Move shell completion logic to Java

Refactor bash shell completion to move the majority of the logic into
the Java code. This commit also removes the need for the '--' prefix on
every command.

spring-boot-cli/src/main/java/org/springframework/boot/cli/Command.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.cli;
 
+import java.util.Collection;
+
 /**
  * A single command that can be run from the CLI.
  * 
@@ -35,6 +37,13 @@ public interface Command {
 	 */
 	String getDescription();
 
+	/**
+	 * Returns {@code true} if this is an 'option command'. An option command is a special
+	 * type of command that usually makes more sense to present as if it is an option. For
+	 * example '--version'.
+	 */
+	boolean isOptionCommand();
+
 	/**
 	 * Returns usage help for the command. This should be a simple one-line string
 	 * describing basic usage. e.g. '[options] <file>'. Do not include the name of
@@ -48,6 +57,11 @@ public interface Command {
 	 */
 	String getHelp();
 
+	/**
+	 * Returns help for each supported option.
+	 */
+	Collection<OptionHelp> getOptionsHelp();
+
 	/**
 	 * Run the command.
 	 * @param args command arguments (this will not include the command itself)

spring-boot-cli/src/main/java/org/springframework/boot/cli/OptionHelp.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * 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 org.springframework.boot.cli;
+
+import java.util.Set;
+
+/**
+ * Help for a specific option.
+ * 
+ * @author Phillip Webb
+ */
+public interface OptionHelp {
+
+	/**
+	 * Returns the set of options that are mutually synonymous.
+	 */
+	Set<String> getOptions();
+
+	/**
+	 * Returns usage help for the option.
+	 */
+	String getUsageHelp();
+
+}

spring-boot-cli/src/main/java/org/springframework/boot/cli/SpringCli.java

@@ -18,11 +18,15 @@ package org.springframework.boot.cli;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.EnumSet;
 import java.util.List;
 import java.util.ServiceLoader;
 import java.util.Set;
 
+import org.springframework.boot.cli.command.AbstractCommand;
+
 /**
  * Spring Command Line Interface. This is the main entry-point for the Spring command line
  * application. This class will parse input arguments and delegate to a suitable
@@ -61,6 +65,7 @@ public class SpringCli {
 			}
 		}
 		this.commands.add(0, new HelpCommand());
+		this.commands.add(new HintCommand());
 	}
 
 	/**
@@ -71,6 +76,7 @@ public class SpringCli {
 	public void setCommands(List<? extends Command> commands) {
 		this.commands = new ArrayList<Command>(commands);
 		this.commands.add(0, new HelpCommand());
+		this.commands.add(new HintCommand());
 	}
 
 	/**
@@ -122,42 +128,51 @@ public class SpringCli {
 		}
 		String commandName = args[0];
 		String[] commandArguments = Arrays.copyOfRange(args, 1, args.length);
-		find(commandName).run(commandArguments);
+		Command command = find(commandName);
+		if (command == null) {
+			throw new NoSuchCommandException(commandName);
+		}
+		command.run(commandArguments);
 	}
 
-	private Command find(String name) {
-		if (name.startsWith("--")) {
-			name = name.substring("--".length());
-		}
+	protected final Command find(String name) {
 		for (Command candidate : this.commands) {
-			if (candidate.getName().equals(name)) {
+			if (candidate.getName().equals(name)
+					|| (candidate.isOptionCommand() && ("--" + candidate.getName())
+							.equals(name))) {
 				return candidate;
 			}
 		}
-		throw new NoSuchCommandException(name);
+		return null;
 	}
 
