src/main/java/de/unixwork/uwproj/Main.java

package de.unixwork.uwproj;

import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.VelocityEngine;
import org.xml.sax.SAXException;

import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.SchemaFactory;
import java.io.*;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.nio.file.attribute.PosixFilePermissions;
import java.util.Arrays;
import java.util.Objects;

public class Main {

    public final static String IN_FILE_DEFAULT = "make/project.xml";
    public final static String TPL_FILE_DEFAULT = "make/configure.vm";
    public final static String OUT_FILE_DEFAULT = "configure";

    static Project loadProjectFile(String fileName) {
        try (final var xsdResource = Objects.requireNonNull(Main.class.getClassLoader().getResourceAsStream("make/uwproj.xsd"))) {
            // Create the XSD validator
            final var factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
            final var schema = factory.newSchema(new StreamSource(xsdResource));
            final var validator = schema.newValidator();

            // Load the DOM from the input file
            final var dom = DocumentBuilderFactory.
                    newDefaultNSInstance().
                    newDocumentBuilder().
                    parse(fileName).
                    getDocumentElement();

            // Validate the XML
            validator.validate(new DOMSource(dom));

            // Parse the XML
            return new Project(dom);
        } catch (SAXException saxerror) {
            System.err.println(saxerror.getMessage());
            throw new RuntimeException("XML validation failed.");
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    static void writeConfigureScript(Writer out, String tplFileName, Project project) {
        var context = new VelocityContext();
        context.put("targets", project.getTargets());
        context.put("namedDependencies", project.getNamedDependencies());
        context.put("dependencies", project.getDependencies());
        context.put("options", project.getOptions());
        context.put("features", project.getFeatures());
        context.put("project", project);
        context.put("vars", project.getVars());
        context.put("languages", project.getLang());
        new VelocityEngine().getTemplate(tplFileName).merge(context, out);
    }

    private static void abort() {
        System.err.println("Abort.");
        System.exit(1);
    }

    private static void printUsage() {
        System.err.println("Usage: uwproj [OPTIONS]");
        System.err.println();
        System.err.println("OPTIONS:");
        System.err.println("  -h --help              Print help text and exit");
        System.err.println("     --init              Creates default files in directory 'make'");
        System.err.println("  -o --output <file>     Path to the output file");
        System.err.printf("                         (default: %s)\n", OUT_FILE_DEFAULT);
        System.err.println("  -p --project <file>    Path to the project.xml file");
        System.err.printf("                         (default: %s)\n", IN_FILE_DEFAULT);
        System.err.println("  -t --template <file>   Path to the velocity template");
        System.err.printf("                         (default: %s)\n", TPL_FILE_DEFAULT);
        System.err.println("     --update            Same as --init, but overwrites existing files");
    }

    private static void extract(Path path) {
        try (final var res = Objects.requireNonNull(Main.class.getClassLoader().getResourceAsStream(path.toString()))) {
            Files.copy(res, path, StandardCopyOption.REPLACE_EXISTING);
        } catch (Throwable t) {
            System.err.printf("Cannot extract '%s': %s\n", path, t.getMessage());
            abort();
        }
    }

    private static void init(boolean force) {
        final var files = new String[]{
                "cc.mk", "gcc.mk", "clang.mk", "suncc.mk",
                "configure.vm", "toolchain.sh", "uwproj.xsd"
        };

        // (1) create the make dir if it does not exist
        final var make = Paths.get("make");
        if (Files.exists(make)) {
            if (!Files.isDirectory(make)) {
                System.err.println("A file with name 'make' already exists, but it's not a directory.");
                abort();
            }
            if (!force) {
                System.err.println("uwproj files already exist. You can use --update instead.");
                abort();
            }
        } else {
            try {
                Files.createDirectory(make);
            } catch (Throwable t) {
                System.err.printf("Creating directory failed: %s\n", t.getMessage());
                abort();
            }
        }

        // (2) create project.xml ONLY if it does not exist
        final var project = make.resolve("project.xml");
        if (Files.notExists(project)) {
            extract(project);
        }

        // (3) create or update remaining uwproj files
        Arrays.stream(files).map(make::resolve).forEach(Main::extract);

        // (4) stop
        System.out.printf("uwproj files %s.\n", force ? "updated" : "created");
        System.exit(0);
    }

    private static void checkOneMoreArg(int i, int length) {
        if (i+1 >= length) {
            printUsage();
            System.exit(1);
        }
    }

    public static void main(String[] args) {
        var inFileName = IN_FILE_DEFAULT;
        var tplFileName = TPL_FILE_DEFAULT;
        var outFileName = OUT_FILE_DEFAULT;
        boolean opsOptionsUsed = false;
        boolean doInit = false;
        boolean forceInit = false;

        for (int i = 0 ; i < args.length ; i++) {
            switch (args[i]) {
                case "-o":
                case "--output":
                    checkOneMoreArg(i, args.length);
                    outFileName = args[++i];
                    opsOptionsUsed = true;
                    break;
                case "-p":
                case "--project":
                    checkOneMoreArg(i, args.length);
                    inFileName = args[++i];
                    opsOptionsUsed = true;
                    break;

                case "-t":
                case "--template":
                    checkOneMoreArg(i, args.length);
                    tplFileName = args[++i];
                    opsOptionsUsed = true;
                    break;
                case "--init":
                    doInit = true;
                    break;
                case "--update":
                    doInit = true;
                    forceInit = true;
                    break;
                case "--help":
                case "-h":
                    printUsage();
                    System.exit(0);
                default:
                    printUsage();
                    System.exit(1);
            }
        }

        if (opsOptionsUsed && doInit) {
            System.err.println("Cannot use --init or --update with other options.");
            abort();
        }

        if (doInit) {
            init(forceInit);
        }

        System.out.println("In:  " + inFileName);
        System.out.println("Tpl: " + tplFileName);

        final var outFilePath = Path.of(outFileName);
        try {
            final var tmp = File.createTempFile("uwproj", null);
            try (var out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(tmp)))) {
                writeConfigureScript(out, tplFileName, loadProjectFile(inFileName));
            }
            Files.copy(tmp.toPath(), outFilePath, StandardCopyOption.REPLACE_EXISTING);
        } catch (Throwable t) {
            System.err.printf("Unexpected error: %s\n", t.getMessage());
            abort();
        }

        System.out.println("Out: " + outFileName);
        try {
            Files.setPosixFilePermissions(outFilePath, PosixFilePermissions.fromString("rwxr-xr-x"));
        } catch (Throwable t) {
            System.err.printf("WARN: Setting file permissions failed: %s\n", t.getMessage());
        }
    }
}