import shutil
import tempfile
import os

from electrum import constants, blockchain
from electrum.simple_config import SimpleConfig
from electrum.blockchain import Blockchain, deserialize_header, hash_header, InvalidHeader
from electrum.util import bfh, make_dir

from . import ElectrumTestCase


class TestBlockchain(ElectrumTestCase):

    HEADERS = {
        'A': deserialize_header(bfh("0100000000000000000000000000000000000000000000000000000000000000000000003ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4adae5494dffff7f2002000000"), 0),
        'B': deserialize_header(bfh("0000002006226e46111a0b59caaf126043eb5bbf28c34f3a5e332a1fc7b2b73cf188910f186c8dfd970a4545f79916bc1d75c9d00432f57c89209bf3bb115b7612848f509c25f45bffff7f2000000000"), 1),
        'C': deserialize_header(bfh("00000020686bdfc6a3db73d5d93e8c9663a720a26ecb1ef20eb05af11b36cdbc57c19f7ebf2cbf153013a1c54abaf70e95198fcef2f3059cc6b4d0f7e876808e7d24d11cc825f45bffff7f2000000000"), 2),
        'D': deserialize_header(bfh("00000020122baa14f3ef54985ae546d1611559e3f487bd2a0f46e8dbb52fbacc9e237972e71019d7feecd9b8596eca9a67032c5f4641b23b5d731dc393e37de7f9c2f299e725f45bffff7f2000000000"), 3),
        'E': deserialize_header(bfh("00000020f8016f7ef3a17d557afe05d4ea7ab6bde1b2247b7643896c1b63d43a1598b747a3586da94c71753f27c075f57f44faf913c31177a0957bbda42e7699e3a2141aed25f45bffff7f2001000000"), 4),
        'F': deserialize_header(bfh("000000201d589c6643c1d121d73b0573e5ee58ab575b8fdf16d507e7e915c5fbfbbfd05e7aee1d692d1615c3bdf52c291032144ce9e3b258a473c17c745047f3431ff8e2ee25f45bffff7f2000000000"), 5),
        'O': deserialize_header(bfh("00000020b833ed46eea01d4c980f59feee44a66aa1162748b6801029565d1466790c405c3a141ce635cbb1cd2b3a4fcdd0a3380517845ba41736c82a79cab535d31128066526f45bffff7f2001000000"), 6),
        'P': deserialize_header(bfh("00000020abe8e119d1877c9dc0dc502d1a253fb9a67967c57732d2f71ee0280e8381ff0a9690c2fe7c1a4450c74dc908fe94dd96c3b0637d51475e9e06a78e944a0c7fe28126f45bffff7f2000000000"), 7),
        'Q': deserialize_header(bfh("000000202ce41d94eb70e1518bc1f72523f84a903f9705d967481e324876e1f8cf4d3452148be228a4c3f2061bafe7efdfc4a8d5a94759464b9b5c619994d45dfcaf49e1a126f45bffff7f2000000000"), 8),
        'R': deserialize_header(bfh("00000020552755b6c59f3d51e361d16281842a4e166007799665b5daed86a063dd89857415681cb2d00ff889193f6a68a93f5096aeb2d84ca0af6185a462555822552221a626f45bffff7f2000000000"), 9),
        'S': deserialize_header(bfh("00000020a13a491cbefc93cd1bb1938f19957e22a134faf14c7dee951c45533e2c750f239dc087fc977b06c24a69c682d1afd1020e6dc1f087571ccec66310a786e1548fab26f45bffff7f2000000000"), 10),
        'T': deserialize_header(bfh("00000020dbf3a9b55dfefbaf8b6e43a89cf833fa2e208bbc0c1c5d76c0d71b9e4a65337803b243756c25053253aeda309604363460a3911015929e68705bd89dff6fe064b026f45bffff7f2002000000"), 11),
        'U': deserialize_header(bfh("000000203d0932b3b0c78eccb39a595a28ae4a7c966388648d7783fd1305ec8d40d4fe5fd67cb902a7d807cee7676cb543feec3e053aa824d5dfb528d5b94f9760313d9db726f45bffff7f2001000000"), 12),
        'G': deserialize_header(bfh("00000020b833ed46eea01d4c980f59feee44a66aa1162748b6801029565d1466790c405c3a141ce635cbb1cd2b3a4fcdd0a3380517845ba41736c82a79cab535d31128066928f45bffff7f2001000000"), 6),
        'H': deserialize_header(bfh("00000020e19e687f6e7f83ca394c114144dbbbc4f3f9c9450f66331a125413702a2e1a719690c2fe7c1a4450c74dc908fe94dd96c3b0637d51475e9e06a78e944a0c7fe26a28f45bffff7f2002000000"), 7),
        'I': deserialize_header(bfh("0000002009dcb3b158293c89d7cf7ceeb513add122ebc3880a850f47afbb2747f5e48c54148be228a4c3f2061bafe7efdfc4a8d5a94759464b9b5c619994d45dfcaf49e16a28f45bffff7f2000000000"), 8),
        'J': deserialize_header(bfh("000000206a65f3bdd3374a5a6c4538008ba0b0a560b8566291f9ef4280ab877627a1742815681cb2d00ff889193f6a68a93f5096aeb2d84ca0af6185a462555822552221c928f45bffff7f2000000000"), 9),
        'K': deserialize_header(bfh("00000020bb3b421653548991998f96f8ba486b652fdb07ca16e9cee30ece033547cd1a6e9dc087fc977b06c24a69c682d1afd1020e6dc1f087571ccec66310a786e1548fca28f45bffff7f2000000000"), 10),
        'L': deserialize_header(bfh("00000020c391d74d37c24a130f4bf4737932bdf9e206dd4fad22860ec5408978eb55d46303b243756c25053253aeda309604363460a3911015929e68705bd89dff6fe064ca28f45bffff7f2000000000"), 11),
        'M': deserialize_header(bfh("000000206a65f3bdd3374a5a6c4538008ba0b0a560b8566291f9ef4280ab877627a1742815681cb2d00ff889193f6a68a93f5096aeb2d84ca0af6185a4625558225522214229f45bffff7f2000000000"), 9),
        'N': deserialize_header(bfh("00000020383dab38b57f98aa9b4f0d5ff868bc674b4828d76766bf048296f4c45fff680a9dc087fc977b06c24a69c682d1afd1020e6dc1f087571ccec66310a786e1548f4329f45bffff7f2003000000"), 10),
        'X': deserialize_header(bfh("0000002067f1857f54b7fef732cb4940f7d1b339472b3514660711a820330fd09d8fba6b03b243756c25053253aeda309604363460a3911015929e68705bd89dff6fe0649b29f45bffff7f2002000000"), 11),
        'Y': deserialize_header(bfh("00000020db33c9768a9e5f7c37d0f09aad88d48165946c87d08f7d63793f07b5c08c527fd67cb902a7d807cee7676cb543feec3e053aa824d5dfb528d5b94f9760313d9d9b29f45bffff7f2000000000"), 12),
        'Z': deserialize_header(bfh("0000002047822b67940e337fda38be6f13390b3596e4dea2549250256879722073824e7f0f2596c29203f8a0f71ae94193092dc8f113be3dbee4579f1e649fa3d6dcc38c622ef45bffff7f2003000000"), 13),
    }
    # tree of headers:
    #                                            - M <- N <- X <- Y <- Z
    #                                          /
    #                             - G <- H <- I <- J <- K <- L
    #                           /
    # A <- B <- C <- D <- E <- F <- O <- P <- Q <- R <- S <- T <- U