 	protected void showUsage() {
-		Log.info("usage: " + CLI_APP + " ");
+		Log.infoPrint("usage: " + CLI_APP + " ");
+		for (Command command : this.commands) {
+			if (command.isOptionCommand()) {
+				Log.infoPrint("[--" + command.getName() + "] ");
+			}
+		}
 		Log.info("");
 		Log.info("       <command> [<args>]");
 		Log.info("");
 		Log.info("Available commands are:");
 		for (Command command : this.commands) {
-			String usageHelp = command.getUsageHelp();
-			String description = command.getDescription();
-			String name = command.getName();
-			if (!name.startsWith("--")) {
-				name = "--" + name + ", " + name;
+			if (!command.isOptionCommand() && !(command instanceof HintCommand)) {
+				String usageHelp = command.getUsageHelp();
+				String description = command.getDescription();
+				Log.info(String.format("\n  %1$s %2$-15s\n    %3$s", command.getName(),
+						(usageHelp == null ? "" : usageHelp), (description == null ? ""
+								: description)));
 			}
-			Log.info(String.format("\n  %1$s %2$-15s\n    %3$s", name,
-					(usageHelp == null ? "" : usageHelp), (description == null ? ""
-							: description)));
 		}
+		Log.info("");
+		Log.info("Common options:");
 		Log.info(String.format("\n  %1$s %2$-15s\n    %3$s", "-d, --debug",
 				"Verbose mode",
 				"Print additional status information for the command you are running"));
 		Log.info("");
+		Log.info("");
 		Log.info("See '" + CLI_APP
 				+ " help <command>' for more information on a specific command.");
 	}
@@ -185,7 +200,44 @@ public class SpringCli {
 	/**
 	 * Internal {@link Command} used for 'help' requests.
 	 */
-	private class HelpCommand implements Command {
+	private class HelpCommand extends AbstractCommand {
+
+		public HelpCommand() {
+			super("help", "Get help on commands", true);
+		}
+
+		@Override
+		public String getUsageHelp() {
+			return "command";
+		}
+
+		@Override
+		public String getHelp() {
+			return null;
+		}
+
+		@Override
+		public Collection<OptionHelp> getOptionsHelp() {
+			List<OptionHelp> help = new ArrayList<OptionHelp>();
+			for (final Command command : SpringCli.this.commands) {
+				if (!(command instanceof HelpCommand)
+						&& !(command instanceof HintCommand)) {
+					help.add(new OptionHelp() {
+
+						@Override
+						public Set<String> getOptions() {
+							return Collections.singleton(command.getName());
+						}
+
+						@Override
+						public String getUsageHelp() {
+							return "";
+						}
+					});
+				}
+			}
+			return help;
+		}
 
 		@Override
 		public void run(String... args) throws Exception {
@@ -212,26 +264,78 @@ public class SpringCli {
 			throw new NoSuchCommandException(commandName);
 		}
 
-		@Override
-		public String getName() {
-			return "help";
+	}
+
+	/**
+	 * Provides hints for shell auto-completion. Expects to be called with the current
+	 * index followed by a list of arguments already typed.
+	 */
+	private class HintCommand extends AbstractCommand {
+
+		public HintCommand() {
+			super("hint", "Provides hints for shell auto-completion");
 		}
 
 		@Override
-		public String getDescription() {
-			return "Get help on commands";
+		public void run(String... args) throws Exception {
+			try {
+				int index = (args.length == 0 ? 0 : Integer.valueOf(args[0]) - 1);
+				List<String> arguments = new ArrayList<String>(args.length);
+				for (int i = 2; i < args.length; i++) {
+					arguments.add(args[i]);
+				}
+				String starting = "";
+				if (index < arguments.size()) {
+					starting = arguments.remove(index);
+				}
+				if (index == 0) {
+					showCommandHints(starting);
+				}
+				else if ((arguments.size() > 0) && (starting.length() > 0)) {
+					String command = arguments.remove(0);
+					showCommandOptionHints(command,
+							Collections.unmodifiableList(arguments), starting);
+				}
+			}
+			catch (Exception ex) {
+				// Swallow and provide no hints
+			}
 		}
 
-		@Override
-		public String getUsageHelp() {
-			return "command";
+		private void showCommandHints(String starting) {
+			for (Command command : SpringCli.this.commands) {
+				if (command.getName().startsWith(starting)
+						|| (command.isOptionCommand() && ("--" + command.getName())
+								.startsWith(starting))) {
+					Log.info(command.getName() + " " + command.getDescription());
+				}
+			}
 		}
 
-		@Override
-		public String getHelp() {
-			return null;
+		private void showCommandOptionHints(String commandName,
+				List<String> specifiedArguments, String starting) {
+			Command command = find(commandName);
+			if (command != null) {
+				for (OptionHelp help : command.getOptionsHelp()) {
+					if (!alreadyUsed(help, specifiedArguments)) {
+						for (String option : help.getOptions()) {
+							if (option.startsWith(starting)) {
+								Log.info(option + " " + help.getUsageHelp());
+							}
+						}
+					}
+				}
+			}
 		}
 
+		private boolean alreadyUsed(OptionHelp help, List<String> specifiedArguments) {
+			for (String argument : specifiedArguments) {
+				if (help.getOptions().contains(argument)) {
+					return true;
+				}
+			}
+			return false;
+		}
 	}
 
 	static class NoHelpCommandArgumentsException extends SpringCliException {

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/AbstractCommand.java

@@ -16,7 +16,11 @@
 
 package org.springframework.boot.cli.command;
 
