feat: add Streaks.new, Streaks.record and Terrain.slide

src/streaks.lua

@@ -0,0 +1,57 @@
+-- Win/loss streak tracking over meta.lua's own run history: not "how many
+-- wins in total" (Meta.recordRun's own totalRuns/wins tally already answers
+-- that) but how many of the *most recent* runs in a row ended the same
+-- way - the number that actually swings the instant a lucky or unlucky run
+-- lands, unlike a lifetime win rate that a hundred prior runs already numbs.
+
+local Streaks = {}
+
+Streaks.HISTORY_CAP = 50
+
+function Streaks.new()
+  return {}
+end
+
+-- Appends `won` (a boolean) as the newest entry, trimming the oldest once
+-- history grows past Streaks.HISTORY_CAP - a streak only ever needs to look
+-- back so far, and an unbounded history would grow meta.lua's save file
+-- forever for no further benefit.
+function Streaks.record(history, won)
+  history[#history + 1] = won
+  while #history > Streaks.HISTORY_CAP do
+    table.remove(history, 1)
+  end
+end
+
+-- Length of the run of identical outcomes ending at the most recent entry,
+-- and which outcome that is - (0, nil) for an empty history. A single win
+-- right after a loss reads as a streak of exactly 1, not 0: the run just
+-- recorded is itself part of its own streak.
+function Streaks.current(history)
+  if #history == 0 then return 0, nil end
+  local outcome = history[#history]
+  local length = 0
+  for i = #history, 1, -1 do
+    if history[i] ~= outcome then break end
+    length = length + 1
+  end
+  return length, outcome
+end
+
+-- The longest run of consecutive wins anywhere in history, not just the one
+-- still active - a player's all-time best winning streak survives even
+-- after it eventually breaks.
+function Streaks.bestWinStreak(history)
+  local best, running = 0, 0
+  for _, won in ipairs(history) do
+    if won then
+      running = running + 1
+      if running > best then best = running end
+    else
+      running = 0
+    end
+  end
+  return best
+end
+
+return Streaks

src/terrain.lua

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+-- Permanent map terrain that punishes careless movement, as opposed to
+-- hazards.lua's fire and gas which are timed and spawned mid-game. Lava
+-- scorches whoever stands on it every time they step there, a chasm drops
+-- the player to the floor below (or swallows a monster outright), and ice
+-- keeps sliding a traveller in the direction they started moving until
+-- something stops them. None of it spreads, fades, or needs saving beyond
+-- the glyph already baked into the map by the builder.
+
+local Tiles = require("tiles")
+local Status = require("status")
+local Resistances = require("resistances")
+
+local Terrain = {}
+
+Terrain.LAVA_DAMAGE = 8
+
+-- Slides entity through consecutive ice tiles in direction (dx, dy), from
+-- wherever it just came to rest. Stops the instant the current tile isn't
+-- ice, the next cell is unwalkable, or another actor already occupies it -
+-- so ice never carries a traveller through a wall or on top of someone else.
+function Terrain.slide(level, entity, dx, dy)
+  local map = level.map
+  while map:get(entity.x, entity.y) == Tiles.ICE do
+    local nx, ny = entity.x + dx, entity.y + dy
+    if not map:isWalkable(nx, ny) then break end
+    if level:entityAt(nx, ny) then break end
+    entity.x, entity.y = nx, ny
+  end
+end
+
+-- Applies lava's burn to whoever is currently standing on it. Returns a log
+-- line, or nil when the tile underfoot isn't lava.
+function Terrain.afflictLava(level, entity)
+  if level.map:get(entity.x, entity.y) ~= Tiles.LAVA then return nil end
+  local dealt = Resistances.apply(entity, Terrain.LAVA_DAMAGE, Resistances.FIRE)
+  entity.hp = entity.hp - dealt
+  if dealt <= 0 then
+    return entity.kind == "player" and "you wade through the lava unharmed"
+      or string.format("%s wades through the lava unharmed", entity.name)
+  end
+  Status.apply(entity, Status.BURNING, 2, math.max(1, dealt // 3))
+  return string.format("molten rock sears %s for %d", entity.name, dealt)
+end
+
+function Terrain.isChasm(level, entity)
+  return level.map:get(entity.x, entity.y) == Tiles.CHASM
+end
+
+return Terrain

