/*

 * 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

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 * questions.

 */

package com.sun.tools.sjavac;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.io.Writer;

import java.net.URI;

import java.nio.file.NoSuchFileException;

import java.text.SimpleDateFormat;

import java.util.Collection;

import java.util.Collections;

import java.util.Date;

import java.util.HashMap;

import java.util.HashSet;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.stream.Collectors;

import com.sun.tools.sjavac.comp.CompilationService;

import com.sun.tools.sjavac.options.Options;

import com.sun.tools.sjavac.pubapi.PubApi;

/**

 * The javac state class maintains the previous (prev) and the current (now)

 * build states and everything else that goes into the javac_state file.

 *

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 */

public class JavacState {

    // The arguments to the compile. If not identical, then it cannot

    // be an incremental build!

    String theArgs;

    // The number of cores limits how many threads are used for heavy concurrent work.

    int numCores;

    // The bin_dir/javac_state

    private File javacState;

    // The previous build state is loaded from javac_state

    private BuildState prev;

    // The current build state is constructed during the build,

    // then saved as the new javac_state.

    private BuildState now;

    // Something has changed in the javac_state. It needs to be saved!

    private boolean needsSaving;

    // If this is a new javac_state file, then do not print unnecessary messages.

    private boolean newJavacState;

    // These are packages where something has changed and the package

    // needs to be recompiled. Actions that trigger recompilation:

    // * source belonging to the package has changed

    // * artifact belonging to the package is lost, or its timestamp has been changed.

    // * an unknown artifact has appeared, we simply delete it, but we also trigger a recompilation.

    // * a package that is tainted, taints all packages that depend on it.

    private Set<String> taintedPackages;

    // After a compile, the pubapis are compared with the pubapis stored in the javac state file.

    // Any packages where the pubapi differ are added to this set.

    // Later we use this set and the dependency information to taint dependent packages.

    private Set<String> packagesWithChangedPublicApis;

    // When a module-info.java file is changed, taint the module,

    // then taint all modules that depend on that that module.

    // A module dependency can occur directly through a require, or

    // indirectly through a module that does a public export for the first tainted module.

    // When all modules are tainted, then taint all packages belonging to these modules.

    // Then rebuild. It is perhaps possible (and valuable?) to do a more finegrained examination of the

    // change in module-info.java, but that will have to wait.

    private Set<String> taintedModules;

    // The set of all packages that has been recompiled.

    // Copy over the javac_state for the packages that did not need recompilation,

    // verbatim from the previous (prev) to the new (now) build state.

    private Set<String> recompiledPackages;

    // The output directories filled with tasty artifacts.

    private File binDir, gensrcDir, headerDir, stateDir;

    // The current status of the file system.

    private Set<File> binArtifacts;

    private Set<File> gensrcArtifacts;

    private Set<File> headerArtifacts;

    // The status of the sources.

    Set<Source> removedSources = null;

    Set<Source> addedSources = null;

    Set<Source> modifiedSources = null;

    // Visible sources for linking. These are the only

    // ones that -sourcepath is allowed to see.

    Set<URI> visibleSrcs;

    // Setup transform that always exist.

    private CompileJavaPackages compileJavaPackages = new CompileJavaPackages();

    // Command line options.

    private Options options;

    JavacState(Options op, boolean removeJavacState) {

        options = op;

        numCores = options.getNumCores();

        theArgs = options.getStateArgsString();

        binDir = Util.pathToFile(options.getDestDir());

        gensrcDir = Util.pathToFile(options.getGenSrcDir());

        headerDir = Util.pathToFile(options.getHeaderDir());

        stateDir = Util.pathToFile(options.getStateDir());

        javacState = new File(stateDir, "javac_state");

        if (removeJavacState && javacState.exists()) {

            javacState.delete();

        }

        newJavacState = false;

        if (!javacState.exists()) {

            newJavacState = true;

            // If there is no javac_state then delete the contents of all the artifact dirs!

            // We do not want to risk building a broken incremental build.

