"""
Download MIMIC-CXR images required by qa.json from PhysioNet.

Prerequisites:
  1. Create a PhysioNet account at https://physionet.org/
  2. Complete the required CITI training course
  3. Sign the data use agreement for MIMIC-CXR-JPG v2.1.0
     https://physionet.org/content/mimic-cxr-jpg/2.1.0/

Usage:
  python download_mimic.py --user <username> --password <password>
"""

import argparse
import json
import os
import subprocess
import sys


BASE_URL = "https://physionet.org/files/mimic-cxr-jpg/2.1.0/files"


def get_required_images(qa_path: str) -> list[str]:
    """Extract unique MIMIC image paths from qa.json."""
    with open(qa_path) as f:
        data = json.load(f)

    images = set()
    for entry in data:
        for key in ("image_1", "image_2"):
            path = entry.get(key, "")
            if path.startswith("images/mimic/"):
                images.add(path)
    return sorted(images)


def download_images(images: list[str], user: str, password: str, root_dir: str):
    """Download images from PhysioNet and place them at the expected paths."""
    total = len(images)
    print(f"Found {total} MIMIC-CXR images to download.\n")

    skipped = 0
    downloaded = 0
    failed = 0

    for i, image_path in enumerate(images, 1):
        dest = os.path.join(root_dir, image_path)

        if os.path.exists(dest):
            skipped += 1
            continue

        # images/mimic/p15/p15592981/s55194630/xxx.jpg -> p15/p15592981/s55194630/xxx.jpg
        physionet_path = image_path.removeprefix("images/mimic/")
        url = f"{BASE_URL}/{physionet_path}"

        os.makedirs(os.path.dirname(dest), exist_ok=True)

        print(f"[{i}/{total}] Downloading {physionet_path} ...")
        result = subprocess.run(
            [
                "wget", "-q", "-O", dest,
                "--user", user,
                "--password", password,
                url,
            ],
            capture_output=True,
            text=True,
        )

        if result.returncode != 0:
            failed += 1
            print(f"  FAILED: {result.stderr.strip()}")
            # Remove empty file on failure
            if os.path.exists(dest) and os.path.getsize(dest) == 0:
                os.remove(dest)
        else:
            downloaded += 1

    print(f"\nDone: {downloaded} downloaded, {skipped} skipped (already exist), {failed} failed.")
    if failed > 0:
        print("Re-run the script to retry failed downloads.")


def main():
    parser = argparse.ArgumentParser(description="Download MIMIC-CXR images for VLM-SubtleBench.")
    parser.add_argument("--user", required=True, help="PhysioNet username")
    parser.add_argument("--password", required=True, help="PhysioNet password")
    parser.add_argument("--qa-path", default=None, help="Path to qa.json (default: qa.json in the same directory as this script)")
    args = parser.parse_args()

    root_dir = os.path.dirname(os.path.abspath(__file__))
    qa_path = args.qa_path or os.path.join(root_dir, "qa.json")

    if not os.path.exists(qa_path):
        print(f"Error: qa.json not found at {qa_path}", file=sys.stderr)
        sys.exit(1)

    images = get_required_images(qa_path)
    if not images:
        print("No MIMIC-CXR images found in qa.json.")
        sys.exit(0)

    download_images(images, args.user, args.password, root_dir)


if __name__ == "__main__":
    main()