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/*
 * Copyright © 2015 Stefan Niederhauser ([email protected])
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package guru.nidi.graphviz.engine;

import guru.nidi.graphviz.service.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.annotation.Nullable;
import java.io.*;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.TimeUnit;

import static guru.nidi.graphviz.engine.GraphvizLoader.isOnClasspath;
import static guru.nidi.graphviz.service.CommandRunner.isExecutableFile;
import static guru.nidi.graphviz.service.CommandRunner.isExecutableFound;
import static guru.nidi.graphviz.service.SystemUtils.pathOf;
import static java.util.Locale.ENGLISH;

/**
 * Engine that tries to parse the dot file using the GraphvizEngine installed on the host.
 *
 * @author daank
 */
public class GraphvizCmdLineEngine extends AbstractGraphvizEngine {
    private static final Logger LOG = LoggerFactory.getLogger(AbstractGraphvizEngine.class);
    static final boolean AVAILABLE = isOnClasspath("org/apache/commons/exec/CommandLine.class");

    @Nullable
    private final String executable;
    private final String envPath;
    private final CommandRunner cmdRunner;

    @Nullable
    private String outputFilePath;
    @Nullable
    private String outputFileName;

    public GraphvizCmdLineEngine() {
        this(null, Optional.ofNullable(System.getenv("PATH")).orElse(""), runner(defaultExecutor()));
    }

    public GraphvizCmdLineEngine(String executable) {
        this(executable, Optional.ofNullable(System.getenv("PATH")).orElse(""), runner(defaultExecutor()));
    }

    private GraphvizCmdLineEngine(@Nullable String executable, String envPath, CommandRunner cmdRunner) {
        super(true);
        this.executable = executable;
        this.envPath = envPath;
        this.cmdRunner = cmdRunner;
    }

    public GraphvizCmdLineEngine searchPath(String path) {
        return new GraphvizCmdLineEngine(executable, path, cmdRunner);
    }

    public GraphvizCmdLineEngine executor(CommandLineExecutor executor) {
        return new GraphvizCmdLineEngine(executable, envPath, runner(executor));
    }

    private static CommandRunner runner(CommandLineExecutor executor) {
        return new CommandBuilder()
                .withShellWrapper(true)
                .withCommandExecutor(executor)
                .build();
    }

    private static CommandLineExecutor defaultExecutor() {
        if (!AVAILABLE) {
            throw new MissingDependencyException("Command line engine is not available.",
                    "org.apache.commons:commons-exec");
        }
        return new CommandLineExecutor();
    }

    @SuppressWarnings("unchecked")
    public GraphvizCmdLineEngine timeout(int amount, TimeUnit unit) {
        return super.timeout(amount, unit);
    }

    @Override
    protected void doInit() {
        getEngineExecutable();
    }

    @Override
    public EngineResult execute(String src, Options options, Rasterizer rasterizer) {
        try {
            final Path path = Files.createTempDirectory(getOrCreateTempDirectory().toPath(), "DotEngine");
            final File dotFile = getDotFile(path);
            try (final BufferedWriter bw = new BufferedWriter(
                    new OutputStreamWriter(new FileOutputStream(dotFile), StandardCharsets.UTF_8))) {
                bw.write(preprocessCode(src, options));
            }
            return doExecute(path, dotFile, options, rasterizer);
        } catch (IOException | InterruptedException e) {
            throw new GraphvizException(e.getMessage(), e);
        }
    }

    private EngineResult doExecute(Path path, File dotFile, Options options, Rasterizer rasterizer)
            throws IOException, InterruptedException {
        final String format = getFormatName(options.format, rasterizer);
        final String command = getEngineExecutable()
                + (options.yInvert != null && options.yInvert ? " -y" : "")
                + " -K" + options.engine.toString().toLowerCase(ENGLISH)
                + " -T" + format
                + " " + dotFile.getAbsolutePath() + " -ooutfile." + format;
        cmdRunner.exec(command, path.toFile(), timeout);
        final Path outFile = path.resolve("outfile." + format);
        if (rasterizer instanceof BuiltInRasterizer) {
            return EngineResult.fromFile(outFile.toFile());
        }
        final byte[] data = Files.readAllBytes(outFile);
        return EngineResult.fromString(new String(data, StandardCharsets.UTF_8));
    }

    protected String preprocessCode(String src, Options options) {
        final String imgReplaced = replacePaths(src, IMG_SRC, path -> replacePath(path, options.basedir));
        return replacePaths(imgReplaced, IMAGE_ATTR, path -> replacePath(path, options.basedir));
    }

    private String getEngineExecutable() {
        if (executable != null) {
            if (isExecutableFile(pathOf(executable)) || isExecutableFound(executable, envPath)) {
                return executable;
            }
            LOG.warn("Executable '" + executable + "' not found directly and not on PATH. Trying with 'dot'.");
        }
        final List exes = SystemUtils.executableNames("dot");
        for (final String exe : exes) {
            if (isExecutableFound(exe, envPath)) {
                return exe;
            }
        }
        final GraphvizException e = new GraphvizException(exes + " command not found");
        e.setStackTrace(new StackTraceElement[0]);
        throw e;
    }

    private String getFormatName(Format format, Rasterizer rasterizer) {
        if (rasterizer instanceof BuiltInRasterizer) {
            final BuiltInRasterizer natRast = (BuiltInRasterizer) rasterizer;
            String f = natRast.format;
            if (natRast.renderer != null) {
                f += ":" + natRast.renderer;
            }
            if (natRast.formatter != null) {
                f += ":" + natRast.formatter;
            }
            return f;
        }
        return format.vizName;
    }

    private File getOrCreateTempDirectory() {
        final File tempDir = new File(System.getProperty("java.io.tmpdir") + File.separator + "GraphvizJava");
        if (!tempDir.exists() && tempDir.mkdir()) {
            LOG.debug("Created GraphvizJava temporary directory");
        }
        return tempDir;
    }

    private File getDotFile(Path path) {
        final String dotFileName = outputFileName == null ? "dotfile.dot" : outputFileName + ".dot";
        final String baseDir = outputFilePath == null ? path.toString() : outputFilePath;
        return new File(baseDir, dotFileName);
    }

    public void setDotOutputFile(String path, String name) {
        outputFilePath = path;
        outputFileName = name;
    }
}