"""Independently decode the published transparent regtest transactions.
Usage: python verify-evidence.py results.json
Uses no node and no network. Checks byte counts, weight, vsize, IDs and conservation.
It does not independently verify ECDSA signatures or prove the node-state transcript.
"""
import hashlib,json,math,pathlib,sys

def digest(raw):return hashlib.sha256(hashlib.sha256(raw).digest()).digest()[::-1].hex()
def decode(raw):
 p=0
 def take(n):
  nonlocal p
  if p+n>len(raw):raise ValueError('Truncated transaction')
  result=raw[p:p+n];p+=n;return result
 def compact():
  first=take(1)[0]
  return first if first<253 else int.from_bytes(take({253:2,254:4,255:8}[first]),'little')
 version=take(4);witness=raw[p:p+2]==b'\x00\x01'
 if witness:take(2)
 body_start=p;count=compact();inputs=[]
 for _ in range(count):
  txid=take(32)[::-1].hex();vout=int.from_bytes(take(4),'little');take(compact());take(4);inputs.append((txid,vout))
 outputs=[]
 for _ in range(compact()):outputs.append((int.from_bytes(take(8),'little'),take(compact()).hex()))
 body=raw[body_start:p]
 if witness:
  for _ in range(count):
   for _ in range(compact()):take(compact())
 lock=take(4)
 if p!=len(raw):raise ValueError('Unsupported trailing data')
 stripped=version+body+lock;weight=len(stripped)*3+len(raw)
 return {'bytes':len(raw),'weight':weight,'vsize':math.ceil(weight/4),'txid':digest(stripped),'wtxid':digest(raw),'inputs':inputs,'outputs':outputs}

def main():
 data=json.loads(pathlib.Path(sys.argv[1]).read_text());total=0
 assert data['network']=='regtest' and len(data['cases'])==12 and len(data['flow'])==3
 for row in data['cases']+data['flow']:
  actual=decode(bytes.fromhex(row['hex']))
  for key in ['bytes','weight','vsize','txid','wtxid']:assert actual[key]==row[key],(row['id'],key)
  assert actual['inputs']==[(x['txid'],x['vout']) for x in row['prevouts']]
  assert actual['outputs']==[(x['valueLitoshi'],x['scriptHex']) for x in row['decodedOutputs']]
  assert sum(x['valueLitoshi'] for x in row['prevouts'])==row['inputTotalLitoshi']
  assert row['inputTotalLitoshi']-sum(x[0] for x in actual['outputs'])==row['feeLitoshi']
  assert row['recipientLitoshi']+row['changeLitoshi']+row['feeLitoshi']==row['inputTotalLitoshi']
  assert row['mempoolAllowed'] is True;total+=1
 steps={x['key']:x for x in data['timeline']}
 assert steps['lagging-observer']['A']['confirmations']==2 and steps['lagging-observer']['B']['status']=='not-seen'
 assert steps['reorganized']['A']['confirmations']==0 and steps['reorganized']['A']['tip']==steps['reorganized']['B']['tip']
 assert int(steps['reorganized']['A']['chainwork'],16)>int(steps['lagging-observer']['A']['chainwork'],16)
 assert steps['synchronized']['A']['confirmations']==steps['synchronized']['B']['confirmations']==1
 assert all(c['passed'] for c in data['checks'])
 print(json.dumps({'decodedTransactions':total,'checked':'bytes, weight, vsize, txid, wtxid, prevout identity, output values/scripts, fee conservation; transcript consistency','nodeChecks':len(data['checks'])}))
if __name__=='__main__':main()