            // BUT since the makefiles still copy things straight into the bin_dir et al,

            // we avoid deleting files here, if the option --permit-unidentified-classes was supplied.

            if (!options.areUnidentifiedArtifactsPermitted()) {

                deleteContents(binDir);

                deleteContents(gensrcDir);

                deleteContents(headerDir);

            }

            needsSaving = true;

        }

        prev = new BuildState();

        now = new BuildState();

        taintedPackages = new HashSet<>();

        recompiledPackages = new HashSet<>();

        packagesWithChangedPublicApis = new HashSet<>();

    }

    public BuildState prev() { return prev; }

    public BuildState now() { return now; }

    /**

     * Remove args not affecting the state.

     */

    static String[] removeArgsNotAffectingState(String[] args) {

        String[] out = new String[args.length];

        int j = 0;

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

            if (args[i].equals("-j")) {

                // Just skip it and skip following value

                i++;

            } else if (args[i].startsWith("--server:")) {

                // Just skip it.

            } else if (args[i].startsWith("--log=")) {

                // Just skip it.

            } else if (args[i].equals("--compare-found-sources")) {

                // Just skip it and skip verify file name

                i++;

            } else {

                // Copy argument.

                out[j] = args[i];

                j++;

            }

        }

        String[] ret = new String[j];

        System.arraycopy(out, 0, ret, 0, j);

        return ret;

    }

    /**

     * Specify which sources are visible to the compiler through -sourcepath.

     */

    public void setVisibleSources(Map<String,Source> vs) {

        visibleSrcs = new HashSet<>();

        for (String s : vs.keySet()) {

            Source src = vs.get(s);

            visibleSrcs.add(src.file().toURI());

        }

    }

    /**

     * Returns true if this is an incremental build.

     */

    public boolean isIncremental() {

        return !prev.sources().isEmpty();

    }

    /**

     * Find all artifacts that exists on disk.

     */

    public void findAllArtifacts() {

        binArtifacts = findAllFiles(binDir);

        gensrcArtifacts = findAllFiles(gensrcDir);

        headerArtifacts = findAllFiles(headerDir);

    }

    /**

     * Lookup the artifacts generated for this package in the previous build.

     */

    private Map<String,File> fetchPrevArtifacts(String pkg) {

        Package p = prev.packages().get(pkg);

        if (p != null) {

            return p.artifacts();

        }

        return new HashMap<>();

    }

    /**

     * Delete all prev artifacts in the currently tainted packages.

     */

    public void deleteClassArtifactsInTaintedPackages() {

        for (String pkg : taintedPackages) {

            Map<String,File> arts = fetchPrevArtifacts(pkg);

            for (File f : arts.values()) {

                if (f.exists() && f.getName().endsWith(".class")) {

                    f.delete();

                }

            }

        }

    }

    /**

     * Mark the javac_state file to be in need of saving and as a side effect,

     * it gets a new timestamp.

     */

    private void needsSaving() {

        needsSaving = true;

    }

    /**

     * Save the javac_state file.

     */

    public void save() throws IOException {

        if (!needsSaving)

            return;

        try (FileWriter out = new FileWriter(javacState)) {

            StringBuilder b = new StringBuilder();

            long millisNow = System.currentTimeMillis();

            Date d = new Date(millisNow);

            SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss SSS");

            b.append("# javac_state ver 0.4 generated "+millisNow+" "+df.format(d)+"\n");

            b.append("# This format might change at any time. Please do not depend on it.\n");

            b.append("# R arguments\n");

            b.append("# M module\n");

            b.append("# P package\n");

            b.append("# S C source_tobe_compiled timestamp\n");

            b.append("# S L link_only_source timestamp\n");

            b.append("# G C generated_source timestamp\n");

            b.append("# A artifact timestamp\n");

            b.append("# D S dependant -> source dependency\n");

            b.append("# D C dependant -> classpath dependency\n");

            b.append("# I pubapi\n");

            b.append("R ").append(theArgs).append("\n");

            // Copy over the javac_state for the packages that did not need recompilation.

            now.copyPackagesExcept(prev, recompiledPackages, new HashSet<String>());

            // Save the packages, ie package names, dependencies, pubapis and artifacts!

