#!/usr/bin/env python3
"""Silent attended decryption of the hash-verified primary archive download."""
import argparse
from datetime import datetime, timezone
import hashlib
import json
import os
from pathlib import Path
import subprocess
from state_hub_preflight_lane import bao, data


def digest(path):
    with path.open('rb') as source: return hashlib.file_digest(source,'sha256').hexdigest()


def main():
    p=argparse.ArgumentParser(description=__doc__)
    for name in ['source','output','transfer-receipt','receipt']: p.add_argument('--'+name,required=True,type=Path)
    a=p.parse_args();receipt={'schema':'platform.forgejo-primary-decryption.v1','status':'failed','started_at':datetime.now(timezone.utc).isoformat()}
    fd=os.open(a.receipt,os.O_WRONLY|os.O_CREAT|os.O_EXCL,0o600)
    try:
        raw=a.transfer_receipt.read_bytes()
        transfer=json.loads(raw)
        receipt['transfer_receipt_sha256']=hashlib.sha256(raw).hexdigest()
        if (transfer.get('schema')!='platform.forgejo-primary-archive.v1'
                or transfer.get('status')!='primary_fetched_pending_application_restore'
                or transfer.get('download_hash_matches') is not True
                or digest(a.source)!=transfer.get('ciphertext_sha256')):
            raise ValueError('verified_primary_download_required')
        value=data(bao(['read','-format=json','platform/data/workloads/railiance/backup/offsite-lane']))['data']['data']['AGE_PRIVATE_KEY']
        with a.output.open('xb') as target:
            a.output.chmod(0o600)
            result=subprocess.run(['age','-d','-i','/dev/stdin',str(a.source)],input=(value.strip()+'\n').encode(),stdout=target,stderr=subprocess.PIPE,timeout=1200)
        if result.returncode: raise ValueError('primary_decryption_failed')
        # Preserve this operation's schema and times, not the transfer's.
        for key in ('destination','ciphertext_sha256','ciphertext_bytes','download_hash_matches','archive_profile'):
            if key in transfer: receipt[key]=transfer[key]
        receipt.update(status='primary_fetched_pending_application_restore',
                       decrypted=True,plaintext_sha256=digest(a.output))
    except Exception:
        receipt['error']='bounded_primary_decryption_failed'
    finally:
        receipt['finished_at']=datetime.now(timezone.utc).isoformat()
        with os.fdopen(fd,'w') as output: json.dump(receipt,output,indent=2)
    return int(receipt['status']=='failed')
if __name__=='__main__': raise SystemExit(main())