package com.infomancers.collections.yield.asmtree.enhancers;

import com.infomancers.collections.yield.asmbase.YielderInformationContainer;
import com.infomancers.collections.yield.asmtree.CodeStack;
import com.infomancers.collections.yield.asmtree.Util;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.*;

import java.util.List;

/**
 * Copyright (c) 2009, Aviad Ben Dov
 * <p/>
 * All rights reserved.
 * <p/>
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * <p/>
 * 1. Redistributions of source code must retain the above copyright notice, this list
 * of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice, this
 * list of conditions and the following disclaimer in the documentation and/or other
 * materials provided with the distribution.
 * 3. Neither the name of Infomancers, Ltd. nor the names of its contributors may be
 * used to endorse or promote products derived from this software without specific
 * prior written permission.
 * <p/>
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * Stack should be [..., array, index].
 * <p/>
 * Note: Special case for the BALOAD opcode, which might load from a [B or a [Z (boolean array)!
 * <p/>
 * in that case, the bytecode will be replaced to:
 * <code>
 * if (arr.getClass().getComponentType().equals(Byte.TYPE)) {
 * CHECKCAST [B
 * else
 * CHECKCAST [Z
 * <p/>
 * BALOAD
 * </code>
 */
public final class ArrayLoadEnhancer implements PredicatedInsnEnhancer {
    private static final String[] descs = "[I,[J,[F,[D,[Ljava/lang/Object;,[B,[C,[S".split(",");

    public AbstractInsnNode enhance(ClassNode clz, InsnList instructions, List<AbstractInsnNode> limits, YielderInformationContainer info, AbstractInsnNode instruction) {
        if (instruction.getOpcode() == Opcodes.BALOAD) {
            LabelNode l1 = new LabelNode();
            LabelNode l2 = new LabelNode();

            final AbstractInsnNode ret;

            InsnList testAndCast = Util.createList(
                    ret = new InsnNode(Opcodes.DUP_X1),   // stack: [..., index, array, index]
                    new InsnNode(Opcodes.POP),      // stack: [..., index, array]
                    new InsnNode(Opcodes.DUP_X1),   // stack: [..., array, index, array]
                    new MethodInsnNode(Opcodes.INVOKEVIRTUAL, "java/lang/Object", "getClass", "()Ljava/lang/Class;"),
                    new MethodInsnNode(Opcodes.INVOKEVIRTUAL, "java/lang/Class", "getComponentType", "()Ljava/lang/Class;"),
                    new FieldInsnNode(Opcodes.GETSTATIC, "java/lang/Byte", "TYPE", "Ljava/lang/Class;"),
                    new JumpInsnNode(Opcodes.IF_ACMPNE, l1),
                    new MethodInsnNode(Opcodes.INVOKESTATIC, "java/lang/reflect/Array", "getByte", "(Ljava/lang/Object;I)B"),
                    new JumpInsnNode(Opcodes.GOTO, l2),
                    l1,
                    new MethodInsnNode(Opcodes.INVOKESTATIC, "java/lang/reflect/Array", "getBoolean", "(Ljava/lang/Object;I)Z"),
                    l2
            );

            Util.insertOrAdd(instructions, instruction, testAndCast);
            instructions.remove(instruction);

            return ret;
        } else {
            AbstractInsnNode prev = CodeStack.backUntilStackSizedAt(instruction, 0, false, limits);

            TypeInsnNode checkcast = new TypeInsnNode(Opcodes.CHECKCAST, descs[instruction.getOpcode() - Opcodes.IALOAD]);

            Util.insertOrAdd(instructions, prev, checkcast);

            return instruction;
        }
    }

    public boolean shouldEnhance(AbstractInsnNode node) {
        return node.getOpcode() >= Opcodes.IALOAD && node.getOpcode() <= Opcodes.SALOAD;
    }
}