.com/oauth2/access_token?client_id={client_id}&
    #    redirect_uri=http%3A%2F%2Flocalhost%2Foauth%2Fcb&client_secret={client_secret}&
    #    grant_type=authorization_code&code=aXW2c6bYz
    #
    def webserver_token_url(opts={})
      opts[:scope] = normalize_scope(opts[:scope]) if opts[:scope]
      opts[:client_secret] = @client_secret
      authorization_code.token_path(opts)
    end

    # Makes a request to Yammer server that will swap your authorization code for an access
    # token
    #
    # @see https://developer.yammer.com/api/oauth2.html#server-side
    #
    # @opts [Hash] must include authorization code and redirect uri in additon to others
    #
    # >> client = YammerClient.new(config)
    # >> client.exchange_auth_code_for_token({
    #      :redirect_uri => 'https://localhost:3000/oauth/v2/callback',
    #      :code => 'G3Y6jU3a',
    #    })
    #
    # POST /oauth2/access_token HTTP/1.1
    # Host: www.yammer.com
    # Content-Type: application/x-www-form-urlencoded

    #  client_id={client_id}&code=G3Y6jU3a&grant_type=authorization_code&
    #  redirect_uri=http%3A%2F%2Flocalhost%2Foauth%2Fcb&client_secret={client_secret}

    def exchange_auth_code_for_token(opts={})
      unless (opts[:params] && opts[:params][:code])
        raise ArgumentError.new("You must include an authorization code as a parameter")
      end
      opts[:authenticate] ||= :body
      code = opts[:params].delete(:code)
      authorization_code.get_token(code, opts)
    end
  end
end