#!/usr/bin/env python3
# Copyright (c) 2019-2020 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Test the generation of UTXO snapshots using `dumptxoutset`.
"""
from test_framework.test_framework import BitcoinTestFramework
from test_framework.util import assert_equal, assert_raises_rpc_error

import hashlib
from pathlib import Path


class DumptxoutsetTest(BitcoinTestFramework):
    def set_test_params(self):
        self.setup_clean_chain = True
        self.num_nodes = 1

    def run_test(self):
        """Test a trivial usage of the dumptxoutset RPC command."""
        node = self.nodes[0]
        mocktime = node.getblockheader(node.getblockhash(0))['time'] + 1
        node.setmocktime(mocktime)
        node.generate(100)

        FILENAME = 'txoutset.dat'
        out = node.dumptxoutset(FILENAME)
        expected_path = Path(node.datadir) / self.chain / FILENAME

        assert expected_path.is_file()

        assert_equal(out['coins_written'], 100)
        assert_equal(out['base_height'], 100)
        assert_equal(out['path'], str(expected_path))
        # Blockhash should be deterministic based on mocked time.
        # Dogecoin: Full disclosure, I've used the calculated value after introducing Scrypt and Dogecoin rewards, and trusted it's correct.
        #           This is presumed safe none of this code changed, so we're updating the value for future changes to test against.
        assert_equal(
            out['base_hash'],
            'eec7e2fd4d81b77ee3122f9500723c3723ef48aa7b45cbb54fae0c6b39f13208')

        with open(str(expected_path), 'rb') as f:
            digest = hashlib.sha256(f.read()).hexdigest()
            # UTXO snapshot hash should be deterministic based on mocked time.
            assert_equal(
                digest, '77d1eca936df34f2b3d769ce589f710ac4b92b0306fd925d775336a6067658b5')

        # Specifying a path to an existing file will fail.
        assert_raises_rpc_error(
            -8, '{} already exists'.format(FILENAME),  node.dumptxoutset, FILENAME)

if __name__ == '__main__':
    DumptxoutsetTest().main()
