## Conway's Game of Life
##	Rule 1 - Any live cell with fewer than two live neighbours dies (underpopulation)
##	Rule 2 - Any live cell with two or three live neighbours lives
##	Rule 3 - Any live cell with more than three live neighbours dies (overpopulation)
##	Rule 4 - Any dead cell with exactly three live neighbours becomes a live cell (reproduction)
extends Node2D


enum CellStates {
	DEAD,
	ALIVE,
}

## UI
@onready var background_ui: Control = $UI/Background

@onready var debug_ui: MarginContainer = $UI/Debug
@onready var debug_generation_counter: Label = $UI/Debug/VBoxContainer/GenerationCounter
@onready var debug_living_cells_counter: Label = $UI/Debug/VBoxContainer/LivingCellsCounter
@onready var debug_world_seed: Label = $UI/Debug/VBoxContainer/WorldSeed

@onready var generation_ui: MarginContainer = $UI/WorldGeneration
@onready var generation_seed: LineEdit = $UI/WorldGeneration/VBoxContainer/Seed/Input
@onready var generation_world_size_x: LineEdit = $UI/WorldGeneration/VBoxContainer/WorldSize/Input_x
@onready var generation_world_size_y: LineEdit = $UI/WorldGeneration/VBoxContainer/WorldSize/Input_y
@onready var gneration_cell_size_x: LineEdit = $UI/WorldGeneration/VBoxContainer/CellSize/Input_x
@onready var gneration_cell_size_y: LineEdit = $UI/WorldGeneration/VBoxContainer/CellSize/Input_y

## Other
@onready var camera: Camera2D = $Camera2D
@onready var generation_timer: Timer = $GenerationTimer

@export var world_seed: int
@export var cell_size: Vector2 = Vector2(16, 16)
@export var cell_texture: Texture2D
@export var world_size: Vector2 = Vector2(32, 32)

var cell_instance
var generation: int = 1
var is_paused: int = false
var total_living: int = 0
var world: Array = []


func _ready() -> void:
	update_generation_ui()
	debug_ui.visible = false
	background_ui.visible = true
	generation_ui.visible = true

func _input(event: InputEvent) -> void:
	if event.is_action_pressed("Pause"):
		is_paused = !is_paused
		background_ui.visible = is_paused
	if event.is_action_pressed("Menu"):
		is_paused = true
		background_ui.visible = true
		generation_ui.visible = true
		update_generation_ui()


#
# UI
#
## Update the Gneration UI with the current settings
func update_generation_ui() -> void:
	if world_seed:
		generation_seed.text = str(world_seed)
	else:
		generation_seed.text = str(randi())
	generation_world_size_x.text = str(world_size.x)
	generation_world_size_y.text = str(world_size.y)
	gneration_cell_size_x.text = str(cell_size.x)
	gneration_cell_size_x.text = str(cell_size.y)


#
# Conway Specific
#
func start_conway() -> void:
	debug_world_seed.text = "World Seeed: %s" % world_seed
	is_paused = false

	generate_world()
	generation_timer.start()

	# Center the camera on the world
	camera.position.x = world_size.x * cell_size.x / 2
	camera.position.y = world_size.y * cell_size.y / 2


## Check a cell against the Conway rules and return True if cell shoudl be alive
##  The logic in this could be cleaned up pretty easily. Only verbose for understanding.
func cell_is_alive(pos: Vector2) -> bool:
	var neighbors := count_living_neighbors(pos)
	var currently_alive = world[pos.x][pos.y] is RID

	# Rule 1 - Any live cell with fewer than two live neighbours dies (underpopulation)
	if currently_alive and neighbors < 2:
		return false
	# Rule 2 - Any live cell with two or three live neighbours lives
	elif currently_alive and (neighbors == 2 or neighbors == 3):
		return true
	# Rule 3 - Any live cell with more than three live neighbours dies (overpopulation)
	elif currently_alive and neighbors > 3:
		return false
	# Rule 4 - Any dead cell with exactly three live neighbours becomes a live cell (reproduction)
	elif not currently_alive and neighbors == 3:
		return true

	return false

## Count all neighbors surrounding a cell
func count_living_neighbors(pos: Vector2) -> int:
	var count := 0

	@warning_ignore("incompatible_ternary")
	var x_min = 0 if pos.x - 1 < 0 else pos.x - 1
	@warning_ignore("incompatible_ternary")
	var y_min = 0 if pos.y - 1 < 0 else pos.y - 1
	var x_max = world_size.x if pos.x + 2 > world_size.x else pos.x + 2
	var y_max = world_size.y if pos.y + 2 > world_size.y else pos.y + 2

	for x in range(x_min, x_max):
		for y in range(y_min, y_max):
			if x == pos.x and y == pos.y: continue # Current cell - Don't count
			if world[x][y] is RID:
				count += 1
	return count

## Loop through the world and create or kill cells depending on rules
func process_generation() -> void:
	if is_paused: return

	generation += 1
	total_living = 0

	var new_world: Array= []
	for x in range(world_size.x):
		new_world.append([])
		new_world[x].resize(world_size.x)
		for y in range(world_size.y):
			var pos = Vector2(x, y)
			if cell_is_alive(pos):
				total_living += 1
				new_world[x][y] = create_cell(pos)
			else:
				new_world[x][y] = kill_cell(pos)

	world = new_world


## Create the cell using the rendering server
func create_cell(pos: Vector2) -> RID:
	if world[pos.x][pos.y] is RID: return world[pos.x][pos.y]

	var rs = RenderingServer

	cell_instance = rs.canvas_item_create()
	rs.canvas_item_set_parent(cell_instance, get_canvas_item())

	var rect: Rect2 = Rect2(-cell_size.x/2, -cell_size.y/2, cell_size.x, cell_size.y) # Centered with cell size
	rs.canvas_item_add_texture_rect(cell_instance, rect, cell_texture)

	var pos_fixed = Vector2(pos.x * cell_size.x, pos.y * cell_size.y)
	var trans = Transform2D(0, pos_fixed)
	rs.canvas_item_set_transform(cell_instance, trans)

	return cell_instance

## Remove the cell from the RenderingServer, if it exists
func kill_cell(pos: Vector2) -> CellStates:
	if world[pos.x][pos.y] is RID:
		RenderingServer.free_rid(world[pos.x][pos.y])
	return CellStates.DEAD


## Generate the world with cells in random states (alive or dead)
func generate_world() -> void:
	for x in range(world_size.x):
		world.append([])
		world[x].resize(world_size.x)
		for y in range(world_size.y):
			if randi_range(0, 1):
				total_living += 1
				world[x][y] = create_cell(Vector2(x, y))
			else:
				world[x][y] = CellStates.DEAD


func _on_generation_timer_timeout() -> void:
	process_generation()

	debug_generation_counter.text = "Generation: %s" % generation
	debug_living_cells_counter.text = "Living Cells: %s" % total_living

	generation_timer.start()

func _on_quit_button_pressed() -> void:
	get_tree().quit()

func _on_run_button_pressed() -> void:
	if not generation_seed.text.strip_edges():
		world_seed = randi()
	else:
		world_seed = int(generation_seed.text)
	world_size = Vector2(int(generation_world_size_x.text), int(generation_world_size_y.text))
	cell_size = Vector2(int(gneration_cell_size_x.text), int(gneration_cell_size_x.text))

	debug_ui.visible = true
	generation_ui.visible = false
	background_ui.visible = false
	seed(world_seed)

	start_conway()

func _on_world_seed_generate_pressed() -> void:
	generation_seed.text = str(randi())