--!name Billy's Blackjack
--!icon game

local BANK_START = 500
local MIN_BET, MAX_BET, BET_STEP = 5, 500, 5

local phase, deck, you, billy = "bet", {}, {}, {}
local bank, bet, message, outcome = BANK_START, 25, "", ""
local doubled, wins, losses, pushes = false, 0, 0, 0
local net = 0   -- what the last hand moved, for the settled screen

local RANKS = {
  {"A", 11}, {"2", 2}, {"3", 3}, {"4", 4}, {"5", 5}, {"6", 6}, {"7", 7},
  {"8", 8}, {"9", 9}, {"10", 10}, {"J", 10}, {"Q", 10}, {"K", 10},
}
local SUITS = {"S", "H", "D", "C"}

local function shuffle()
  deck = {}
  for s = 1, 4 do
    for r = 1, 13 do
      deck[#deck + 1] = {face = RANKS[r][1] .. SUITS[s], v = RANKS[r][2], rank = r}
    end
  end
  for i = #deck, 2, -1 do
    local j = math.random(i)
    deck[i], deck[j] = deck[j], deck[i]
  end
end

local function draw_card(hand)
  if #deck == 0 then shuffle() end
  hand[#hand + 1] = table.remove(deck)
end

local function total(hand)
  local t, aces = 0, 0
  for _, c in ipairs(hand) do
    t = t + c.v
    if c.rank == 1 then aces = aces + 1 end
  end
  while t > 21 and aces > 0 do t, aces = t - 10, aces - 1 end
  return t
end

local function soft(hand)
  local t, aces = 0, 0
  for _, c in ipairs(hand) do
    t = t + c.v
    if c.rank == 1 then aces = aces + 1 end
  end
  while t > 21 and aces > 0 do t, aces = t - 10, aces - 1 end
  return aces > 0
end

local function is_blackjack(hand)
  return #hand == 2 and total(hand) == 21
end

local function hand_spec(hand, hide)
  local out = {}
  for i, c in ipairs(hand) do
    out[i] = (hide and i == 2) and "?" or c.face
  end
  return table.concat(out, " ")
end

local function save()
  snail.save(string.format("%d %d %d %d", bank, wins, losses, pushes))
end

local function load()
  local s = snail.load()
  if not s then return end
  local b, w, l, p = s:match("(%-?%d+) (%d+) (%d+) (%d+)")
  if b then
    bank, wins, losses, pushes = tonumber(b), tonumber(w), tonumber(l), tonumber(p)
  end
  if bank < MIN_BET then bank = BANK_START end
end

local function clamp_bet()
  bet = math.max(MIN_BET, math.min(bet, MAX_BET, bank))
end

local function billy_says(kind)
  local lines = {
    deal    = {"Place it and we'll see.", "Cards are cards.", "Let's have a look."},
    hit     = {"Bold.", "Another, then.", "You want it, you got it."},
    close   = {"That's a working hand.", "I'd sit on that.", "Now we're talking."},
    bust    = {"Over. Happens.", "Twenty-two is still twenty-two.",
               "The house thanks you."},
    bbust   = {"Over. Yours.", "I've overdone it.", "The deck turned on me."},
    dealbj  = {"Blackjack. Don't look at me like that.",
               "Twenty-one on the deal. That's the game."},
    yourbj  = {"Blackjack. Pays three to two.", "Well. Look at that."},
    win     = {"You take it.", "Fair and square.", "Good hand."},
    lose    = {"Mine.", "That's the house.", "Better luck next one."},
    push    = {"Nobody's hand.", "Push. Try again.", "A tie is a rest."},
    broke   = {"That's the bankroll. I'll spot you a fresh one.",
               "Cleaned out. Sit, I'll deal you back in."},
  }
  local set = lines[kind] or lines.deal
  return set[math.random(#set)]
end

local function settle()
  local yt, bt = total(you), total(billy)
  local ybj, bbj = is_blackjack(you), is_blackjack(billy)
  local stake = doubled and bet * 2 or bet

