/*

 * Copyright (c) 2000, 2017, 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

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 */

package com.sun.tools.jdi;

import java.lang.ref.SoftReference;

import java.util.ArrayList;

import java.util.Collections;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import com.sun.jdi.AbsentInformationException;

import com.sun.jdi.LocalVariable;

import com.sun.jdi.Location;

import com.sun.jdi.VirtualMachine;

import com.sun.tools.jdi.JDWP.Method.VariableTable;

import com.sun.tools.jdi.JDWP.Method.VariableTableWithGeneric;

/**

 * Represents methods with method bodies.

 * That is, non-native non-abstract methods.

 * Private to MethodImpl.

 */

public class ConcreteMethodImpl extends MethodImpl {

    /*

     * A subset of the line number info that is softly cached

     */

    static private class SoftLocationXRefs {

        final String stratumID;                        // The stratum of this information

        final Map<Integer, List<Location>> lineMapper; // Maps line number to location(s)

        final List<Location> lineLocations;            // List of locations ordered by code index

        /*

         * Note: these do not necessarily correspond to

         * the line numbers of the first and last elements

         * in the lineLocations list. Use these only for bounds

         * checking and with lineMapper.

         */

        @SuppressWarnings("unused")

        final int lowestLine;

        @SuppressWarnings("unused")

        final int highestLine;

        SoftLocationXRefs(String stratumID, Map<Integer, List<Location>> lineMapper,

                          List<Location> lineLocations, int lowestLine, int highestLine) {

            this.stratumID = stratumID;

            this.lineMapper = Collections.unmodifiableMap(lineMapper);

            this.lineLocations = Collections.unmodifiableList(lineLocations);

            this.lowestLine = lowestLine;

            this.highestLine = highestLine;

        }

    }

    private Location location = null;

    private SoftReference<SoftLocationXRefs> softBaseLocationXRefsRef;

    private SoftReference<SoftLocationXRefs> softOtherLocationXRefsRef;

    private SoftReference<List<LocalVariable>> variablesRef = null;

    private boolean absentVariableInformation = false;

    private long firstIndex = -1;

    private long lastIndex = -1;

    private SoftReference<byte[]> bytecodesRef = null;

    private int argSlotCount = -1;

    ConcreteMethodImpl(VirtualMachine vm, ReferenceTypeImpl declaringType,

                       long ref, String name, String signature,

                       String genericSignature, int modifiers)

    {

        // The generic signature is set when this is created

        super(vm, declaringType, ref, name, signature, genericSignature, modifiers);

    }

    public Location location() {

        if (location == null) {

            getBaseLocations();

        }

        return location;

    }

    List<Location> sourceNameFilter(List<Location> list,

                                    SDE.Stratum stratum,

                                    String sourceName)

                            throws AbsentInformationException {

        if (sourceName == null) {

            return list;

        } else {

            /* needs sourceName filteration */

            List<Location> locs = new ArrayList<>();

            for (Location loc : list) {

                if (((LocationImpl)loc).sourceName(stratum).equals(sourceName)) {

                    locs.add(loc);

                }

            }

            return locs;

        }

    }

    List<Location> allLineLocations(SDE.Stratum stratum,

                                    String sourceName)

                            throws AbsentInformationException {

        List<Location> lineLocations = getLocations(stratum).lineLocations;

        if (lineLocations.size() == 0) {

            throw new AbsentInformationException();

        }

        return Collections.unmodifiableList(

            sourceNameFilter(lineLocations, stratum, sourceName));

    }

    List<Location> locationsOfLine(SDE.Stratum stratum,

                                   String sourceName,

                                   int lineNumber)

                            throws AbsentInformationException {

        SoftLocationXRefs info = getLocations(stratum);

        if (info.lineLocations.size() == 0) {

            throw new AbsentInformationException();

        }

        /*

         * Find the locations which match the line number

         * passed in.

