#!/usr/bin/env python3
from pathlib import Path
import argparse

parser = argparse.ArgumentParser()
parser.add_argument("bids_root")
args = parser.parse_args()

root = Path(args.bids_root)

for dwi_dir in sorted(root.glob("sub-*/ses-001/dwi")):
    sub = dwi_dir.parents[1].name
    ses = dwi_dir.parent.name

    for acq in ["b1200", "mshell"]:
        old_bval = dwi_dir / f"{sub}_{ses}_acq-{acq}_dwi.bval"
        old_bvec = dwi_dir / f"{sub}_{ses}_acq-{acq}_dwi.bvec"
        new_bval = dwi_dir / f"{sub}_{ses}_acq-{acq}_dir-PA_dwi.bval"
        new_bvec = dwi_dir / f"{sub}_{ses}_acq-{acq}_dir-PA_dwi.bvec"

        if old_bval.exists() and not new_bval.exists():
            old_bval.rename(new_bval)
            print(f"RENAMED {old_bval} -> {new_bval}")

        if old_bvec.exists() and not new_bvec.exists():
            old_bvec.rename(new_bvec)
            print(f"RENAMED {old_bvec} -> {new_bvec}")