    @classmethod
    def setUpClass(cls):
        super().setUpClass()
        constants.BitcoinRegtest.set_as_network()

    @classmethod
    def tearDownClass(cls):
        super().tearDownClass()
        constants.BitcoinMainnet.set_as_network()

    def setUp(self):
        super().setUp()
        self.data_dir = self.electrum_path
        make_dir(os.path.join(self.data_dir, 'forks'))
        self.config = SimpleConfig({'electrum_path': self.data_dir})
        blockchain.blockchains = {}

    def _append_header(self, chain: Blockchain, header: dict):
        self.assertTrue(chain.can_connect(header))
        chain.save_header(header)

    def test_get_height_of_last_common_block_with_chain(self):
        blockchain.blockchains[constants.net.GENESIS] = chain_u = Blockchain(
            config=self.config, forkpoint=0, parent=None,
            forkpoint_hash=constants.net.GENESIS, prev_hash=None)
        open(chain_u.path(), 'w+').close()
        self._append_header(chain_u, self.HEADERS['A'])
        self._append_header(chain_u, self.HEADERS['B'])
        self._append_header(chain_u, self.HEADERS['C'])
        self._append_header(chain_u, self.HEADERS['D'])
        self._append_header(chain_u, self.HEADERS['E'])
        self._append_header(chain_u, self.HEADERS['F'])
        self._append_header(chain_u, self.HEADERS['O'])
        self._append_header(chain_u, self.HEADERS['P'])
        self._append_header(chain_u, self.HEADERS['Q'])

