from PIL import Image
import os
import re

frame_folder = "./output"
output_gif = "output.gif"

# same duration for every frame (in milliseconds)
frame_duration = 250

def frame_number(filename):
    return int(re.search(r"frame_(\d+)\.png", filename).group(1))

files = [
    f for f in os.listdir(frame_folder)
    if f.startswith("frame_") and f.endswith(".png")
]

files.sort(key=frame_number)

frames = [
    Image.open(os.path.join(frame_folder, f)).convert("RGBA")
    for f in files
]

frames[0].save(
    output_gif,
    save_all=True,
    append_images=frames[1:],
    duration=frame_duration,
    loop=0
)

print(f"Saved {output_gif}")