/*

 * Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.lang.invoke;

import jdk.internal.org.objectweb.asm.ClassWriter;

import jdk.internal.org.objectweb.asm.Label;

import jdk.internal.org.objectweb.asm.MethodVisitor;

import jdk.internal.org.objectweb.asm.Opcodes;

import jdk.internal.org.objectweb.asm.Type;

import sun.invoke.util.VerifyAccess;

import sun.invoke.util.VerifyType;

import sun.invoke.util.Wrapper;

import sun.reflect.misc.ReflectUtil;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.lang.reflect.Modifier;

import java.util.Arrays;

import java.util.HashMap;

import java.util.Map;

import java.util.stream.Stream;

import static java.lang.invoke.LambdaForm.*;

import static java.lang.invoke.LambdaForm.BasicType.*;

import static java.lang.invoke.MethodHandleNatives.Constants.*;

import static java.lang.invoke.MethodHandleStatics.*;

/**

 * Code generation backend for LambdaForm.

 * <p>

 * @author John Rose, JSR 292 EG

 */

class InvokerBytecodeGenerator {

    /** Define class names for convenience. */

    private static final String MH      = "java/lang/invoke/MethodHandle";

    private static final String MHI     = "java/lang/invoke/MethodHandleImpl";

    private static final String LF      = "java/lang/invoke/LambdaForm";

    private static final String LFN     = "java/lang/invoke/LambdaForm$Name";

    private static final String CLS     = "java/lang/Class";

    private static final String OBJ     = "java/lang/Object";

    private static final String OBJARY  = "[Ljava/lang/Object;";

    private static final String LF_SIG  = "L" + LF + ";";

    private static final String LFN_SIG = "L" + LFN + ";";

    private static final String LL_SIG  = "(L" + OBJ + ";)L" + OBJ + ";";

    private static final String LLV_SIG = "(L" + OBJ + ";L" + OBJ + ";)V";

    /** Name of its super class*/

    private static final String superName = OBJ;

    /** Name of new class */

    private final String className;

    /** Name of the source file (for stack trace printing). */

    private final String sourceFile;

    private final LambdaForm lambdaForm;

    private final String     invokerName;

    private final MethodType invokerType;

    /** Info about local variables in compiled lambda form */

    private int[]       localsMap;    // index

    private Class<?>[]  localClasses; // type

    /** ASM bytecode generation. */

    private ClassWriter cw;

    private MethodVisitor mv;

    private static final MemberName.Factory MEMBERNAME_FACTORY = MemberName.getFactory();

    private static final Class<?> HOST_CLASS = LambdaForm.class;

    /** Main constructor; other constructors delegate to this one. */

    private InvokerBytecodeGenerator(LambdaForm lambdaForm, int localsMapSize,

                                     String className, String invokerName, MethodType invokerType) {

        if (invokerName.contains(".")) {

            int p = invokerName.indexOf('.');

            className = invokerName.substring(0, p);

            invokerName = invokerName.substring(p+1);

        }

        if (DUMP_CLASS_FILES) {

            className = makeDumpableClassName(className);

        }

        this.className  = LF + "$" + className;

        this.sourceFile = "LambdaForm$" + className;

        this.lambdaForm = lambdaForm;

        this.invokerName = invokerName;

        this.invokerType = invokerType;

        this.localsMap = new int[localsMapSize+1]; // last entry of localsMap is count of allocated local slots

        this.localClasses = new Class<?>[localsMapSize+1];

    }

    /** For generating LambdaForm interpreter entry points. */

    private InvokerBytecodeGenerator(String className, String invokerName, MethodType invokerType) {

        this(null, invokerType.parameterCount(),

             className, invokerName, invokerType);

        // Create an array to map name indexes to locals indexes.

        for (int i = 0; i < localsMap.length; i++) {

            localsMap[i] = invokerType.parameterSlotCount() - invokerType.parameterSlotDepth(i);

        }

    }

    /** For generating customized code for a single LambdaForm. */

    private InvokerBytecodeGenerator(String className, LambdaForm form, MethodType invokerType) {

        this(form, form.names.length,

             className, form.debugName, invokerType);

        // Create an array to map name indexes to locals indexes.

