/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 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 the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * 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.
 */
package org.glowroot.agent.weaving;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.objectweb.asm.ConstantDynamic;
import org.objectweb.asm.Handle;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.commons.GeneratorAdapter;

// copied and modified from org.objectweb.asm.commons.AdviceAdapter
// modifications include
// * tracking stack frames for all methods (not just constructors)
// * tracking double words on the stack via SECOND_WORD
// * field "stackFrameTracking" to allow subclass to temporarily suppress stack frame tracking
// * fix in visitFieldInsn switch case PUTFIELD
// (reported fix at http://forge.ow2.org/tracker/?group_id=23&atid=100023&func=detail&aid=317604)
// * clearing stackFrame on GOTO
abstract class AdviceAdapter extends GeneratorAdapter implements Opcodes {

    /** The "uninitialized this" value. */
    static final Object UNINITIALIZED_THIS = new Object();

    protected static final Object SECOND_WORD = new Object();

    /** Any value other than "uninitialized this". */
    private static final Object OTHER = new Object();

    /** Prefix of the error message when invalid opcodes are found. */
    private static final String INVALID_OPCODE = "Invalid opcode ";

    /** The access flags of the visited method. */
    protected int methodAccess;

    /** The descriptor of the visited method. */
    protected String methodDesc;

    /** Whether the visited method is a constructor. */
    private final boolean isConstructor;

    /**
     * Whether the super class constructor has been called (if the visited method is a constructor),
     * at the current instruction. There can be multiple call sites to the super constructor (e.g.
     * for Java code such as {@code super(expr ? value1 : value2);}), in different branches. When
     * scanning the bytecode linearly, we can move from one branch where the super constructor has
     * been called to another where it has not been called yet. Therefore, this value can change
     * from false to true, and vice-versa.
     */
    private boolean superClassConstructorCalled;

    /**
     * The values on the current execution stack frame (long and double are represented by two
     * elements). Each value is either {@link #UNINITIALIZED_THIS} (for the uninitialized this
     * value), or {@link #OTHER} (for any other value). This field is only maintained for
     * constructors, in branches where the super class constructor has not been called yet.
     */
    protected List<Object> stackFrame = new ArrayList<>();

    /**
     * The stack map frames corresponding to the labels of the forward jumps made *before* the super
     * class constructor has been called (note that the Java Virtual Machine forbids backward jumps
     * before the super class constructor is called). Note that by definition (cf. the 'before'),
     * when we reach a label from this map, {@link #superClassConstructorCalled} must be reset to
     * false. This field is only maintained for constructors.
     */
    private Map<Label, List<Object>> forwardJumpStackFrames = new HashMap<>();

    protected boolean stackFrameTracking = true;

    /**
     * Constructs a new {@link AdviceAdapter}.
     *
     * @param api
     *            the ASM API version implemented by this visitor. Must be one of
     *            {@link Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or
     *            {@link Opcodes#ASM9}.
     * @param methodVisitor
     *            the method visitor to which this adapter delegates calls.
     * @param access
     *            the method's access flags (see {@link Opcodes}).
     * @param name
     *            the method's name.
     * @param descriptor
     *            the method's descriptor (see {@link Type Type}).
     */
    protected AdviceAdapter(final int api, final MethodVisitor methodVisitor, final int access,
            final String name, final String descriptor) {
        super(api, methodVisitor, access, name, descriptor);
        methodAccess = access;
        methodDesc = descriptor;
        isConstructor = "<init>".equals(name);
    }

    @Override
    public void visitCode() {
        super.visitCode();
        onMethodPreEnter();
        if (!isConstructor) {
            superClassConstructorCalled = true;
            onMethodEnter();
        }
    }

    @Override
    public void visitLabel(final Label label) {
        super.visitLabel(label);
        if (stackFrameTracking && forwardJumpStackFrames != null) {
            List<Object> labelStackFrame = forwardJumpStackFrames.get(label);
            if (labelStackFrame != null) {
                stackFrame = labelStackFrame;
                superClassConstructorCalled = false;
                forwardJumpStackFrames.remove(label);
            }
        }
    }

