import json
import random
import copy
import math

from . import hexDraw
from funcs import logThis, getName, getID

BOARDWIDTH = 11
ALL_POSITIONS = [(i,j) for i in range(11) for j in range(11)]
ALL_SET = set(ALL_POSITIONS)
EMPTY_DIJKSTRA = {}
for position in ALL_POSITIONS:
    EMPTY_DIJKSTRA[position] = math.inf # an impossibly high number
HEX_DIRECTIONS = [(0,1),(-1,1),(-1,0),(0,-1),(1,-1),(1,0)]

# Parses command
def parseHex(command, channel, user):
    commands = command.lower().split()
    with open("resources/games/hexGames.json", "r") as f:
            data = json.load(f)
    
    if command == "" or command == " ":
        return "I didn't get that. Use \"!hex start [opponent]\" to start a game.", False, False, False, False
    
    elif commands[0] == "start":
        # Starting a game
        if len(commands) == 1: # if the commands is "!hex start", the opponent is Gwendolyn at difficulty 2
            commands.append("2")
        logThis("Starting a hex game with hexStart(). "+str(user)+" challenged "+commands[1])
        return hexStart(channel,user,commands[1]) # commands[1] is the opponent
    
    # If using a command with no game, return error
    elif channel not in data:
        return "There's no game in this channel", False, False, False, False

    # Stopping the game
    elif commands[0] == "stop":
        if user in data[channel]["players"]:
            return "Ending game.", False, False, True, False
        else:
            return "You can't end a game where you're not a player.", False, False, False, False
    
    # Placing a piece
    elif commands[0] == "place":
        try:
            return placeHex(channel,commands[1], user)
        except:
            return "I didn't get that. To place a piece use \"!hex place [position]\". A valid position is e.g. \"E2\".", False, False, False, False
    
    # Undo
    elif commands[0] == "undo":
        return undoHex(channel, user)
    
    # Surrender
    elif commands[0] == "surrender":
        players = data[channel]["players"]
        if user in players:
            opponent = (players.index(user) + 1) % 2
            data[channel]["winner"] = opponent + 1
            return "{} surrendered. That means {} won! Adding 30 Gwendobucks to their account.".format(getName(user),getName(players[opponent])), False, False, True, False
        else:
            return "You can't surrender when you're not a player.", False, False, False, False

    # Swap
    elif commands[0] == "swap":
        if len(data[channel]["gameHistory"]) == 1: # Only after the first move
            data[channel]["players"] = data[channel]["players"][::-1] # Swaps their player-number
            with open("resources/games/hexGames.json", "w") as f:
                json.dump(data,f,indent=4)
            # Swaps the color of the hexes on the board drawing:
            hexDraw.drawSwap(channel)
            player2 = data[channel]["players"][1]
            gwendoTurn = (player2 == "Gwendolyn")
            return "The color of both players were swapped. It is now {}'s turn".format(player2), True, True, False, gwendoTurn
        else:
            return "You can only swap as the second player after the very first move.", False, False, False, False

    else:
        return "I didn't get that. Use \"!hex start [opponent]\" to start a game, \"!hex place [position]\" to place a piece, \"!hex undo\" to undo your last move or \"!hex stop\" to stop a current game.", False, False, False, False


# Starts the game
def hexStart(channel, user, opponent):
    with open("resources/games/hexGames.json", "r") as f:
        data = json.load(f)
    
    if channel not in data:
        if opponent in ["1","2","3","4","5"]:
            difficulty = int(opponent)
            diffText = " with difficulty "+opponent
            opponent = "Gwendolyn"
        elif opponent.lower() == "gwendolyn":
            difficulty = 2
            diffText = " with difficulty 2"
            opponent = "Gwendolyn"
        else:
            try:
                int(opponent)
                return "That difficulty doesn't exist", False, False, False, False
            except:
                opponent = getID(opponent)
                if opponent == None:
                    return "I can't find that user", False, False, False, False
                else:
                    # Opponent is another player
                    difficulty = 3
                    diffText = ""
        