            // I.e. the lot.

            Module.saveModules(now.modules(), b);

            String s = b.toString();

            out.write(s, 0, s.length());

        }

    }

    /**

     * Load a javac_state file.

     */

    public static JavacState load(Options options) {

        JavacState db = new JavacState(options, false);

        Module  lastModule = null;

        Package lastPackage = null;

        Source  lastSource = null;

        boolean noFileFound = false;

        boolean foundCorrectVerNr = false;

        boolean newCommandLine = false;

        boolean syntaxError = false;

        Log.debug("Loading javac state file: " + db.javacState);

        try (BufferedReader in = new BufferedReader(new FileReader(db.javacState))) {

            for (;;) {

                String l = in.readLine();

                if (l==null) break;

                if (l.length()>=3 && l.charAt(1) == ' ') {

                    char c = l.charAt(0);

                    if (c == 'M') {

                        lastModule = db.prev.loadModule(l);

                    } else

                    if (c == 'P') {

                        if (lastModule == null) { syntaxError = true; break; }

                        lastPackage = db.prev.loadPackage(lastModule, l);

                    } else

                    if (c == 'D') {

                        if (lastModule == null || lastPackage == null) { syntaxError = true; break; }

                        char depType = l.charAt(2);

                        if (depType != 'S' && depType != 'C')

                            throw new RuntimeException("Bad dependency string: " + l);

                        lastPackage.parseAndAddDependency(l.substring(4), depType == 'C');

                    } else

                    if (c == 'I') {

                        if (lastModule == null || lastPackage == null) { syntaxError = true; break; }

                        lastPackage.getPubApi().appendItem(l.substring(2)); // Strip "I "

                    } else

                    if (c == 'A') {

                        if (lastModule == null || lastPackage == null) { syntaxError = true; break; }

                        lastPackage.loadArtifact(l);

                    } else

                    if (c == 'S') {

                        if (lastModule == null || lastPackage == null) { syntaxError = true; break; }

                        lastSource = db.prev.loadSource(lastPackage, l, false);

                    } else

                    if (c == 'G') {

                        if (lastModule == null || lastPackage == null) { syntaxError = true; break; }

                        lastSource = db.prev.loadSource(lastPackage, l, true);

                    } else

                    if (c == 'R') {

                        String ncmdl = "R "+db.theArgs;

                        if (!l.equals(ncmdl)) {

                            newCommandLine = true;

                        }

                    } else

                         if (c == '#') {

                        if (l.startsWith("# javac_state ver ")) {

                            int sp = l.indexOf(" ", 18);

                            if (sp != -1) {

                                String ver = l.substring(18,sp);

                                if (!ver.equals("0.4")) {

                    break;

                                 }

                foundCorrectVerNr = true;

                            }

                        }

                    }

                }

            }

        } catch (FileNotFoundException | NoSuchFileException e) {

            // Silently create a new javac_state file.

            noFileFound = true;

        } catch (IOException e) {

            Log.warn("Dropping old javac_state because of errors when reading it.");

            db = new JavacState(options, true);

            foundCorrectVerNr = true;

            newCommandLine = false;

            syntaxError = false;

    }

        if (foundCorrectVerNr == false && !noFileFound) {

            Log.debug("Dropping old javac_state since it is of an old version.");

            db = new JavacState(options, true);

        } else

        if (newCommandLine == true && !noFileFound) {

            Log.debug("Dropping old javac_state since a new command line is used!");

            db = new JavacState(options, true);

        } else

        if (syntaxError == true) {

            Log.warn("Dropping old javac_state since it contains syntax errors.");

            db = new JavacState(options, true);

        }

        db.prev.calculateDependents();

        return db;

    }

    /**

     * Mark a java package as tainted, ie it needs recompilation.