        Name[] names = form.names;

        for (int i = 0, index = 0; i < localsMap.length; i++) {

            localsMap[i] = index;

            if (i < names.length) {

                BasicType type = names[i].type();

                index += type.basicTypeSlots();

            }

        }

    }

    /** instance counters for dumped classes */

    private static final HashMap<String,Integer> DUMP_CLASS_FILES_COUNTERS;

    /** debugging flag for saving generated class files */

    private static final File DUMP_CLASS_FILES_DIR;

    static {

        if (DUMP_CLASS_FILES) {

            DUMP_CLASS_FILES_COUNTERS = new HashMap<>();

            try {

                File dumpDir = new File("DUMP_CLASS_FILES");

                if (!dumpDir.exists()) {

                    dumpDir.mkdirs();

                }

                DUMP_CLASS_FILES_DIR = dumpDir;

                System.out.println("Dumping class files to "+DUMP_CLASS_FILES_DIR+"/...");

            } catch (Exception e) {

                throw newInternalError(e);

            }

        } else {

            DUMP_CLASS_FILES_COUNTERS = null;

            DUMP_CLASS_FILES_DIR = null;

        }

    }

    static void maybeDump(final String className, final byte[] classFile) {

        if (DUMP_CLASS_FILES) {

            java.security.AccessController.doPrivileged(

            new java.security.PrivilegedAction<>() {

                public Void run() {

                    try {

                        String dumpName = className;

                        //dumpName = dumpName.replace('/', '-');

                        File dumpFile = new File(DUMP_CLASS_FILES_DIR, dumpName+".class");

                        System.out.println("dump: " + dumpFile);

                        dumpFile.getParentFile().mkdirs();

                        FileOutputStream file = new FileOutputStream(dumpFile);

                        file.write(classFile);

                        file.close();

                        return null;

                    } catch (IOException ex) {

                        throw newInternalError(ex);

                    }

                }

            });

        }

    }

    private static String makeDumpableClassName(String className) {

        Integer ctr;

        synchronized (DUMP_CLASS_FILES_COUNTERS) {

            ctr = DUMP_CLASS_FILES_COUNTERS.get(className);

            if (ctr == null)  ctr = 0;

            DUMP_CLASS_FILES_COUNTERS.put(className, ctr+1);

        }

        String sfx = ctr.toString();

        while (sfx.length() < 3)

            sfx = "0"+sfx;

        className += sfx;

        return className;

    }

    class CpPatch {

        final int index;

        final String placeholder;

        final Object value;

        CpPatch(int index, String placeholder, Object value) {

            this.index = index;

            this.placeholder = placeholder;

            this.value = value;

        }

        public String toString() {

            return "CpPatch/index="+index+",placeholder="+placeholder+",value="+value;

        }

    }

    Map<Object, CpPatch> cpPatches = new HashMap<>();

    int cph = 0;  // for counting constant placeholders

    String constantPlaceholder(Object arg) {

        String cpPlaceholder = "CONSTANT_PLACEHOLDER_" + cph++;

        if (DUMP_CLASS_FILES) cpPlaceholder += " <<" + debugString(arg) + ">>";  // debugging aid

        if (cpPatches.containsKey(cpPlaceholder)) {

            throw new InternalError("observed CP placeholder twice: " + cpPlaceholder);

        }

        // insert placeholder in CP and remember the patch

        int index = cw.newConst((Object) cpPlaceholder);  // TODO check if already in the constant pool

        cpPatches.put(cpPlaceholder, new CpPatch(index, cpPlaceholder, arg));

        return cpPlaceholder;

    }

    Object[] cpPatches(byte[] classFile) {

        int size = getConstantPoolSize(classFile);

        Object[] res = new Object[size];

        for (CpPatch p : cpPatches.values()) {

            if (p.index >= size)

                throw new InternalError("in cpool["+size+"]: "+p+"\n"+Arrays.toString(Arrays.copyOf(classFile, 20)));

            res[p.index] = p.value;

        }

        return res;

    }

    private static String debugString(Object arg) {

        if (arg instanceof MethodHandle) {

            MethodHandle mh = (MethodHandle) arg;

            MemberName member = mh.internalMemberName();

            if (member != null)

                return member.toString();

            return mh.debugString();

        }

        return arg.toString();

    }

    /**

     * Extract the number of constant pool entries from a given class file.

     *

     * @param classFile the bytes of the class file in question.

     * @return the number of entries in the constant pool.

     */

    private static int getConstantPoolSize(byte[] classFile) {

        // The first few bytes:

        // u4 magic;

        // u2 minor_version;

        // u2 major_version;

        // u2 constant_pool_count;

        return ((classFile[8] & 0xFF) << 8) | (classFile[9] & 0xFF);

    }

    /**

     * Extract the MemberName of a newly-defined method.

