/*
 * Copyright (c) 2010, 2013, 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 jdk.nashorn.internal.codegen;

import static jdk.nashorn.internal.codegen.CompilerConstants.CONSTANTS;
import static jdk.nashorn.internal.codegen.CompilerConstants.DEFAULT_SCRIPT_NAME;
import static jdk.nashorn.internal.codegen.CompilerConstants.LAZY;
import static jdk.nashorn.internal.codegen.CompilerConstants.SCOPE;
import static jdk.nashorn.internal.codegen.CompilerConstants.SOURCE;
import static jdk.nashorn.internal.codegen.CompilerConstants.THIS;

import java.io.File;
import java.lang.reflect.Field;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Arrays;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.logging.Level;
import jdk.internal.dynalink.support.NameCodec;
import jdk.nashorn.internal.codegen.ClassEmitter.Flag;
import jdk.nashorn.internal.codegen.types.Type;
import jdk.nashorn.internal.ir.FunctionNode;
import jdk.nashorn.internal.ir.FunctionNode.CompilationState;
import jdk.nashorn.internal.ir.Node;
import jdk.nashorn.internal.ir.visitor.NodeVisitor;
import jdk.nashorn.internal.runtime.CodeInstaller;
import jdk.nashorn.internal.runtime.DebugLogger;
import jdk.nashorn.internal.runtime.ScriptEnvironment;
import jdk.nashorn.internal.runtime.Source;
import jdk.nashorn.internal.runtime.Timing;
import jdk.nashorn.internal.runtime.options.Options;

/**
 * Responsible for converting JavaScripts to java byte code. Main entry
 * point for code generator. The compiler may also install classes given some
 * predefined Code installation policy, given to it at construction time.
 * @see CodeInstaller
 */
public final class Compiler {

    /** Name of the scripts package */
    public static final String SCRIPTS_PACKAGE = "jdk/nashorn/internal/scripts";

    /** Name of the objects package */
    public static final String OBJECTS_PACKAGE = "jdk/nashorn/internal/objects";

    private final Map<String, byte[]> bytecode;

    private final Set<CompileUnit> compileUnits;

    private final ConstantData constantData;

    private final FunctionNode functionNode;

    private final CompilationSequence sequence;

    private final ScriptEnvironment env;

    private final String scriptName;

    private boolean strict;

    private CodeInstaller<ScriptEnvironment> installer;

    /** logger for compiler, trampolines, splits and related code generation events
     *  that affect classes */
    public static final DebugLogger LOG = new DebugLogger("compiler");

    /**
     * This array contains names that need to be reserved at the start
     * of a compile, to avoid conflict with variable names later introduced.
     * See {@link CompilerConstants} for special names used for structures
     * during a compile.
     */
    private static String[] RESERVED_NAMES = {
        SCOPE.tag(),
        THIS.tag()
    };

    /**
     * This class makes it possible to do your own compilation sequence
     * from the code generation package. There are predefined compilation
     * sequences already
     */
    @SuppressWarnings("serial")
    static class CompilationSequence extends LinkedList<CompilationPhase> {

        CompilationSequence(final CompilationPhase... phases) {
            super(Arrays.asList(phases));
        }

        CompilationSequence(final CompilationSequence sequence) {
            this(sequence.toArray(new CompilationPhase[sequence.size()]));
        }

        CompilationSequence insertAfter(final CompilationPhase phase, final CompilationPhase newPhase) {
            final CompilationSequence newSeq = new CompilationSequence();
            for (final CompilationPhase elem : this) {
                newSeq.add(phase);
                if (elem.equals(phase)) {
                    newSeq.add(newPhase);
                }
            }
            assert newSeq.contains(newPhase);
            return newSeq;
        }

        CompilationSequence insertBefore(final CompilationPhase phase, final CompilationPhase newPhase) {
            final CompilationSequence newSeq = new CompilationSequence();
            for (final CompilationPhase elem : this) {
                if (elem.equals(phase)) {
                    newSeq.add(newPhase);
                }
                newSeq.add(phase);
            }
            assert newSeq.contains(newPhase);
            return newSeq;
        }

