/*
 * 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.CHECKCAST;
import static org.objectweb.asm.Opcodes.GETFIELD;
import static org.objectweb.asm.Opcodes.GOTO;
import static org.objectweb.asm.Opcodes.IFNE;
import static org.objectweb.asm.Opcodes.INVOKEINTERFACE;
import static org.objectweb.asm.Opcodes.INVOKEVIRTUAL;

import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.spongepowered.api.event.filter.type.Include;

import java.lang.reflect.Method;

public class IncludeSubtypeFilterDelegate extends SubtypeFilterDelegate {

    public IncludeSubtypeFilterDelegate(Include anno) {
        super(anno.value());
    }

    @Override
    public int write(String name, ClassWriter cw, MethodVisitor mv, Method method, int locals) {
        // TODO could do an optimization here to inline a single instanceof if
        // the set would contain only a single member

        Label successLabel = new Label();

        mv.visitVarInsn(ALOAD, 0);
        mv.visitFieldInsn(GETFIELD, name, "classes", "Ljava/util/Set;");
        // Loop through the classes set's members
        mv.visitMethodInsn(INVOKEINTERFACE, "java/util/Set", "iterator", "()Ljava/util/Iterator;", true);
        mv.visitVarInsn(ASTORE, locals);
        Label continueLabel = new Label();
        mv.visitJumpInsn(GOTO, continueLabel);
        Label loopStart = new Label();
        mv.visitLabel(loopStart);
        mv.visitVarInsn(ALOAD, locals);
        mv.visitMethodInsn(INVOKEINTERFACE, "java/util/Iterator", "next", "()Ljava/lang/Object;", true);
        mv.visitTypeInsn(CHECKCAST, "java/lang/Class");
        mv.visitVarInsn(ALOAD, 1);
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Class", "isInstance", "(Ljava/lang/Object;)Z", false);

        // If isInstance returns true, jump to success (jump over return)
        mv.visitJumpInsn(Opcodes.IFNE, successLabel);
        mv.visitLabel(continueLabel);
        mv.visitVarInsn(ALOAD, locals);
        mv.visitMethodInsn(INVOKEINTERFACE, "java/util/Iterator", "hasNext", "()Z", true);

        // If there are any classes left, continue looping. Otherwise, fail and return out (no @Include matches were found)
        mv.visitJumpInsn(IFNE, loopStart);

        mv.visitInsn(ACONST_NULL);
        mv.visitInsn(ARETURN);

        mv.visitLabel(successLabel);

        return locals + 1;
    }

}