     */

    private MemberName loadMethod(byte[] classFile) {

        Class<?> invokerClass = loadAndInitializeInvokerClass(classFile, cpPatches(classFile));

        return resolveInvokerMember(invokerClass, invokerName, invokerType);

    }

    /**

     * Define a given class as anonymous class in the runtime system.

     */

    private static Class<?> loadAndInitializeInvokerClass(byte[] classBytes, Object[] patches) {

        Class<?> invokerClass = UNSAFE.defineAnonymousClass(HOST_CLASS, classBytes, patches);

        UNSAFE.ensureClassInitialized(invokerClass);  // Make sure the class is initialized; VM might complain.

        return invokerClass;

    }

    private static MemberName resolveInvokerMember(Class<?> invokerClass, String name, MethodType type) {

        MemberName member = new MemberName(invokerClass, name, type, REF_invokeStatic);

        try {

            member = MEMBERNAME_FACTORY.resolveOrFail(REF_invokeStatic, member, HOST_CLASS, ReflectiveOperationException.class);

        } catch (ReflectiveOperationException e) {

            throw newInternalError(e);

        }

        return member;

    }

    /**

     * Set up class file generation.

     */

    private void classFilePrologue() {

        final int NOT_ACC_PUBLIC = 0;  // not ACC_PUBLIC

        cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);

        cw.visit(Opcodes.V1_8, NOT_ACC_PUBLIC + Opcodes.ACC_FINAL + Opcodes.ACC_SUPER, className, null, superName, null);

        cw.visitSource(sourceFile, null);

        String invokerDesc = invokerType.toMethodDescriptorString();

        mv = cw.visitMethod(Opcodes.ACC_STATIC, invokerName, invokerDesc, null, null);

    }

    /**

     * Tear down class file generation.

     */

    private void classFileEpilogue() {

        mv.visitMaxs(0, 0);

        mv.visitEnd();

    }

    /*

     * Low-level emit helpers.

     */

    private void emitConst(Object con) {

        if (con == null) {

            mv.visitInsn(Opcodes.ACONST_NULL);

            return;

        }

        if (con instanceof Integer) {

            emitIconstInsn((int) con);

            return;

        }

        if (con instanceof Byte) {

            emitIconstInsn((byte)con);

            return;

        }

        if (con instanceof Short) {

            emitIconstInsn((short)con);

            return;

        }

        if (con instanceof Character) {

            emitIconstInsn((char)con);

            return;

        }

        if (con instanceof Long) {

            long x = (long) con;

            short sx = (short)x;

            if (x == sx) {

                if (sx >= 0 && sx <= 1) {

                    mv.visitInsn(Opcodes.LCONST_0 + (int) sx);

                } else {

                    emitIconstInsn((int) x);

                    mv.visitInsn(Opcodes.I2L);

                }

                return;

            }

        }

        if (con instanceof Float) {

            float x = (float) con;

            short sx = (short)x;

            if (x == sx) {

                if (sx >= 0 && sx <= 2) {

                    mv.visitInsn(Opcodes.FCONST_0 + (int) sx);

                } else {

                    emitIconstInsn((int) x);

                    mv.visitInsn(Opcodes.I2F);

                }

                return;

            }

        }

        if (con instanceof Double) {

            double x = (double) con;

            short sx = (short)x;

            if (x == sx) {

                if (sx >= 0 && sx <= 1) {

                    mv.visitInsn(Opcodes.DCONST_0 + (int) sx);

                } else {

                    emitIconstInsn((int) x);

                    mv.visitInsn(Opcodes.I2D);

                }

                return;

            }

        }

        if (con instanceof Boolean) {

            emitIconstInsn((boolean) con ? 1 : 0);

            return;

        }

        // fall through:

        mv.visitLdcInsn(con);

    }

    private void emitIconstInsn(final int cst) {

        if (cst >= -1 && cst <= 5) {

            mv.visitInsn(Opcodes.ICONST_0 + cst);

        } else if (cst >= Byte.MIN_VALUE && cst <= Byte.MAX_VALUE) {

            mv.visitIntInsn(Opcodes.BIPUSH, cst);

        } else if (cst >= Short.MIN_VALUE && cst <= Short.MAX_VALUE) {

            mv.visitIntInsn(Opcodes.SIPUSH, cst);

        } else {

            mv.visitLdcInsn(cst);

        }

    }

    /*

     * NOTE: These load/store methods use the localsMap to find the correct index!

