class_name GeneratorSimple
extends RefCounted

const NAME := "simple"

var noise := FastNoiseLite.new()
var array := PackedByteArray()

var bias_air   :=  0.0 # Above this, always air
var bias_solid := 64.0 # Below this, always solid

func _init() -> void:
	noise.seed       = randi()
	noise.noise_type = FastNoiseLite.TYPE_SIMPLEX

	noise.fractal_gain       = 0.75
	noise.fractal_lacunarity = 2.5
	noise.fractal_octaves    = 3

	array.resize((Chunk.SIZE + 4) * (Chunk.SIZE + 4))

func generate(world: World, chunk: Chunk) -> void:
	const THRESHOLD := 0.5
	var region := chunk.region.extend(2)

	var i := 0
	for pos in region:
		var bias := (pos.y - bias_air) / (bias_solid - bias_air)
		array[i] = int((noise.get_noise_2dv(Vector2(pos)) + bias) >= THRESHOLD)
		i += 1

	var matter: Matter.Layer = chunk.get_or_create_layer(Matter)
	var shapes: Shape.Layer  = chunk.get_or_create_layer(Shape)
	for pos in BlockRegion.LOCAL_CHUNK:
		var shape: Shape

		var a := array
		const W := (Chunk.SIZE + 4)
		i = (pos.x + 2) + (pos.y + 2) * W

		var values: Array[int] = [
			a[i-2-W*2], a[i-1-W*2], a[i-W*2], a[i+1-W*2], a[i+2-W*2],
			a[i-2-W  ], a[i-1-W  ], a[i-W  ], a[i+1-W  ], a[i+2-W  ],
			a[i-2    ], a[i-1    ], a[i    ], a[i+1    ], a[i+2    ],
			a[i-2+W  ], a[i-1+W  ], a[i+W  ], a[i+1+W  ], a[i+2+W  ],
			a[i-2+W*2], a[i-1+W*2], a[i+W*2], a[i+1+W*2], a[i+2+W*2],
		]

		# TODO: Implement custom pattern matching that can handle rotation and mirroring.
		# var x := -1
		# var pattern: Array[int] = [
		# 	x, x, x, x, x,
		# 	x, x, 0, 0, 0,
		# 	x, 0, 0, 1, 1,
		# 	x, 1, 1, 1, x,
		# 	x, x, x, x, x,
		# ]

		match values:
			# HALF_SLOPE (non-mirrored)
			[
				_, _, _, _, _,
				_, _, 0, 0, 0,
				_, 0, 0, 1, 1,
				_, 1, 1, 1, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE.variants[0]
			[
				_, 0, 1, _, _,
				_, 0, 1, 1, _,
				_, 0, 0, 1, _,
				_, _, 0, 1, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE.variants[1]
			[
				_, _, _, _, _,
				_, 1, 1, 1, _,
				1, 1, 0, 0, _,
				0, 0, 0, _, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE.variants[2]
			[
				_, _, _, _, _,
				_, 1, 0, _, _,
				_, 1, 0, 0, _,
				_, 1, 1, 0, _,
				_, _, 1, 0, _,
			]:
				shape = Shape.Base.HALF_SLOPE.variants[3]

			[
				_, _, _, _, _,
				_, 0, 0, 0, _,
				0, 0, 1, 1, _,
				1, 1, 1, _, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE_BIG.variants[0]
			[
				_, _, _, _, _,
				_, 0, 1, _, _,
				_, 0, 1, 1, _,
				_, 0, 0, 1, _,
				_, _, 0, 1, _,
			]:
				shape = Shape.Base.HALF_SLOPE_BIG.variants[1]
			[
				_, _, _, _, _,
				_, _, 1, 1, 1,
				_, 1, 1, 0, 0,
				_, 0, 0, 0, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE_BIG.variants[2]
			[
				_, 1, 0, _, _,
				_, 1, 0, 0, _,
				_, 1, 1, 0, _,
				_, _, 1, 0, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE_BIG.variants[3]

			# HALF_SLOPE (mirrored)
			[
				_, _, _, _, _,
				0, 0, 0, _, _,
				1, 1, 0, 0, _,
				_, 1, 1, 1, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE.variants[4]
			[
				_, _, _, _, _,
				_, _, 0, 1, _,
				_, 0, 0, 1, _,
				_, 0, 1, 1, _,
				_, 0, 1, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE.variants[5]
			[
				_, _, _, _, _,
				_, 1, 1, 1, _,
				_, 0, 0, 1, 1,
				_, _, 0, 0, 0,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE.variants[6]
			[
				_, _, 1, 0, _,
				_, 1, 1, 0, _,
				_, 1, 0, 0, _,
				_, 1, 0, _, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE.variants[7]

			[
				_, _, _, _, _,
				_, 0, 0, 0, _,
				_, 1, 1, 0, 0,
				_, _, 1, 1, 1,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE_BIG.variants[4]
			[
				_, _, 0, 1, _,
				_, 0, 0, 1, _,
				_, 0, 1, 1, _,
				_, 0, 1, _, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE_BIG.variants[5]
			[
				_, _, _, _, _,
				1, 1, 1, _, _,
				0, 0, 1, 1, _,
				_, 0, 0, 0, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE_BIG.variants[6]
			[
				_, _, _, _, _,
				_, _, 1, 0, _,
				_, 1, 1, 0, _,
				_, 1, 0, 0, _,
				_, 1, 0, _, _,
			]:
				shape = Shape.Base.HALF_SLOPE_BIG.variants[7]

			# SLOPE
			[
				_, _, _, _, _,
				_, _, 0, _, _,
				_, 0, 0, 1, _,
				_, _, 1, _, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.SLOPE.variants[0]
			[
				_, _, _, _, _,
				_, _, 1, _, _,
				_, 0, 0, 1, _,
				_, _, 0, _, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.SLOPE.variants[1]
			[
				_, _, _, _, _,
				_, _, 1, _, _,
				_, 1, 0, 0, _,
				_, _, 0, _, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.SLOPE.variants[2]
			[
				_, _, _, _, _,
				_, _, 0, _, _,
				_, 1, 0, 0, _,
				_, _, 1, _, _,
				_, _, _, _, _,
			]:
				shape = Shape.Base.SLOPE.variants[3]

			# FULL
			[
				_, _, _, _, _,
				_, _, _, _, _,
				_, _, 1, _, _,
				_, _, _, _, _,
				_, _, _, _, _,
			]:
				shape = Shape.FULL

		if shape:
			matter.set_at(pos, Matter.PLASTIC)
			shapes.set_at(pos, shape)