        CompilationSequence insertFirst(final CompilationPhase phase) {
            final CompilationSequence newSeq = new CompilationSequence(this);
            newSeq.addFirst(phase);
            return newSeq;
        }

        CompilationSequence insertLast(final CompilationPhase phase) {
            final CompilationSequence newSeq = new CompilationSequence(this);
            newSeq.addLast(phase);
            return newSeq;
        }
    }

    /**
     * Standard (non-lazy) compilation, that basically will take an entire script
     * and JIT it at once. This can lead to long startup time and fewer type
     * specializations
     */
    final static CompilationSequence SEQUENCE_EAGER = new CompilationSequence(
        CompilationPhase.CONSTANT_FOLDING_PHASE,
        CompilationPhase.LOWERING_PHASE,
        CompilationPhase.ATTRIBUTION_PHASE,
        CompilationPhase.SPLITTING_PHASE,
        CompilationPhase.TYPE_FINALIZATION_PHASE,
        CompilationPhase.BYTECODE_GENERATION_PHASE);

    final static CompilationSequence SEQUENCE_LAZY =
        SEQUENCE_EAGER.insertFirst(CompilationPhase.LAZY_INITIALIZATION_PHASE);

    private static CompilationSequence sequence(final boolean lazy) {
        return lazy ? SEQUENCE_LAZY : SEQUENCE_EAGER;
    }

    boolean isLazy() {
        return sequence == SEQUENCE_LAZY;
    }

    private static String lazyTag(final FunctionNode functionNode) {
        if (functionNode.isLazy()) {
            return '$' + LAZY.tag() + '$' + functionNode.getName();
        }
        return "";
    }

    /**
     * Constructor
     *
     * @param installer    code installer
     * @param functionNode function node (in any available {@link CompilationState}) to compile
     * @param sequence     {@link Compiler#CompilationSequence} of {@link CompilationPhase}s to apply as this compilation
     * @param strict       should this compilation use strict mode semantics
     */
    //TODO support an array of FunctionNodes for batch lazy compilation
    Compiler(final ScriptEnvironment env, final CodeInstaller<ScriptEnvironment> installer, final FunctionNode functionNode, final CompilationSequence sequence, final boolean strict) {
        this.env           = env;
        this.functionNode  = functionNode;
        this.sequence      = sequence;
        this.installer     = installer;
        this.strict        = strict || functionNode.isStrictMode();
        this.constantData  = new ConstantData();
        this.compileUnits  = new HashSet<>();
        this.bytecode      = new HashMap<>();

        final StringBuilder sb = new StringBuilder();
        sb.append(functionNode.uniqueName(DEFAULT_SCRIPT_NAME.tag() + lazyTag(functionNode))).
                append('$').
                append(safeSourceName(functionNode.getSource()));

        this.scriptName = sb.toString();
    }

    /**
     * Constructor
     *
     * @param installer    code installer
     * @param functionNode function node (in any available {@link CompilationState}) to compile
     * @param strict       should this compilation use strict mode semantics
     */
    public Compiler(final CodeInstaller<ScriptEnvironment> installer, final FunctionNode functionNode, final boolean strict) {
        this(installer.getOwner(), installer, functionNode, sequence(installer.getOwner()._lazy_compilation), strict);
    }

    /**
     * Constructor - compilation will use the same strict semantics as in script environment
     *
     * @param installer    code installer
     * @param functionNode function node (in any available {@link CompilationState}) to compile
     */
    public Compiler(final CodeInstaller<ScriptEnvironment> installer, final FunctionNode functionNode) {
        this(installer.getOwner(), installer, functionNode, sequence(installer.getOwner()._lazy_compilation), installer.getOwner()._strict);
    }

    /**
     * Constructor - compilation needs no installer, but uses a script environment
     * Used in "compile only" scenarios
     * @param env a script environment
     * @param functionNode functionNode to compile
     */
    public Compiler(final ScriptEnvironment env, final FunctionNode functionNode) {
        this(env, null, functionNode, sequence(env._lazy_compilation), env._strict);
    }

    /**
     * Execute the compilation this Compiler was created with
     * @params param types if known, for specialization
     * @throws CompilationException if something goes wrong
     * @return this compiler, for possible chaining
     */
    public Compiler compile() throws CompilationException {
        return compile(null);
    }

