Commands commands = new OkaeriCommands();
commands.registerCommand(ExampleCommand.class); // built for DI (accepts empty constructor by default)
// commands.registerCommand(new ExampleCommand()); // pass own instance (e.g. with custom constructor parameters)

// call manually
commands.call("cmd hello");

// call and get result
Object result = commands.call("cmd woah");

// TODO

// platform specific (bukkit)
// makes all executors async,
// to include/exclude single use @Async/@Sync
@Async
// declare command service using annotation
// aliases can be also specified here
@Command(label = "cmd", description = "Example command service")
public class ExampleCommand implements CommandService {

    // cmd
    //
    // empty pattern represents command without
    // arguments (similar to @Default in other frameworks)
    //
    // no pattern + method name starting with underscore 
    // is the same as using @Executor(pattern = "")
    //
    @Executor
    public String _def() {
        return "called default";
    }

    // cmd woah
    //
    // simple commands with no additional effort
    // using method name is same as pattern = "woah"
    //
    // it also works for simple arguments:
    // @Executor
    // String woah(@Arg String name) -> cmd woah <name>
    //
    @Executor(description = "Prints woah message")
    public String woah() {
        return "woah!";
    }

    // cmd hello
    // cmd hello everyone
    //
    // two patterns are possible in single method, they should
    // however match (e.g. have all the same non-static arguments)
    //
    @Executor(pattern = {"hello", "hello everyone"}, description = "Prints hello message")
    public String hello_everyone() {
        return "hello!";
    }

    // cmd hi
    // cmd hii
    //
    // overwrite usage/description with Commands#resolveText()
    // available out-of-the-box in OkaeriPoland/okaeri-platform i18n integration
    //
    @Executor(pattern = {"hi", "hii"}, description = "${command-cmd-hi-description}", usage = "${command-cmd-hi-usage}")
    public String hi() {
        return "hi!";
    }

    // cmd hello <name>
    //
    // required arguments can be specified using '<PARAMETER_NAME>'
    // or '*' (recommended with -parameters compiler option, uses in-order param name)
    //
    @Completion(arg = "name", value = "@allplayers")
    @Executor(pattern = "hello *", description = "Prints hello message with name")
    public String hello_name(@Arg("name") String name) {
        return "hello " + name;
    }

    // cmd hi [name]
    //
    // optional arguments can be specified using '[PARAMETER_NAME]'
    // or '?' (recommended with -parameters compiler option, uses in-order param name)
    //
    // optional arguments require param to be an Optional or preferably
    // in-house eu.okaeri.commands.service.Option with additional utilities
    //
    @Executor(pattern = "hi ?", description = "Prints hi message with optional name")
    public String hi_name(@Arg("name") Option<String> name) {
        return "hi, " + name.getOr("guest");
    }

    // cmd salute [nameAndSurname]
    // cmd salute John Doe
    //
    // accepts specific number of arguments into one parameter
    // example: *:2 same as <name:2>, ?:2 same as [name:2]
    //
    // optional arguments require param to be an Optional or preferably
    // in-house eu.okaeri.commands.service.Option with additional utilities
    //
    @Executor(pattern = "salute ?:2" , description = "Prints salute message with optional name and surname")
    public String salute_nameAndSurname(@Arg("nameAndSurname") Option<String> name) {
        return "salute " + name.getOr("some guest") + "!";
    }

    // cmd print <message>
    // cmd print Some message with unspecified length
    //
    // accepts all sequential arguments into one parameter
    //
    @Executor(pattern = "print *..." , description = "Prints system out message")
    public void log_message(@Arg("message") String message) {
        System.out.println(message);
    }

    // cmd player <player> set <perm> <value> [flag]
    //
    // mix and match pattern elements, return values to be processed by adapter
    // see below for recommended and simplified pattern variant (for -parameters compiler flag)
    //
    @Executor(pattern = "player <player> set <perm> <value> [flag]", description = "Complex command test")
    public String complex1(@Arg("player") String name, @Arg("perm") String perm, @Arg("value") String value, @Arg("flag") Option<String> flag) {
        return name + " " + perm + " " + value + " " + flag;
    }

    // recommended usage
    //
    // mix param types and resolve unknown values by overriding Commands#resolveMissingArgument (e.g. DI)
    // preserve param names using javac's -parameters or specify them manually @Arg("name")
    //
    // specify inline string completions or use previously registered named completion from Commands#registerCompletion
    // you can also pass @CompletionData and read it in your custom completion implementation as you like
    //
    @Completion(arg = "name", value = "@allplayers", data = @CompletionData(name = "limit", value = "10"))
    @Completion(arg = "perm", value = {"build", "break", "place"})
    @Completion(arg = "value", value = {"allow", "deny"})
    @Completion(arg = "flag", value = {"-silent"})
    @Executor(pattern = "player * set2 * * ?", description = "Complex command test")
    public String complex2(@Arg String name, int huh, @Arg String perm, @RawArgs String[] args, @Arg String value, String randomElement, @Arg Option<String> flag) {
        return (">> " + name + " " + perm + " " + value + " " + flag + "\n" + Arrays.toString(args));
    }
}