/*
 *  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 org.codehaus.groovy.transform;

import groovy.transform.ToString;
import org.codehaus.groovy.ast.ASTNode;
import org.codehaus.groovy.ast.AnnotatedNode;
import org.codehaus.groovy.ast.AnnotationNode;
import org.codehaus.groovy.ast.ClassHelper;
import org.codehaus.groovy.ast.ClassNode;
import org.codehaus.groovy.ast.Parameter;
import org.codehaus.groovy.control.CompilePhase;
import org.codehaus.groovy.control.SourceUnit;

import static org.codehaus.groovy.ast.ClassHelper.make;
import static org.codehaus.groovy.ast.tools.GeneralUtils.constX;
import static org.codehaus.groovy.ast.tools.GeneralUtils.returnS;
import static org.codehaus.groovy.transform.StubberSupport.addStubMethod;
import static org.objectweb.asm.Opcodes.ACC_PUBLIC;

/**
 * Joint-compilation stubber for {@link ToString}. Adds a placeholder
 * {@code toString()} so the @ToString-generated override is visible in the
 * stub even though Object already provides one. Useful for Java code that
 * does {@code super.toString()} chaining or for tooling that examines
 * declared (rather than inherited) methods.
 *
 * <p>The placeholder body returns an empty string. The full
 * {@link ToStringASTTransformation} at CANONICALIZATION recognises the
 * stubber tag and replaces the body with the real implementation.
 *
 * @since 6.0.0
 */
@GroovyASTTransformation(phase = CompilePhase.CONVERSION)
public class ToStringASTStubber extends AbstractASTTransformation {

    private static final ClassNode MY_TYPE = make(ToString.class);

    @Override
    public void visit(ASTNode[] nodes, SourceUnit source) {
        init(nodes, source);
        AnnotationNode annotation = (AnnotationNode) nodes[0];
        AnnotatedNode parent = (AnnotatedNode) nodes[1];
        if (!MY_TYPE.equals(annotation.getClassNode())) return;
        if (!(parent instanceof ClassNode classNode) || classNode.isInterface()) return;

        // Honour any user-declared toString that's already present.
        if (classNode.getDeclaredMethod("toString", Parameter.EMPTY_ARRAY) != null) return;

        addStubMethod(classNode, "toString", ACC_PUBLIC,
                ClassHelper.STRING_TYPE, Parameter.EMPTY_ARRAY, ClassNode.EMPTY_ARRAY,
                returnS(constX("")));
    }
}
