Speck_Sys = {}
Speck_Sys.__index = Speck_Sys

function Speck_Sys.new()
  local self = setmetatable({}, Speck_Sys)

  self.data = {
    size = 0,
    pos = {},
    vel = {},

    lifetime = {},
    lifetime_max = {},

    scale_start = {},
    scale_end = {}
  }

  self.scale_curve = lerp
  self.scale_start_min = 1
  self.scale_start_max = 1

  self.scale_end_min = 0
  self.scale_end_max = 0

  self.lifetime_min = 1
  self.lifetime_max = 5

  self.interval = 0.1
  self.spawn_timer = self.interval

  self.texture = get_tex("res/img/speck.png")

  self.x = 0
  self.y = 0
  return self
end

function Speck_Sys:update(dt)
  local data = self.data

  self.spawn_timer = self.spawn_timer - dt
  if self.spawn_timer <= 0 then
    self.spawn_timer = self.interval

    data.size = data.size + 1
    data.pos[data.size] = { x = self.x, y = self.y }
    data.vel[data.size] = { x = 0, y = 0 }

    data.lifetime[data.size] = lmath.random(
      self.lifetime_min, self.lifetime_max)
    data.lifetime_max[data.size] = data.lifetime[data.size]

    data.scale_start[data.size] = lmath.random(
      self.scale_start_min, self.scale_start_max)
    data.scale_end[data.size] = lmath.random(
      self.scale_end_min, self.scale_end_max)
  end

  for i = 1, data.size do
    if data.lifetime[i] <= 0 then
      goto next_speck_update
    end

    data.pos[i].x = data.pos[i].x + data.vel[i].x * dt
    data.pos[i].y = data.pos[i].y + data.vel[i].y * dt

    data.lifetime[i] = data.lifetime[i] - dt

    ::next_speck_update::
  end
end

function Speck_Sys:draw()
  local scale_curve = self.scale_curve
  local data = self.data

  for i = 1, data.size do
    if data.lifetime[i] <= 0 then
      goto next_speck_draw
    end

    local anim = 1 - data.lifetime[i] / data.lifetime_max[i]
    local scale = scale_curve(data.scale_start[i], data.scale_end[i], anim)

    lg.draw(
      self.texture, data.pos[i].x, data.pos[i].y, 0, scale
    )
    ::next_speck_draw::
  end
end

register_comp("Speck_System", function(ent)
  ent.speck_sys = Speck_Sys.new()
end)

function speck_update_sys(ent, dt)
  ent.speck_sys.x = ent.x
  ent.speck_sys.y = ent.y

  ent.speck_sys:update(dt)
end

function speck_draw_sys(ent)
  ent.speck_sys:draw()
end