+import java.util.Collection;
+import java.util.Collections;
+
 import org.springframework.boot.cli.Command;
+import org.springframework.boot.cli.OptionHelp;
 
 /**
  * Abstract {@link Command} implementation.
@@ -26,18 +30,31 @@ import org.springframework.boot.cli.Command;
  */
 public abstract class AbstractCommand implements Command {
 
-	private String name;
+	private final String name;
 
-	private String description;
+	private final String description;
+
+	private final boolean optionCommand;
 
 	/**
 	 * Create a new {@link AbstractCommand} instance.
 	 * @param name the name of the command
 	 * @param description the command description
 	 */
-	public AbstractCommand(String name, String description) {
+	protected AbstractCommand(String name, String description) {
+		this(name, description, false);
+	}
+
+	/**
+	 * Create a new {@link AbstractCommand} instance.
+	 * @param name the name of the command
+	 * @param description the command description
+	 * @param optionCommand if this command is an option command
+	 */
+	protected AbstractCommand(String name, String description, boolean optionCommand) {
 		this.name = name;
 		this.description = description;
+		this.optionCommand = optionCommand;
 	}
 
 	@Override
@@ -45,6 +62,11 @@ public abstract class AbstractCommand implements Command {
 		return this.name;
 	}
 
+	@Override
+	public boolean isOptionCommand() {
+		return this.optionCommand;
+	}
+
 	@Override
 	public String getDescription() {
 		return this.description;
@@ -60,4 +82,9 @@ public abstract class AbstractCommand implements Command {
 		return null;
 	}
 
+	@Override
+	public Collection<OptionHelp> getOptionsHelp() {
+		return Collections.emptyList();
+	}
+
 }

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/OptionHandler.java

@@ -21,12 +21,25 @@ import groovy.lang.Closure;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeSet;
 
+import joptsimple.BuiltinHelpFormatter;
+import joptsimple.HelpFormatter;
+import joptsimple.OptionDescriptor;
 import joptsimple.OptionParser;
 import joptsimple.OptionSet;
 import joptsimple.OptionSpecBuilder;
 
+import org.springframework.boot.cli.OptionHelp;
+
 /**
  * Delegate used by {@link OptionParsingCommand} to parse options and run the command.
  * 
@@ -40,6 +53,10 @@ public class OptionHandler {
 
 	private Closure<Void> closure;
 
+	private String help;
+
+	private Collection<OptionHelp> optionHelp;
+
 	public OptionSpecBuilder option(String name, String description) {
 		return getParser().accepts(name, description);
 	}
@@ -80,14 +97,87 @@ public class OptionHandler {
 	}
 
 	public String getHelp() {
-		OutputStream out = new ByteArrayOutputStream();
-		try {
-			getParser().printHelpOn(out);
+		if (this.help == null) {
+			getParser().formatHelpWith(new BuiltinHelpFormatter(80, 2));
+			OutputStream out = new ByteArrayOutputStream();
+			try {
+				getParser().printHelpOn(out);
+			}
+			catch (IOException ex) {
+				return "Help not available";
+			}
+			this.help = out.toString();
 		}
-		catch (IOException ex) {
-			return "Help not available";
-		}
-		return out.toString();
+		return this.help;
 	}
 
+	public Collection<OptionHelp> getOptionsHelp() {
+		if (this.optionHelp == null) {
+			OptionHelpFormatter formatter = new OptionHelpFormatter();
+			getParser().formatHelpWith(formatter);
+			try {
+				getParser().printHelpOn(new ByteArrayOutputStream());
+			}
+			catch (Exception ex) {
+				// Ignore and provide no hints
+			}
+			this.optionHelp = formatter.getOptionHelp();
+		}
+		return this.optionHelp;
+	}
+
+	private static class OptionHelpFormatter implements HelpFormatter {
+
+		private final List<OptionHelp> help = new ArrayList<OptionHelp>();
+
+		@Override
+		public String format(Map<String, ? extends OptionDescriptor> options) {
+			Comparator<OptionDescriptor> comparator = new Comparator<OptionDescriptor>() {
+				public int compare(OptionDescriptor first, OptionDescriptor second) {
+					return first.options().iterator().next()
+							.compareTo(second.options().iterator().next());
+				}
+			};
+
+			Set<OptionDescriptor> sorted = new TreeSet<OptionDescriptor>(comparator);
+			sorted.addAll(options.values());
+
+			for (OptionDescriptor descriptor : sorted) {
+				if (!descriptor.representsNonOptions()) {
+					this.help.add(new OptionHelpAdapter(descriptor));
+				}
+			}
+			return "";
+		}
+
+		public Collection<OptionHelp> getOptionHelp() {
+			return Collections.unmodifiableList(this.help);
+		}
+
+	}
+
+	private static class OptionHelpAdapter implements OptionHelp {
+
+		private final LinkedHashSet<String> options;
+
+		private final String description;
+
+		public OptionHelpAdapter(OptionDescriptor descriptor) {
+			this.options = new LinkedHashSet<String>();
+			for (String option : descriptor.options()) {
+				this.options.add((option.length() == 1 ? "-" : "--") + option);
+			}
+			this.description = descriptor.description();
+		}
+
+		@Override
+		public Set<String> getOptions() {
+			return this.options;
+		}
+
+		@Override
+		public String getUsageHelp() {
+			return this.description;
+		}
+	}
 }

