store camel stack positions (also slower apparently)

game.nim

@@ -53,9 +53,13 @@ type
     camels*: ColorStack
     tile*: Option[Tile]
 
+  CamelPos* = object
+    square*: range[1..16]
+    stackIdx*: int8
+
   Board* = object
     squares*: array[1..16, Square]
-    camels*: array[Color, range[1..16]]
+    camels*: array[Color, CamelPos]
     diceRolled*: array[Color, bool]
     leader*: Option[Color]
     gameOver*: bool
@@ -103,13 +107,17 @@ proc setState*(b: var Board;
                tiles: openArray[tuple[t: Tile, p: int]]) =
   for (color, dest) in camels: # note that `camels` is ordered, as this determines stacking
     b[dest].camels.add(color)
-    b.camels[color] = dest
+    let height = b[dest].camels.high
+    b.camels[color] = CamelPos(square: dest, stackIdx: height)
 
   for (tile, dest) in tiles:
     b[dest].tile = some(tile)
 
-  let leadCamel = b[max(b.camels)].camels[^1] # top camel in the last currently-occupied space
-  b.leader = some(leadCamel)
+  for sq in b.squares:
+    if sq.camels.len > 0:
+      let squareLeader = sq.camels[^1]
+      if b.leader.isNone or b.leader.get != squareLeader:
+        b.leader = some(squareLeader)
 
 
 proc diceRemaining*(b: Board): ColorStack =
@@ -126,7 +134,7 @@ proc resetDice*(b: var Board) =
 proc advance*(b: var Board, die: Die) =
   let
     (color, roll) = die
-    startPos = b.camels[color]
+    startPos = b.camels[color].square
   var endPos = startPos + roll
   
   if endPos > 16: # camel has passed the finish line
@@ -144,18 +152,18 @@ proc advance*(b: var Board, die: Die) =
   if prepend:
     b[startPos].camels.moveSubstackPre(b[endPos].camels, stackStart)
     let stackLen = b[startPos].camels.len - stackStart
-    for i in 0 ..< stackLen:
+    for i in 0'i8 ..< stackLen:
       # we know how many camels we added to the bottom, so set the position for each of those
-      b.camels[b[endPos].camels[i]] = endPos
+      b.camels[b[endPos].camels[i]] = CamelPos(square: endPos, stackIdx: i) # replace with cast later?
   else:
     let dstPrevHigh = b[endPos].camels.high
     b[startPos].camels.moveSubstack(b[endPos].camels, stackStart)
     # the camels that have moved start immediately after the previous high camel
     for i in (dstPrevHigh + 1) .. b[endPos].camels.high:
-      b.camels[b[endPos].camels[i]] = endPos
+      b.camels[b[endPos].camels[i]] = CamelPos(square: endPos, stackIdx: i)
   
   # if we are stacking on or moving past the previous leader
-  if endPos >= b.camels[b.leader.get]:
+  if endPos >= b.camels[b.leader.get].square:
     b.leader = some(b[endPos].camels[^1])
   
   b.diceRolled[color] = true