#!/usr/bin/env python3
"""Generate a handwritten 1-8 digit image from a numeric prompt."""

from __future__ import annotations

import argparse
from pathlib import Path

import torch
from PIL import Image

from tiny_digit_diffusion import ddim_sample, load_model

DEFAULT_REPO_ID = "shibatch/tinydigitdiffusion3m"


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser()
    parser.add_argument("prompt", help="A numeric prompt containing 1-8 digits, for example 2026.")
    parser.add_argument(
        "--model-dir",
        default=None,
        help="Local model directory. If omitted, download the model from Hugging Face.",
    )
    parser.add_argument("--repo-id", default=DEFAULT_REPO_ID)
    parser.add_argument("--revision", default="main")
    parser.add_argument("--output", default="generated_digits.png")
    parser.add_argument("--steps", type=int, default=50)
    parser.add_argument("--guidance-scale", type=float, default=1.0)
    parser.add_argument("--seed", type=int, default=0)
    parser.add_argument("--device", choices=["auto", "cpu", "cuda"], default="auto")
    return parser.parse_args()


def resolve_model_dir(
    model_dir: str | None,
    repo_id: str,
    revision: str,
) -> Path:
    if model_dir is not None:
        return Path(model_dir).expanduser().resolve()

    from huggingface_hub import snapshot_download

    snapshot_dir = snapshot_download(
        repo_id=repo_id,
        revision=revision,
        allow_patterns=["model/config.json", "model/model.safetensors"],
    )
    return Path(snapshot_dir) / "model"


def main() -> None:
    args = parse_args()
    device = torch.device(
        "cuda" if args.device == "auto" and torch.cuda.is_available() else
        "cpu" if args.device == "auto" else args.device
    )
    model_dir = resolve_model_dir(args.model_dir, args.repo_id, args.revision)
    model = load_model(model_dir, device)
    image = ddim_sample(
        model,
        [args.prompt],
        device,
        sampling_steps=args.steps,
        guidance_scale=args.guidance_scale,
        seed=args.seed,
    )[0, 0]
    pixels = ((image.cpu() + 1) * 127.5).round().clamp(0, 255).byte().numpy()
    output = Path(args.output)
    output.parent.mkdir(parents=True, exist_ok=True)
    Image.fromarray(pixels, mode="L").save(output)
    print(output.resolve())


if __name__ == "__main__":
    main()