/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 com.facebook.presto.bytecode.control;

import java.util.List;
import com.facebook.presto.bytecode.BytecodeBlock;
import com.facebook.presto.bytecode.BytecodeNode;
import com.facebook.presto.bytecode.BytecodeVisitor;
import com.facebook.presto.bytecode.MethodGenerationContext;
import com.facebook.presto.bytecode.instruction.LabelNode;
import org.objectweb.asm.MethodVisitor;

import static com.facebook.presto.bytecode.BytecodeUtils.checkState;

public class DoWhileLoop
    implements FlowControl {
    private final String comment;
    private final BytecodeBlock body = new BytecodeBlock();
    private final BytecodeBlock condition = new BytecodeBlock();

    private final LabelNode beginLabel = new LabelNode("begin");
    private final LabelNode continueLabel = new LabelNode("continue");
    private final LabelNode endLabel = new LabelNode("end");

    public DoWhileLoop() {
        this.comment = null;
    }

    public DoWhileLoop(String format, Object... args) {
        this.comment = String.format(format, args);
    }

    @Override
    public String getComment() {
        return comment;
    }

    public LabelNode getContinueLabel() {
        return continueLabel;
    }

    public LabelNode getEndLabel() {
        return endLabel;
    }

    public BytecodeBlock body() {
        return body;
    }

    public DoWhileLoop body(BytecodeNode node) {
        checkState(body.isEmpty(), "body already set");
        body.append(node);
        return this;
    }

    public BytecodeBlock condition() {
        return condition;
    }

    public DoWhileLoop condition(BytecodeNode node) {
        checkState(condition.isEmpty(), "condition already set");
        condition.append(node);
        return this;
    }

    @Override
    public void accept(MethodVisitor visitor, MethodGenerationContext generationContext) {
        checkState(!condition.isEmpty(), "DoWhileLoop does not have a condition set");

        BytecodeBlock block = new BytecodeBlock()
            .visitLabel(beginLabel)
            .append(new BytecodeBlock()
                .setDescription("body")
                .append(body))
            .visitLabel(continueLabel)
            .append(new BytecodeBlock()
                .setDescription("condition")
                .append(condition))
            .ifFalseGoto(endLabel)
            .gotoLabel(beginLabel)
            .visitLabel(endLabel);

        block.accept(visitor, generationContext);
    }

    @Override
    public List<BytecodeNode> getChildNodes() {
        return List.of(body, condition);
    }

    @Override
    public <T> T accept(BytecodeNode parent, BytecodeVisitor<T> visitor) {
        return visitor.visitDoWhile(parent, this);
    }
}
