/*******************************************************************************
 * Copyright (c) 2009, 2019 Mountainminds GmbH & Co. KG and Contributors
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Nikolay Krasko - initial API and implementation
 *
 *******************************************************************************/
package org.jacoco.core.internal.analysis.filter;

import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.MethodNode;

/**
 * Filters methods generated by the Kotlin compiler. Kotlin classes are
 * identified by the <code>@kotlin.Metadata</code> annotations. In such classes
 * generated methods do not have line numbers.
 */
public class KotlinGeneratedFilter implements IFilter {

	static final String KOTLIN_METADATA_DESC = "Lkotlin/Metadata;";

	static boolean isKotlinClass(final IFilterContext context) {
		return context.getClassAnnotations().contains(KOTLIN_METADATA_DESC);
	}

	public void filter(final MethodNode methodNode,
			final IFilterContext context, final IFilterOutput output) {

		if (context.getSourceFileName() == null) {
			// probably full debug information is missing
			// disabled filtering as all methods might be erroneously skipped
			return;
		}

		if (!isKotlinClass(context)) {
			return;
		}

		if (hasLineNumber(methodNode)) {
			return;
		}

		output.ignore(methodNode.instructions.getFirst(),
				methodNode.instructions.getLast());
	}

	private boolean hasLineNumber(final MethodNode methodNode) {
		for (AbstractInsnNode i = methodNode.instructions
				.getFirst(); i != null; i = i.getNext()) {
			if (AbstractInsnNode.LINE == i.getType()) {
				return true;
			}
		}
		return false;
	}

}
