# Lots of scrolling squares
# This serves as a test of dynamically spawing and despawning entities.

from color import rgb, hsv
from geometry import vec2
from number import pi_4
from random import bool as random_bool, number as random_number

from utils import palette
from utils.math import lerp

palette = palette.make_palette
  (rgb 0.99, 0.95, 0.31),
  (rgb 0.59, 0.05, 0.91),
  (rgb 0.39, 0.95, 0.31),
  (rgb 0.19, 0.29, 0.99),

background_color = hsv 100, 0.1, 0.8 

screen_bound = 1.2
max_shape_count = 50
speed_max = 0.3
fade_duration = 2
scene_rate = 0.125
scene_count = size palette
color_variation = 0.8
alpha_min = 0.2
alpha_max = 0.9

random_lerp = |min, max| lerp min, max, random_number()

random_color = |time|
  x = random_lerp 0.24, 0.99
  scene = (time * scene_rate % scene_count).floor()
  offset = (random_number() - 0.5) * color_variation
  palette
    .get scene + offset
    .set_alpha 0.9

spawn_rect = |time, id|
  position =
    vec2 (random_lerp -screen_bound, screen_bound), (random_lerp -screen_bound, screen_bound)
  velocity =
    vec2 (random_lerp -speed_max, speed_max), (random_lerp -speed_max, speed_max)
  shape_size = random_lerp 0.2, 0.6
  color = ((random_color time) * 2).set_a 0
  target_alpha = random_lerp alpha_min, alpha_max
  rotation = if random_bool() then pi_4 else 0

  shape.square()
    .set_color color
    .set_size shape_size
    .set_position position, id
    .set_rotation rotation
    .set_state {position, velocity, color, target_alpha, rotation, id, is_active: true}
    .on_update |time_delta|
      this = self.state()
      this.position += this.velocity * time_delta
      self.set_position this.position, this.id
      x, y = this.position
      if x.abs() > screen_bound or y.abs() > screen_bound
        this.target_alpha = 0.0 # Fade the shape out before it gets removed
      a = this.color.a()
      if a < this.target_alpha
        this.color.set_a (a + fade_duration * time_delta).min this.target_alpha
      else if a > this.target_alpha
        this.color.set_a (a - fade_duration * time_delta).max this.target_alpha
      else if this.target_alpha == 0
        this.is_active = false
      self.set_color this.color

export
  setup: ||
    rects: []
    time: 0
    id: 0

  on_load: |state|
    # Uncomment the following line to regenerate the rects when the script reloads
    # state.rects = []
    set_clear_color background_color

  update: |state, time_delta|
    state.time += time_delta
    # Remove rects that have gone out of bounds
    state.rects.retain |rect| rect.state().is_active
    # Make new rects to replace ones that have been removed
    state.rects.resize_with max_shape_count, ||
      # The ID is used for Z-order, and has a max of 999
      state.id = if state.id < 999 then state.id + 1 else 0
      spawn_rect state.time, state.id