Introduce BisqHelpFormatter

Prior to this commit, help output for Bisq executables, e.g. Bisq
Desktop itself used JOptSimple's default HelpFormatter implementation,
which creates a quite cramped and hard-to-read output.

This commit introduces a custom HelpFormatter implementation modeled
after bitcoind's own help output. It maximizes readability while making
full use of an 80-character width.

core/src/main/java/bisq/core/app/BisqExecutable.java

@@ -114,6 +114,7 @@ public abstract class BisqExecutable implements GracefulShutDownHandler {
 
     public void execute(String[] args) throws Exception {
         OptionParser parser = new OptionParser();
+        parser.formatHelpWith(new BisqHelpFormatter());
         parser.accepts(HELP_KEY, "This help text").forHelp();
 
         this.customizeOptionParsing(parser);

core/src/main/java/bisq/core/app/BisqHelpFormatter.java

@@ -0,0 +1,120 @@
+/*
+ * This file is part of Bisq.
+ *
+ * Bisq is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Bisq 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 Affero General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Bisq. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package bisq.core.app;
+
+import joptsimple.HelpFormatter;
+import joptsimple.OptionDescriptor;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+public class BisqHelpFormatter implements HelpFormatter {
+
+    public String format(Map<String, ? extends OptionDescriptor> descriptors) {
+
+        StringBuilder output = new StringBuilder();
+        output.append("Options:\n");
+        output.append("\n");
+
+        for (Map.Entry<String, ? extends OptionDescriptor> entry : descriptors.entrySet()) {
+            String optionName = entry.getKey();
+            OptionDescriptor optionDesc = entry.getValue();
+
+            if (optionDesc.representsNonOptions())
+                continue;
+
+            output.append(String.format("%s\n", formatOptionSyntax(optionName, optionDesc)));
+            output.append(String.format("%s\n", formatOptionDescription(optionDesc)));
+        }
+
+        return output.toString();
+    }
+
+    private String formatOptionSyntax(String optionName, OptionDescriptor optionDesc) {
+        StringBuilder result = new StringBuilder(String.format("  --%s", optionName));
+
+        if (optionDesc.acceptsArguments())
+            result.append(String.format("=<%s>", formatArgDescription(optionDesc)));
+
+        List<?> defaultValues = optionDesc.defaultValues();
+        if (defaultValues.size() > 0)
+            result.append(String.format(" (default: %s)", formatDefaultValues(defaultValues)));
+
+        return result.toString();
+    }
+
+    private String formatArgDescription(OptionDescriptor optionDesc) {
+        String argDescription = optionDesc.argumentDescription();
+
+        if (argDescription.length() > 0)
+            return argDescription;
+
+        String typeIndicator = optionDesc.argumentTypeIndicator();
+
+        if (typeIndicator == null)
+            return "value";
+
+        try {
+            Class<?> type = Class.forName(typeIndicator);
+            return type.isEnum() ?
+                    Arrays.stream(type.getEnumConstants()).map(Object::toString).collect(Collectors.joining("|")) :
+                    typeIndicator.substring(typeIndicator.lastIndexOf('.') + 1);
+        } catch (ClassNotFoundException ex) {
+            // typeIndicator is something other than a class name, which can occur
+            // in certain cases e.g. where OptionParser.withValuesConvertedBy is used.
+            return typeIndicator;
+        }
+    }
+
+    private Object formatDefaultValues(List<?> defaultValues) {
+        return defaultValues.size() == 1 ?
+                defaultValues.get(0) :
+                defaultValues.toString();
+    }
+
+    private String formatOptionDescription(OptionDescriptor optionDesc) {
+        StringBuilder output = new StringBuilder();
+
+        String remainder = optionDesc.description().trim();
+
+        // Wrap description text at 80 characters with 8 spaces of indentation and a
+        // maximum of 72 chars of text, wrapping on spaces. Strings longer than 72 chars
+        // without any spaces (e.g. a URL) are allowed to overflow the 80-char margin.
+        while (remainder.length() > 72) {
+            int idxFirstSpace = remainder.indexOf(' ');
+            int chunkLen = idxFirstSpace == -1 ? remainder.length() : idxFirstSpace > 73 ? idxFirstSpace : 73;
+            String chunk = remainder.substring(0, chunkLen);
+            int idxLastSpace = chunk.lastIndexOf(' ');
+            int idxBreak = idxLastSpace > 0 ? idxLastSpace : chunk.length();
+            String line = remainder.substring(0, idxBreak);
+            output.append(formatLine(line));
+            remainder = remainder.substring(chunk.length() - (chunk.length() - idxBreak)).trim();
+        }
+
+        if (remainder.length() > 0)
+            output.append(formatLine(remainder));
+
+        return output.toString();
+    }
+
+    private String formatLine(String line) {
+        return String.format("        %s\n", line.trim());
+    }
+}

