/*
 * This file is part of LanternServer, licensed under the MIT License (MIT).
 *
 * Copyright (c) LanternPowered <https://www.lanternpowered.org>
 * Copyright (c) SpongePowered <https://www.spongepowered.org>
 * Copyright (c) contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the Software), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED AS IS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package org.lanternpowered.server.event.filter.delegate;

import static org.objectweb.asm.Opcodes.ACONST_NULL;
import static org.objectweb.asm.Opcodes.ALOAD;
import static org.objectweb.asm.Opcodes.ARETURN;
import static org.objectweb.asm.Opcodes.ASTORE;
import static org.objectweb.asm.Opcodes.DUP;
import static org.objectweb.asm.Opcodes.GOTO;
import static org.objectweb.asm.Opcodes.IFEQ;
import static org.objectweb.asm.Opcodes.IFNE;
import static org.objectweb.asm.Opcodes.INSTANCEOF;
import static org.objectweb.asm.Opcodes.INVOKEVIRTUAL;

import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Type;
import org.spongepowered.api.event.cause.Cause;
import org.spongepowered.api.event.filter.cause.Last;

import java.lang.reflect.Parameter;

public class LastCauseFilterSourceDelegate extends CauseFilterSourceDelegate {

    private final Last anno;

    public LastCauseFilterSourceDelegate(Last anno) {
        this.anno = anno;
    }

    @Override
    protected void insertCauseCall(MethodVisitor mv, Parameter param, Class<?> targetType) {
        mv.visitLdcInsn(Type.getType(targetType));
        mv.visitMethodInsn(INVOKEVIRTUAL, Type.getInternalName(Cause.class), "last",
                "(Ljava/lang/Class;)Ljava/util/Optional;", false);
    }

    @Override
    protected void insertTransform(MethodVisitor mv, Parameter param, Class<?> targetType, int local) {
        mv.visitVarInsn(ALOAD, local);
        Label failure = new Label();
        Label success = new Label();

        mv.visitMethodInsn(INVOKEVIRTUAL, "java/util/Optional", "isPresent", "()Z", false);
        mv.visitJumpInsn(IFEQ, failure);

        mv.visitVarInsn(ALOAD, local);
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/util/Optional", "get", "()Ljava/lang/Object;", false);

        mv.visitVarInsn(ASTORE, local);
        mv.visitVarInsn(ALOAD, local);

        mv.visitTypeInsn(INSTANCEOF, Type.getInternalName(targetType));

        if (this.anno.typeFilter().length != 0) {
            mv.visitJumpInsn(IFEQ, failure);
            mv.visitVarInsn(ALOAD, local);
            // For each type we do an instance check and jump to either failure or success if matched
            for (int i = 0; i < this.anno.typeFilter().length; i++) {
                Class<?> filter = this.anno.typeFilter()[i];
                if (i < this.anno.typeFilter().length - 1) {
                    mv.visitInsn(DUP);
                }
                mv.visitTypeInsn(INSTANCEOF, Type.getInternalName(filter));
                if (this.anno.inverse()) {
                    mv.visitJumpInsn(IFNE, failure);
                } else {
                    mv.visitJumpInsn(IFNE, success);
                }
            }
            if (this.anno.inverse()) {
                mv.visitJumpInsn(GOTO, success);
            }
            // If the annotation was not reversed then we fall into failure as no types were matched
        } else {
            mv.visitJumpInsn(IFNE, success);
        }
        mv.visitLabel(failure);
        mv.visitInsn(ACONST_NULL);
        mv.visitInsn(ARETURN);

        mv.visitLabel(success);
    }

}