extends Node

var screen_size = Vector2(1920.0, 1080.0)  # Default screen size (this is a float for some reason)
var viewport_size
@onready var extent: Rect2 = get_viewport().get_visible_rect()

# Main menu & game spawning
@onready
var mainMenuScene = preload("res://main_menu.tscn").instantiate()
@onready
var gameScene = preload("res://molecular/molecular_stage.tscn").instantiate()

# utils.
var rng = RandomNumberGenerator.new()
var eps: float = 1e-4

# managers
@onready
var foodManager = gameScene.get_node("FoodManager")

# A world "current"
# polar
var flow_dir: float  # [0, 2pi)
var flow_mag: float  # [0, 1]
# cartesian
var flow_x: float
var flow_y: float
# Swap period
var flowT: float = 10

# A game timer
var t: float = 0.0


func _ready() -> void:
	# Create viewport
	viewport_size = get_viewport().get_visible_rect().size
	
	# Create game (main menu)
	add_child(mainMenuScene)
	
	# initial world current
	get_new_flow()

func _physics_process(delta: float) -> void:
	t += delta
	
	# Flow current change
	if abs(fmod(t, flowT)) < eps:
		get_new_flow()
	
func start_game() -> void:
	add_child(gameScene)

# TODO: This needs to be called from a script inheriting a CharacterBody2D (e.g. the player)
# Alternative would be to pass the player reference to this script (which might be better?)
func init_screen_size(x:float, y:float) -> void:
	screen_size.x = x
	screen_size.y = y

# This can take a vector of any size (but should be 2d, other components are unused)
func get_boundaried_position(position):
	# clamp
	#return position.clamp(Vector2.ZERO, screen_size)
	
	# periodic
	position.x = wrapf(position.x, 0, screen_size.x)
	position.y = wrapf(position.y, 0, screen_size.y)
	return position
	
func get_new_flow():
	flow_dir = rng.randf()*2*PI
	flow_mag = rng.randf()
	
	flow_x = flow_mag * cos(flow_dir)
	flow_y = flow_mag * sin(flow_dir)
	
	

func calc_distance(one, two) -> float:
	var candidate = one.distance_to(two)
	var onedup = one
	# FIXME: doesnt work-- predators lose track across game boundary
	if one.x < screen_size.x/2:
		if one.y < screen_size.y/2:
			# top left
			onedup.y -= screen_size.y
			candidate = min(candidate, onedup.distance_to(two))	
			onedup.y += screen_size.y
			onedup.x -= screen_size.x
			candidate = min(candidate, onedup.distance_to(two))	
		else:
			# bottom left
			onedup.y += screen_size.y
			candidate = min(candidate, onedup.distance_to(two))	
			onedup.y -= screen_size.y
			onedup.x -= screen_size.x
			candidate = min(candidate, onedup.distance_to(two))	
	else:
		if one.y < screen_size.y/2:
			# top  right
			onedup.y -= screen_size.y
			candidate = min(candidate, onedup.distance_to(two))	
			onedup.y += screen_size.y
			onedup.x += screen_size.x
			candidate = min(candidate, onedup.distance_to(two))	
		else:
			# botom right
			onedup.y += screen_size.y
			candidate = min(candidate, onedup.distance_to(two))	
			onedup.y -= screen_size.y
			onedup.x += screen_size.x
			candidate = min(candidate, onedup.distance_to(two))	
	return candidate