board=klass()

function board:init(ruleset)
 self.ruleset=ruleset
 self.cursor=cursor:new(self)
 self.animator=animator:new()
 self.checkpoint=nil
 self.slots={}
 self.wells={}

 -- board slots
 -- ...n_slots: normal
 for i=1,ruleset.n_slots do
  add(self.slots,slot:new(ruleset))
 end
 -- n_slots+1: special
 add(self.slots,slot:new(ruleset,1))

 -- wells:
 -- ...n_suits: wands, cups, swords, pentacles, etc
 local function add_suit(_self,suit)
  local w=well:new(_self.ruleset, function(lst,new)
   assert(lst)  -- the ace is always present initially
   if (new.suit!=suit) return
   return new.suit==suit and new.rank==lst.rank+1
  end)
  w.obscured_by_extra_slot=true
  add(_self.wells, w)
 end
 for suit in all(self.ruleset.deck.suits) do
  add_suit(self,suit)
 end
 -- n_suits+1: arcana ascending
 add(self.wells,well:new(self.ruleset,function(lst,new)
  if (new.suit!='a') return
  if (not lst) return new.rank==0
  return new.rank==lst.rank+1
 end))
 -- n_suits+2: arcana descending
 add(self.wells,well:new(self.ruleset,function(lst,new)
  if (new.suit!='a') return
  if (not lst) return new.rank==self.ruleset.n_arcana-1
  return new.rank==lst.rank-1
 end))

 local seed=seeds:choose(self.ruleset.pool)
 printh("chosen seed: "..tostr(seed,2))
 self:deal(seeds:choose(self.ruleset.pool))
end

function board:deal(seed)
 local deal=deal(self.ruleset,seed)
 local n_usable_slots=self.ruleset.n_slots - 1

 for i=1,#self.ruleset.deck.aces do
  local well=self.wells[i]
  local ace=self.ruleset.deck.aces[i]
  self:animate_move_ace_to_well(ace,i)
 end

 local rows=#deal[1]
 for y=1,rows do
  for x=1,#deal do
   local outx=x
   if (x>n_usable_slots\2) outx+=1
   self:animate_move_new_card_to_slot(deal[x][y],outx)
  end
 end
end

function board:undo()
 if (self.checkpoint) self.checkpoint:apply(self) print("applied")
 self.checkpoint=nil
end

function board:on_idle()
 self:find_automove()
end

function board:pre_move(card)
 self.checkpoint=checkpoint:new(self,card)
end

function board:on_move()
 self:find_automove()
end

function board:is_won() 
 if (not self:can_take_input()) return false
 for s=1,#self.slots do
  if (self.slots[s]:peek()) return false
 end
 return true
end

function board:find_automove()
 for s=1,#self.slots do
  local top=self.slots[s]:peek()
  if top then
   for w=1,#self.wells do
    if w<=self.ruleset.n_suits and self.slots[self.ruleset.n_slots+1]:peek()!=nil then
     -- the top wells are blocked
    elseif self.wells[w]:would_accept(top) then
     self:animate_and_move_to_well(s,w)

     return true
    end
   end
  end
 end
end

function board:can_take_input()
 return self.animator:idle()
end

function board:update()
 local was_idle=self.animator:idle()
 self.animator:update()
 local is_idle=self.animator:idle()
 if (not was_idle and is_idle) then
  self:on_idle()
 end
end

function board:draw()
 local extra_slot_full=self.slots[self.ruleset.n_slots+1]:peek()!=nil
 for w_ix=1,#self.wells do
  local w=self.wells[w_ix]
  local l=self.ruleset.layouts:well(w_ix)

  local shadowed=nil
  if w.obscured_by_extra_slot and extra_slot_full then
   shadowed=true
  end

  for i=1,#w.contents do
   local x,y=l:place_card(i)
   self.ruleset.deck:draw_card(x,y,w.contents[i],{shadowed=shadowed})
  end
 end

 local function forall_slots(cb)
  for s_ix=1,#self.slots do
   local s=self.slots[s_ix]
   local l=self.ruleset.layouts:slot(s_ix)

   local n=#s.contents
   if (self.cursor.grabbed==s_ix) n-=1

   cb(x,y,s_ix,s,l,n)
  end
 end

 forall_slots(function(x,y,s_ix,s,l,n)
  for i=1,n do
   local x,y=l:place_card(i)
   self.ruleset.deck:draw_card(x,y,s.contents[i],{rotate=l.rotated})
  end
 end)

 if self.checkpoint then
  local cpl=self.ruleset.layouts:checkpoint()
  local x,y=cpl:place_card(0)
  self.ruleset.deck:draw_card(x,y,self.checkpoint.card,{shadowed=true})
  print("❎",x+1,y+9,7)
 end

 self.animator:draw()

 if self.animator:idle() then
  local hover_slot=self.cursor:hover_slot()
  forall_slots(function(x,y,s_ix,s,l,n)
   if hover_slot==s_ix then
    local x,y=l:place_card(n+1)
    self.cursor:draw_at(l,x,y)
   end
  end)
 end
end

slot=klass()
function slot:init(ruleset,max_n)
 self.ruleset=ruleset
 self.contents={}
 self.max_n=max_n
end
function slot:would_accept(new)
 local n=#self.contents
 if (n==self.max_n) return 

 local lst=self.contents[n]
 if (not lst) return true
 lst=self.ruleset.deck.cards[lst]
 new=self.ruleset.deck.cards[new]
 return lst.suit==new.suit and (lst.rank==new.rank-1 or lst.rank==new.rank+1) 
end
function slot:add(card)
 add(self.contents,card)
end
function slot:peek()
 return self.contents[#self.contents]
end
function slot:pop()
 return deli(self.contents,#self.contents)
end

well=klass()
function well:init(ruleset,accept_cb)
 self.ruleset=ruleset
 self.accept_cb=accept_cb
 self.contents={}
end
function well:would_accept(new)
 local lst=self.contents[#self.contents]
 if (lst) lst=self.ruleset.deck.cards[lst]
 assert(new,"must be populated")
 new=self.ruleset.deck.cards[new]
 assert(new,"must be populated")
 return self.accept_cb(lst,new)
end
function well:add(card)
 add(self.contents,card)
end
function well:clear()
 self.contents={}
end