/*
 * 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.io;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

import net.morilib.lisp.ConsIterator;
import net.morilib.lisp.Datum;
import net.morilib.lisp.Environment;
import net.morilib.lisp.LispBoolean;
import net.morilib.lisp.LispMessage;
import net.morilib.lisp.MultiValues;
import net.morilib.lisp.Subr;
import net.morilib.lisp.r6rs.io.transcd.ILispTranscoder;
import net.morilib.lisp.subr.NoArgs;
import net.morilib.lisp.subr.SubrUtils;
import net.morilib.lisp.uvector.LispU8Vector;
import net.morilib.util.Iterators;

/**
 *
 *
 * @author MORIGUCHI, Yuichiro 2012/01/03
 */
public class OpenBytevectorOutputPort extends Subr {

	/* (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) {
		ConsIterator itr = new ConsIterator(body);
		Datum tr = Iterators.nextIf(itr, LispBoolean.FALSE), r1;
		final ByteArrayOutputStream ous;
		final LispByteArrayBinaryOutputPort bop;
		Subr  r2;

		SubrUtils.checkTerminated(itr, body, mesg);
		if(tr.isTrue() && !(tr instanceof ILispTranscoder)) {
			throw mesg.getError("err.io.require.transcoder", tr);
		} else if(tr.isTrue()) {
			try {
				ous = new ByteArrayOutputStream();
				r1  = (Datum)((ILispTranscoder)tr).newOutput(ous);
				r2  = new NoArgs("extract bytevector") {
	
					@Override
					protected Datum execute(Environment env,
							LispMessage mesg) {
						return new LispU8Vector(ous.toByteArray());
					}
	
				};
				return MultiValues.newValues(r1, r2);
			} catch(IOException e) {
				throw mesg.getError("err.io", e.getMessage());
			}
		} else {
			bop = new LispByteArrayBinaryOutputPort();
			r2  = new NoArgs("extract bytevector") {

				@Override
				protected Datum execute(Environment env,
						LispMessage mesg) {
					return new LispU8Vector(bop.toByteArray());
				}

			};
			return MultiValues.newValues(bop, r2);
		}
	}

}