    @Override
    public void visitInsn(final int opcode) {
        if (stackFrameTracking) {
            int stackSize;
            switch (opcode) {
                case IRETURN:
                case FRETURN:
                case ARETURN:
                    popValue();
                    onMethodExit(opcode);
                    break;
                case LRETURN:
                case DRETURN:
                    popValue();
                    popValue();
                    onMethodExit(opcode);
                    break;
                case RETURN: // empty stack
                    onMethodExit(opcode);
                    endConstructorBasicBlockWithoutSuccessor();
                    break;
                case ATHROW: // 1 before n/a after
                    popValue();
                    onMethodExit(opcode);
                    endConstructorBasicBlockWithoutSuccessor();
                    break;
                case NOP:
                case LALOAD: // remove 2 add 2
                case DALOAD: // remove 2 add 2
                case LNEG:
                case DNEG:
                case FNEG:
                case INEG:
                case L2D:
                case D2L:
                case F2I:
                case I2B:
                case I2C:
                case I2S:
                case I2F:
                case ARRAYLENGTH:
                    break;
                case ACONST_NULL:
                case ICONST_M1:
                case ICONST_0:
                case ICONST_1:
                case ICONST_2:
                case ICONST_3:
                case ICONST_4:
                case ICONST_5:
                case FCONST_0:
                case FCONST_1:
                case FCONST_2:
                case F2L: // 1 before 2 after
                case F2D:
                case I2L:
                case I2D:
                    pushValue(OTHER);
                    break;
                case LCONST_0:
                case LCONST_1:
                case DCONST_0:
                case DCONST_1:
                    pushValue(OTHER);
                    pushValue(SECOND_WORD);
                    break;
                case IALOAD: // remove 2 add 1
                case FALOAD: // remove 2 add 1
                case AALOAD: // remove 2 add 1
                case BALOAD: // remove 2 add 1
                case CALOAD: // remove 2 add 1
                case SALOAD: // remove 2 add 1
                case POP:
                case IADD:
                case FADD:
                case ISUB:
                case LSHL: // 3 before 2 after
                case LSHR: // 3 before 2 after
                case LUSHR: // 3 before 2 after
                case L2I: // 2 before 1 after
                case L2F: // 2 before 1 after
                case D2I: // 2 before 1 after
                case D2F: // 2 before 1 after
                case FSUB:
                case FMUL:
                case FDIV:
                case FREM:
                case FCMPL: // 2 before 1 after
                case FCMPG: // 2 before 1 after
                case IMUL:
                case IDIV:
                case IREM:
                case ISHL:
                case ISHR:
                case IUSHR:
                case IAND:
                case IOR:
                case IXOR:
                case MONITORENTER:
                case MONITOREXIT:
                    popValue();
                    break;
                case POP2:
                case LSUB:
                case LMUL:
                case LDIV:
                case LREM:
                case LADD:
                case LAND:
                case LOR:
                case LXOR:
                case DADD:
                case DMUL:
                case DSUB:
                case DDIV:
                case DREM:
                    popValue();
                    popValue();
                    break;
                case IASTORE:
                case FASTORE:
                case AASTORE:
                case BASTORE:
                case CASTORE:
                case SASTORE:
                case LCMP: // 4 before 1 after
                case DCMPL:
                case DCMPG:
                    popValue();
                    popValue();
                    popValue();
                    break;
                case LASTORE:
                case DASTORE:
                    popValue();
                    popValue();
                    popValue();
                    popValue();
                    break;
                case DUP:
                    pushValue(peekValue());
                    break;
                case DUP_X1:
                    stackSize = stackFrame.size();
                    stackFrame.add(stackSize - 2, stackFrame.get(stackSize - 1));
                    break;
                case DUP_X2:
                    stackSize = stackFrame.size();
                    stackFrame.add(stackSize - 3, stackFrame.get(stackSize - 1));
                    break;
                case DUP2:
                    stackSize = stackFrame.size();
                    stackFrame.add(stackSize - 2, stackFrame.get(stackSize - 1));
                    stackFrame.add(stackSize - 2, stackFrame.get(stackSize - 1));
                    break;
                case DUP2_X1:
                    stackSize = stackFrame.size();
                    stackFrame.add(stackSize - 3, stackFrame.get(stackSize - 1));
                    stackFrame.add(stackSize - 3, stackFrame.get(stackSize - 1));
                    break;
                case DUP2_X2:
                    stackSize = stackFrame.size();
                    stackFrame.add(stackSize - 4, stackFrame.get(stackSize - 1));
                    stackFrame.add(stackSize - 4, stackFrame.get(stackSize - 1));
                    break;
                case SWAP:
                    stackSize = stackFrame.size();
                    stackFrame.add(stackSize - 2, stackFrame.get(stackSize - 1));
                    stackFrame.remove(stackSize);
                    break;
                case RET:
                    endConstructorBasicBlockWithoutSuccessor();
                    break;
                default:
                    throw new IllegalArgumentException(INVALID_OPCODE + opcode);
            }
        } else {
            switch (opcode) {
                case RETURN:
                case IRETURN:
                case FRETURN:
                case ARETURN:
                case LRETURN:
                case DRETURN:
                case ATHROW:
                    onMethodExit(opcode);
                    break;
                default:
                    break;
            }
        }
        super.visitInsn(opcode);
    }

