Apply correct completion

- This commit fixes two issues.
- Firstly complete with correct option as existing bug was
  to wrongly always complete with first option which used
  wrong provider.
- Secondly filter out duplicate option proposals giving better
  result when options is already in place.
- Fixes #495

spring-shell-core/src/main/java/org/springframework/shell/Shell.java

@@ -288,8 +288,8 @@ public class Shell {
 
 			// Try to complete arguments
 			List<CommandOption> matchedArgOptions = new ArrayList<>();
-			if (argsContext.getWords().size() > 0) {
-				matchedArgOptions.addAll(matchOptions(registration.getOptions(), argsContext.getWords().get(0)));
+			if (argsContext.getWords().size() > 0 && argsContext.getWordIndex() > 0 && argsContext.getWords().size() > argsContext.getWordIndex()) {
+				matchedArgOptions.addAll(matchOptions(registration.getOptions(), argsContext.getWords().get(argsContext.getWordIndex() - 1)));
 			}
 
 			List<CompletionProposal> argProposals =	matchedArgOptions.stream()

spring-shell-core/src/main/java/org/springframework/shell/completion/RegistrationOptionsCompletionResolver.java

@@ -38,11 +38,15 @@ public class RegistrationOptionsCompletionResolver implements CompletionResolver
 		List<CompletionProposal> candidates = new ArrayList<>();
 		context.getCommandRegistration().getOptions().stream()
 			.flatMap(o -> Stream.of(o.getLongNames()))
-			.map(ln -> new CompletionProposal("--" + ln))
+			.map(ln -> "--" + ln)
+			.filter(ln -> !context.getWords().contains(ln))
+			.map(CompletionProposal::new)
 			.forEach(candidates::add);
 		context.getCommandRegistration().getOptions().stream()
 			.flatMap(o -> Stream.of(o.getShortNames()))
-			.map(ln -> new CompletionProposal("-" + ln))
+			.map(ln -> "-" + ln)
+			.filter(ln -> !context.getWords().contains(ln))
+			.map(CompletionProposal::new)
 			.forEach(candidates::add);
 		return candidates;
 	}

spring-shell-core/src/test/java/org/springframework/shell/ShellTests.java

@@ -311,6 +311,39 @@ public class ShellTests {
 		assertThat(proposals).containsExactlyInAnyOrder("--arg1");
 	}
 
+	@Test
+	public void shouldCompleteWithCorrectArgument() throws Exception {
+		CommandRegistration registration1 = CommandRegistration.builder()
+			.command("hello world")
+			.withTarget()
+				.method(this, "helloWorld")
+				.and()
+			.withOption()
+				.longNames("arg1")
+				.completion(ctx -> Arrays.asList("arg1Comp1").stream().map(CompletionProposal::new).collect(Collectors.toList()))
+				.and()
+			.withOption()
+				.longNames("arg2")
+				.completion(ctx -> Arrays.asList("arg2Comp1").stream().map(CompletionProposal::new).collect(Collectors.toList()))
+				.and()
+			.build();
+		Map<String, CommandRegistration> registrations = new HashMap<>();
+		registrations.put("hello world", registration1);
+		when(commandRegistry.getRegistrations()).thenReturn(registrations);
+
+		List<String> proposals1 = shell.complete(new CompletionContext(Arrays.asList("hello", "world", "--arg1", ""), 3, "".length(), null, null))
+				.stream().map(CompletionProposal::value).collect(Collectors.toList());
+		assertThat(proposals1).containsExactlyInAnyOrder("--arg2", "arg1Comp1");
+
+		List<String> proposals2 = shell.complete(new CompletionContext(Arrays.asList("hello", "world", "--arg1", "xxx", "--arg2", ""), 5, "".length(), null, null))
+				.stream().map(CompletionProposal::value).collect(Collectors.toList());
+		assertThat(proposals2).containsExactlyInAnyOrder("arg2Comp1");
+
+		List<String> proposals3 = shell.complete(new CompletionContext(Arrays.asList("hello", "world", "--arg2", "xxx", "--arg1", ""), 5, "".length(), null, null))
+				.stream().map(CompletionProposal::value).collect(Collectors.toList());
+		assertThat(proposals3).containsExactlyInAnyOrder("arg1Comp1");
+	}
+
 	private static class Exit extends RuntimeException {
 	}
 

spring-shell-core/src/test/java/org/springframework/shell/completion/RegistrationOptionsCompletionResolverTests.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2022 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
+ *
+ *      https://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.shell.completion;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.shell.CompletionContext;
+import org.springframework.shell.CompletionProposal;
+import org.springframework.shell.command.CommandRegistration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class RegistrationOptionsCompletionResolverTests {
+
+	private final RegistrationOptionsCompletionResolver resolver = new RegistrationOptionsCompletionResolver();
+
+	@Test
+	void completesAllOptions() {
+		CommandRegistration registration = CommandRegistration.builder()
+			.command("hello world")
+			.withTarget()
+				.consumer(ctx -> {})
+				.and()
+			.withOption()
+				.longNames("arg1")
+				.and()
+			.withOption()
+				.longNames("arg2")
+				.and()
+			.build();
+		CompletionContext ctx = new CompletionContext(Arrays.asList("hello", "world", ""), 2, "".length(), registration, null);
+		List<CompletionProposal> proposals = resolver.apply(ctx);
+		assertThat(proposals).isNotNull();
+		assertThat(proposals).hasSize(2);
+	}
+
+	@Test
+	void completesNonExistingOptions() {
+		CommandRegistration registration = CommandRegistration.builder()
+			.command("hello world")
+			.withTarget()
+				.consumer(ctx -> {})
+				.and()
+			.withOption()
+				.longNames("arg1")
+				.and()
+			.withOption()
+				.longNames("arg2")
+				.and()
+			.build();
+		CompletionContext ctx = new CompletionContext(Arrays.asList("hello", "world", "--arg1", ""), 2, "".length(), registration, null);
+		List<CompletionProposal> proposals = resolver.apply(ctx);
+		assertThat(proposals).isNotNull();
+		assertThat(proposals).hasSize(1);
+	}
+
+}