  if yt > 21 then
    outcome, net, losses = "BUST", -stake, losses + 1
    message = billy_says("bust")
  elseif ybj and not bbj then
    outcome, net, wins = "BLACKJACK", math.floor(stake * 3 / 2), wins + 1
    message = billy_says("yourbj")
  elseif bbj and not ybj then
    outcome, net, losses = "BILLY HAS IT", -stake, losses + 1
    message = billy_says("dealbj")
  elseif bt > 21 then
    outcome, net, wins = "BILLY BUSTS", stake, wins + 1
    message = billy_says("bbust")
  elseif yt > bt then
    outcome, net, wins = "YOU WIN", stake, wins + 1
    message = billy_says("win")
  elseif bt > yt then
    outcome, net, losses = "BILLY WINS", -stake, losses + 1
    message = billy_says("lose")
  else
    outcome, net, pushes = "PUSH", 0, pushes + 1
    message = billy_says("push")
  end
  bank = bank + net

  if bank < MIN_BET then
    bank = BANK_START
    message = billy_says("broke")
  end
  clamp_bet()
  phase = "over"
  snail.hint("OK deal again   BACK menu")
  save()
end

local function dealer_plays()
  while total(billy) < 17 do draw_card(billy) end
  settle()
end

local function play_hint()
  snail.hint(#you == 2 and bank >= bet * 2
             and "OK hit   DOWN stand   LEFT double   BACK menu"
             or  "OK hit   DOWN stand   BACK menu")
end

local function deal()
  shuffle()
  you, billy, doubled = {}, {}, false
  draw_card(you); draw_card(billy); draw_card(you); draw_card(billy)
  phase = "play"
  message = billy_says("deal")
  if is_blackjack(you) or is_blackjack(billy) then settle() end
end

function start()
  snail.ink("fast")   -- solid tiles, so the short waveform is honest here
  load()
  clamp_bet()
  phase = "bet"
  message = "Sit down."
  snail.hint("UP/DOWN bet   OK deal   BACK menu")
end

function key(k)
  if phase == "bet" then
    if k == "up"   then bet = math.min(math.min(MAX_BET, bank), bet + BET_STEP)
    elseif k == "down" then bet = math.max(MIN_BET, bet - BET_STEP)
    elseif k == "left" then bet = MIN_BET
    elseif k == "right" then bet = math.min(MAX_BET, bank)
    elseif k == "ok" then
      deal()
      if phase == "play" then play_hint() end
    end

  elseif phase == "play" then
    if k == "ok" then
      draw_card(you)
      local t = total(you)
      if t > 21 then
        settle()
      elseif t == 21 then
        dealer_plays()
      else
        message = billy_says(t >= 17 and "close" or "hit")
        play_hint()   -- double left the table with the third card
      end
    elseif k == "down" then
      dealer_plays()
    elseif k == "left" and #you == 2 and bank >= bet * 2 then
      doubled = true
      draw_card(you)
      if total(you) > 21 then settle() else dealer_plays() end
    end

  else -- over
    if k == "ok" then
      phase = "bet"
      clamp_bet()
      message = "Again?"
      snail.hint("UP/DOWN bet   OK deal   BACK menu")
    end
  end
end

function draw()
  if phase == "bet" then
    snail.center(true)
    snail.image("billy")
    snail.title("$" .. bank)
    snail.small(string.format("%d won   %d lost   %d pushed", wins, losses, pushes))
    snail.gap()
    snail.title("BET  $" .. bet)
    snail.gap()
    snail.text(message)
    return
  end

  snail.center(true)
  snail.small("BILLY")
  snail.cards(hand_spec(billy, phase == "play"))
  snail.small(phase == "play"
              and ("showing " .. billy[1].v)
              or  ("total " .. total(billy)))
  snail.gap()
  snail.small("YOU" .. (doubled and "   (doubled)" or ""))
  snail.cards(hand_spec(you, false))
  snail.small(string.format("total %d%s", total(you),
              soft(you) and "  soft" or ""))
  snail.gap()
  if phase == "over" then
    snail.title(outcome .. (net > 0 and ("  +$" .. net)
                or  net < 0 and ("  -$" .. -net) or ""))
    snail.text(message)
    snail.gap()
    snail.small("bank $" .. bank)
  else
    snail.text(message)
  end
end