    @Override
    public void visitVarInsn(final int opcode, final int var) {
        super.visitVarInsn(opcode, var);
        if (stackFrameTracking) {
            switch (opcode) {
                case ILOAD:
                case FLOAD:
                    pushValue(OTHER);
                    break;
                case LLOAD:
                case DLOAD:
                    pushValue(OTHER);
                    pushValue(SECOND_WORD);
                    break;
                case ALOAD:
                    pushValue(var == 0 ? UNINITIALIZED_THIS : OTHER);
                    break;
                case ASTORE:
                case ISTORE:
                case FSTORE:
                    popValue();
                    break;
                case LSTORE:
                case DSTORE:
                    popValue();
                    popValue();
                    break;
                default:
                    throw new IllegalArgumentException(INVALID_OPCODE + opcode);
            }
        }
    }

    @Override
    public void visitFieldInsn(final int opcode, final String owner, final String name,
            final String descriptor) {
        super.visitFieldInsn(opcode, owner, name, descriptor);
        if (stackFrameTracking) {
            char firstDescriptorChar = descriptor.charAt(0);
            boolean longOrDouble = firstDescriptorChar == 'J' || firstDescriptorChar == 'D';
            switch (opcode) {
                case GETSTATIC:
                    pushValue(OTHER);
                    if (longOrDouble) {
                        pushValue(SECOND_WORD);
                    }
                    break;
                case PUTSTATIC:
                    popValue();
                    if (longOrDouble) {
                        popValue();
                    }
                    break;
                case PUTFIELD:
                    popValue();
                    popValue();
                    if (longOrDouble) {
                        popValue();
                    }
                    break;
                case GETFIELD:
                    if (longOrDouble) {
                        pushValue(SECOND_WORD);
                    }
                    break;
                default:
                    throw new IllegalArgumentException(INVALID_OPCODE + opcode);
            }
        }
    }

    @Override
    public void visitIntInsn(final int opcode, final int operand) {
        super.visitIntInsn(opcode, operand);
        if (stackFrameTracking && opcode != NEWARRAY) {
            pushValue(OTHER);
        }
    }

    @Override
    public void visitLdcInsn(final Object value) {
        super.visitLdcInsn(value);
        if (stackFrameTracking) {
            pushValue(OTHER);
            if (value instanceof Double || value instanceof Long
                    || (value instanceof ConstantDynamic
                            && ((ConstantDynamic) value).getSize() == 2)) {
                pushValue(SECOND_WORD);
            }
        }
    }

    @Override
    public void visitMultiANewArrayInsn(final String descriptor, final int numDimensions) {
        super.visitMultiANewArrayInsn(descriptor, numDimensions);
        if (stackFrameTracking) {
            for (int i = 0; i < numDimensions; i++) {
                popValue();
            }
            pushValue(OTHER);
        }
    }

    @Override
    public void visitTypeInsn(final int opcode, final String type) {
        super.visitTypeInsn(opcode, type);
        // ANEWARRAY, CHECKCAST or INSTANCEOF don't change stack.
        if (stackFrameTracking && opcode == NEW) {
            pushValue(OTHER);
        }
    }

