#!/usr/bin/env python3
"""Transfer an explicit source delta to this task's dedicated Ubuntu guest."""
import argparse
import hashlib
import io
import json
import os
from pathlib import Path
import re
import subprocess
import tarfile

ROOT = Path(__file__).resolve().parents[2]
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument('--name', required=True)
parser.add_argument('files', nargs='+')
args = parser.parse_args()
if not re.fullmatch(r'[a-z0-9][a-z0-9-]{0,63}', args.name):
    parser.error('Use a short lowercase name for a new delta')
work = Path(os.environ.get('DOCVIEW_VM_WORK', ROOT / 'build-ubuntu-vm')).resolve()
output = work / 'source-deltas' / args.name
output.mkdir(parents=True, exist_ok=False)
rows, payload = [], {}
for name in sorted(set(args.files)):
    relative = Path(name)
    if relative.is_absolute() or '..' in relative.parts or str(relative) != name:
        raise SystemExit('Only canonical repository-relative source paths are allowed')
    if relative.parts[0] not in ('src', 'qml', 'resources', 'cmake', 'tools', 'tests', 'CMakeLists.txt', 'README.md'):
        raise SystemExit('Path is not in the allowed source set')
    path = ROOT / relative
    if path.is_symlink() or not path.resolve().is_relative_to(ROOT) or not path.is_file():
        raise SystemExit('Only regular local source files are allowed')
    data = path.read_bytes()
    if len(data) > 8 * 1024 * 1024 or len(payload) >= 256:
        raise SystemExit('Source delta exceeds finite limits')
    payload[name] = data
    rows.append({'path': name, 'size': len(data), 'sha256': hashlib.sha256(data).hexdigest()})
archive = output / 'patch.tar.gz'
with tarfile.open(archive, 'w:gz') as stream:
    for name, data in payload.items():
        info = tarfile.TarInfo(name)
        info.size, info.mode = len(data), 0o644
        stream.addfile(info, io.BytesIO(data))
record = {'name': args.name, 'files': rows,
          'archiveSha256': hashlib.sha256(archive.read_bytes()).hexdigest()}
manifest = output / 'patch.json'
manifest.write_text(json.dumps(record, indent=2) + '\n')
apply = output / 'apply.py'
apply.write_text('''import hashlib,json,shutil,tarfile
from pathlib import Path
here=Path(__file__).resolve().parent
record=json.loads((here/'patch.json').read_text())
assert hashlib.sha256((here/'patch.tar.gz').read_bytes()).hexdigest()==record['archiveSha256']
source=Path.home()/'docview-source'
history=Path.home()/'validation/source-deltas'/record['name']
history.mkdir(parents=True,exist_ok=False)
changes=[]
with tarfile.open(here/'patch.tar.gz') as archive:
 for row in record['files']:
  rel=Path(row['path'])
  assert not rel.is_absolute() and '..' not in rel.parts
  data=archive.extractfile(row['path']).read()
  assert len(data)==row['size'] and hashlib.sha256(data).hexdigest()==row['sha256']
  target=source/rel
  assert target.resolve().is_relative_to(source) and not target.is_symlink()
  before=None
  if target.exists():
   before=hashlib.sha256(target.read_bytes()).hexdigest()
   original=history/'originals'/rel
   original.parent.mkdir(parents=True,exist_ok=True)
   shutil.copyfile(target,original)
  target.parent.mkdir(parents=True,exist_ok=True)
  target.write_bytes(data)
  changes.append({**row,'previousSha256':before,'changed':before!=row['sha256']})
(history/'record.json').write_text(json.dumps({**record,'files':changes},indent=2)+'\\n')
print(json.dumps({'sourceDelta':record['name'],'files':len(changes),'changed':sum(x['changed'] for x in changes)}))
''')
base = ['-i', str(work / 'private/id_ed25519'), '-o', 'IdentitiesOnly=yes', '-o', 'BatchMode=yes',
        '-o', 'StrictHostKeyChecking=yes', '-o', 'UserKnownHostsFile=' + str(work / 'private/known_hosts')]
remote = 'incoming/delta-' + args.name
ssh = ['ssh', *base, '-p', '22224', 'docview@127.0.0.1']
subprocess.run([*ssh, 'mkdir -p ' + remote], check=True)
subprocess.run(['scp', *base, '-P', '22224', str(archive), str(manifest), str(apply),
                'docview@127.0.0.1:' + remote + '/'], check=True)
subprocess.run([*ssh, 'python3 ' + remote + '/apply.py'], check=True)