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.slf4j.LoggerFactory;

import java.io.*;

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 {
            return new Project(new File(fileName));
        } 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 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("  -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);
    }

    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;

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

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

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

        try (var out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(outFileName)))) {
            writeConfigureScript(out, tplFileName, loadProjectFile(inFileName));
        } catch (Exception ex) {
            LoggerFactory.getLogger(Main.class).error(
                    "Uncaught Exception",
                    ex
            );
        }

        System.out.println("Out: " + outFileName);
    }
}