    @Override
    public void visitMethodInsn(final int opcodeAndSource, final String owner, final String name,
            final String descriptor, final boolean isInterface) {
        if (api < Opcodes.ASM5 && (opcodeAndSource & Opcodes.SOURCE_DEPRECATED) == 0) {
            // Redirect the call to the deprecated version of this method.
            super.visitMethodInsn(opcodeAndSource, owner, name, descriptor, isInterface);
            return;
        }
        super.visitMethodInsn(opcodeAndSource, owner, name, descriptor, isInterface);
        int opcode = opcodeAndSource & ~Opcodes.SOURCE_MASK;

        doVisitMethodInsn(opcode, name, descriptor);
    }

    private void doVisitMethodInsn(final int opcode, final String name, final String descriptor) {
        if (stackFrameTracking) {
            for (Type argumentType : Type.getArgumentTypes(descriptor)) {
                popValue();
                if (argumentType.getSize() == 2) {
                    popValue();
                }
            }
            switch (opcode) {
                case INVOKEINTERFACE:
                case INVOKEVIRTUAL:
                    popValue();
                    break;
                case INVOKESPECIAL:
                    Object value = popValue();
                    if (value == UNINITIALIZED_THIS
                            && !superClassConstructorCalled
                            && name.equals("<init>")) {
                        superClassConstructorCalled = true;
                        onMethodEnter();
                    }
                    break;
                default:
                    break;
            }

            Type returnType = Type.getReturnType(descriptor);
            if (returnType != Type.VOID_TYPE) {
                pushValue(OTHER);
                if (returnType.getSize() == 2) {
                    pushValue(SECOND_WORD);
                }
            }
        }
    }

    @Override
    public void visitInvokeDynamicInsn(final String name, final String descriptor,
            final Handle bootstrapMethodHandle, final Object... bootstrapMethodArguments) {
        super.visitInvokeDynamicInsn(name, descriptor, bootstrapMethodHandle,
                bootstrapMethodArguments);
        doVisitMethodInsn(Opcodes.INVOKEDYNAMIC, name, descriptor);
    }

    @Override
    public void visitJumpInsn(final int opcode, final Label label) {
        super.visitJumpInsn(opcode, label);
        if (stackFrameTracking) {
            switch (opcode) {
                case IFEQ:
                case IFNE:
                case IFLT:
                case IFGE:
                case IFGT:
                case IFLE:
                case IFNULL:
                case IFNONNULL:
                    popValue();
                    break;
                case IF_ICMPEQ:
                case IF_ICMPNE:
                case IF_ICMPLT:
                case IF_ICMPGE:
                case IF_ICMPGT:
                case IF_ICMPLE:
                case IF_ACMPEQ:
                case IF_ACMPNE:
                    popValue();
                    popValue();
                    break;
                case JSR:
                    pushValue(OTHER);
                    break;
                case GOTO:
                    endConstructorBasicBlockWithoutSuccessor();
                    break;
                default:
                    break;
            }
            addForwardJump(label);
            if (opcode == GOTO) {
                stackFrame = new ArrayList<>();
            }
        }
    }

    @Override
    public void visitLookupSwitchInsn(final Label dflt, final int[] keys, final Label[] labels) {
        super.visitLookupSwitchInsn(dflt, keys, labels);
        if (stackFrameTracking) {
            popValue();
            addForwardJumps(dflt, labels);
            endConstructorBasicBlockWithoutSuccessor();
        }
    }

    @Override
    public void visitTableSwitchInsn(final int min, final int max, final Label dflt,
            final Label... labels) {
        super.visitTableSwitchInsn(min, max, dflt, labels);
        if (stackFrameTracking) {
            popValue();
            addForwardJumps(dflt, labels);
            endConstructorBasicBlockWithoutSuccessor();
        }
    }

