Completion issues

[fonimus]

Hello there, I bumped to the last released version (2.1.0) and I noticed that the completion does not work properly :
the command options are always displayed (even if we want the enum values of specific option or if the option is already given in the command line.

Here is a small example with the getting started example, we can see the option --a is in completion proposal even if we should put option value (here the number) and if it is already in the command.

I made the following fix by extended shell in my project (maybe I didn't think of everything so you can probably check this / test it / improve it :

Location : org.springframework.shell.Shell#complete

public List<CompletionProposal> complete(CompletionContext context) {

	String prefix = context.upToCursor();

	List<CompletionProposal> candidates = new ArrayList<>();
	candidates.addAll(commandsStartingWith(prefix));

	String best = findLongestCommand(prefix);
	if (best != null) {
		context = context.drop(best.split(" ").length);
		CommandRegistration registration = commandRegistry.getRegistrations().get(best);
		CompletionContext argsContext = context.commandRegistration(registration);

		// current code
		//for (CompletionResolver resolver : completionResolvers) {
		//	List<CompletionProposal> resolved = resolver.apply(argsContext);
		//	candidates.addAll(resolved);
		//}

		// Try to complete arguments
		//List<CommandOption> matchedArgOptions = new ArrayList<>();
		//if (argsContext.getWords().size() > 0) {
		//	matchedArgOptions.addAll(matchOptions(registration.getOptions(), argsContext.getWords().get(0)));
		//}
		// end of current code


		// new code
		final List<String> words = context.getWords().stream().filter(StringUtils::hasText).collect(Collectors.toList());
                String lastWord = words.isEmpty() ? null : words.get(words.size() - 1);

                List<CommandOption> matchedArgOptions = new ArrayList<>();
                if (lastWord != null) {
                    // last word used instead of first to check if matching args
                    matchedArgOptions.addAll(matchOptions(registration.getOptions(), lastWord));
                }
                if (matchedArgOptions.isEmpty()) {
                    // only add command options if last word did not match option
                    for (CompletionResolver resolver : completionResolvers) {
                        List<CompletionProposal> resolved = resolver.apply(argsContext);
                        candidates.addAll(resolved.stream().filter(cp -> !words.contains(cp.value())).collect(Collectors.toList()));
                    }
                }
		// end of new code

		List<CompletionProposal> argProposals =	matchedArgOptions.stream()
			.flatMap(o -> {
				Function<CompletionContext, List<CompletionProposal>> completion = o.getCompletion();
				if (completion != null) {
					List<CompletionProposal> apply = completion.apply(argsContext.commandOption(o));
					return apply.stream();
				}
				return Stream.empty();
			})
			.collect(Collectors.toList());

		candidates.addAll(argProposals);
	}
	return candidates;
}

[jvalkeal]

Dup of #495. It's backported for next release 2.1.1.