Rewrite some error messages for wrong argument amounts

The modularization file was heavily interfering with the addition and usage of the commons-cli
dependency which does not have a static module name.

Since the benefits it gave this very small application were miniscule, I have decided to
delete / comment out all relevant configuration

build.gradle.kts

@@ -13,7 +13,7 @@ repositories {
 }
 
 dependencies {
-    implementation(group="org.apache", name="commons-cli", version="1.5.0")
+    implementation(group="commons-cli", name="commons-cli", version="1.5.0")
 }
 
 fun versionBanner(): String {
@@ -40,8 +40,8 @@ tasks.jar {
         attributes(
             "Implementation-Title" to project.name,
             "Implementation-Version" to project.version,
-            "Main-Class" to "de.jotoho.waituntil.Main",
-            "Main-Module" to "de.jotoho.waituntil.main"
+            "Main-Class" to "de.jotoho.waituntil.Main"
+            //"Main-Module" to "de.jotoho.waituntil.main"
         )
     }
 }
@@ -49,5 +49,5 @@ tasks.jar {
 application {
     // Define the main class for the application.
     mainClass.set("de.jotoho.waituntil.Main")
-    mainModule.set("de.jotoho.waituntil.main")
+    //mainModule.set("de.jotoho.waituntil.main")
 }

src/main/java/de/jotoho/waituntil/AppOptions.java

@@ -0,0 +1,23 @@
+package de.jotoho.waituntil;
+
+import org.apache.commons.cli.Option;
+import org.apache.commons.cli.Options;
+
+final class AppOptions {
+    // Disable Instance Creation
+    private AppOptions() {}
+
+    public final static Option help =
+        Option.builder().argName("h").longOpt("help").desc("Shows this help " +
+            "message and exits").build();
+    public final static Option version =
+        Option.builder().argName("v").longOpt("version").desc("Shows version information and exits").build();
+
+    private final static Options options = new Options()
+                                            .addOption(help)
+                                            .addOption(version);
+
+    public static Options getOptions() {
+        return options;
+    }
+}

src/main/java/de/jotoho/waituntil/Main.java

@@ -18,8 +18,8 @@ package de.jotoho.waituntil;
     along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
-import java.util.HashSet;
-import java.util.Map;
+import org.apache.commons.cli.DefaultParser;
+import org.apache.commons.cli.ParseException;
 
 import static de.jotoho.waituntil.GlobalConf.applicationOutputLanguage;
 
@@ -28,53 +28,67 @@ import static de.jotoho.waituntil.GlobalConf.applicationOutputLanguage;
 // Author: Jonas Tobias Hopusch (@jotoho)
 
 public final class Main {
-    public static void main(final String[] args) {
-        final var optionDictionary = Map.of("-h", "--help", "-v", "--version");
 
-        final var options = new HashSet<String>();
-        final var words = new HashSet<String>();
+    private static void printVersionInformation() {
+        final var thisPackage = Main.class.getPackage();
+        final var appVersion = thisPackage.getImplementationVersion() != null ? thisPackage.getImplementationVersion() : "version unknown";
+        System.out.println("waituntil " + appVersion);
+        System.out.println("""
 
-        for (final String arg : args) {
-            if (arg.startsWith("--")) {
-                options.add(arg.substring(2));
-            } else if (arg.startsWith("-")) {
-                if (optionDictionary.containsKey(arg))
-                    options.add(optionDictionary.get(arg).substring(2));
-                else
-                    System.err.println("Short-hand '$arg' does not exist. Ignoring!");
-            } else {
-                words.add(arg);
-            }
+                This program is free software: you can redistribute it and/or modify it under the terms of the
+                GNU General Public License as published by the Free Software Foundation, either version 3 of the
+                License, or (at your option) any later version.
+
+                This program 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 for more details.""");
+    }
+
+    private static void printHelpInformation() {
+        switch (applicationOutputLanguage) {
+            case GlobalConf.langGerman -> System.out.println("Hilfe kommt noch. (Nicht implementiert)");
+            default -> System.out.println("Help is yet to come. (Not implemented)");
         }
+    }
 
-        if (options.contains("help")) {
-            switch (applicationOutputLanguage) {
-                case GlobalConf.langGerman -> System.out.println("Hilfe kommt noch. (Nicht implementiert)");
-                default -> System.out.println("Help is yet to come. (Not implemented)");
-            }
-        } else if (options.contains("version")) {
-            final var thisPackage = Main.class.getPackage();
-            final var appVersion = thisPackage.getImplementationVersion() != null
-                    ? thisPackage.getImplementationVersion()
-                    : "version unknown";
-            System.out.println("waituntil " + appVersion);
-            System.out.println("""
-
-                    This program is free software: you can redistribute it and/or modify it under the terms of the
-                    GNU General Public License as published by the Free Software Foundation, either version 3 of the
-                    License, or (at your option) any later version.
-
-                    This program 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 for more details.""");
-        } else if (words.size() == 1) {
-            final var target = TimeCalculator.calculateAndAnnounceTargetTime(words.iterator().next());
-            Sleep.waitUntilTimeStamp(target);
-        } else {
-            switch (applicationOutputLanguage) {
-                case GlobalConf.langGerman -> System.err.println("FATAL: Es wurde exact ein nicht-flag Argument erwartet. (" + words.size() + " erhalten)");
-                default -> System.err.println("FATAL: Expected one non-flag argument. (Got " + words.size() + ")");
+    public static void main(final String[] args) {
+        try {
+            final var parsedArguments =
+                DefaultParser.builder()
+                    .setStripLeadingAndTrailingQuotes(true)
+                    .build()
+                    .parse(AppOptions.getOptions(), args);
+
+            final var userData = parsedArguments.getArgs();
+
+            if (parsedArguments.hasOption(AppOptions.help)) {
+                printHelpInformation();
+            } else if (parsedArguments.hasOption(AppOptions.version)) {
+                printVersionInformation();
+            } else if (userData.length == 0) {
+                switch (applicationOutputLanguage) {
+                    case GlobalConf.langGerman -> System.err.println("FATAL: " +
+                        "Es wurde keine Uhrzeit angegeben.");
+                    default -> System.err.println("FATAL: No target time was " +
+                        "provided.");
+                }
+                System.exit(1);
+            } else if (userData.length > 1) {
+                switch (applicationOutputLanguage) {
+                    case GlobalConf.langGerman -> System.err.println("FATAL: " +
+                        "Zu viele Argumente wurden angegeben.");
+                    default -> System.err.println("FATAL: Too many arguments " +
+                        "provided.");
+                }
+                System.exit(1);
+            } else {
+                final var target =
+                    TimeCalculator.calculateAndAnnounceTargetTime(userData[0]);
+                Sleep.waitUntilTimeStamp(target);
             }
+        } catch (final ParseException e) {
+            System.getLogger("main").log(System.Logger.Level.ERROR, "Parsing " +
+                "of arguments failed and the program cannot continue.", e);
             System.exit(1);
         }
     }

src/main/java/module-info.java

@@ -1,2 +0,0 @@
-module de.jotoho.waituntil.main {
-}