        # board is 11x11
        board = [ [ 0 for i in range(BOARDWIDTH) ] for j in range(BOARDWIDTH) ]
        players = [user,opponent]
        random.shuffle(players) # random starting player
        gameHistory = []

        data[channel] = {"board":board, "winner":0,
            "players":players, "turn":1, "difficulty":difficulty, "gameHistory":gameHistory}

        with open("resources/games/hexGames.json", "w") as f:
            json.dump(data,f,indent=4)
        
        # draw the board
        hexDraw.drawBoard(channel)
        
        gwendoTurn = True if players[0] == "Gwendolyn" else False
        showImage = True
        return "Started Hex game against "+getName(opponent)+ diffText+". It's "+getName(players[0])+"'s turn", showImage, False, False, gwendoTurn
    else:
        return "There's already a hex game going on in this channel", False, False, False, False

# Places a piece at the given location and checks things afterwards
def placeHex(channel : str,position : str, user):
    with open("resources/games/hexGames.json", "r") as f:
        data = json.load(f)
    
    if channel in data:
        players = data[channel]["players"]
        if user in players:
            turn = data[channel]["turn"]
            if players[0] == players[1]:
                player = turn
            else:
                player = players.index(user)+1
            
            if player == turn:
                board = data[channel]["board"]

                logThis("Placing a piece on the board with placeHex()")
                # Places on board
                board = placeOnHexBoard(board,player,position)
                
                if isinstance(board, list):
                    # If the move is valid:
                    data[channel]["board"] = board
                    turn = 1 if turn == 2 else 2
                    data[channel]["turn"] = turn
                    

                    # Checking for a win
                    logThis("Checking for win")
                    score, winner = evaluateBoard(data[channel]["board"])

                    if winner == 0: # Continue with the game. 
                        gameWon = False
                        message = getName(data[channel]["players"][player-1])+" placed at "+position.upper()+". It's now "+getName(data[channel]["players"][turn-1])+"'s turn. The score is "+str(score)
                        
                    else: # Congratulations!
                        gameWon = True
                        data[channel]["winner"] = winner
                        message = getName(data[channel]["players"][player-1])+" placed at "+position.upper()+" and won!"
                        if data[channel]["players"][winner-1] != "Gwendolyn":
                            winAmount = data[channel]["difficulty"]*10
                            message += " Adding "+str(winAmount)+" GwendoBucks to their account."
                    
                    data[channel]["gameHistory"].append((int(position[1])-1, ord(position[0])-97))
                    
                    # Is it now Gwendolyn's turn?
                    gwendoTurn = False
                    if data[channel]["players"][turn-1] == "Gwendolyn":
                        logThis("It's Gwendolyn's turn")
                        gwendoTurn = True
                    
                    # Save the data
                    with open("resources/games/hexGames.json", "w") as f:
                        json.dump(data,f,indent=4)
                    
                    # Update the board
                    hexDraw.drawHexPlacement(channel,player,position)

                    return message, True, True, gameWon, gwendoTurn
                else:
                    # Invalid move. "board" is the error message
                    message = board
                    return message, False, False, False, False
            else:
                # Move out of turn
                message = "It isn't your turn, it is "+getName(data[channel]["players"][turn-1])+"'s turn."
                return message, False, False, False, False
        else:
            message = "You can't place when you're not in the game. The game's players are: "+getName(data[channel]["players"][0])+" and "+getName(data[channel]["players"][1])+"."
            return message, False, False, False, False
    else:
        return "There's no game in this channel", False, False, False, False


# Returns a board where the placement has occured
def placeOnHexBoard(board,player,position):
    # Translates the position
    position = position.lower()
    # Error handling
    try:
        column = ord(position[0]) - 97   # ord() translates from letter to number
        row = int(position[1:]) - 1
        if column not in range(BOARDWIDTH) or row not in range(BOARDWIDTH):
            logThis("Position out of bounds (error code 1533)")
            return "Error. That position is out of bounds."
    except:
        logThis("Invalid position (error code 1531)")
        return "Error. The position should be a letter followed by a number, e.g. \"e2\"."
    # Place at the position
    if board[row][column] == 0:
        board[row][column] = player
        return board
    else:
        logThis("Cannot place on existing piece (error code 1532)")
        return "Error. You must place on an empty space."


