package one

import (
	"strings"
)

type graph struct {
	robot point
	boxes map[point]struct{}
	data  []string
}

func newGraph() *graph {
	return &graph{boxes: make(map[point]struct{})}
}

func (g *graph) String() string {
	return strings.Join(g.data, "\n")
}

func (g *graph) valueAt(point point) rune {
	return rune(g.data[point.y][point.x])
}

func (g *graph) updateRobot(dir direction) {
	new := neighbours(g.robot)[dir]

	g.updateEach(g.robot, '.')
	g.updateEach(new, '@')
	g.robot = new
}

func (g *graph) updateBox(point point, dir direction) {
	g.deleteBox(point)
	g.addBox(neighbours(point)[dir])
}

func (g *graph) deleteBox(point point) {
	delete(g.boxes, point)
	g.updateEach(point, '.')
}

func (g *graph) addBox(point point) {
	g.boxes[point] = struct{}{}
	g.updateEach(point, 'O')
}

func (g *graph) updateEach(point point, r rune) {
	g.data[point.y] = replaceAtIndex(g.data[point.y], r, point.x)
}