#!/usr/bin/env python3

# Based on spend-p2sh-txout.py from python-bitcoinlib.
# Copyright (C) 2017 The Zcash developers

import sys
if sys.version_info.major < 3:
    sys.stderr.write('Sorry, Python 3.x required by this example.\n')
    sys.exit(1)

import bitcoin
import bitcoin.rpc
from bitcoin import SelectParams
from bitcoin.core import b2x, lx, b2lx, COIN, COutPoint, CMutableTxOut, CMutableTxIn, CMutableTransaction, Hash160
from bitcoin.core.script import CScript, OP_DUP, OP_IF, OP_ELSE, OP_ENDIF, OP_HASH160, OP_EQUALVERIFY, OP_CHECKSIG, SignatureHash, SIGHASH_ALL
from bitcoin.core.script import OP_DROP, OP_CHECKLOCKTIMEVERIFY, OP_SHA256, OP_TRUE
from bitcoin.core.scripteval import VerifyScript, SCRIPT_VERIFY_P2SH
from bitcoin.wallet import CBitcoinAddress, CBitcoinSecret

import hashlib

# SelectParams('testnet')
# To get transactions not in your wallet, must set -txindex=1
SelectParams('regtest')
proxy = bitcoin.rpc.Proxy()

# The parameters needed for the htlc - hash preimage, sender/seller address, recipient/buyer address, num of blocks for timeout
preimage = b'preimage'
h = hashlib.sha256(preimage).digest()

# proxy.getnewaddress() returns CBitcoinAddress
recipientpubkey = proxy.getnewaddress()
senderpubkey = proxy.getnewaddress()
# privkey of the recipient, used to sign the redeemTx
seckey = proxy.dumpprivkey(recipientpubkey)

lockduration = 10
blocknum = proxy.getblockcount()
redeemblocknum = blocknum + lockduration
# Create a htlc redeemScript. Similar to a scriptPubKey the redeemScript must be
# satisfied for the funds to be spent.
txin_redeemScript = CScript([OP_IF, OP_SHA256, h, OP_EQUALVERIFY,OP_DUP, OP_HASH160,
                             recipientpubkey, OP_ELSE, redeemblocknum, OP_CHECKLOCKTIMEVERIFY, OP_DROP, OP_DUP, OP_HASH160,
                             senderpubkey, OP_ENDIF,OP_EQUALVERIFY, OP_CHECKSIG])

print("redeem script:", b2x(txin_redeemScript))

# Create P2SH scriptPubKey from redeemScript.
txin_scriptPubKey = txin_redeemScript.to_p2sh_scriptPubKey()
print("p2sh_scriptPubKey", b2x(txin_scriptPubKey))

# Convert the P2SH scriptPubKey to a base58 Bitcoin address
txin_p2sh_address = CBitcoinAddress.from_scriptPubKey(txin_scriptPubKey)
p2sh = str(txin_p2sh_address)
print('Pay to:', p2sh)

# AUTOMATE Send funds to p2sh
send_amount = 1.0*COIN
# sendtoaddress return the id of the created tx
fund_tx = proxy.sendtoaddress(txin_p2sh_address, send_amount)

print('fund tx sent. It\'s id is:', b2x(lx(b2x(fund_tx))))

# Now receiver receives txid and checks that it is on the blockchain to the right address
rec_tx = proxy.getrawtransaction(fund_tx)
outputAddress = CBitcoinAddress.from_scriptPubKey(rec_tx.vout[0].scriptPubKey)
output_amount = rec_tx.vout[0].nValue
print('output amount', output_amount)
if (outputAddress != txin_p2sh_address):
    print('fund tx to wrong address!')
    quit()

if (output_amount < send_amount):
    print('fund tx to small!')
    quit()

print('sender fund tx has been confirmed, now receiver making their fund tx:')

rec_fund_tx = proxy.sendtoaddress(txin_p2sh_address, send_amount)
print('rec fund tx sent. It\'s id is:', b2x(lx(b2x(fund_tx))))