         */

        List<Location> list = info.lineMapper.get(lineNumber);

        if (list == null) {

            list = new ArrayList<>(0);

        }

        return Collections.unmodifiableList(

            sourceNameFilter(list, stratum, sourceName));

    }

    public Location locationOfCodeIndex(long codeIndex) {

        if (firstIndex == -1) {

            getBaseLocations();

        }

        /*

         * Check for invalid code index.

         */

        if (codeIndex < firstIndex || codeIndex > lastIndex) {

            return null;

        }

        return new LocationImpl(virtualMachine(), this, codeIndex);

    }

    LineInfo codeIndexToLineInfo(SDE.Stratum stratum,

                                 long codeIndex) {

        if (firstIndex == -1) {

            getBaseLocations();

        }

        /*

         * Check for invalid code index.

         */

        if (codeIndex < firstIndex || codeIndex > lastIndex) {

            throw new InternalError("Location with invalid code index");

        }

        List<Location> lineLocations = getLocations(stratum).lineLocations;

        /*

         * Check for absent line numbers.

         */

        if (lineLocations.size() == 0) {

            return super.codeIndexToLineInfo(stratum, codeIndex);

        }

        Iterator<Location> iter = lineLocations.iterator();

        /*

         * Treat code before the beginning of the first line table

         * entry as part of the first line.  javac will generate

         * code like this for some local classes. This "prolog"

         * code contains assignments from locals in the enclosing

         * scope to synthetic fields in the local class.  Same for

         * other language prolog code.

         */

        LocationImpl bestMatch = (LocationImpl)iter.next();

        while (iter.hasNext()) {

            LocationImpl current = (LocationImpl)iter.next();

            if (current.codeIndex() > codeIndex) {

                break;

            }

            bestMatch = current;

        }

        return bestMatch.getLineInfo(stratum);

    }

    public List<LocalVariable> variables() throws AbsentInformationException {

        return getVariables();

    }

    public List<LocalVariable> variablesByName(String name) throws AbsentInformationException {

        List<LocalVariable> variables = getVariables();

        List<LocalVariable> retList = new ArrayList<>(2);

        Iterator<LocalVariable> iter = variables.iterator();

        while(iter.hasNext()) {

            LocalVariable variable = iter.next();

            if (variable.name().equals(name)) {

                retList.add(variable);

            }

        }

        return retList;

    }

    public List<LocalVariable> arguments() throws AbsentInformationException {

        List<LocalVariable> variables = getVariables();

        List<LocalVariable> retList = new ArrayList<>(variables.size());

        Iterator<LocalVariable> iter = variables.iterator();

        while(iter.hasNext()) {

            LocalVariable variable = iter.next();

            if (variable.isArgument()) {

                retList.add(variable);

            }

        }

        return retList;

    }

    public byte[] bytecodes() {

        byte[] bytecodes = (bytecodesRef == null) ? null :

                                     bytecodesRef.get();

        if (bytecodes == null) {

            try {

                bytecodes = JDWP.Method.Bytecodes.

                                 process(vm, declaringType, ref).bytes;

            } catch (JDWPException exc) {

                throw exc.toJDIException();

            }

            bytecodesRef = new SoftReference<>(bytecodes);

        }

        /*

         * Arrays are always modifiable, so it is a little unsafe

         * to return the cached bytecodes directly; instead, we

         * make a clone at the cost of using more memory.

         */

        return bytecodes.clone();

    }

    int argSlotCount() throws AbsentInformationException {

        if (argSlotCount == -1) {

            getVariables();

        }

        return argSlotCount;

    }

    private SoftLocationXRefs getLocations(SDE.Stratum stratum) {

        if (stratum.isJava()) {

            return getBaseLocations();

        }

        String stratumID = stratum.id();

        SoftLocationXRefs info =

            (softOtherLocationXRefsRef == null) ? null :

               softOtherLocationXRefsRef.get();

        if (info != null && info.stratumID.equals(stratumID)) {

            return info;

        }

        List<Location> lineLocations = new ArrayList<Location>();

