package soko

import "opslag.de/schobers/geom"

type Direction int

const (
	DirectionUp Direction = iota
	DirectionRight
	DirectionDown
	DirectionLeft
)

var Directions = [4]Direction{DirectionUp, DirectionRight, DirectionDown, DirectionLeft}

func (d Direction) Invert() Direction {
	switch d {
	case DirectionUp:
		return DirectionDown
	case DirectionRight:
		return DirectionLeft
	case DirectionDown:
		return DirectionUp
	case DirectionLeft:
		return DirectionRight
	}
	panic("invalid direction")
}

func (d Direction) String() string {
	switch d {
	case DirectionUp:
		return "up"
	case DirectionRight:
		return "right"
	case DirectionDown:
		return "down"
	case DirectionLeft:
		return "left"
	}
	return "invalid"
}

func (d Direction) ToPoint() geom.Point {
	switch d {
	case DirectionUp:
		return geom.Pt(0, -1)
	case DirectionRight:
		return geom.Pt(1, 0)
	case DirectionDown:
		return geom.Pt(0, 1)
	case DirectionLeft:
		return geom.Pt(-1, 0)
	}
	return geom.Point{}
}

func Neighbours(p geom.Point) []geom.Point {
	neighbours := make([]geom.Point, 4)
	for i, dir := range Directions {
		neighbours[i] = p.Add(dir.ToPoint())
	}
	return neighbours
}