getPossibleMoves, getBoard, and getTurnedOverDiscs methods for reversi BGA tutorial

reversi.game.php

class Reversi extends Table
{
    
    //////////////////////////////////////////////////////////////////////////////
    //////////// Utility functions    (functions used everywhere)
    ////////////
    
    // Get the list of returned disc when "player" we play at this place ("x", "y"),
    //  or a void array if no disc is returned (invalid move)
    function getTurnedOverDiscs( $x, $y, $player, $board )
    {
        $turnedOverDiscs = array();

        if( $board[ $x ][ $y ] === null ) // If there is already a disc on this place, this can't be a valid move
        {
            // For each directions...
            $directions = array(
                array( -1,-1 ), array( -1,0 ), array( -1, 1 ), array( 0, -1),
                array( 0,1 ), array( 1,-1), array( 1,0 ), array( 1, 1 )
            );

            foreach( $directions as $direction )
            {
                // Starting from the square we want to place a disc...
                $current_x = $x;
                $current_y = $y;
                $bContinue = true;
                $mayBeTurnedOver = array();

                while( $bContinue )
                {
                    // Go to the next square in this direction
                    $current_x += $direction[0];
                    $current_y += $direction[1];

                    if( $current_x<1 || $current_x>8 || $current_y<1 || $current_y>8 )
                        $bContinue = false; // Out of the board => stop here for this direction
                    else if( $board[ $current_x ][ $current_y ] === null )
                        $bContinue = false; // An empty square => stop here for this direction
                    else if( $board[ $current_x ][ $current_y ] != $player )
                    {
                        // There is a disc from our opponent on this square
                        // => add it to the list of the "may be turned over", and continue on this direction
                        $mayBeTurnedOver[] = array( 'x' => $current_x, 'y' => $current_y );
                    }
                    else if( $board[ $current_x ][ $current_y ] == $player )
                    {
                        // This is one of our disc

                        if( count( $mayBeTurnedOver ) == 0 )
                        {
                            // There is no disc to be turned over between our 2 discs => stop here for this direction
                            $bContinue = false;
                        }
                        else
                        {
                            // We found some disc to be turned over between our 2 discs
                            // => add them to the result and stop here for this direction
                            $turnedOverDiscs = array_merge( $turnedOverDiscs, $mayBeTurnedOver );
                            $bContinue = false;
                        }
                    }
                }
            }
        }

        return $turnedOverDiscs;
    }

    // Get the complete board with a double associative array
    function getBoard()
    {
        return self::getDoubleKeyCollectionFromDB( "SELECT board_x x, board_y y, board_player player
                                                       FROM board", true );
    }

    // Get the list of possible moves (x => y => true)
    function getPossibleMoves( $player_id )
    {
        $result = array();

        $board = self::getBoard();

        for( $x=1; $x<=8; $x++ )
        {
            for( $y=1; $y<=8; $y++ )
            {
                $returned = self::getTurnedOverDiscs( $x, $y, $player_id, $board );
                if( count( $returned ) == 0 )
                {
                    // No discs returned => not a possible move
                }
                else
                {
                    // Okay => set this coordinate to "true"
                    if( ! isset( $result[$x] ) )
                        $result[$x] = array();

                    $result[$x][$y] = true;
                }
            }
        }

        return $result;
    }
}