/*

 Copyright (C) 2016 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Game state class encapsulates the current board state, player turn, and game rules (e.g. win conditions, piece placement).

 */

#import "AAPLTicTacToeGame.h"

@interface AAPLTicTacToeGame ()

@property (nonatomic, strong) AAPLTicTacToeBoard *board;

@property (nonatomic) AAPLTicTacToeGameState state;

@property (nonatomic) AAPLTicTacToeGameWinType winType;

@property (nonatomic) NSUInteger winningRow;

@property (nonatomic) NSUInteger winningColumn;

@end

@implementation AAPLTicTacToeGame

- (AAPLTicTacToeSquare *)winner:(AAPLTicTacToeBoard *)board

{

    AAPLTicTacToeSquare *firstSquare;

    AAPLTicTacToeSquare *square;

    NSInteger numRows = board.numRows;

    NSInteger numColumns = board.numColumns;

    // check rows

    for ( NSUInteger row = 0; row < numRows; row++ )

    {

        firstSquare = [board squareAtRow:row column:0];

        NSUInteger column;

        for ( column = 0; column < numColumns; column++ )

        {

            square = [board squareAtRow:row column:column];

            if ( ![square sameTypeAs:firstSquare] || square.isEmpty )

            {

                break;

            }

        }

        if ( column == numColumns )

        {

            self.winType = AAPLTicTacToeGameWinTypeRow;

            self.winningRow = row;

            return square;

        }

    }

    // check columns

    for ( NSUInteger column = 0; column < numColumns; column++ )

    {

        firstSquare = [board squareAtRow:0 column:column];

        NSUInteger row;

        for ( row = 0; row < numRows; row++ )

        {

            square = [board squareAtRow:row column:column];

            if ( ![square sameTypeAs:firstSquare] || square.isEmpty )

            {

                break;

            }

        }

        if ( row == numRows )

        {

            self.winType = AAPLTicTacToeGameWinTypeColumn;

            self.winningColumn = column;

            return square;

        }

    }

    // check top left diagonal

    firstSquare = [board squareAtRow:0 column:0];

    NSUInteger column;

    NSUInteger row;

    for ( column = 0, row = 0; column < numColumns && row < numRows; column++, row++ )

    {

        square = [board squareAtRow:row column:column];

        if ( ![square sameTypeAs:firstSquare] || square.isEmpty )

        {

            break;

        }

    }

    if ( column == numColumns || row == numRows )

    {

        self.winType = AAPLTicTacToeGameWinTypeTopLeftDiagonal;

        return square;

    }

    // check top right diagonal

    firstSquare = [board squareAtRow:0 column:numColumns - 1];

    for ( column = 0, row = 0; column < numColumns && row < numRows; column++, row++ )

    {

        square = [board squareAtRow:row column:numColumns - column - 1];

        if ( ![square sameTypeAs:firstSquare] || square.isEmpty )

        {

            break;

        }

    }

    if ( column == numColumns || row == numRows )

    {

        self.winType = AAPLTicTacToeGameWinTypeTopRightDiagonal;

        return square;

    }

    return [AAPLTicTacToeSquare Empty];

}

- (instancetype)init

{

    self = [super init];

    if ( self != nil )

    {

        self.board = [AAPLTicTacToeBoard new];

        [self reset];

    }

    return self;

}

- (AAPLTicTacToeSquare *)playSquareAtRow:(NSUInteger)row column:(NSUInteger)column

{

    AAPLTicTacToeBoard *board = self.board;

    AAPLTicTacToeSquare *square = [board squareAtRow:row column:column];

    AAPLTicTacToeGameState state = self.state;

    if ( square == nil || !square.isEmpty )

    {

        return NO;

    }

    if ( state == AAPLTicTacToeGameStateXTurn )

    {

        square.type = AAPLTicTacToeSquareTypeX;

    }

    else if ( state == AAPLTicTacToeGameStateOTurn )

    {

        square.type = AAPLTicTacToeSquareTypeO;

    }

    AAPLTicTacToeSquare *winner = [self winner:board];

    if ( winner.isX )

    {

        state = AAPLTicTacToeGameStateXWin;

    }

    else if ( winner.isO )

    {

        state = AAPLTicTacToeGameStateOWin;

    }

    else if ( winner.isEmpty )

    {

        if ( [board isFull] )

        {

            state = AAPLTicTacToeGameStateTie;

        }

        else if ( state == AAPLTicTacToeGameStateXTurn )

        {

            state = AAPLTicTacToeGameStateOTurn;

        }

        else if ( state == AAPLTicTacToeGameStateOTurn )

        {

            state = AAPLTicTacToeGameStateXTurn;

        }

    }

    self.state = state;

    return square;

}

- (void)reset

{

    [self.board reset];

    self.state = AAPLTicTacToeGameStateXTurn;

    self.winType = AAPLTicTacToeGameWinTypeNone;

    self.winningRow = 0;

    self.winningColumn = 0;

}

@end