        Map<Integer, List<Location>> lineMapper = new HashMap<>();

        int lowestLine = -1;

        int highestLine = -1;

        SDE.LineStratum lastLineStratum = null;

        SDE.Stratum baseStratum = declaringType.stratum(SDE.BASE_STRATUM_NAME);

        Iterator<Location> it = getBaseLocations().lineLocations.iterator();

        while(it.hasNext()) {

            LocationImpl loc = (LocationImpl)it.next();

            int baseLineNumber = loc.lineNumber(baseStratum);

            SDE.LineStratum lineStratum =

                  stratum.lineStratum(declaringType, baseLineNumber);

            if (lineStratum == null) {

                // location not mapped in this stratum

                continue;

            }

            int lineNumber = lineStratum.lineNumber();

            // remove unmapped and dup lines

            if ((lineNumber != -1) &&

                          (!lineStratum.equals(lastLineStratum))) {

                lastLineStratum = lineStratum;

                // Remember the largest/smallest line number

                if (lineNumber > highestLine) {

                    highestLine = lineNumber;

                }

                if ((lineNumber < lowestLine) || (lowestLine == -1)) {

                    lowestLine = lineNumber;

                }

                loc.addStratumLineInfo(

                    new StratumLineInfo(stratumID,

                                        lineNumber,

                                        lineStratum.sourceName(),

                                        lineStratum.sourcePath()));

                // Add to the location list

                lineLocations.add(loc);

                // Add to the line -> locations map

                Integer key = lineNumber;

                List<Location> mappedLocs = lineMapper.get(key);

                if (mappedLocs == null) {

                    mappedLocs = new ArrayList<Location>(1);

                    lineMapper.put(key, mappedLocs);

                }

                mappedLocs.add(loc);

            }

        }

        info = new SoftLocationXRefs(stratumID, lineMapper, lineLocations,

                                     lowestLine, highestLine);

        softOtherLocationXRefsRef = new SoftReference<>(info);

        return info;

    }

    private SoftLocationXRefs getBaseLocations() {

        SoftLocationXRefs info = (softBaseLocationXRefsRef == null) ? null :

                                     softBaseLocationXRefsRef.get();

        if (info != null) {

            return info;

        }

        JDWP.Method.LineTable lntab = null;

        try {

            lntab = JDWP.Method.LineTable.process(vm, declaringType, ref);

        } catch (JDWPException exc) {

            /*

             * Note: the absent info error shouldn't happen here

             * because the first and last index are always available.

             */

            throw exc.toJDIException();

        }

        int count  = lntab.lines.length;

        List<Location> lineLocations = new ArrayList<>(count);

        Map<Integer, List<Location>>lineMapper = new HashMap<>();

        int lowestLine = -1;

        int highestLine = -1;

        for (int i = 0; i < count; i++) {

            long bci = lntab.lines[i].lineCodeIndex;

            int lineNumber = lntab.lines[i].lineNumber;

            /*

             * Some compilers will point multiple consecutive

             * lines at the same location. We need to choose

             * one of them so that we can consistently map back

             * and forth between line and location. So we choose

             * to record only the last line entry at a particular

             * location.

             */

            if ((i + 1 == count) || (bci != lntab.lines[i+1].lineCodeIndex)) {

                // Remember the largest/smallest line number

                if (lineNumber > highestLine) {

                    highestLine = lineNumber;

                }

                if ((lineNumber < lowestLine) || (lowestLine == -1)) {

                    lowestLine = lineNumber;

                }

                LocationImpl loc =

                    new LocationImpl(virtualMachine(), this, bci);

                loc.addBaseLineInfo(

                    new BaseLineInfo(lineNumber, declaringType));

                // Add to the location list

                lineLocations.add(loc);

                // Add to the line -> locations map

                Integer key = lineNumber;

                List<Location> mappedLocs = lineMapper.get(key);

                if (mappedLocs == null) {

                    mappedLocs = new ArrayList<>(1);

                    lineMapper.put(key, mappedLocs);

                }

                mappedLocs.add(loc);

            }

        }

        /*

         * firstIndex, lastIndex, and startLocation need to be

         * retrieved only once since they are strongly referenced.