    @Override
    public void visitTryCatchBlock(final Label start, final Label end, final Label handler,
            final String type) {
        super.visitTryCatchBlock(start, end, handler, type);
        // By definition of 'forwardJumpStackFrames', 'handler' should be pushed only if there is an
        // instruction between 'start' and 'end' at which the super class constructor is not yet
        // called. Unfortunately, try catch blocks must be visited before their labels, so we have
        // no
        // way to know this at this point. Instead, we suppose that the super class constructor has
        // not
        // been called at the start of *any* exception handler. If this is wrong, normally there
        // should
        // not be a second super class constructor call in the exception handler (an object can't be
        // initialized twice), so this is not issue (in the sense that there is no risk to emit a
        // wrong
        // 'onMethodEnter').
        if (stackFrameTracking && !forwardJumpStackFrames.containsKey(handler)) {
            List<Object> handlerStackFrame = new ArrayList<>();
            handlerStackFrame.add(OTHER);
            forwardJumpStackFrames.put(handler, handlerStackFrame);
        }
    }

    private void addForwardJumps(final Label dflt, final Label[] labels) {
        addForwardJump(dflt);
        for (Label label : labels) {
            addForwardJump(label);
        }
    }

    private void addForwardJump(final Label label) {
        if (forwardJumpStackFrames.containsKey(label)) {
            return;
        }
        forwardJumpStackFrames.put(label, new ArrayList<>(stackFrame));
    }

    private void endConstructorBasicBlockWithoutSuccessor() {
        // The next instruction is not reachable from this instruction. If it is dead code, we
        // should not try to simulate stack operations, and there is no need to insert advices
        // here. If it is reachable with a backward jump, the only possible case is that the super
        // class constructor has already been called (backward jumps are forbidden before it is
        // called). If it is reachable with a forward jump, there are two sub-cases. Either the
        // super class constructor has already been called when reaching the next instruction, or
        // it has not been called. But in this case there must be a forwardJumpStackFrames entry
        // for a Label designating the next instruction, and superClassConstructorCalled will be
        // reset to false there. We can therefore always reset this field to true here.
        superClassConstructorCalled = true;
    }

    private Object popValue() {
        if (stackFrame.isEmpty()) {
            // this is to handle less-than-perfect bytecode, see
            // WeaverTest.shouldExecuteAdviceOnMoreNotPerfectBytecode()
            return OTHER;
        }
        return stackFrame.remove(stackFrame.size() - 1);
    }

    private Object peekValue() {
        if (stackFrame.isEmpty()) {
            // this is to handle less-than-perfect bytecode, see
            // WeaverTest.shouldExecuteAdviceOnMoreNotPerfectBytecode()
            return OTHER;
        }
        return stackFrame.get(stackFrame.size() - 1);
    }

    private void pushValue(final Object value) {
        stackFrame.add(value);
    }

    protected void onMethodPreEnter() {}

    /**
     * Generates the "before" advice for the visited method. The default implementation of this
     * method does nothing. Subclasses can use or change all the local variables, but should not
     * change state of the stack. This method is called at the beginning of the method or after
     * super class constructor has been called (in constructors).
     */
    protected void onMethodEnter() {}

    /**
     * Generates the "after" advice for the visited method. The default implementation of this
     * method does nothing. Subclasses can use or change all the local variables, but should not
     * change state of the stack. This method is called at the end of the method, just before return
     * and athrow instructions. The top element on the stack contains the return value or the
     * exception instance. For example:
     *
     * <pre>
     * public void onMethodExit(final int opcode) {
     *   if (opcode == RETURN) {
     *     visitInsn(ACONST_NULL);
     *   } else if (opcode == ARETURN || opcode == ATHROW) {
     *     dup();
     *   } else {
     *     if (opcode == LRETURN || opcode == DRETURN) {
     *       dup2();
     *     } else {
     *       dup();
     *     }
     *     box(Type.getReturnType(this.methodDesc));
     *   }
     *   visitIntInsn(SIPUSH, opcode);
     *   visitMethodInsn(INVOKESTATIC, owner, "onExit", "(Ljava/lang/Object;I)V");
     * }
     *
     * // An actual call back method.
     * public static void onExit(final Object exitValue, final int opcode) {
     *   ...
     * }
     * </pre>
     *
     * @param opcode
     *            one of {@link Opcodes#RETURN}, {@link Opcodes#IRETURN}, {@link Opcodes#FRETURN},
     *            {@link Opcodes#ARETURN}, {@link Opcodes#LRETURN}, {@link Opcodes#DRETURN} or
     *            {@link Opcodes#ATHROW}.
     */
    protected void onMethodExit(final int opcode) {}
}