     */

    public void taintPackage(String name, String because) {

        if (!taintedPackages.contains(name)) {

            if (because != null) Log.debug("Tainting "+Util.justPackageName(name)+" because "+because);

            // It has not been tainted before.

            taintedPackages.add(name);

            needsSaving();

            Package nowp = now.packages().get(name);

            if (nowp != null) {

                for (String d : nowp.dependents()) {

                    taintPackage(d, because);

                }

            }

        }

    }

    /**

     * This packages need recompilation.

     */

    public Set<String> taintedPackages() {

        return taintedPackages;

    }

    /**

     * Clean out the tainted package set, used after the first round of compiles,

     * prior to propagating dependencies.

     */

    public void clearTaintedPackages() {

        taintedPackages = new HashSet<>();

    }

    /**

     * Go through all sources and check which have been removed, added or modified

     * and taint the corresponding packages.

     */

    public void checkSourceStatus(boolean check_gensrc) {

        removedSources = calculateRemovedSources();

        for (Source s : removedSources) {

            if (!s.isGenerated() || check_gensrc) {

                taintPackage(s.pkg().name(), "source "+s.name()+" was removed");

            }

        }

        addedSources = calculateAddedSources();

        for (Source s : addedSources) {

            String msg = null;

            if (isIncremental()) {

                // When building from scratch, there is no point

                // printing "was added" for every file since all files are added.

                // However for an incremental build it makes sense.

                msg = "source "+s.name()+" was added";

            }

            if (!s.isGenerated() || check_gensrc) {

                taintPackage(s.pkg().name(), msg);

            }

        }

        modifiedSources = calculateModifiedSources();

        for (Source s : modifiedSources) {

            if (!s.isGenerated() || check_gensrc) {

                taintPackage(s.pkg().name(), "source "+s.name()+" was modified");

            }

        }

    }

    /**

     * Acquire the compile_java_packages suffix rule for .java files.

     */

    public Map<String,Transformer> getJavaSuffixRule() {

        Map<String,Transformer> sr = new HashMap<>();

        sr.put(".java", compileJavaPackages);

        return sr;

    }

    /**

     * If artifacts have gone missing, force a recompile of the packages

     * they belong to.

     */

    public void taintPackagesThatMissArtifacts() {

        for (Package pkg : prev.packages().values()) {

            for (File f : pkg.artifacts().values()) {

                if (!f.exists()) {

                    // Hmm, the artifact on disk does not exist! Someone has removed it....

                    // Lets rebuild the package.

                    taintPackage(pkg.name(), ""+f+" is missing.");

                }

            }

        }

    }

    /**

     * Propagate recompilation through the dependency chains.

     * Avoid re-tainting packages that have already been compiled.

     */

    public void taintPackagesDependingOnChangedPackages(Set<String> pkgsWithChangedPubApi, Set<String> recentlyCompiled) {

        // For each to-be-recompiled-candidates...

        for (Package pkg : new HashSet<>(prev.packages().values())) {

            // Find out what it depends upon...

            Set<String> deps = pkg.typeDependencies()

                                  .values()

                                  .stream()

                                  .collect(Collectors.toSet());

            for (String dep : deps) {

                String depPkg = ":" + dep.substring(0, dep.lastIndexOf('.'));

                if (depPkg.equals(pkg.name()))

                    continue;

                // Checking if that dependency has changed

                if (pkgsWithChangedPubApi.contains(depPkg) && !recentlyCompiled.contains(pkg.name())) {

                    taintPackage(pkg.name(), "its depending on " + depPkg);

                }

            }

        }

    }

    /**

     * Compare the javac_state recorded public apis of packages on the classpath

     * with the actual public apis on the classpath.

     */

    public void taintPackagesDependingOnChangedClasspathPackages() throws IOException {

        // 1. Collect fully qualified names of all interesting classpath dependencies

        Set<String> fqDependencies = new HashSet<>();

        for (Package pkg : prev.packages().values()) {

            // Check if this package was compiled. If it's presence is recorded

            // because it was on the class path and we needed to save it's

            // public api, it's not a candidate for tainting.

            if (pkg.sources().isEmpty())