/**
* select_piece() - Creates $possible_moves
* The returned data will be used when building markup with clickable pieces
*/
function select_piece($board_array, $current_player, $from_field)
{
// Find fields, this piece can generally move to
// Also checks for obstacles and possible captures
$clickable = possible_move_list($board_array, $current_player, $from_field);
// Eliminate moves that would end in own king being in check
$new = array($clickable[0]);
list($f_row, $f_col) = field_to_rowcol($from_field);
$piece = $board_array[$f_row][$f_col];
foreach ($clickable as $to_field) {
if ($from_field != $to_field) {
// Ignore deselection
list($t_row, $t_col) = field_to_rowcol($to_field);
$new_array = apply_move($board_array, $f_row, $f_col, $t_row, $t_col);
$king_field = find_king($new_array, $current_player);
$hot_fields = hot_fields($new_array, $current_player);
if (!in_array($king_field, $hot_fields)) {
// King is NOT under attack when doing the move
$attacked = false;
// Not direclty, at least
// Check, if we try to castle and any fields
// are under attack, preventing the move.
$dir = $t_col - $f_col;
if ($piece == 'L') {
// White king
if ($dir == -2) {
// B, C, D must be free
$attacked = in_array('B1', $hot_fields) || in_array('C1', $hot_fields) || in_array('D1', $hot_fields);
} else {
if ($dir == +2) {
// F and G must be free
$attacked = in_array('F1', $hot_fields) || in_array('G1', $hot_fields);
}
}
}
if ($piece == 'l') {
// Black king
if ($dir == -2) {
// B, C, D must be free
$attacked = in_array('B8', $hot_fields) || in_array('C8', $hot_fields) || in_array('D8', $hot_fields);
} else {
if ($dir == +2) {
// F and G must be free
$attacked = in_array('F8', $hot_fields) || in_array('G8', $hot_fields);
}
}
}
if (!$attacked) {
$new[] = $to_field;
}
}
}
}
$clickable = $new;
$selected = array($clickable[0]);
return array($clickable, $selected);
}
/**
* king_in_check() - return true, if king is in check
*/
function king_in_check($board_array, $current_player)
{
$ret = false;
$king_field = find_king($board_array, $current_player);
$opponents_pieces = find_movable_pieces($board_array, !$current_player);
// See, if any of the opponents pieces can capture the player's king
foreach ($opponents_pieces as $o) {
$captures = possible_move_list($board_array, !$current_player, $o);
$ret |= in_array($king_field, $captures);
}
return $ret;
}