     */

    private void emitLoadInsn(BasicType type, int index) {

        int opcode = loadInsnOpcode(type);

        mv.visitVarInsn(opcode, localsMap[index]);

    }

    private int loadInsnOpcode(BasicType type) throws InternalError {

        switch (type) {

            case I_TYPE: return Opcodes.ILOAD;

            case J_TYPE: return Opcodes.LLOAD;

            case F_TYPE: return Opcodes.FLOAD;

            case D_TYPE: return Opcodes.DLOAD;

            case L_TYPE: return Opcodes.ALOAD;

            default:

                throw new InternalError("unknown type: " + type);

        }

    }

    private void emitAloadInsn(int index) {

        emitLoadInsn(L_TYPE, index);

    }

    private void emitStoreInsn(BasicType type, int index) {

        int opcode = storeInsnOpcode(type);

        mv.visitVarInsn(opcode, localsMap[index]);

    }

    private int storeInsnOpcode(BasicType type) throws InternalError {

        switch (type) {

            case I_TYPE: return Opcodes.ISTORE;

            case J_TYPE: return Opcodes.LSTORE;

            case F_TYPE: return Opcodes.FSTORE;

            case D_TYPE: return Opcodes.DSTORE;

            case L_TYPE: return Opcodes.ASTORE;

            default:

                throw new InternalError("unknown type: " + type);

        }

    }

    private void emitAstoreInsn(int index) {

        emitStoreInsn(L_TYPE, index);

    }

    private byte arrayTypeCode(Wrapper elementType) {

        switch (elementType) {

            case BOOLEAN: return Opcodes.T_BOOLEAN;

            case BYTE:    return Opcodes.T_BYTE;

            case CHAR:    return Opcodes.T_CHAR;

            case SHORT:   return Opcodes.T_SHORT;

            case INT:     return Opcodes.T_INT;

            case LONG:    return Opcodes.T_LONG;

            case FLOAT:   return Opcodes.T_FLOAT;

            case DOUBLE:  return Opcodes.T_DOUBLE;

            case OBJECT:  return 0; // in place of Opcodes.T_OBJECT

            default:      throw new InternalError();

        }

    }

    private int arrayInsnOpcode(byte tcode, int aaop) throws InternalError {

        assert(aaop == Opcodes.AASTORE || aaop == Opcodes.AALOAD);

        int xas;

        switch (tcode) {

            case Opcodes.T_BOOLEAN: xas = Opcodes.BASTORE; break;

            case Opcodes.T_BYTE:    xas = Opcodes.BASTORE; break;

            case Opcodes.T_CHAR:    xas = Opcodes.CASTORE; break;

            case Opcodes.T_SHORT:   xas = Opcodes.SASTORE; break;

            case Opcodes.T_INT:     xas = Opcodes.IASTORE; break;

            case Opcodes.T_LONG:    xas = Opcodes.LASTORE; break;

            case Opcodes.T_FLOAT:   xas = Opcodes.FASTORE; break;

            case Opcodes.T_DOUBLE:  xas = Opcodes.DASTORE; break;

            case 0:                 xas = Opcodes.AASTORE; break;

            default:      throw new InternalError();

        }

        return xas - Opcodes.AASTORE + aaop;

    }

    /**

     * Emit a boxing call.

     *

     * @param wrapper primitive type class to box.

     */

    private void emitBoxing(Wrapper wrapper) {

        String owner = "java/lang/" + wrapper.wrapperType().getSimpleName();

        String name  = "valueOf";

        String desc  = "(" + wrapper.basicTypeChar() + ")L" + owner + ";";

        mv.visitMethodInsn(Opcodes.INVOKESTATIC, owner, name, desc, false);

    }

    /**

     * Emit an unboxing call (plus preceding checkcast).

     *

     * @param wrapper wrapper type class to unbox.

     */

    private void emitUnboxing(Wrapper wrapper) {

        String owner = "java/lang/" + wrapper.wrapperType().getSimpleName();

        String name  = wrapper.primitiveSimpleName() + "Value";

        String desc  = "()" + wrapper.basicTypeChar();

        emitReferenceCast(wrapper.wrapperType(), null);

        mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, owner, name, desc, false);

    }

    /**

     * Emit an implicit conversion for an argument which must be of the given pclass.

     * This is usually a no-op, except when pclass is a subword type or a reference other than Object or an interface.

     *

     * @param ptype type of value present on stack

     * @param pclass type of value required on stack

     * @param arg compile-time representation of value on stack (Node, constant) or null if none

     */