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package org.jruby.ext;

import org.jruby.Ruby;
import org.jruby.RubyClass;
import org.jruby.RubyMethod;
import org.jruby.RubyModule;
import org.jruby.RubyObject;
import org.jruby.anno.JRubyMethod;
import org.jruby.internal.runtime.methods.DynamicMethod;
import org.jruby.internal.runtime.methods.JavaMethod.JavaMethodNBlock;
import org.jruby.runtime.Block;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.Visibility;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.runtime.load.Library;

public class DelegateLibrary implements Library{
    public void load(Ruby runtime, boolean wrap) {
        RubyClass delegateClass = runtime.defineClass("Delegator", runtime.getObject(), runtime.getObject().getAllocator());
        delegateClass.defineAnnotatedMethods(Delegator.class);

        delegateClass.undefineMethod("==");
    }

    public static class Delegator {
        @JRubyMethod(visibility = Visibility.PRIVATE)
        public static IRubyObject initialize(ThreadContext context, IRubyObject self, IRubyObject obj) {
            return context.getRuntime().getNil();
        }

        @JRubyMethod(rest = true)
        public static IRubyObject method_missing(ThreadContext context, IRubyObject self, IRubyObject[] args, Block block) {
            IRubyObject[] newArgs;
            if (args.length == 0) {
                newArgs = IRubyObject.NULL_ARRAY;
            } else {
                newArgs = new IRubyObject[args.length - 1];
                System.arraycopy(args, 1, newArgs, 0, newArgs.length);
            }
            String methodName = args[0].asJavaString();
            IRubyObject object = self.callMethod(context, "__getobj__");
            DynamicMethod method = ((RubyObject)object).getMetaClass().searchMethod(methodName);
            if (method.getVisibility().isPrivate()) {
                throw context.getRuntime().newNoMethodError("method `" + methodName + "' is private", methodName, context.getRuntime().getNil());
            }
            return method.call(context, object, object.getMetaClass(), methodName, newArgs, block);
        }

        @JRubyMethod(rest = true)
        public static IRubyObject send(ThreadContext context, IRubyObject self, IRubyObject[] args, Block block) {
            return ((RubyObject)self.callMethod(context, "__getobj__")).send(context, args, block);
        }

        @JRubyMethod
        public static IRubyObject method(ThreadContext context, IRubyObject self, IRubyObject name) {
            final String methodName = name.asJavaString();
            final IRubyObject object = self.callMethod(context, "__getobj__");

            // try to get method from self's metaclass
            if (!self.getMetaClass().searchMethod(methodName).isUndefined()) {
                return (RubyMethod)((RubyObject)self).method(name);
            }

            // try to get method from delegated object
            final RubyMethod method = (RubyMethod)((RubyObject)object).method(name);
            return RubyMethod.newMethod(self.getMetaClass(), methodName, self.getMetaClass(), methodName, new JavaMethodNBlock(self.getMetaClass(), Visibility.PUBLIC) {
                @Override
                public IRubyObject call(ThreadContext context, IRubyObject self, RubyModule clazz, String name, IRubyObject[] args, Block block) {
                    if (self.callMethod(context, "__getobj__") != object) {
                        throw context.getRuntime().newNameError("object changed", "object changed");
                    }
                    return method.call(context, args, block);
                }
            }, self);
        }

        @JRubyMethod(name = "respond_to?")
        public static IRubyObject repond_to_p(ThreadContext context, IRubyObject self, IRubyObject name) {
            if (self.getMetaClass().isMethodBound(name.asJavaString(), false)) return context.getRuntime().getTrue();
            return ((RubyObject)self.callMethod(context, "__getobj__")).callMethod(context, "respond_to?", name);
        }

        @JRubyMethod
        public static IRubyObject __getobj__(ThreadContext context, IRubyObject self) {
            throw context.getRuntime().newNotImplementedError("need to define `__getobj__'");
        }

        @JRubyMethod
        public static IRubyObject marshal_dump(ThreadContext context, IRubyObject self) {
            return ((RubyObject)self.callMethod(context, "__getobj__"));
        }

        @JRubyMethod
        public static IRubyObject marshal_load(ThreadContext context, IRubyObject self, IRubyObject obj) {
            return self.callMethod(context, "__setobj__", obj);
        }
    }
}