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require 'digest/sha1'

require 'openid/store/interface'

module OpenIdAuthentication

  class MemCacheStore < OpenID::Store::Interface

    def initialize(*addresses)

      @connection = ActiveSupport::Cache::MemCacheStore.new(addresses)

    end

    def store_association(server_url, assoc)

      server_key = association_server_key(server_url)

      assoc_key = association_key(server_url, assoc.handle)

      assocs = @connection.read(server_key) || {}

      assocs[assoc.issued] = assoc_key

      @connection.write(server_key, assocs)

      @connection.write(assoc_key, assoc, :expires_in => assoc.lifetime)

    end

    def get_association(server_url, handle = nil)

      if handle

        @connection.read(association_key(server_url, handle))

      else

        server_key = association_server_key(server_url)

        assocs = @connection.read(server_key)

        return if assocs.nil?

        last_key = assocs[assocs.keys.sort.last]

        @connection.read(last_key)

      end

    end

    def remove_association(server_url, handle)

      server_key = association_server_key(server_url)

      assoc_key = association_key(server_url, handle)

      assocs = @connection.read(server_key)

      return false unless assocs && assocs.has_value?(assoc_key)

      assocs = assocs.delete_if { |key, value| value == assoc_key }

      @connection.write(server_key, assocs)

      @connection.delete(assoc_key)

      return true

    end

    def use_nonce(server_url, timestamp, salt)

      return false if @connection.read(nonce_key(server_url, salt))

      return false if (timestamp - Time.now.to_i).abs > OpenID::Nonce.skew

      @connection.write(nonce_key(server_url, salt), timestamp, :expires_in => OpenID::Nonce.skew)

      return true

    end

    private

      def association_key(server_url, handle = nil)

        "openid_association_#{digest(server_url)}_#{digest(handle)}"

      end

      def association_server_key(server_url)

        "openid_association_server_#{digest(server_url)}"

      end

      def nonce_key(server_url, salt)

        "openid_nonce_#{digest(server_url)}_#{digest(salt)}"

      end

      def digest(text)

        Digest::SHA1.hexdigest(text)

      end

  end

end