fix invalid suggestions when parsing of argument fails (#401)

cloud-core/src/main/java/cloud/commandframework/CommandTree.java

@@ -659,9 +659,22 @@ public final class CommandTree<C> {
             // START: Parsing
             commandContext.setCurrentArgument(child.getValue());
             final ArgumentParseResult<?> result = child.getValue().getParser().parse(commandContext, commandQueue);
-            if (result.getParsedValue().isPresent() && !commandQueue.isEmpty()) {
+            final Optional<?> parsedValue = result.getParsedValue();
-                commandContext.store(child.getValue().getName(), result.getParsedValue().get());
+            final boolean parseSuccess = parsedValue.isPresent();
+
+            if (parseSuccess && !commandQueue.isEmpty()) {
+                // the current argument at the position is parsable and there are more arguments following
+                commandContext.store(child.getValue().getName(), parsedValue.get());
                 return this.getSuggestions(commandContext, commandQueue, child);
+            } else if (!parseSuccess && commandQueueOriginal.size() > 1) {
+                // at this point there should normally be no need to reset the command queue as we expect
+                // users to only take out an argument if the parse succeeded. Just to be sure we reset anyway
+                commandQueue.clear();
+                commandQueue.addAll(commandQueueOriginal);
+
+                // there are more arguments following but the current argument isn't matching - there
+                // is no need to collect any further suggestions
+                return Collections.emptyList();
             }
             // END: Parsing
         }
@@ -670,6 +683,13 @@ public final class CommandTree<C> {
         commandQueue.clear();
         commandQueue.addAll(commandQueueOriginal);
 
+        if (!preParseSuccess && commandQueue.size() > 1) {
+            // The preprocessor denied the argument, and there are more arguments following the current one
+            // Therefore we shouldn't list the suggestions of the current argument, as clearly the suggestions of
+            // one of the following arguments is requested
+            return Collections.emptyList();
+        }
+
         // Fallback: use suggestion provider of argument
         commandContext.setCurrentArgument(child.getValue());
         return child.getValue().getSuggestionsProvider().apply(commandContext, this.stringOrEmpty(commandQueue.peek()));

cloud-core/src/test/java/cloud/commandframework/CommandSuggestionsTest.java

@@ -24,6 +24,7 @@
 package cloud.commandframework;
 
 import cloud.commandframework.arguments.compound.ArgumentTriplet;
+import cloud.commandframework.arguments.parser.ArgumentParseResult;
 import cloud.commandframework.arguments.standard.BooleanArgument;
 import cloud.commandframework.arguments.standard.EnumArgument;
 import cloud.commandframework.arguments.standard.IntegerArgument;
@@ -128,6 +129,18 @@ public class CommandSuggestionsTest {
         manager.command(manager.commandBuilder("literal_with_variable")
                 .literal("vici")
                 .literal("later"));
+
+        manager.command(manager.commandBuilder("cmd_with_multiple_args")
+                .argument(IntegerArgument.<TestCommandSender>of("number").addPreprocessor((ctx, input) -> {
+                    String argument = input.peek();
+                    if (argument == null || !argument.equals("1024")) {
+                        return ArgumentParseResult.success(true);
+                    } else {
+                        return ArgumentParseResult.failure(new NullPointerException());
+                    }
+                }))
+                .argument(EnumArgument.of(TestEnum.class, "enum"))
+                .literal("world"));
     }
 
     @Test
@@ -378,6 +391,7 @@ public class CommandSuggestionsTest {
         Assertions.assertEquals(Collections.singletonList("literal"), suggestions9);
     }
 
+    @Test
     void testLiteralWithVariable() {
         final String input = "literal_with_variable ";
         final List<String> suggestions = manager.suggest(new TestCommandSender(), input);
@@ -390,7 +404,7 @@ public class CommandSuggestionsTest {
         Assertions.assertEquals(Arrays.asList("vici", "vidi"), suggestions3);
         final String input4 = "literal_with_variable vidi";
         final List<String> suggestions4 = manager.suggest(new TestCommandSender(), input4);
-        Assertions.assertEquals(Collections.emptyList(), suggestions4);
+        Assertions.assertEquals(Collections.singletonList("vidi"), suggestions4);
         final String input5 = "literal_with_variable vidi ";
         final List<String> suggestions5 = manager.suggest(new TestCommandSender(), input5);
         Assertions.assertEquals(Collections.singletonList("now"), suggestions5);
@@ -399,6 +413,39 @@ public class CommandSuggestionsTest {
         Assertions.assertEquals(Collections.singletonList("later"), suggestions6);
     }
 
+    @Test
+    void testInvalidArgumentShouldNotCauseFurtherCompletion() {
+        // pass preprocess
+        final String input = "cmd_with_multiple_args 512 ";
+        final List<String> suggestions = manager.suggest(new TestCommandSender(), input);
+        Assertions.assertEquals(Arrays.asList("foo", "bar"), suggestions);
+        final String input2 = "cmd_with_multiple_args 512 BAR ";
+        final List<String> suggestions2 = manager.suggest(new TestCommandSender(), input2);
+        Assertions.assertEquals(Collections.singletonList("world"), suggestions2);
+        final String input3 = "cmd_with_multiple_args test ";
+        final List<String> suggestions3 = manager.suggest(new TestCommandSender(), input3);
+        Assertions.assertEquals(Collections.emptyList(), suggestions3);
+        final String input4 = "cmd_with_multiple_args 512 f";
+        final List<String> suggestions4 = manager.suggest(new TestCommandSender(), input4);
+        Assertions.assertEquals(Collections.singletonList("foo"), suggestions4);
+        final String input5 = "cmd_with_multiple_args world f";
+        final List<String> suggestions5 = manager.suggest(new TestCommandSender(), input5);
+        Assertions.assertEquals(Collections.emptyList(), suggestions5);
+        // trigger preprocess fail
+        final String input6 = "cmd_with_multiple_args 1024";
+        final List<String> suggestions6 = manager.suggest(new TestCommandSender(), input6);
+        Assertions.assertEquals(11, suggestions6.size());
+        final String input7 = "cmd_with_multiple_args 1024 ";
+        final List<String> suggestions7 = manager.suggest(new TestCommandSender(), input7);
+        Assertions.assertEquals(Collections.emptyList(), suggestions7);
+        final String input8 = "cmd_with_multiple_args 1024 f";
+        final List<String> suggestions8 = manager.suggest(new TestCommandSender(), input8);
+        Assertions.assertEquals(Collections.emptyList(), suggestions8);
+        final String input9 = "cmd_with_multiple_args 1024 foo w";
+        final List<String> suggestions9 = manager.suggest(new TestCommandSender(), input9);
+        Assertions.assertEquals(Collections.emptyList(), suggestions9);
+    }
+
     @Test
     void testFlagYieldingGreedyStringFollowedByFlagArgument() {
         // Arrange