mchess-server/chess/free_squares.go

package chess

import "mchess_server/types"

func (b *Board) GetNonBlockedRowAndColumn(fromSquare types.Coordinate) []types.Coordinate {
	squaresLeft := fromSquare.GetStraightInDirection(types.Coordinate.Left)
	squaresRight := fromSquare.GetStraightInDirection(types.Coordinate.Right)
	squaresAbove := fromSquare.GetStraightInDirection(types.Coordinate.Up)
	squaresBelow := fromSquare.GetStraightInDirection(types.Coordinate.Down)

	nonBlocked := b.getNonBlockedConsecutive(squaresLeft, fromSquare)
	nonBlocked = append(nonBlocked, b.getNonBlockedConsecutive(squaresRight, fromSquare)...)
	nonBlocked = append(nonBlocked, b.getNonBlockedConsecutive(squaresAbove, fromSquare)...)
	nonBlocked = append(nonBlocked, b.getNonBlockedConsecutive(squaresBelow, fromSquare)...)

	return nonBlocked
}

func (b *Board) GetNonBlockedDiagonals(fromSquare types.Coordinate) []types.Coordinate {
	rightUp := fromSquare.GetDiagonalInDirection(types.Coordinate.Right, types.Coordinate.Up)
	leftUp := fromSquare.GetDiagonalInDirection(types.Coordinate.Left, types.Coordinate.Up)
	leftDown := fromSquare.GetDiagonalInDirection(types.Coordinate.Left, types.Coordinate.Down)
	rightDown := fromSquare.GetDiagonalInDirection(types.Coordinate.Right, types.Coordinate.Down)

	nonBlocked := b.getNonBlockedConsecutive(rightUp, fromSquare)
	nonBlocked = append(nonBlocked, b.getNonBlockedConsecutive(leftUp, fromSquare)...)
	nonBlocked = append(nonBlocked, b.getNonBlockedConsecutive(leftDown, fromSquare)...)
	nonBlocked = append(nonBlocked, b.getNonBlockedConsecutive(rightDown, fromSquare)...)

	return nonBlocked
}

func (b *Board) GetNonBlockedKingMoves(fromSquare types.Coordinate) []types.Coordinate {
    return b.getNonBlockedConsecutive(fromSquare.GetAllKingMoves(), fromSquare)
}

func (b *Board) GetNonBlockedKnightMoves(fromSquare types.Coordinate) []types.Coordinate {
	allKnightMoves := fromSquare.GetAllKnightMoves()
	return b.getNonBlockedForKnights(allKnightMoves, fromSquare)
}

func (b *Board) getNonBlockedConsecutive(
	squaresToCheck []types.Coordinate,
	sourceSquare types.Coordinate,
) []types.Coordinate {
	pieceOnSourceSquare := b.getPieceAt(sourceSquare)
	nonBlocked := []types.Coordinate{}

	for _, square := range squaresToCheck {
		piece := b.getPieceAt(square)
		if piece != nil {
			if piece.GetColor() == pieceOnSourceSquare.GetColor() {
                //We do not append squares with same-colored pieces
                //and also not the squares behind it
				break
			}
			// if there is an opposite colored piece we append it but
			// stop appending the squares behind it
			nonBlocked = append(nonBlocked, square)
			break
		}
		nonBlocked = append(nonBlocked, square)
	}
	return nonBlocked
}

func (b *Board) getNonBlockedForKnights(
	squaresToCheck []types.Coordinate,
	sourceSquare types.Coordinate,
) []types.Coordinate {
    pieceOnSourceSquare := b.getPieceAt(sourceSquare)
    nonBlocked := []types.Coordinate{}

    for _, square := range squaresToCheck {
        piece := b.getPieceAt(square)
        if piece == nil || piece.GetColor() != pieceOnSourceSquare.GetColor() {
            nonBlocked = append(nonBlocked, square)
        }
    }
    return nonBlocked
}