Implements the add condition command and its tab completion

src/main/java/net/knarcraft/paidsigns/command/AddConditionTabCompleter.java

@@ -0,0 +1,57 @@
+package net.knarcraft.paidsigns.command;
+
+import net.knarcraft.paidsigns.utility.TabCompleteHelper;
+import net.knarcraft.paidsigns.utility.Tokenizer;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.command.TabCompleter;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.List;
+
+/**
+ * The tab completer for the add paid sign condition command
+ */
+public class AddConditionTabCompleter implements TabCompleter {
+
+    private List<String> lineIndices;
+    private List<String> stringsToMatch;
+    private List<String> booleans;
+    private List<String> optionStates;
+
+    @Nullable
+    @Override
+    public List<String> onTabComplete(@NotNull CommandSender sender, @NotNull Command command, @NotNull String alias,
+                                      @NotNull String[] args) {
+        if (lineIndices == null) {
+            initializeValues();
+        }
+
+        List<String> arguments = Tokenizer.tokenize(String.join(" ", args));
+        int argumentSize = args[args.length - 1].isEmpty() ? arguments.size() : arguments.size() - 1;
+        if (argumentSize < 1) {
+            return TabCompleteHelper.getPaidSignNames();
+        } else if (argumentSize < 2) {
+            return this.lineIndices;
+        } else if (argumentSize < 3) {
+            return stringsToMatch;
+        } else if (argumentSize < 4) {
+            return booleans;
+        } else if (argumentSize < 6) {
+            return optionStates;
+        }
+        return null;
+    }
+
+    /**
+     * Initializes the values available for tab completion
+     */
+    private void initializeValues() {
+        lineIndices = TabCompleteHelper.getSignLines();
+        stringsToMatch = TabCompleteHelper.getExampleConditionStrings();
+        booleans = TabCompleteHelper.getBooleans();
+        optionStates = TabCompleteHelper.getOptionStates();
+    }
+
+}