# After your move, you have the option to undo get your turn back #TimeTravel
def undoHex(channel, user):
    with open("resources/games/hexGames.json", "r") as f:
        data = json.load(f)
    if user in data[channel]["players"]:
        if len(data[channel]["gameHistory"]):
            turn = data[channel]["turn"]
            # You can only undo after your turn, which is the opponent's turn. 
            if user == data[channel]["players"][(turn % 2)]: # If it's not your turn
                logThis("Undoing {}'s last move".format(getName(user)))

                lastMove = data[channel]["gameHistory"].pop()
                data[channel]["board"][lastMove[0]][lastMove[1]] = 0
                data[channel]["turn"] = turn%2 + 1
                # Save the data
                with open("resources/games/hexGames.json", "w") as f:
                    json.dump(data,f,indent=4)
                    
                # Update the board
                hexDraw.drawHexPlacement(channel,0,"abcdefghijk"[lastMove[1]]+str(lastMove[0]+1)) # The zero makes the hex disappear
                return "You undid your last move at {}".format(lastMove), True, True, False, False
            else:
                # Sassy
                return "Nice try. You can't undo your opponent's move. ", False, False, False, False
        else:
            # Sassy
            return "Really? You undo right at the start of the game?", False, False, False, False

    else:
        return "You're not a player in the game", False, False, False, False


# Plays as the AI
def hexAI(channel):
    logThis("Figuring out best move")
    with open("resources/games/hexGames.json", "r") as f:
        data = json.load(f)
    board = data[channel]["board"]
    
    if len(data[channel]["gameHistory"]):
        lastMove = data[channel]["gameHistory"][-1]
    else:
        lastMove = (5,5)
    
    # These moves are the last move +- 2. 
    moves = [[(lastMove[0]+j-2,lastMove[1]+i-2) for i in range(5) if lastMove[1]+i-2 in range(11)] for j in range(5) if lastMove[0]+j-2 in range(11)]
    moves = sum(moves,[])
    movesCopy = moves.copy()
    for move in movesCopy:
        if board[move[0]][move[1]] != 0:
            moves.remove(move)
    chosenMove = random.choice(moves)
    
    """
    GwenColor = data[channel]["players"].index("Gwendolyn") + 1 # either 1 or 2 - red or blue
    if len(data[channel]["gameHistory"]) == 0:
        return placeHex(channel,"F6", "Gwendolyn") # If starting, start in the middle
    board = data[channel]["board"]
    difficulty = data[channel]["difficulty"]
    possiblePlaces = [i for i,v in enumerate(sum(board,[])) if v == 0]
    judgements = [float('nan')]*len(possiblePlaces) # All possible moves are yet to be judged
    
    current_score = evaluateBoard(board)[0]
    for i in possiblePlaces:
        testBoard = copy.deepcopy(board)
        testBoard[i // BOARDWIDTH][i % BOARDWIDTH] = GwenColor
        if evaluateBoard(testBoard)[0] != current_score: # only think about a move if it improves the score (it's impossible to get worse)
            # Testing a move and evaluating it
            judgements[i] = minimaxHex(testBoard,difficulty,-math.inf,math.inf,GwenColor==2)
            logThis("Best score for place {} is {}".format((i // BOARDWIDTH,i % BOARDWIDTH),judgements[i]))

    bestScore = max(judgements) if (GwenColor == 1) else min(judgements) # this line has an error
    indices = [i for i, x in enumerate(judgements) if x == bestScore] # which moves got that score?
    i = random.choice(indices)
    chosenMove = (i // BOARDWIDTH , i % BOARDWIDTH)
    """
    placement = "abcdefghijk"[chosenMove[1]]+str(chosenMove[0]+1)
    logThis("ChosenMove is {} at {}".format(chosenMove,placement))
    return placeHex(channel,placement, "Gwendolyn")


