from util import EMPTY,BLACK,WHITE
from . import core


def transitionSequence(state1, state2, diff, limit=0):
	return []


class SpecGo(core.Go):
	def __init__(self,boardSize=19):
		super().__init__(boardSize)

	def listRelevantMoves(self,diff):
		"""There can be 3 different changes in the diff: additions, deletions and replacements.
		Additions can be taken as relevant right away.
		Deletions and replacements had to be captured, so we add their liberties.
		Also any non-missing stones of partially deleted (or replaced) groups had to be replayed, so add them too.
		Needs to handle snapback, throw-in.
		There's no end to what could be theoretically relevant, but such sequences are long and we will pretend they won't happen."""
		res=(set(),set())
		for d in diff:
			(r,c,action,color)=d
			colorKey=(1-color)>>1 # {-1,1}->{1,0}
			if action!="-" and (r,c) not in res[colorKey]:
				res[colorKey].add((r,c))
				for (ri,ci) in self.listNeighbours(r,c): # in case a stone was played and captured. !! might want to add even more
					res[1-colorKey].add((ri,ci))
			# this is rather sloppy but correct. the time will show if it is effective enough
			# just floodFill from the current intersection, add everything you find and also all the neighbours to be sure
			if action!="+" and (r,c) not in res[colorKey] and (r,c) not in res[1-colorKey]:
				self._helper.clear()
				self._helper.floodFill(color if action=="-" else 1-color, r, c)
				res[colorKey].union(self._helper.getContinuousArea())
				for (ri,ci) in self._helper.getContinuousArea():
					res[colorKey].add((ri,ci))
					res[1-colorKey].add((ri,ci))
					for (rj,cj) in self.listNeighbours(ri,ci):
						res[colorKey].add((rj,cj))
						res[1-colorKey].add((rj,cj))
		return res

	def listNeighbours(self,r,c):
		if r>0: yield (r-1,c)
		if r+1<self.boardSize: yield (r+1,c)
		if c>0: yield (r,c-1)
		if c+1<self.boardSize: yield (r,c+1)


class Engine:
	def __init__(self,g=None):
		self._g=g or SpecGo()
		self._moveList=(set(),set())

	def load(self,state1,diff):
		self._g.load(state1)
		self._moveList=self._g.listRelevantMoves(diff)

	def iterativelyDeepen(self,state2,toMove=None):
		for i in range(1,10):
			for color in [toMove] if toMove else [BLACK,WHITE]:
				self._g.toMove=color
				seq=self.dfs(state2,i)
				if seq:
					seq.reverse()
					return seq

	def dfs(self,state2,limit):
		g=self._g
		moveSet=self._moveList[(1-g.toMove)>>1]
		for (r,c) in moveSet.copy():
			if g.board[r][c]!=EMPTY: continue
			neighbours=(
				g.board[r-1][c] if r>0 else None,
				g.board[r+1][c] if r+1<g.boardSize else None,
				g.board[r][c-1] if c>0 else None,
				g.board[r][c+1] if c+1<g.boardSize else None
			)
			if not g.doMove(g.toMove,r,c): continue
			moveSet.remove((r,c))
			captured=tuple(
				coords for (i,coords) in enumerate(((r-1,c),(r+1,c),(r,c-1),(r,c+1)))
				if neighbours[i] is not None and neighbours[i]!=EMPTY and g.board[coords[0]][coords[1]]==EMPTY
			)

			if g.hash()==state2.hash():
				g.undoMove(r,c,captured)
				moveSet.add((r,c))
				return [(g.toMove,r,c)]

			if limit>1:
				seq=self.dfs(state2,limit-1)
				if seq:
					g.undoMove(r,c,captured)
					moveSet.add((r,c))
					seq.append((g.toMove,r,c))
					return seq

			g.undoMove(r,c,captured)
			moveSet.add((r,c))
		return False

eng=Engine()