# Now sender checks if the lock time is passed, if so she redeems her own tx
if(proxy.getblockcount()>=redeemblocknum):
    # The default nSequence of FFFFFFFF won't let you redeem when there's a CHECKTIMELOCKVERIFY
    txin.nSequence = 0
    # Create the txout. Pays out to recipient, so uses recipient's pubkey
    # Withdraw full amount minus fee
    default_fee = 0.001*COIN
    txout = CMutableTxOut(amount - default_fee, senderpubkey.to_scriptPubKey())
    # Create the unsigned raw transaction.
    tx = CMutableTransaction([txin], [txout])
    # nLockTime needs to be at least as large as parameter of CHECKLOCKTIMEVERIFY for script to verify
    tx.nLockTime=redeemblocknum
    # Calculate the signature hash for that transaction. Note how the script we use
    # is the redeemScript, not the scriptPubKey. EvalScript() will be evaluating the redeemScript
    sighash = SignatureHash(txin_redeemScript, tx, 0, SIGHASH_ALL)
    sig = seckey.sign(sighash) + bytes([SIGHASH_ALL])
    txin.scriptSig = CScript([sig, seckey.pub, OP_FALSE, txin_redeemScript])
    print("Time lock has passed, sender redeeming their own tx:")
    print("Redeem tx hex:", b2x(tx.serialize()))
    VerifyScript(txin.scriptSig, txin_scriptPubKey, tx, 0, (SCRIPT_VERIFY_P2SH,))
    txid = proxy.sendrawtransaction(tx)
    print("Txid of submitted redeem tx: ", b2x(lx(b2x(txid))))
    quit()

#Otherwise, check that receiver fund tx is on blockchain to correct address with sufficient amount

send_rec_tx = proxy.getrawtransaction(rec_fund_tx)
outputAddress = CBitcoinAddress.from_scriptPubKey(send_rec_tx.vout[0].scriptPubKey)
output_amount = send_rec_tx.vout[0].nValue
print('output amount', output_amount)
if (outputAddress != txin_p2sh_address):
    print('fund tx to wrong address!')
    quit()

if (output_amount < send_amount):
    print('fund tx to small!')
    quit()
print('receiver fund tx confirmed, redeeming it with the hash preimage:')

# Create the txout. Pays out to recipient, so uses recipient's pubkey
# Withdraw full amount minus fee
default_fee = 0.001*COIN
txout = CMutableTxOut(amount - default_fee, senderpubkey.to_scriptPubKey())
# Create the unsigned raw transaction.
tx = CMutableTransaction([txin], [txout])
# nLockTime needs to be at least as large as parameter of CHECKLOCKTIMEVERIFY for script to verify
tx.nLockTime=redeemblocknum
sighash = SignatureHash(txin_redeemScript, tx, 0, SIGHASH_ALL)
sig = seckey.sign(sighash) + bytes([SIGHASH_ALL])
txin.scriptSig = CScript([sig, seckey.pub, OP_FALSE, txin_redeemScript])
print("Redeem tx hex:", b2x(tx.serialize()))
VerifyScript(txin.scriptSig, txin_scriptPubKey, tx, 0, (SCRIPT_VERIFY_P2SH,))
txid = proxy.sendrawtransaction(tx)
print("Txid of submitted redeem tx: ", b2x(lx(b2x(txid))))






















print('Now redeeming.........')

# AUTOMATE getting vout of funding tx
txinfo = proxy.gettransaction(fund_tx)
details = txinfo['details'][0] # what is the zero here
vout = details['vout'] 

# Create the txin structure. scriptSig defaults to being empty.
# The input is the p2sh funding transaction txid, vout is its index
txin = CMutableTxIn(COutPoint(fund_tx, vout))

# Create the txout. Pays out to recipient, so uses recipient's pubkey
# Withdraw full amount minus fee
default_fee = 0.001*COIN
txout = CMutableTxOut(send_amount - default_fee, recipientpubkey.to_scriptPubKey())

# Create the unsigned raw transaction.
tx = CMutableTransaction([txin], [txout])

# Calculate the signature hash for that transaction. Note how the script we use
# is the redeemScript, not the scriptPubKey. EvalScript() will be evaluating the redeemScript
sighash = SignatureHash(txin_redeemScript, tx, 0, SIGHASH_ALL)

# Now sign it. We have to append the type of signature we want to the end, in
# this case the usual SIGHASH_ALL.
sig = seckey.sign(sighash) + bytes([SIGHASH_ALL])

# Set the scriptSig of our transaction input appropriately.
txin.scriptSig = CScript([ sig, seckey.pub, preimage, OP_TRUE, txin_redeemScript])

print("Redeem tx hex:", b2x(tx.serialize()))

# Verify the signature worked.
VerifyScript(txin.scriptSig, txin_scriptPubKey, tx, 0, (SCRIPT_VERIFY_P2SH,))

print("Now sending redeem transaction.......")
txid = proxy.sendrawtransaction(tx)
print("Txid of submitted redeem tx: ", b2x(lx(b2x(txid))))