core/src/test/java/bisq/core/app/BisqHelpFormatterTest.java

@@ -0,0 +1,134 @@
+/*
+ * This file is part of Bisq.
+ *
+ * Bisq is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Bisq 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 Affero General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Bisq. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package bisq.core.app;
+
+import joptsimple.OptionParser;
+
+import java.net.URISyntaxException;
+
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.PrintStream;
+
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+public class BisqHelpFormatterTest {
+
+    @Test
+    public void testHelpFormatter() throws IOException, URISyntaxException {
+
+        OptionParser parser = new OptionParser();
+
+        parser.formatHelpWith(new BisqHelpFormatter());
+
+        parser.accepts("name",
+                "The name of the Bisq node")
+                .withRequiredArg()
+                .ofType(String.class)
+                .defaultsTo("Bisq");
+
+        parser.accepts("another-option",
+                "This is a long description which will need to break over multiple linessssssssssss such " +
+                        "that no line is longer than 80 characters in the help output.")
+                .withRequiredArg()
+                .ofType(String.class)
+                .defaultsTo("WAT");
+
+        parser.accepts("exactly-72-char-description",
+                "012345678911234567892123456789312345678941234567895123456789612345678971")
+                .withRequiredArg()
+                .ofType(String.class);
+
+        parser.accepts("exactly-72-char-description-with-spaces",
+                " 123456789 123456789 123456789 123456789 123456789 123456789 123456789 1")
+                .withRequiredArg()
+                .ofType(String.class);
+
+        parser.accepts("90-char-description-without-spaces",
+                "-123456789-223456789-323456789-423456789-523456789-623456789-723456789-823456789-923456789")
+                .withRequiredArg()
+                .ofType(String.class);
+
+        parser.accepts("90-char-description-with-space-at-char-80",
+                "-123456789-223456789-323456789-423456789-523456789-623456789-723456789-823456789 923456789")
+                .withRequiredArg()
+                .ofType(String.class);
+
+        parser.accepts("90-char-description-with-spaces-at-chars-5-and-80",
+                "-123 56789-223456789-323456789-423456789-523456789-623456789-723456789-823456789 923456789")
+                .withRequiredArg()
+                .ofType(String.class);
+
+        parser.accepts("90-char-description-with-space-at-char-73",
+                "-123456789-223456789-323456789-423456789-523456789-623456789-723456789-8 3456789-923456789")
+                .withRequiredArg()
+                .ofType(String.class);
+
+        parser.accepts("1-char-description-with-only-a-space", " ")
+                .withRequiredArg()
+                .ofType(String.class);
+
+        parser.accepts("empty-description", "")
+                .withRequiredArg()
+                .ofType(String.class);
+
+        parser.accepts("no-description")
+                .withRequiredArg()
+                .ofType(String.class);
+
+        parser.accepts("no-arg", "Some description");
+
+        parser.accepts("optional-arg",
+                "Option description")
+                .withOptionalArg();
+
+        parser.accepts("with-default-value",
+                "Some option with a default value")
+                .withRequiredArg()
+                .ofType(String.class)
+                .defaultsTo("Wat");
+
+        parser.accepts("data-dir",
+                "Application data directory")
+                .withRequiredArg()
+                .ofType(File.class)
+                .defaultsTo(new File("/Users/cbeams/Library/Applicaton Support/Bisq"));
+
+        parser.accepts("enum-opt",
+                "Some option that accepts an enum value as an argument")
+                .withRequiredArg()
+                .ofType(AnEnum.class)
+                .defaultsTo(AnEnum.foo);
+
+        ByteArrayOutputStream actual = new ByteArrayOutputStream();
+        String expected = new String(Files.readAllBytes(Paths.get(getClass().getResource("cli-output.txt").toURI())));
+
+        parser.printHelpOn(new PrintStream(actual));
+        assertThat(actual.toString(), equalTo(expected));
+    }
+
+
+    enum AnEnum {foo, bar, baz}
+}

core/src/test/resources/bisq/core/app/cli-output.txt

@@ -0,0 +1,53 @@
+Options:
+
+  --name=<String> (default: Bisq)
+        The name of the Bisq node
+
+  --another-option=<String> (default: WAT)
+        This is a long description which will need to break over multiple
+        linessssssssssss such that no line is longer than 80 characters in the
+        help output.
+
+  --exactly-72-char-description=<String>
+        012345678911234567892123456789312345678941234567895123456789612345678971
+
+  --exactly-72-char-description-with-spaces=<String>
+        123456789 123456789 123456789 123456789 123456789 123456789 123456789 1
+
+  --90-char-description-without-spaces=<String>
+        -123456789-223456789-323456789-423456789-523456789-623456789-723456789-823456789-923456789
+
+  --90-char-description-with-space-at-char-80=<String>
+        -123456789-223456789-323456789-423456789-523456789-623456789-723456789-823456789
+        923456789
+
+  --90-char-description-with-spaces-at-chars-5-and-80=<String>
+        -123
+        56789-223456789-323456789-423456789-523456789-623456789-723456789-823456789
+        923456789
+
+  --90-char-description-with-space-at-char-73=<String>
+        -123456789-223456789-323456789-423456789-523456789-623456789-723456789-8
+        3456789-923456789
+
+  --1-char-description-with-only-a-space=<String>
+
+  --empty-description=<String>
+
+  --no-description=<String>
+
+  --no-arg
+        Some description
+
+  --optional-arg=<value>
+        Option description
+
+  --with-default-value=<String> (default: Wat)
+        Some option with a default value
+
+  --data-dir=<File> (default: /Users/cbeams/Library/Applicaton Support/Bisq)
+        Application data directory
+
+  --enum-opt=<foo|bar|baz> (default: foo)
+        Some option that accepts an enum value as an argument
+