Changed command system (#304)

* Save Cacheable expansions data on shutdown

* Prepare for 1.16

* 1.16.1 is out apparently

* Further fixes, still not done

* Inline JSONMessages & fix for 1.16

* Done :O

* Done for real now, (hopefully)

* Changed to static instead of DI for plugin instance

* Cleanup

* Modified tab completions. Removed extra command.

* Apparently this is needed

* Started cleaning stuff up

basically just pushing so I can continue on laptop

* did more cleaning, probs like half way done

* more cleaning. reverted back to a min arg system somewhat similar to what frosty had, but less boilerplate.

* Started debugging and fixing runtime/compile errors

* Fixed bugs, still needs thorough testing

* Re-enable metrics

* relocated stuff again

* - Remove json message relocation
- uncomment other relocations
- reformat pom
- remove useless scope declaration
- Fix metrics constructor
- Switch commands to use inline json message

Co-authored-by: iGabyTM <contactgabytm@gmail.com>
Co-authored-by: darbyjack <admin@glaremasters.me>
Co-authored-by: PiggyPiglet <noreply@piggypiglet.me>

src/main/java/me/clip/placeholderapi/commands/Command.java

@@ -0,0 +1,82 @@
+package me.clip.placeholderapi.commands;
+
+import com.google.common.collect.ImmutableSet;
+import org.bukkit.command.CommandSender;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+public abstract class Command {
+    private static final Options EMPTY_OPTIONS = new Options(null, 0, null);
+
+    private final String match;
+    private final String usage;
+    private final int minimumArguments;
+    private final Set<String> permissions;
+
+    protected Command(@NotNull final String match) {
+        this(match, EMPTY_OPTIONS);
+    }
+
+    protected Command(@NotNull final String match, @NotNull final Options options) {
+        this.match = match;
+        this.usage = options.usage == null ? "/papi " + match + " <required args> [optional args]" : options.usage;
+        this.permissions = options.permissions == null ? Collections.emptySet() : ImmutableSet.copyOf(options.permissions);
+        this.minimumArguments = options.minimumArguments;
+    }
+
+    protected static Options usage(@NotNull final String usage, final int minimumArguments) {
+        return new Options(usage, minimumArguments, null);
+    }
+
+    protected static Options permissions(@NotNull final String... permissions) {
+        return new Options(null, 0, permissions);
+    }
+
+    protected static Options options(@NotNull final String usage, final int minimumArguments,
+                                     @NotNull final String... permissions) {
+        return new Options(usage, minimumArguments, permissions);
+    }
+
+    @NotNull
+    public String getMatch() {
+        return match;
+    }
+
+    @NotNull
+    public String getUsage() {
+        return usage;
+    }
+
+    public int getMinimumArguments() {
+        return minimumArguments;
+    }
+
+    @NotNull
+    public Set<String> getPermissions() {
+        return permissions;
+    }
+
+    public abstract void execute(@NotNull final CommandSender sender, @NotNull final String[] args);
+
+    @NotNull
+    public List<String> handleCompletion(@NotNull final CommandSender sender, @NotNull final String[] args) {
+        return Collections.emptyList();
+    }
+
+    private static class Options {
+        private final String usage;
+        private final int minimumArguments;
+        private final String[] permissions;
+
+        private Options(@Nullable final String usage, final int minimumArguments,
+                        @Nullable final String[] permissions) {
+            this.usage = usage;
+            this.minimumArguments = minimumArguments;
+            this.permissions = permissions;
+        }
+    }
+}