from __future__ import annotations

import os
import shutil
import sys
from pathlib import Path

LOCAL_ROOT = Path(__file__).resolve().parents[1]
if str(LOCAL_ROOT) not in sys.path:
    sys.path.insert(0, str(LOCAL_ROOT))

from utils.weight_downloader import WEIGHT_REGISTRY, ensure_weights
from wrapper_common import ROOT, main_for


def _safe_link_or_copy(src: Path, dst: Path) -> None:
    if dst.exists():
        return
    try:
        os.symlink(src, dst, target_is_directory=True)
    except OSError:
        print(f"[ChangeMamba] WARNING: symlink failed for {dst}; copying directory tree.")
        shutil.copytree(src, dst, dirs_exist_ok=True)


def make_changemamba_dataset_config(dataset_cfg: dict, split: str, output_path: str) -> str:
    data_root = Path(dataset_cfg["data_root"])
    split_dir = data_root / dataset_cfg.get("splits", {}).get(split, split)
    mapping = {
        "T1": split_dir / dataset_cfg.get("image_a_folder", "A"),
        "T2": split_dir / dataset_cfg.get("image_b_folder", "B"),
        "GT": split_dir / dataset_cfg.get("mask_folder", "label"),
    }
    for link_name, src in mapping.items():
        if src.exists():
            _safe_link_or_copy(src, split_dir / link_name)

    out = Path(output_path)
    out.parent.mkdir(parents=True, exist_ok=True)
    out.write_text(
        "\n".join([
            "# Generated by train/train_changemamba.py",
            f"dataset_name = {dataset_cfg['name']!r}",
            f"data_root = {str(data_root)!r}",
            f"crop_size = {int(dataset_cfg.get('img_size', 256))!r}",
            f"batch_size = {int(dataset_cfg.get('batch_size', 8))!r}",
            f"num_workers = {int(dataset_cfg.get('num_workers', 4))!r}",
            f"mean = {dataset_cfg.get('mean_a', [0.485, 0.456, 0.406])!r}",
            f"std = {dataset_cfg.get('std_a', [0.229, 0.224, 0.225])!r}",
            f"train_split = {dataset_cfg.get('splits', {}).get('train', 'train')!r}",
            f"val_split = {dataset_cfg.get('splits', {}).get('val', 'val')!r}",
            f"test_split = {dataset_cfg.get('splits', {}).get('test', 'test')!r}",
            "",
        ]),
        encoding="utf-8",
    )
    return str(out)


def ensure_changemamba_weights(cfg: dict) -> str:
    variant_key = f"vmamba_{cfg.get('vmamba_variant', 'tiny')}"
    if variant_key not in WEIGHT_REGISTRY:
        raise KeyError(f"Unknown ChangeMamba VMamba variant: {variant_key}")
    return ensure_weights(variant_key)


if __name__ == "__main__":
    raise SystemExit(main_for("changemamba"))