    /**
     * Execute the compilation this Compiler was created with
     * @param paramTypes param types if known, for specialization
     * @throws CompilationException if something goes wrong
     * @return this compiler, for possible chaining
     */
    public Compiler compile(final Class<?> paramTypes) throws CompilationException {
        for (final String reservedName : RESERVED_NAMES) {
            functionNode.uniqueName(reservedName);
        }

        final boolean fine = !LOG.levelAbove(Level.FINE);
        final boolean info = !LOG.levelAbove(Level.INFO);

        long time = 0L;

        for (final CompilationPhase phase : sequence) {
            phase.apply(this, functionNode);

            final long duration = Timing.isEnabled() ? (phase.getEndTime() - phase.getStartTime()) : 0L;
            time += duration;

            if (fine) {
                final StringBuilder sb = new StringBuilder();

                sb.append(phase.toString()).
                    append(" done for function '").
                    append(functionNode.getName()).
                    append('\'');

                if (duration > 0L) {
                    sb.append(" in ").
                        append(duration).
                        append(" ms ");
                }

                LOG.fine(sb.toString());
            }
        }

        if (info) {
            final StringBuilder sb = new StringBuilder();
            sb.append("Compile job for '").
                append(functionNode.getName()).
                append("' finished");

            if (time > 0L) {
                sb.append(" in ").
                    append(time).
                    append(" ms");
            }

            LOG.info(sb.toString());
        }

        return this;
    }

    private Class<?> install(final String className, final byte[] code) {
        LOG.fine("Installing class " + className);

        final Class<?> clazz = installer.install(Compiler.binaryName(className), code);

        try {
            final Source   source    = getSource();
            final Object[] constants = getConstantData().toArray();
            // Need doPrivileged because these fields are private
            AccessController.doPrivileged(new PrivilegedExceptionAction<Void>() {
                @Override
                public Void run() throws Exception {
                    //use reflection to write source and constants table to installed classes
                    final Field sourceField    = clazz.getDeclaredField(SOURCE.tag());
                    final Field constantsField = clazz.getDeclaredField(CONSTANTS.tag());
                    sourceField.setAccessible(true);
                    constantsField.setAccessible(true);
                    sourceField.set(null, source);
                    constantsField.set(null, constants);
                    return null;
                }
            });
        } catch (final PrivilegedActionException e) {
            throw new RuntimeException(e);
        }

        return clazz;
    }

    /**
     * Install compiled classes into a given loader
     * @return root script class - if there are several compile units they will also be installed
     */
    public Class<?> install() {
        final long t0 = Timing.isEnabled() ? System.currentTimeMillis() : 0L;

        assert functionNode.hasState(CompilationState.EMITTED) : functionNode.getName() + " has no bytecode and cannot be installed";

        final Map<String, Class<?>> installedClasses = new HashMap<>();

        final String   rootClassName = firstCompileUnitName();
        final byte[]   rootByteCode  = bytecode.get(rootClassName);
        final Class<?> rootClass     = install(rootClassName, rootByteCode);

        int length = rootByteCode.length;

        installedClasses.put(rootClassName, rootClass);

        for (final Entry<String, byte[]> entry : bytecode.entrySet()) {
            final String className = entry.getKey();
            if (className.equals(rootClassName)) {
                continue;
            }
            final byte[] code = entry.getValue();
            length += code.length;

            installedClasses.put(className, install(className, code));
        }

        for (final CompileUnit unit : compileUnits) {
            unit.setCode(installedClasses.get(unit.getUnitClassName()));
        }

        functionNode.accept(new NodeVisitor() {
            @Override
            public Node enterFunctionNode(final FunctionNode node) {
                if (node.isLazy()) {
                    return null;
                }
                node.setState(CompilationState.INSTALLED);
                return node;
            }
        });

        final StringBuilder sb;
        if (LOG.isEnabled()) {
            sb = new StringBuilder();
            sb.append("Installed class '").
                append(rootClass.getSimpleName()).
                append('\'').
                append(" bytes=").
                append(length).
                append('.');
            if (bytecode.size() > 1) {
                sb.append(' ').append(bytecode.size()).append(" compile units.");
            }
        } else {
            sb = null;
        }

