06 requirement system

Requirement System

Requirements dictate the conditions under which an event or action should be allowed to process.

Built-in Requirements

KLibrary usually ships with several basic requirements:

• permission: Checks if the player has a specific permission node.
• money: Integrates with Vault to check if the player has enough balance.
• inventory-open: Checks if a player currently has an active KLibrary inventory session.

Logical Grouping (AND / OR)

KLibrary's requirement engine natively supports grouping logic.

When defining requirements via the config, you can specify type: AND or type: OR and supply nested lists.

requirements:
  can-open-crate:
    type: "AND"
    requirements:
      has-key:
        type: "item"
        material: "TRIPWIRE_HOOK"
        amount: 1
      is-vip:
        type: "permission"
        permission: "server.vip"
        deny-actions:
          - "[message] <red>Only VIPs can open this crate!"

If the entire group evaluates to false, the group's deny-actions will be executed.

Custom Requirements

Creating custom requirements is identical to the Action System workflow.

1. Extend the Requirement Abstraction

import io.github.kaivian.klibrary.requirement.api.Requirement;
import io.github.kaivian.klibrary.requirement.api.RequirementResult;
import io.github.kaivian.klibrary.action.api.Action;
import org.bukkit.entity.Player;
import java.util.List;

public class LevelRequirement extends Requirement {
    private final int minLevel;

    public LevelRequirement(int minLevel, List<Action> denyActions) {
        super(denyActions); // Pass deny actions to the superclass
        this.minLevel = minLevel;
    }

    @Override
    public RequirementResult evaluate(Player player) {
        if (player.getLevel() >= minLevel) {
            return RequirementResult.SUCCESS;
        } else {
            return RequirementResult.failure(this); // Triggers execution of denyActions
        }
    }
}

2. Register the Requirement

// Register via your factory instance
requirementFactory.register("level", node -> {
    // Deserialize arguments from the ConfigNode
    int level = node.getInt("level", 1);
    List<Action> denyActions = node.getActionList("deny-actions");
    return new LevelRequirement(level, denyActions);
});