require_relative "built_in/py_runtime"
require_relative "std/math"
require_relative "std/time"
require_relative "utils/gif"


# 06: Sample that sweeps Julia-set parameters and outputs a GIF.

def julia_palette()
  palette = __pytra_bytearray(256 * 3)
  __pytra_set_index(palette, 0, 0)
  __pytra_set_index(palette, 1, 0)
  __pytra_set_index(palette, 2, 0)
  i = 1
  while i < 256
    t = ((__pytra_float(i - 1)) / 254.0)
    r = __pytra_int((255.0 * ((((9.0 * (1.0 - t)) * t) * t) * t)))
    g = __pytra_int((255.0 * ((((15.0 * (1.0 - t)) * (1.0 - t)) * t) * t)))
    b = __pytra_int((255.0 * ((((8.5 * (1.0 - t)) * (1.0 - t)) * (1.0 - t)) * t)))
    __pytra_set_index(palette, (i * 3 + 0), r)
    __pytra_set_index(palette, (i * 3 + 1), g)
    __pytra_set_index(palette, (i * 3 + 2), b)
    i += 1
  end
  return __pytra_bytes(palette)
end

def render_frame(width, height, cr, ci, max_iter, phase)
  frame = __pytra_bytearray(width * height)
  y = 0
  while y < height
    row_base = y * width
    zy0 = ((-1.2) + (2.4 * __pytra_div(y, (height - 1))))
    x = 0
    while x < width
      zx = ((-1.8) + (3.6 * __pytra_div(x, (width - 1))))
      zy = zy0
      i = 0
      while i < max_iter
        zx2 = zx * zx
        zy2 = zy * zy
        if zx2 + zy2 > 4.0
          break
        end
        zy = ((2.0 * zx * zy) + ci)
        zx = (zx2 - zy2 + cr)
        i += 1
      end
      if i >= max_iter
        __pytra_set_index(frame, row_base + x, 0)
      else
        color_index = (1 + (((i * 224 / max_iter) + phase) % 255))
        __pytra_set_index(frame, row_base + x, color_index)
      end
      x += 1
    end
    y += 1
  end
  return __pytra_bytes(frame)
end

def run_06_julia_parameter_sweep()
  width = 320
  height = 240
  frames_n = 72
  max_iter = 180
  out_path = "sample/out/06_julia_parameter_sweep.gif"
  start = perf_counter()
  frames = []
  center_cr = (-0.745)
  center_ci = 0.186
  radius_cr = 0.12
  radius_ci = 0.1
  start_offset = 20
  phase_offset = 180
  i = 0
  while i < frames_n
    t = __pytra_div(((i + start_offset) % frames_n), frames_n)
    angle = (2.0 * pi * t)
    cr = (center_cr + radius_cr * cos(angle))
    ci = (center_ci + radius_ci * sin(angle))
    phase = ((phase_offset + i * 5) % 255)
    frames.append(render_frame(width, height, cr, ci, max_iter, phase))
    i += 1
  end
  save_gif(out_path, width, height, frames, julia_palette(), 8, 0)
  elapsed = perf_counter() - start
  __pytra_print("output:", out_path)
  __pytra_print("frames:", frames_n)
  __pytra_print("elapsed_sec:", elapsed)
end

if __FILE__ == $PROGRAM_NAME
  run_06_julia_parameter_sweep()
end