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/OptionParsingCommand.java

@@ -16,7 +16,10 @@
 
 package org.springframework.boot.cli.command;
 
+import java.util.Collection;
+
 import org.springframework.boot.cli.Command;
+import org.springframework.boot.cli.OptionHelp;
 
 /**
  * Base class for a {@link Command} that parse options using an {@link OptionHandler}.
@@ -29,8 +32,13 @@ public abstract class OptionParsingCommand extends AbstractCommand {
 
 	private OptionHandler handler;
 
-	public OptionParsingCommand(String name, String description, OptionHandler handler) {
-		super(name, description);
+	protected OptionParsingCommand(String name, String description, OptionHandler handler) {
+		this(name, description, false, handler);
+	}
+
+	protected OptionParsingCommand(String name, String description,
+			boolean optionCommand, OptionHandler handler) {
+		super(name, description, optionCommand);
 		this.handler = handler;
 	}
 
@@ -39,6 +47,11 @@ public abstract class OptionParsingCommand extends AbstractCommand {
 		return this.handler.getHelp();
 	}
 
+	@Override
+	public Collection<OptionHelp> getOptionsHelp() {
+		return this.handler.getOptionsHelp();
+	}
+
 	@Override
 	public final void run(String... args) throws Exception {
 		this.handler.run(args);

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/ScriptCommand.java

@@ -26,11 +26,14 @@ import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.net.URL;
+import java.util.Collection;
+import java.util.Collections;
 
 import joptsimple.OptionParser;
 
 import org.codehaus.groovy.control.CompilationFailedException;
 import org.springframework.boot.cli.Command;
+import org.springframework.boot.cli.OptionHelp;
 import org.springframework.boot.cli.compiler.GroovyCompiler;
 import org.springframework.boot.cli.compiler.GroovyCompilerConfiguration;
 import org.springframework.boot.cli.compiler.GroovyCompilerScope;
@@ -66,6 +69,11 @@ public class ScriptCommand implements Command {
 		return this.name;
 	}
 
+	@Override
+	public boolean isOptionCommand() {
+		return false;
+	}
+
 	@Override
 	public String getDescription() {
 		if (getMain() instanceof Command) {
@@ -85,6 +93,17 @@ public class ScriptCommand implements Command {
 		return null;
 	}
 
+	@Override
+	public Collection<OptionHelp> getOptionsHelp() {
+		if (getMain() instanceof OptionHandler) {
+			return ((OptionHandler) getMain()).getOptionsHelp();
+		}
+		if (getMain() instanceof Command) {
+			return ((Command) getMain()).getOptionsHelp();
+		}
+		return Collections.emptyList();
+	}
+
 	@Override
 	public void run(String... args) throws Exception {
 		run(getMain(), args);

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/TestCommand.java

@@ -38,6 +38,11 @@ public class TestCommand extends OptionParsingCommand {
 		super("test", "Run a spring groovy script test", new TestOptionHandler());
 	}
 
+	@Override
+	public String getUsageHelp() {
+		return "[options] <files> [--] [args]";
+	}
+
 	private static class TestOptionHandler extends OptionHandler {
 
 		private OptionSpec<Void> noGuessImportsOption;

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/VersionCommand.java

@@ -27,7 +27,7 @@ import org.springframework.boot.cli.Log;
 public class VersionCommand extends AbstractCommand {
 
 	public VersionCommand() {
-		super("version", "Show the version");
+		super("version", "Show the version", true);
 	}
 
 	@Override