def evaluateBoard(board):
    scores = {1:0, 2:0}
    winner = 0
    # Here, I use Dijkstra's algorithm to evaluate the board, as proposed by this article: https://towardsdatascience.com/hex-creating-intelligent-adversaries-part-2-heuristics-dijkstras-algorithm-597e4dcacf93
    for player in [1,2]:
        Distance = copy.deepcopy(EMPTY_DIJKSTRA)
        # Initialize the starting hexes. For the blue player, this is the leftmost column. For the red player, this is the tom row. 
        for start in (ALL_POSITIONS[::11] if player == 2 else ALL_POSITIONS[:11]):
            # An empty hex adds a of distance of 1. A hex of own color add distance 0. Opposite color adds infinite distance. 
            Distance[start] = 1 if (board[start[0]][start[1]] == 0) else 0 if (board[start[0]][start[1]] == player) else math.inf
        visited = set() # Also called sptSet, short for "shortest path tree Set"
        for _ in range(BOARDWIDTH**2): # We can at most check every 121 hexes
            # Find the next un-visited hex, that has the lowest distance
            remainingHexes = ALL_SET.difference(visited)
            A = [Distance[k] for k in remainingHexes] # Find the distance to each un-visited hex
            u = list(remainingHexes)[A.index(min(A))] # Chooses the one with the lowest distance
            
            # Find neighbors of the hex u
            for di in HEX_DIRECTIONS:
                v = (u[0] + di[0] , u[1] + di[1]) # v is a neighbor of u
                if v[0] in range(11) and v[1] in range(11) and v not in visited:
                    new_dist = Distance[u] + (1 if (board[v[0]][v[1]] == 0) else 0 if (board[v[0]][v[1]] == player) else math.inf)
                    Distance[v] = min(Distance[v], new_dist)
            # After a hex has been visited, this is noted
            visited.add(u)
            #logThis("Distance from player {}'s start to {} is {}".format(player,u,Distance[u]))
            if u[player-1] == 10: # if the right coordinate of v is 10, it means we're at the goal
                scores[player] = Distance[u] # A player's score is the shortest distance to goal. Which equals the number of remaining moves they need to win if unblocked by the opponent. 
                break
        else:
            logThis("For some reason, no path to the goal was found. ")
        if scores[player] == 0:
            winner = player
            break # We don't need to check the other player's score, if player1 won. 
    return scores[2]-scores[1], winner


def minimaxHex(board, depth, alpha, beta, maximizingPlayer):
    # The depth is how many moves ahead the computer checks. This value is the difficulty. 
    if depth == 0 or 0 not in sum(board,[]):
        score = evaluateBoard(board)[0]
        return score
    # if final depth is not reached, look another move ahead:
    if maximizingPlayer: # red player predicts next move
        maxEval = -math.inf
        possiblePlaces = [i for i,v in enumerate(sum(board,[])) if v == 0]
        #logThis("Judging a red move at depth {}".format(depth))
        for i in possiblePlaces:
            testBoard = copy.deepcopy(board)
            testBoard[i // BOARDWIDTH][i % BOARDWIDTH] = 1 # because maximizingPlayer is Red which is number 1
            evaluation = minimaxHex(testBoard,depth-1,alpha,beta,False)
            maxEval = max(maxEval, evaluation)
            alpha = max(alpha, evaluation)
            if beta <= alpha:
                #logThis("Just pruned something!")
                break
        return maxEval
    else: # blue player predicts next move
        minEval = math.inf
        possiblePlaces = [i for i,v in enumerate(sum(board,[])) if v == 0]
        #logThis("Judging a blue move at depth {}".format(depth))
        for i in possiblePlaces:
            testBoard = copy.deepcopy(board)
            testBoard[i // BOARDWIDTH][i % BOARDWIDTH] = 2 # because minimizingPlayer is Blue which is number 2
            evaluation = minimaxHex(testBoard,depth-1,alpha,beta,True)
            minEval = min(minEval, evaluation)
            beta = min(beta, evaluation)
            if beta <= alpha:
                #logThis("Just pruned something!")
                break
        return minEval