class Embulk::JavaPlugin

def self.classloader(dir)
  jars = Dir["#{dir}/**/*.jar"]
  urls = jars.map {|jar| java.io.File.new(File.expand_path(jar)).toURI.toURL }
  begin
    expected_temporary_variable_name = Java::org.embulk.jruby.JRubyPluginSource::PLUGIN_CLASS_LOADER_FACTORY_VARIABLE_NAME
  rescue => e
    raise PluginLoadError.new "Java's org.embulk.jruby.JRubyPluginSource does not define PLUGIN_CLASS_LOADER_FACTORY_VARIABLE_NAME unexpectedly."
  end
  if expected_temporary_variable_name != "$temporary_internal_plugin_class_loader_factory__"
    raise PluginLoadError.new "Java's org.embulk.jruby.JRubyPluginSource does not define PLUGIN_CLASS_LOADER_FACTORY_VARIABLE_NAME correctly."
  end
  factory = $temporary_internal_plugin_class_loader_factory__
  factory.create(urls, JRuby.runtime.getJRubyClassLoader())
end

def self.new_java
  Java::org.embulk.plugin.PluginManager.newPluginInstance(plugin_java_class, Embulk::Java::EmbulkSystemProperties)
end

def self.plugin_java_class
  self::PLUGIN_JAVA_CLASS
end

def self.register_decoder(name, class_fqdn, jar_dir)
  java_class = classloader(jar_dir).loadClass(class_fqdn)
  Plugin.register_java_decoder(name, java_class)
end

def self.register_encoder(name, class_fqdn, jar_dir)
  java_class = classloader(jar_dir).loadClass(class_fqdn)
  Plugin.register_java_encoder(name, java_class)
end

def self.register_executor(name, class_fqdn, jar_dir)
  java_class = classloader(jar_dir).loadClass(class_fqdn)
  Plugin.register_java_executor(name, java_class)
end

def self.register_filter(name, class_fqdn, jar_dir)
  java_class = classloader(jar_dir).loadClass(class_fqdn)
  Plugin.register_java_filter(name, java_class)
end

def self.register_formatter(name, class_fqdn, jar_dir)
  java_class = classloader(jar_dir).loadClass(class_fqdn)
  Plugin.register_java_formatter(name, java_class)
end

def self.register_guess(name, class_fqdn, jar_dir)
  java_class = classloader(jar_dir).loadClass(class_fqdn)
  Plugin.register_java_guess(name, java_class)
end

def self.register_input(name, class_fqdn, jar_dir)
  java_class = classloader(jar_dir).loadClass(class_fqdn)  # TODO handle class not found error
  Plugin.register_java_input(name, java_class)
end

def self.register_output(name, class_fqdn, jar_dir)
  java_class = classloader(jar_dir).loadClass(class_fqdn)
  Plugin.register_java_output(name, java_class)
end

def self.register_parser(name, class_fqdn, jar_dir)
  java_class = classloader(jar_dir).loadClass(class_fqdn)
  Plugin.register_java_parser(name, java_class)
end

def self.ruby_adapter_class(java_class, ruby_base_class, ruby_module)
  Class.new(ruby_base_class) do
    const_set(:PLUGIN_JAVA_CLASS, java_class)
    include ruby_module
    extend ruby_module::ClassMethods
    unless method_defined?(:plugin_java_object)
      def plugin_java_object
        @plugin_java_object ||= self.class.new_java
      end
    end
    unless (class<<self;self;end).method_defined?(:plugin_java_class)
      def self.plugin_java_class
        self::PLUGIN_JAVA_CLASS
      end
    end
    # TODO ruby_base_class already implements new_java. So
    #      this line returns always true:
    #unless (class<<self;self;end).method_defined?(:new_java)
    #      but this line could return false unexpectedly if
    #      ruby_module::ClassMethods includes other modules.
    unless ruby_module::ClassMethods.method_defined?(:new_java)
      def self.new_java
        Java::org.embulk.plugin.PluginManager.newPluginInstance(plugin_java_class, Embulk::Java::EmbulkSystemProperties)
      end
    end
  end
end

def plugin_java_object
  @plugin_java_object ||= self.class.new_java
end