function newBoard = make_move(board, player)
%MAKE_MOVE Determine the next move of a player for tic tac toe
%   Given a board setup and a player, determine the "best" move for the
%   current player and update and return the board setup after this move
%   has been made.
%
%   The process is :
%       1. Find a winning position. If found, make the move and exit
%       the function;
%       2. Find a position to block the other player from winning. If
%       found, make the move and exit the function;
%       3. Otherwise, make a move to a random free location
%
%   board: The tic tac toe matricx
%   player: 1 for player one, -1 for player two
%


    % the nested function switches the player, and will return either a -1
    % for player two, or 1 for player one
    function player = getCurrentPlayer(oldPlayer)
        if (oldPlayer == 1)
            player = -1;
        elseif (oldPlayer == -1)
            player = 1;
        else
            fprintf(1, 'The current player %d is not valid!', oldPlayer);
        end
    end

    % Generetaes a random position which will be returned as a 1 by 2
    % column matrix.
    function randomPosition = generateRandomSpot()
        randomPosition = zeros(1, 2);
        randomPosition(1, 1) = randi([1 3]);
        randomPosition(1, 2) = randi([1 3]);
    end

    % If a winning move is unable to be found, we will now find an empty,
    % randomposition and set the value of empty random position to be
    % equal to the player's value.
    function updatedBoard = moveRandomFreeSpot(oldBoard, player)
        hasFoundEmptySpot = 0;
        updatedBoard = oldBoard;
        while (hasFoundEmptySpot == 0)
            pos = generateRandomSpot();
            if (oldBoard(pos(1), pos(2)) == 0)
                hasFoundEmptySpot = 1;
                oldBoard(pos(1), pos(2))
                updatedBoard(pos(1), pos(2)) = player;
            end
        end
    end

    % A winning move for either of the players will be found. The function
    % takes the absolute of the row/column/diagonal sums and checks which
    % ones (if any) are equal to 2, which will enable us to make the
    % winning move.
    function updatedBoard = findWinningMove(oldBoard, player)
        winnerFound = 0;
        updatedBoard = oldBoard;
        for (currentValue = 1 : 3)
            rowSum = sum(oldBoard(currentValue, :));
            if (rowSum == 2)
                winnerFound = 1;
                index = getIndex(oldBoard(currentValue, :));
                updatedBoard(currentValue, index) = player;
                return;
            end
            if (winnerFound == 0)
                columnSum = sum(oldBoard(:, currentValue));
                if (columnSum == 2)
                    winnerFound = 1;
                    index = getIndex(oldBoard(:, currentValue));
                    updatedBoard(index, currentValue) = player;
                    return;
                end
            end
        end

        % If there was no winning move beforehand, we will check the
        % diagonals of the board, and see if there is a viable move that
        % will allow us to make a winning/block a winning move.
        if (winnerFound == 0)
            diagSum = sum(diag(oldBoard));
            if (diagSum == 2)
                winnerFound = 1;
                index = getDiagonalIndex(oldBoard, 1);
                updatedBoard(index(1, 1), index(2, 1));
                return;
            end
        end
    end

    % Returns a matrix (2 by 1) that will give us the coordinares of the
    % potential winning move position in the matrix
    function result = getDia

    % Finds the index of the element in the vector
    function result = getIndex(theVector)
        for (i = 1 : length(theVector))
            if (theVector(i) == 0)
                result = i;
            end
        end
    end

    % We will try and find a winning move, and if there are no winning
    % moves, then we will provide a random position.
    updatedBoard = findWinningMove(board, player);
    if (updatedBoard == board)
        updatedBoard = moveRandomFreeSpot(board, player);
    end
    newBoard = updatedBoard;
end