         */

        if (location == null) {

            firstIndex = lntab.start;

            lastIndex = lntab.end;

            /*

             * The startLocation is the first one in the

             * location list if we have one;

             * otherwise, we construct a location for a

             * method start with no line info

             */

            if (count > 0) {

                location = lineLocations.get(0);

            } else {

                location = new LocationImpl(virtualMachine(), this,

                                            firstIndex);

            }

        }

        info = new SoftLocationXRefs(SDE.BASE_STRATUM_NAME,

                                     lineMapper, lineLocations,

                                     lowestLine, highestLine);

        softBaseLocationXRefsRef = new SoftReference<SoftLocationXRefs>(info);

        return info;

    }

    private List<LocalVariable> getVariables1_4() throws AbsentInformationException {

        JDWP.Method.VariableTable vartab = null;

        try {

            vartab = JDWP.Method.VariableTable.

                                     process(vm, declaringType, ref);

        } catch (JDWPException exc) {

            if (exc.errorCode() == JDWP.Error.ABSENT_INFORMATION) {

                absentVariableInformation = true;

                throw new AbsentInformationException();

            } else {

                throw exc.toJDIException();

            }

        }

        // Get the number of slots used by argument variables

        argSlotCount = vartab.argCnt;

        int count = vartab.slots.length;

        List<LocalVariable> variables = new ArrayList<>(count);

        for (int i=0; i<count; i++) {

            JDWP.Method.VariableTable.SlotInfo si = vartab.slots[i];

            /*

             * Skip "this*" entries because they are never real

             * variables from the JLS perspective.

             */

            if (!si.name.startsWith("this$") && !si.name.equals("this")) {

                Location scopeStart = new LocationImpl(virtualMachine(),

                                                       this, si.codeIndex);

                Location scopeEnd =

                    new LocationImpl(virtualMachine(), this,

                                     si.codeIndex + si.length - 1);

                LocalVariable variable =

                    new LocalVariableImpl(virtualMachine(), this,

                                          si.slot, scopeStart, scopeEnd,

                                          si.name, si.signature, null);

                // Add to the variable list

                variables.add(variable);

            }

        }

        return variables;

    }

    private List<LocalVariable> getVariables1() throws AbsentInformationException {

        if (!vm.canGet1_5LanguageFeatures()) {

            return getVariables1_4();

        }

        JDWP.Method.VariableTableWithGeneric vartab = null;

        try {

            vartab = JDWP.Method.VariableTableWithGeneric.

                                     process(vm, declaringType, ref);

        } catch (JDWPException exc) {

            if (exc.errorCode() == JDWP.Error.ABSENT_INFORMATION) {

                absentVariableInformation = true;

                throw new AbsentInformationException();

            } else {

                throw exc.toJDIException();

            }

        }

        // Get the number of slots used by argument variables

        argSlotCount = vartab.argCnt;

        int count = vartab.slots.length;

        List<LocalVariable> variables = new ArrayList<LocalVariable>(count);

        for (int i=0; i<count; i++) {

            JDWP.Method.VariableTableWithGeneric.SlotInfo si = vartab.slots[i];

            /*

             * Skip "this*" entries because they are never real

             * variables from the JLS perspective.

             */

            if (!si.name.startsWith("this$") && !si.name.equals("this")) {

                Location scopeStart = new LocationImpl(virtualMachine(),

                                                       this, si.codeIndex);

                Location scopeEnd =

                    new LocationImpl(virtualMachine(), this,

                                     si.codeIndex + si.length - 1);

                LocalVariable variable =

                    new LocalVariableImpl(virtualMachine(), this,

                                          si.slot, scopeStart, scopeEnd,

                                          si.name, si.signature,

                                          si.genericSignature);