/*
 * Copyright 2009-2010 Yuichiro Moriguchi
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.morilib.lisp.r6rs.record;

import net.morilib.lisp.Datum;
import net.morilib.lisp.Environment;
import net.morilib.lisp.LispMessage;
import net.morilib.lisp.LispUtils;
import net.morilib.lisp.Procedure;
import net.morilib.lisp.Scheme;
import net.morilib.lisp.Subr;
import net.morilib.lisp.subr.SubrUtils;
import net.morilib.lisp.subr.UnaryArgs;

/**
 *
 *
 * @author MORIGUCHI, Yuichiro 2011/09/13
 */
public class DefaultProtocol extends UnaryArgs {

	//
	private static class Nest1 extends Subr {

		//
		private RecordTypeDescriptor rtd;
		private Procedure prtcl;

		//
		private Nest1(RecordTypeDescriptor rtd, Procedure prtcl) {
			this.rtd   = rtd;
			this.prtcl = prtcl;
		}

		/* (non-Javadoc)
		 * @see net.morilib.lisp.Subr#eval(net.morilib.lisp.Datum, net.morilib.lisp.Environment, net.morilib.lisp.LispMessage)
		 */
		@Override
		public Datum eval(Datum body, Environment env,
				LispMessage mesg) {
			int   siz = rtd.getAllFieldNames().size();
			int   sz2 = rtd.getInheritedFieldNames().size();
			Datum d1  = SubrUtils.cndr(body, siz, mesg);
			Datum p;

			if(d1 == null || !d1.isNil()) {
				throw mesg.getError("err.argument", body);
			} else if(rtd.getParent() != null) {
				p = Scheme.call(prtcl, env, mesg,
						LispUtils.take(body, sz2));
				if(!(p instanceof Procedure)) {
					throw mesg.getError("err.require.procedure");
				}
				return Scheme.call(p, env, mesg,
						SubrUtils.cndr(body, sz2, mesg));
			} else {
				return Scheme.call(prtcl, env, mesg, body);
			}
		}

	}

	//
	private RecordTypeDescriptor rtd;

	/**
	 * 
	 * @param rtd
	 */
	public DefaultProtocol(RecordTypeDescriptor rtd) {
		this.rtd = rtd;
	}

	/* (non-Javadoc)
	 * @see net.morilib.lisp.subr.UnaryArgs#execute(net.morilib.lisp.Datum, net.morilib.lisp.Environment, net.morilib.lisp.LispMessage)
	 */
	@Override
	protected Datum execute(Datum c1a, Environment env,
			LispMessage mesg) {
		if(c1a instanceof Procedure) {
			return new Nest1(rtd, (Procedure)c1a);
		} else {
			throw mesg.getError("err.require.procedure", c1a);
		}
	}

}
