class_name OceanScroll
extends Node2D
## 滚动海面：三贴图循环 + 岛屿装饰随机飘过。
## 视口 540x960，贴图世界尺寸 540：3 块连续贴图在任意滚动相位下
## 都能覆盖 [0,960]，2 块会在屏幕底部留缺口。

const TILE := preload("res://assets/svg/ocean_tile.svg")
const ISLAND := preload("res://assets/svg/island.svg")
const SPEED := 120.0
const TILE_WORLD := 540.0
const CENTER_X := 270.0
const TILE_COUNT := 3

var _offset := 0.0
var _tiles: Array[Sprite2D] = []
var _islands: Array[Sprite2D] = []
var _island_timer := 4.0


func _ready() -> void:
	var tile_scale := TILE_WORLD / 256.0
	for i in TILE_COUNT:
		var tile := Sprite2D.new()
		tile.texture = TILE
		tile.scale = Vector2(tile_scale, tile_scale)
		tile.position.x = CENTER_X
		add_child(tile)
		_tiles.append(tile)


func _process(delta: float) -> void:
	_offset = fmod(_offset + SPEED * delta, TILE_WORLD)
	for i in TILE_COUNT:
		_tiles[i].position.y = _offset - TILE_WORLD * 0.5 + TILE_WORLD * float(i)

	_update_islands(delta)


func _update_islands(delta: float) -> void:
	_island_timer -= delta
	if _island_timer <= 0.0:
		_island_timer = randf_range(5.0, 9.0)
		if _islands.size() < 3:
			_spawn_island()
	for island in _islands:
		island.position.y += SPEED * delta
	for island in _islands.duplicate():
		if island.position.y > 1060.0:
			_islands.erase(island)
			island.queue_free()


func _spawn_island() -> void:
	var island := Sprite2D.new()
	island.texture = ISLAND
	island.position = Vector2(randf_range(90.0, 450.0), -90.0)
	island.scale = Vector2.ONE * randf_range(0.7, 1.15)
	add_child(island)
	_islands.append(island)