/*
 * Copyright (c) 2014, 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
 * questions.
 */
package com.oracle.svm.hosted.c;

import static com.oracle.svm.core.util.VMError.shouldNotReachHere;
import static java.nio.file.FileVisitResult.CONTINUE;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.List;

import com.oracle.svm.core.SubstrateUtil;
import org.graalvm.collections.UnmodifiableEconomicMap;
import org.graalvm.compiler.options.Option;

import com.oracle.svm.core.option.HostedOptionKey;
import com.oracle.svm.core.option.SubstrateOptionsParser;
import com.oracle.svm.core.util.UserError;
import com.oracle.svm.hosted.c.info.NativeCodeInfo;
import com.oracle.svm.hosted.c.query.QueryResultParser;
import org.graalvm.compiler.options.OptionKey;
import org.graalvm.compiler.options.OptionValues;
import org.graalvm.nativeimage.ImageSingletons;
import org.graalvm.nativeimage.Platform;

Cache of pre-computed information for the CAnnotationProcessor. The cache is helpful to cut substantially the time to build of an svm image, when many CAnnotation are being used. This is the case, namely for Walnut, when the compilation time to generate the information for the C processor is by far the dominant cost. For simplicity, the cache cannot be updated: it can be re-created from scratch, or used. The two options are mutually exclusive, and the re-creation of the cache erase all previously cached information. responsibility for the accuracy of the cached content is up to the end user. A CAP cache is just a directory with a file for each NativeCodeInfo, where the file is pretty much the output of the "query" program generated by the CAnnotationProcessor. /**
 * Cache of pre-computed information for the {@link CAnnotationProcessor}. The cache is helpful to
 * cut substantially the time to build of an svm image, when many CAnnotation are being used. This
 * is the case, namely for Walnut, when the compilation time to generate the information for the C
 * processor is by far the dominant cost.
 *
 * For simplicity, the cache cannot be updated: it can be re-created from scratch, or used. The two
 * options are mutually exclusive, and the re-creation of the cache erase all previously cached
 * information. responsibility for the accuracy of the cached content is up to the end user.
 *
 * A CAP cache is just a directory with a file for each {@link NativeCodeInfo}, where the file is
 * pretty much the output of the "query" program generated by the CAnnotationProcessor.
 *
 */
public final class CAnnotationProcessorCache {
    private static final String FILE_EXTENSION = ".cap";

    public static class Options {
        @Option(help = "Indicate the C Annotation Processor to use previously cached native information when generating C Type information.")//
        public static final HostedOptionKey<Boolean> UseCAPCache = new HostedOptionKey<Boolean>(false) {
            @Override
            public Boolean getValueOrDefault(UnmodifiableEconomicMap<OptionKey<?>, Object> values) {
                if (!values.containsKey(this)) {
                    // If user hasn't specified this option, we should determine optimal default
                    // value.
                    if (!ExitAfterQueryCodeGeneration.getValue() && !ImageSingletons.lookup(Platform.class).getArchitecture().equals(SubstrateUtil.getArchitectureName())) {
                        // If query code generation isn't explicitly requested, and we are running
                        // cross-arch build, CAP cache should be required (since we cannot run query
                        // code).
                        return true;
                    } else {
                        return false;
                    }
                }
                return (Boolean) values.get(this);
            }

            @Override
            public Boolean getValue(OptionValues values) {
                assert checkDescriptorExists();
                return getValueOrDefault(values.getMap());
            }
        };

        @Option(help = "Create a C Annotation Processor Cache. Will erase any previous cache at that same location.")//
        public static final HostedOptionKey<Boolean> NewCAPCache = new HostedOptionKey<>(false);

        @Option(help = "Directory where information generated by the CAnnotation Processor are cached.")//
        public static final HostedOptionKey<String> CAPCacheDir = new HostedOptionKey<>("");

        @Option(help = "Exit image generation after C Annotation Processor Cache creation.")//
        public static final HostedOptionKey<Boolean> ExitAfterCAPCache = new HostedOptionKey<>(false);

        @Option(help = "Output query code for target platform without executing it")//
        public static final HostedOptionKey<Boolean> ExitAfterQueryCodeGeneration = new HostedOptionKey<>(false);

