Various improvements to command system

- Ensure usage is consistent
 - Allow computer selectors to return multiple values
 - Fix commands being marked as usable when it isn't
 - Add /computercraft turn-on, a counter to /computercraft shutdown

src/main/java/dan200/computercraft/shared/command/CommandComputerCraft.java

@@ -1,6 +1,6 @@
 package dan200.computercraft.shared.command;
 
-import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.core.computer.Computer;
@@ -40,8 +40,8 @@ public final class CommandComputerCraft extends CommandDelegate
 
         root.register( new SubCommandBase(
             "dump", "[id]", "Display the status of computers.", UserLevel.OWNER_OP,
-            "Display the status of all computers or specific information about one computer. You can either specify the computer's instance " +
+            "Display the status of all computers or specific information about one computer. You can specify the " +
-                "id (e.g. 123) or computer id (e.g #123)."
+                "computer's instance id (e.g. 123), computer id (e.g #123) or label (e.g. \"@My Computer\")."
         )
         {
             @Override
@@ -126,25 +126,25 @@ public final class CommandComputerCraft extends CommandDelegate
             {
                 return arguments.size() == 1
                     ? ComputerSelector.completeComputer( arguments.get( 0 ) )
-                    : Collections.<String>emptyList();
+                    : Collections.emptyList();
             }
         } );
 
         root.register( new SubCommandBase(
             "shutdown", "[ids...]", "Shutdown computers remotely.", UserLevel.OWNER_OP,
-            "Shutdown the listed computers or all if none are specified. You can either specify the computer's instance " +
+            "Shutdown the listed computers or all if none are specified. You can specify the computer's instance id " +
-                "id (e.g. 123) or computer id (e.g #123)."
+                "(e.g. 123), computer id (e.g #123) or label (e.g. \"@My Computer\")."
         )
         {
             @Override
             public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
             {
-                List<ServerComputer> computers = Lists.newArrayList();
+                Set<ServerComputer> computers = Sets.newHashSet();
                 if( arguments.size() > 0 )
                 {
                     for( String arg : arguments )
                     {
-                        computers.add( ComputerSelector.getComputer( arg ) );
+                        computers.addAll( ComputerSelector.getComputers( arg ) );
                     }
                 }
                 else
@@ -166,7 +166,48 @@ public final class CommandComputerCraft extends CommandDelegate
             public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
             {
                 return arguments.size() == 0
-                    ? Collections.<String>emptyList()
+                    ? Collections.emptyList()
+                    : ComputerSelector.completeComputer( arguments.get( arguments.size() - 1 ) );
+            }
+        } );
+
+        root.register( new SubCommandBase(
+            "turn-on", "ids...", "Turn computers on remotely.", UserLevel.OWNER_OP,
+            "Turn on the listed computers. You can specify the computer's instance id (e.g. 123), computer id (e.g #123) " +
+                "or label (e.g. \"@My Computer\")."
+        )
+        {
+            @Override
+            public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
+            {
+                Set<ServerComputer> computers = Sets.newHashSet();
+                if( arguments.size() > 0 )
+                {
+                    for( String arg : arguments )
+                    {
+                        computers.addAll( ComputerSelector.getComputers( arg ) );
+                    }
+                }
+                else
+                {
+                    computers.addAll( ComputerCraft.serverComputerRegistry.getComputers() );
+                }
+
+                int on = 0;
+                for( ServerComputer computer : computers )
+                {
+                    if( !computer.isOn() ) on++;
+                    computer.turnOn();
+                }
+                context.getSender().sendMessage( text( "Turned on " + on + " / " + computers.size() + " computers" ) );
+            }
+
+            @Nonnull
+            @Override
+            public List<String> getCompletion( @Nonnull CommandContext context, @Nonnull List<String> arguments )
+            {
+                return arguments.size() == 0
+                    ? Collections.emptyList()
                     : ComputerSelector.completeComputer( arguments.get( arguments.size() - 1 ) );
             }
         } );
@@ -222,7 +263,7 @@ public final class CommandComputerCraft extends CommandDelegate
             {
                 return arguments.size() == 1
                     ? ComputerSelector.completeComputer( arguments.get( 0 ) )
-                    : Collections.<String>emptyList();
+                    : Collections.emptyList();
             }
         } );
 

src/main/java/dan200/computercraft/shared/command/ComputerSelector.java

@@ -12,7 +12,7 @@ import java.util.function.Predicate;
 
 public final class ComputerSelector
 {
-    private static ServerComputer getComputer( Predicate<ServerComputer> predicate, String kind ) throws CommandException
+    private static List<ServerComputer> getComputers( Predicate<ServerComputer> predicate, String selector ) throws CommandException
     {
         // We copy it to prevent concurrent modifications.
         List<ServerComputer> computers = Lists.newArrayList( ComputerCraft.serverComputerRegistry.getComputers() );
@@ -22,41 +22,40 @@ public final class ComputerSelector
             if( predicate.test( searchComputer ) ) candidates.add( searchComputer );
         }
 
