mchess-server/types/common.go

package types

// coordinates starting at 1:1 and end at 8:8
type Coordinate struct {
	Col int `json:"col"`
	Row int `json:"row"`
}

const (
	RangeLastValid  = 8
	RangeFirstValid = 1

	RangeUpperInvalid = 9
	RangeLowerInvalid = 0
)

func (c Coordinate) Up(number int) *Coordinate {
	check := c.Row + number
	if check <= RangeLastValid {
		return &Coordinate{Row: check, Col: c.Col}
	}
	return nil
}
func (c Coordinate) Down(number int) *Coordinate {
	check := c.Row - number
	if check >= RangeFirstValid {
		return &Coordinate{Row: check, Col: c.Col}
	}
	return nil
}

// Right and left is seen from a board where row 1 is on the bottom
func (c Coordinate) Right(number int) *Coordinate {
	check := c.Col + number
	if check >= RangeFirstValid {
		return &Coordinate{Row: c.Row, Col: check}
	}
	return nil
}
func (c Coordinate) Left(number int) *Coordinate {
	check := c.Col - number
	if check >= RangeFirstValid {
		return &Coordinate{Row: c.Row, Col: check}
	}
	return nil
}

type ChessColor string

const (
	White ChessColor = "white"
	Black ChessColor = "black"
)

func (c ChessColor) Opposite() ChessColor {
	if c == White {
		return Black
	} else {
		return White
	}
}