        @Option(help = "Directory where query code for target platform should be output")//
        public static final HostedOptionKey<String> QueryCodeDir = new HostedOptionKey<>("");
    }

    private File cache;
    private File query;

    public CAnnotationProcessorCache() {
        if ((Options.UseCAPCache.getValue() || Options.NewCAPCache.getValue())) {
            if (!Options.ExitAfterQueryCodeGeneration.getValue() &&
                            (Options.CAPCacheDir.getValue() == null || Options.CAPCacheDir.getValue().isEmpty())) {
                throw UserError.abort("Path to C Annotation Processor Cache must be specified using %s when the option %s or %s is used.",
                                SubstrateOptionsParser.commandArgument(Options.CAPCacheDir, ""), SubstrateOptionsParser.commandArgument(Options.UseCAPCache, "+"),
                                SubstrateOptionsParser.commandArgument(Options.NewCAPCache, "+"));
            }
            Path cachePath = FileSystems.getDefault().getPath(Options.CAPCacheDir.getValue()).toAbsolutePath();
            cache = cachePath.toFile();
            if (!cache.exists()) {
                try {
                    cache = Files.createDirectories(cachePath).toFile();
                } catch (IOException e) {
                    throw UserError.abort("Could not create C Annotation Processor Cache directory: %s", e.getMessage());
                }
            } else if (!cache.isDirectory()) {
                throw UserError.abort("Path to C Annotation Processor Cache is not a directory");
            } else if (Options.NewCAPCache.getValue()) {
                clearCache();
            }
        }

        if (Options.QueryCodeDir.hasBeenSet()) {
            Path queryPath = FileSystems.getDefault().getPath(Options.QueryCodeDir.getValue()).toAbsolutePath();
            query = queryPath.toFile();
            if (!query.exists()) {
                try {
                    query = Files.createDirectories(queryPath).toFile();
                } catch (IOException e) {
                    throw UserError.abort("Could not create query code directory: %s", e.getMessage());
                }
            } else if (!query.isDirectory()) {
                throw UserError.abort("Path to query code directory is not a directory");
            }
        } else if (Options.ExitAfterQueryCodeGeneration.hasBeenSet()) {
            throw UserError.abort("Query code directory wasn't specified, use %s option.", SubstrateOptionsParser.commandArgument(Options.QueryCodeDir, "PATH"));
        }
    }

    private static String toPath(NativeCodeInfo nativeCodeInfo) {
        return nativeCodeInfo.getName().replaceAll("\\W", "_").concat(FILE_EXTENSION);
    }

    public void get(NativeLibraries nativeLibs, NativeCodeInfo nativeCodeInfo) {
        File file = new File(cache, toPath(nativeCodeInfo));
        try (FileInputStream fis = new FileInputStream(file)) {
            QueryResultParser.parse(nativeLibs, nativeCodeInfo, fis);
        } catch (IOException e) {
            throw UserError.abort("Could not load CAPCache file. Ensure that options %s and %s are used on the same version of your application. Raw error: %s",
                            Options.UseCAPCache.getName(), Options.NewCAPCache, e.getMessage());
        }
    }

    public void put(NativeCodeInfo nativeCodeInfo, List<String> lines) {
        if (!Options.NewCAPCache.getValue()) {
            return;
        }
        File cachedItem = new File(cache, toPath(nativeCodeInfo));
        try (FileWriter writer = new FileWriter(cachedItem, true)) {
            for (String line : lines) {
                writer.write(line);
                writer.write(Character.LINE_SEPARATOR);
            }
            return;
        } catch (IOException e) {
            throw shouldNotReachHere("Invalid CAnnotation Processor Cache item:" + cachedItem.toString());
        }
    }

    private void clearCache() {
        try {
            final Path cachePath = cache.toPath();
            Files.walkFileTree(cachePath, new SimpleFileVisitor<Path>() {
                @Override
                public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
                    assert file.toString().endsWith(FILE_EXTENSION);
                    Files.delete(file);
                    return CONTINUE;
                }

                @Override
                public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
                    if (!dir.equals(cachePath)) {
                        Files.delete(dir);
                    }
                    return CONTINUE;
                }
            });
        } catch (IOException eio) {
            throw shouldNotReachHere(eio);
        }
    }
}