Build a framework for a maintainable combat plugin

* Uses a hierarchy of WeaponClasses -> Weapons for performing attacks,
  with WeaponClass having a set of styles and associated Attacks for
  those styles. Weapons and their classes are built with an easy to use
  and clean DSL.

* Adds a BonusContainer mixin, so that Equipment, Weapons, and
  WeaponClasses can all have their own set of bonuses which apply to the
  player.

* Allows attacks to be queued to the Mobs CombatState instance from
  external code, allowing e.g., NPCs or auto-cast to queue attacks to be
  executed.

data/plugins/combat/util.rb

@@ -0,0 +1,70 @@
+java_import 'org.apollo.game.model.entity.EquipmentConstants'
+
+class CombatUtil
+
+  def self.calculate_max_hit(source)
+    strength      = source.skill_set.get_skill(Skill::STRENGTH)
+    strength_stat = 5 #source.bonus_stat(:other, :strength)
+
+    effective_strength_damage = (strength.current_level) #* prayer_multiplier
+
+    if [:aggressive, :alt_aggressive].include? source.combat_style
+      effective_strength_damage += 3
+    end
+
+    (1.3 + (effective_strength_damage / 10) + (strength_stat / 80) +
+      ((effective_strength_damage * strength_stat) / 640))
+  end
+
+  def self.calculate_accuracy(source, target)
+    weapon       = EquipmentUtil.equipped_weapon source
+    weapon_class = weapon.weapon_class
+    combat_style = weapon_class.style_at source.combat_style
+    attack_type  = weapon.weapon_class.attack_type combat_style
+
+    attack_stat  = [1, 1].max
+    defence_stat = [1, 1].max
+
+    attack  = source.skill_set.get_skill(Skill::ATTACK).current_level.to_f
+    defence = target.skill_set.get_skill(Skill::DEFENCE).current_level.to_f
+
+    attack_prayer_multiplier = 1 #TODO: Prayer
+    attack_accuracy          = attack_stat * attack * attack_prayer_multiplier
+    attack_accuracy          = 0.1 if attack_accuracy < 0
+
+    defence_prayer_multiplier = 1 #TODO: Prayer
+    defence_accuracy          = defence_stat * defence * defence_prayer_multiplier
+    defence_accuracy          = 1 if defence_accuracy < 0
+
+    base = attack_accuracy / defence_accuracy
+    base > 1 ? 0.9 : base * 0.9
+  end
+
+  # Calculates a hit for the given <i>Mob</i> and special attack flag.
+  def self.calculate_hit(source, target)
+    accuracy = calculate_accuracy source, target
+    max_hit  = calculate_max_hit(source) + 1
+
+    if rand <= accuracy
+      return rand(max_hit)
+    else
+      return 0
+    end
+  end
+end
+
+class EquipmentUtil
+  def self.equipped_weapon(source)
+    item = source.equipment.get(EquipmentConstants::WEAPON)
+
+    if item.nil?
+      return NAMED_WEAPONS[:no_weapon]
+    end
+
+    WEAPONS[item.id]
+  end
+
+  def self.equipped_projectile(source)
+    item = source.equipment.get(EquipmentConstants::ARROWS)
+  end
+end