"""Export the reviewed FAN-R2 firmware changes without writing sibling firmware."""
import difflib
import hashlib
import json
from pathlib import Path

ROOT = Path(__file__).resolve().parents[1]
FILES = ('main/board_pins.h', 'main/rail_cfg.c', 'test/test_rail_cfg.c')


def main():
    source = ROOT.parent / 'firmware'
    candidate = ROOT / 'out/firmware-fan-r2'
    output = ROOT / 'firmware-sync'
    output.mkdir(exist_ok=True)
    patch = []
    manifest = {'source': str(source), 'candidate': str(candidate), 'files': []}
    for name in FILES:
        before = (source / name).read_bytes()
        after = (candidate / name).read_bytes()
        if before == after:
            raise ValueError(f'Expected reviewed change missing: {name}')
        patch.extend(difflib.unified_diff(
            before.decode('utf-8').splitlines(keepends=True),
            after.decode('utf-8').splitlines(keepends=True),
            fromfile='a/firmware/' + name, tofile='b/firmware/' + name))
        manifest['files'].append({
            'path': name,
            'source_sha256': hashlib.sha256(before).hexdigest(),
            'candidate_sha256': hashlib.sha256(after).hexdigest(),
        })
    # Normalize line endings so git can apply the patch to the CRLF source tree.
    patch_text = ''.join(patch).replace('\r\n', '\n')
    with (output / 'fan-r2.patch').open('w', encoding='utf-8', newline='\n') as stream:
        stream.write(patch_text)
    (output / 'manifest.json').write_text(json.dumps(manifest, indent=2) + '\n', encoding='utf-8')
    print(f'Exported {len(FILES)} files to {output / "fan-r2.patch"}')


if __name__ == '__main__':
    main()