        if (Timing.isEnabled()) {
            final long duration = System.currentTimeMillis() - t0;
            Timing.accumulateTime("[Code Installation]", duration);
            if (sb != null) {
                sb.append(" Install time: ").append(duration).append(" ms");
            }
        }

        if (sb != null) {
            LOG.info(sb.toString());
        }

        return rootClass;
    }

    Set<CompileUnit> getCompileUnits() {
        return compileUnits;
    }

    boolean getStrictMode() {
        return strict;
    }

    void setStrictMode(final boolean strict) {
        this.strict = strict;
    }

    FunctionNode getFunctionNode() {
        return functionNode;
    }

    ConstantData getConstantData() {
        return constantData;
    }

    CodeInstaller<ScriptEnvironment> getCodeInstaller() {
        return installer;
    }

    Source getSource() {
        return functionNode.getSource();
    }

    void addClass(final String name, final byte[] code) {
        bytecode.put(name, code);
    }

    ScriptEnvironment getEnv() {
        return this.env;
    }

    private static String safeSourceName(final Source source) {
        String baseName = new File(source.getName()).getName();

        final int index = baseName.lastIndexOf(".js");
        if (index != -1) {
            baseName = baseName.substring(0, index);
        }

        baseName = baseName.replace('.', '_').replace('-', '_');
        final String mangled = NameCodec.encode(baseName);

        return mangled != null ? mangled : baseName;
    }

    private int nextCompileUnitIndex() {
        return compileUnits.size() + 1;
    }

    String firstCompileUnitName() {
        return SCRIPTS_PACKAGE + '/' + scriptName;
    }

    private String nextCompileUnitName() {
        return firstCompileUnitName() + '$' + nextCompileUnitIndex();
    }

    CompileUnit addCompileUnit(final long initialWeight) {
        return addCompileUnit(nextCompileUnitName(), initialWeight);
    }

    CompileUnit addCompileUnit(final String unitClassName) {
        return addCompileUnit(unitClassName, 0L);
    }

    private CompileUnit addCompileUnit(final String unitClassName, final long initialWeight) {
        final CompileUnit compileUnit = initCompileUnit(unitClassName, initialWeight);
        compileUnits.add(compileUnit);
        LOG.fine("Added compile unit " + compileUnit);
        return compileUnit;
    }

    private CompileUnit initCompileUnit(final String unitClassName, final long initialWeight) {
        final ClassEmitter classEmitter = new ClassEmitter(env, functionNode.getSource().getName(), unitClassName, strict);
        final CompileUnit  compileUnit  = new CompileUnit(unitClassName, classEmitter, initialWeight);

        classEmitter.begin();

        final MethodEmitter initMethod = classEmitter.init(EnumSet.of(Flag.PRIVATE));
        initMethod.begin();
        initMethod.load(Type.OBJECT, 0);
        initMethod.newInstance(jdk.nashorn.internal.scripts.JS.class);
        initMethod.returnVoid();
        initMethod.end();

        return compileUnit;
    }

    CompileUnit findUnit(final long weight) {
        for (final CompileUnit unit : compileUnits) {
            if (unit.canHold(weight)) {
                unit.addWeight(weight);
                return unit;
            }
        }

        return addCompileUnit(weight);
    }

    /**
     * Convert a package/class name to a binary name.
     *
     * @param name Package/class name.
     * @return Binary name.
     */
    public static String binaryName(final String name) {
        return name.replace('/', '.');
    }

    /**
     * Should we use integers for arithmetic operations as well?
     * TODO: We currently generate no overflow checks so this is
     * disabled
     *
     * @return true if arithmetic operations should not widen integer
     *   operands by default.
     */
    static boolean shouldUseIntegerArithmetic() {
        return USE_INT_ARITH;
    }

    private static final boolean USE_INT_ARITH;

    static {
        USE_INT_ARITH  =  Options.getBooleanProperty("nashorn.compiler.intarithmetic");
        assert !USE_INT_ARITH : "Integer arithmetic is not enabled";
    }


}