-        if( candidates.size() == 0 )
+        if( candidates.isEmpty() )
         {
-            throw new CommandException( "No such computer for " + kind );
+            throw new CommandException( "No computer matching " + selector );
-        }
-        else if( candidates.size() == 1 )
-        {
-            return candidates.get( 0 );
         }
         else
         {
-            StringBuilder builder = new StringBuilder( "Multiple computers with " )
+            return candidates;
-                .append( kind ).append( " (instances " );
+        }
+    }
 
-            boolean first = true;
+    public static ServerComputer getComputer( String selector ) throws CommandException
-            for( ServerComputer computer : candidates )
+    {
+        List<ServerComputer> computers = getComputers( selector );
+        if( computers.size() == 1 )
+        {
+            return computers.get( 0 );
+        }
+        else
+        {
+            StringBuilder builder = new StringBuilder( "Multiple computers matching " )
+                .append( selector ).append( " (instances " );
+
+            for( int i = 0; i < computers.size(); i++ )
             {
-                if( first )
+                if( i > 1 ) builder.append( ", " );
-                {
+                builder.append( computers.get( i ).getInstanceID() );
-                    first = false;
-                }
-                else
-                {
-                    builder.append( ", " );
-                }
-
-                builder.append( computer.getInstanceID() );
             }
-
             builder.append( ")" );
 
             throw new CommandException( builder.toString() );
         }
     }
 
-    public static ServerComputer getComputer( String selector ) throws CommandException
+    public static List<ServerComputer> getComputers( String selector ) throws CommandException
     {
         if( selector.length() > 0 && selector.charAt( 0 ) == '#' )
         {
@@ -72,17 +71,17 @@ public final class ComputerSelector
                 throw new CommandException( "'" + selector + "' is not a valid number" );
             }
 
-            return getComputer( x -> x.getID() == id, "id " + id );
+            return getComputers( x -> x.getID() == id, selector );
         }
         else if( selector.length() > 0 && selector.charAt( 0 ) == '@' )
         {
             String label = selector.substring( 1 );
-            return getComputer( x -> Objects.equals( label, x.getLabel() ), "label '" + label + "'" );
+            return getComputers( x -> Objects.equals( label, x.getLabel() ), selector );
         }
         else if( selector.length() > 0 && selector.charAt( 0 ) == '~' )
         {
             String familyName = selector.substring( 1 );
-            return getComputer( x -> x.getFamily().name().equalsIgnoreCase( familyName ), "family '" + familyName + "'" );
+            return getComputers( x -> x.getFamily().name().equalsIgnoreCase( familyName ), selector );
         }
         else
         {
@@ -103,7 +102,7 @@ public final class ComputerSelector
             }
             else
             {
-                return computer;
+                return Collections.singletonList( computer );
             }
         }
     }

src/main/java/dan200/computercraft/shared/command/framework/CommandDelegate.java

@@ -36,7 +36,7 @@ public class CommandDelegate implements ICommand
     @Override
     public String getUsage( @Nonnull ICommandSender sender )
     {
-        return "/" + command.getName() + " " + command.getUsage( new CommandContext( sender.getServer(), sender, command ) );
+        return new CommandContext( sender.getServer(), sender, command ).getFullUsage();
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/command/framework/CommandRoot.java

@@ -86,7 +86,7 @@ public class CommandRoot implements ISubCommand
     {
         for( ISubCommand command : subCommands.values() )
         {
-            if( command.checkPermission( context ) ) return true;
+            if( !(command instanceof SubCommandHelp) && command.checkPermission( context ) ) return true;
         }
         return false;
     }
@@ -108,7 +108,7 @@ public class CommandRoot implements ISubCommand
             ISubCommand command = subCommands.get( arguments.get( 0 ) );
             if( command == null || !command.checkPermission( context ) )
             {
-                throw new CommandException( getName() + " " + getUsage( context ) );
+                throw new CommandException( context.getFullUsage() );
             }
 
             command.execute( context.enter( command ), arguments.subList( 1, arguments.size() ) );