src/throwing.lua

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+-- Player ranged option that costs no mana: any spare weapon or potion sitting
+-- in the inventory (not the one currently wielded) can be hurled at a monster
+-- in range and line of sight. A thrown weapon hits harder than a melee swing
+-- and lands where it struck, ready to be picked back up; a thrown potion
+-- shatters and visits its effect on the target instead of the thrower, which
+-- only makes sense for potions with a hostile reading.
+
+local Los = require("los")
+local Status = require("status")
+local Items = require("items")
+local Hazards = require("hazards")
+local Resistances = require("resistances")
+
+local Throwing = {}
+
+Throwing.RANGE = 6
+local POWER_MULT = 2
+
+-- Hostile reading of each potion effect. Potions with no meaningful effect on
+-- an enemy (healing, strength) just shatter harmlessly rather than helping
+-- whoever they were thrown at.
+local hostileEffects = {
+  poison = function(game, target)
+    Status.apply(target, Status.POISON, 6, 3)
+    Hazards.spawnGas(game.level, target.x, target.y, 4, 2)
+    return string.format("the potion shatters, poisoning %s in a cloud of fumes", target.name)
+  end,
+  haste = function(_, target)
+    Status.apply(target, Status.HASTE, 10, 1)
+    return string.format("the potion shatters, and %s bolts away", target.name)
+  end,
+  confuse = function(_, target)
+    Status.apply(target, Status.CONFUSE, 6, 1)
+    return string.format("the potion shatters, and %s reels in confusion", target.name)
+  end,
+  blind = function(_, target)
+    Status.apply(target, Status.BLIND, 6, 1)
+    return string.format("the potion shatters in a blinding flash, and %s is struck blind", target.name)
+  end,
+  -- Same hostile reading as haste above: lifting a dangerous target off the
+  -- ground lets it drift clear of whatever lava, chasm, or trap the thrower
+  -- was counting on to block or punish it (see status.lua's Status.LEVITATE),
+  -- so handing it to an enemy is a liability, not a gift.
+  levitate = function(_, target)
+    Status.apply(target, Status.LEVITATE, 10, 1)
+    return string.format("the potion shatters, and %s rises off the ground", target.name)
+  end,
+}
+
+function Throwing.canThrow(item)
+  return item.kind == Items.WEAPON or item.kind == Items.POTION
+end
+
+function Throwing.canReach(game, x1, y1, x2, y2)
+  local dist = math.max(math.abs(x1 - x2), math.abs(y1 - y2))
+  return dist <= Throwing.RANGE and Los.clear(game.level.map, x1, y1, x2, y2)
+end
+
+-- Resolves a thrown item against a target. Returns (true, lines) if the item
+-- left the thrower's hand - whether or not it did anything useful on arrival
+-- - or (false, lines) if the throw never happened at all.
+function Throwing.resolve(game, thrower, item, target)
+  if not Throwing.canThrow(item) then
+    return false, { "that can't be thrown" }
+  end
+  if not target or not target:isAlive() then
+    return false, { "no target" }
+  end
+  if not Throwing.canReach(game, thrower.x, thrower.y, target.x, target.y) then
+    return false, { "you have no clear throw" }
+  end
+  if item.kind == Items.WEAPON then
+    local dmg = Resistances.apply(target, item.power * POWER_MULT, item.damageType or Resistances.PHYSICAL)
+    target.hp = target.hp - dmg
+    local lines = { string.format("your thrown %s hits %s for %d", item.name, target.name, dmg) }
+    game.level.floorItems[#game.level.floorItems + 1] = { x = target.x, y = target.y, item = item }
+    if not target:isAlive() then game:awardKill(target) end
+    return true, lines
+  end
+  local handler = hostileEffects[item.effect]
+  local line = handler and handler(game, target) or "the potion shatters harmlessly"
+  return true, { line }
+end
+
+return Throwing