feat: extend classes with Classes.isValid and Classes.apply

src/combat.lua

@@ -1,24 +1,53 @@
 -- Deterministic combat: damage is effective attack minus effective defense,
--- floored at 1. Effective stats fold in temporary status modifiers.
+-- floored at 1. Effective stats fold in temporary status modifiers, plus
+-- conditional skill bonuses (berserk/mana shield - see skills.lua, a no-op
+-- for any entity without a `skills` table, i.e. monsters) and any completed
+-- runeword on the wielder's own weapon/armor (see runewords.lua, a no-op for
+-- any item without a matching rune chain), plus any item-set threshold the
+-- wielder's current gear happens to meet (see sets.lua, a no-op below its
+-- lowest 2-piece threshold).
+-- The attack-minus-defense minimum-1 floor happens before elemental
+-- resistance (resistances.lua) gets a say, so a defender immune to the
+-- attack's damage type can still shrug off a hit that combat itself
+-- guaranteed would land.
+
+local Skills = require("skills")
+local Resistances = require("resistances")
+local Runewords = require("runewords")
+local Sets = require("sets")
 
 local Combat = {}
 
 local function attackOf(entity)
-  return entity.effectiveAttack and entity:effectiveAttack() or entity.attack
+  local base = entity.effectiveAttack and entity:effectiveAttack() or entity.attack
+  return base + Skills.attackBonus(entity) + Runewords.attackBonus(entity) + Sets.attackBonus(entity)
 end
 
 local function defenseOf(entity)
-  return entity.effectiveDefense and entity:effectiveDefense() or entity.defense
+  local base = entity.effectiveDefense and entity:effectiveDefense() or entity.defense
+  return base + Skills.defenseBonus(entity) + Runewords.defenseBonus(entity) + Sets.defenseBonus(entity)
 end
 
-function Combat.damage(attacker, defender)
-  local dealt = attackOf(attacker) - defenseOf(defender)
+-- The type of an attacker's raw damage: a weapon retagged by an elemental
+-- affix (flaming/venomed - see affixes.lua) fights with that element instead
+-- of a bare fist or claw's plain physical.
+local function damageTypeOf(attacker)
+  return (attacker.weapon and attacker.weapon.damageType) or Resistances.PHYSICAL
+end
+
+-- `multiplier` scales the raw attack-minus-defense difference before the
+-- floor-at-1 minimum is applied, so a backstab still guarantees at least 1
+-- rather than 2x-ing an already-clamped hit. `damageType` defaults to the
+-- attacker's own weapon typing when omitted.
+function Combat.damage(attacker, defender, multiplier, damageType)
+  local dealt = (attackOf(attacker) - defenseOf(defender)) * (multiplier or 1)
   if dealt < 1 then dealt = 1 end
-  return dealt
+  dealt = math.floor(dealt)
+  return Resistances.apply(defender, dealt, damageType or damageTypeOf(attacker))
 end
 
-function Combat.attack(attacker, defender)
-  local dealt = Combat.damage(attacker, defender)
+function Combat.attack(attacker, defender, multiplier, damageType)
+  local dealt = Combat.damage(attacker, defender, multiplier, damageType)
   defender.hp = defender.hp - dealt
   return { damage = dealt, killed = defender.hp <= 0 }
 end