feat: extend status with Status.remove and Status.cureHostile

src/status.lua

@@ -2,6 +2,12 @@
 -- damage-over-time drains hp, regeneration restores it, stun skips the action,
 -- and haste/slow/strength feed modifiers into speed and combat. Effects are
 -- plain data on entity.statuses so they serialize without special handling.
+-- Poison and burning route their tick damage through resistances.lua, so a
+-- poison-immune undead shrugs off venom entirely and a fire-resistant hide
+-- only smoulders at half the usual potency.
+
+local Resistances = require("resistances")
+local Conductivity = require("conductivity")
 
 local Status = {}
 
@@ -12,20 +18,54 @@ Status.REGEN = "regen"
 Status.HASTE = "haste"
 Status.SLOW = "slow"
 Status.STRENGTH = "strength"
+Status.SHIELD = "shield"
+Status.WEAKEN = "weaken"
+Status.DISCORD = "discord"
+Status.CONFUSE = "confuse"
+Status.BLIND = "blind"
+Status.LEVITATE = "levitate"
+
+-- Odds, rolled fresh each turn a confused actor tries to act, that its own
+-- chosen direction gets overridden by a random one instead - see
+-- Game:movePlayer's stumble branch and Ai.act's mirror of it for monsters.
+Status.CONFUSE_NUMERATOR = 1
+Status.CONFUSE_DENOMINATOR = 2
+
+-- Debuffs a cleansing effect (see effects.lua's "cure" handler) is allowed to
+-- strip early. Buffs (REGEN/HASTE/STRENGTH/SHIELD/LEVITATE) are deliberately
+-- excluded - a curative should not also strip a buff the entity chose to be
+-- carrying.
+Status.HOSTILE = {
+  [Status.POISON] = true,
+  [Status.BURNING] = true,
+  [Status.STUN] = true,
+  [Status.SLOW] = true,
+  [Status.WEAKEN] = true,
+  [Status.DISCORD] = true,
+  [Status.CONFUSE] = true,
+  [Status.BLIND] = true,
+}
 
 Status.defs = {
   [Status.POISON] = {
     glyph = "p",
     tick = function(entity, potency)
-      entity.hp = entity.hp - potency
+      local dealt = Resistances.apply(entity, potency, Resistances.POISON)
-      return string.format("poison saps %s for %d", entity.name, potency)
+      entity.hp = entity.hp - dealt
+      if dealt <= 0 then
+        return entity.kind == "player" and "you shrug off the poison"
+          or string.format("%s shrugs off the poison", entity.name)
+      end
+      return string.format("poison saps %s for %d", entity.name, dealt)
     end,
   },
   [Status.BURNING] = {
     glyph = "b",
     tick = function(entity, potency)
-      entity.hp = entity.hp - potency
+      local dealt = Conductivity.applyFire(entity, potency)
-      return string.format("flames sear %s for %d", entity.name, potency)
+      entity.hp = entity.hp - dealt
+      if dealt <= 0 then return string.format("the flames wash over %s harmlessly", entity.name) end
+      return string.format("flames sear %s for %d", entity.name, dealt)
     end,
   },
   [Status.REGEN] = {
@@ -34,7 +74,9 @@ Status.defs = {
       local before = entity.hp
       entity.hp = math.min(entity.maxHp, entity.hp + potency)
       if entity.hp > before then
-        return string.format("%s knits flesh for %d", entity.name, entity.hp - before)
+        local healed = entity.hp - before
+        return entity.kind == "player" and string.format("you knit flesh for %d", healed)
+          or string.format("%s knits flesh for %d", entity.name, healed)
       end
       return nil
     end,
@@ -43,9 +85,38 @@ Status.defs = {
   [Status.HASTE] = { glyph = "h", speed = 60 },
   [Status.SLOW] = { glyph = "l", speed = -50 },
   [Status.STRENGTH] = { glyph = "S", attack = 3 },
+  [Status.SHIELD] = { glyph = "d", defense = 4 },
+  [Status.WEAKEN] = { glyph = "c", attack = -3 },
+  -- No tick or stat modifier of its own: infighting.lua reads Status.has
+  -- directly to decide whether a monster's turn goes to Ai.act at all.
+  [Status.DISCORD] = { glyph = "o" },
+  -- No tick or stat modifier of its own either: Game:movePlayer and Ai.act
+  -- both read Status.has directly, at the point they would otherwise commit
+  -- to a chosen direction, to roll whether that direction gets overridden.
+  [Status.CONFUSE] = { glyph = "f" },
+  -- No tick or stat modifier of its own: Game:effectiveRadius and
+  -- Game:canSeePlayer both read Status.has directly, clamping vision instead
+  -- of touching hp or combat stats - confuse scrambles where you go, blind
+  -- scrambles what you can tell is there in the first place.
+  [Status.BLIND] = { glyph = "!" },
+  -- No tick or stat modifier of its own: Game:checkTerrainFor and
+  -- Game:checkTrapFor (plus movePlayer's own trap check) read Status.has
+  -- directly, letting a levitating entity drift clear of lava, a chasm's
+  -- drop, an ice tile's slide, and any ground-pressure trap without ever
+  -- touching whatever would otherwise trigger them.
+  [Status.LEVITATE] = { glyph = "y" },
 }
 
+-- Records `kind` as active on `entity` for `duration` more ticks at `potency`,
+-- or refreshes an already-active instance of the same kind to whichever of
+-- the two durations and potencies is stronger. A soaked entity's own
+-- dampness (see conductivity.lua) refuses a BURNING application outright,
+-- before anything is recorded - returns nil and leaves entity.statuses
+-- untouched, exactly as if the call had never been made.
 function Status.apply(entity, kind, duration, potency)
+  if kind == Status.BURNING and Conductivity.resistsIgnition(entity) then
+    return nil
+  end
   potency = potency or 1
   for _, active in ipairs(entity.statuses) do
     if active.kind == kind then
@@ -66,6 +137,36 @@ function Status.has(entity, kind)
   return false
 end
 
+-- Strips one named status outright, independent of its remaining duration.
+-- Returns whether anything was actually removed.
+function Status.remove(entity, kind)
+  for i, active in ipairs(entity.statuses) do
+    if active.kind == kind then
+      table.remove(entity.statuses, i)
+      return true
+    end
+  end
+  return false
+end
+
+-- Strips every active status listed in Status.HOSTILE (poison, burning,
+-- stun, slow, weaken, discord, confuse, blind), leaving buffs untouched.
+-- Returns the kinds actually removed, in the order they were active, for
+-- callers that want to report exactly what a cleansing effect lifted.
+function Status.cureHostile(entity)
+  local removed = {}
+  local kept = {}
+  for _, active in ipairs(entity.statuses) do
+    if Status.HOSTILE[active.kind] then
+      removed[#removed + 1] = active.kind
+    else
+      kept[#kept + 1] = active
+    end
+  end
+  entity.statuses = kept
+  return removed
+end
+
 -- Advances every effect one step, applying its tick and dropping expired ones.
 -- Returns the log lines produced this step, in effect order.
 function Status.tick(entity)
@@ -104,6 +205,15 @@ function Status.attackModifier(entity)
   return delta
 end
 
+function Status.defenseModifier(entity)
+  local delta = 0
+  for _, active in ipairs(entity.statuses) do
+    local def = Status.defs[active.kind]
+    if def.defense then delta = delta + def.defense end
+  end
+  return delta
+end
+
 function Status.skipsTurn(entity)
   for _, active in ipairs(entity.statuses) do
     if Status.defs[active.kind].skipsTurn then return true end