        chain_l = chain_u.fork(self.HEADERS['G'])
        self._append_header(chain_l, self.HEADERS['H'])
        self._append_header(chain_l, self.HEADERS['I'])
        self._append_header(chain_l, self.HEADERS['J'])
        self._append_header(chain_l, self.HEADERS['K'])
        self._append_header(chain_l, self.HEADERS['L'])

        self.assertEqual({chain_u:  8, chain_l: 5}, chain_u.get_parent_heights())
        self.assertEqual({chain_l: 11},             chain_l.get_parent_heights())

        chain_z = chain_l.fork(self.HEADERS['M'])
        self._append_header(chain_z, self.HEADERS['N'])
        self._append_header(chain_z, self.HEADERS['X'])
        self._append_header(chain_z, self.HEADERS['Y'])
        self._append_header(chain_z, self.HEADERS['Z'])

        self.assertEqual({chain_u:  8, chain_z: 5}, chain_u.get_parent_heights())
        self.assertEqual({chain_l: 11, chain_z: 8}, chain_l.get_parent_heights())
        self.assertEqual({chain_z: 13},             chain_z.get_parent_heights())
        self.assertEqual(5, chain_u.get_height_of_last_common_block_with_chain(chain_l))
        self.assertEqual(5, chain_l.get_height_of_last_common_block_with_chain(chain_u))
        self.assertEqual(5, chain_u.get_height_of_last_common_block_with_chain(chain_z))
        self.assertEqual(5, chain_z.get_height_of_last_common_block_with_chain(chain_u))
        self.assertEqual(8, chain_l.get_height_of_last_common_block_with_chain(chain_z))
        self.assertEqual(8, chain_z.get_height_of_last_common_block_with_chain(chain_l))

        self._append_header(chain_u, self.HEADERS['R'])
        self._append_header(chain_u, self.HEADERS['S'])
        self._append_header(chain_u, self.HEADERS['T'])
        self._append_header(chain_u, self.HEADERS['U'])

        self.assertEqual({chain_u: 12, chain_z: 5}, chain_u.get_parent_heights())
        self.assertEqual({chain_l: 11, chain_z: 8}, chain_l.get_parent_heights())
        self.assertEqual({chain_z: 13},             chain_z.get_parent_heights())
        self.assertEqual(5, chain_u.get_height_of_last_common_block_with_chain(chain_l))
        self.assertEqual(5, chain_l.get_height_of_last_common_block_with_chain(chain_u))
        self.assertEqual(5, chain_u.get_height_of_last_common_block_with_chain(chain_z))
        self.assertEqual(5, chain_z.get_height_of_last_common_block_with_chain(chain_u))
        self.assertEqual(8, chain_l.get_height_of_last_common_block_with_chain(chain_z))
        self.assertEqual(8, chain_z.get_height_of_last_common_block_with_chain(chain_l))

    def test_parents_after_forking(self):
        blockchain.blockchains[constants.net.GENESIS] = chain_u = Blockchain(
            config=self.config, forkpoint=0, parent=None,
            forkpoint_hash=constants.net.GENESIS, prev_hash=None)
        open(chain_u.path(), 'w+').close()
        self._append_header(chain_u, self.HEADERS['A'])
        self._append_header(chain_u, self.HEADERS['B'])
        self._append_header(chain_u, self.HEADERS['C'])
        self._append_header(chain_u, self.HEADERS['D'])
        self._append_header(chain_u, self.HEADERS['E'])
        self._append_header(chain_u, self.HEADERS['F'])
        self._append_header(chain_u, self.HEADERS['O'])
        self._append_header(chain_u, self.HEADERS['P'])
        self._append_header(chain_u, self.HEADERS['Q'])

        self.assertEqual(None, chain_u.parent)

        chain_l = chain_u.fork(self.HEADERS['G'])
        self._append_header(chain_l, self.HEADERS['H'])
        self._append_header(chain_l, self.HEADERS['I'])
        self._append_header(chain_l, self.HEADERS['J'])
        self._append_header(chain_l, self.HEADERS['K'])
        self._append_header(chain_l, self.HEADERS['L'])

        self.assertEqual(None,    chain_l.parent)
        self.assertEqual(chain_l, chain_u.parent)

        chain_z = chain_l.fork(self.HEADERS['M'])
        self._append_header(chain_z, self.HEADERS['N'])
        self._append_header(chain_z, self.HEADERS['X'])
        self._append_header(chain_z, self.HEADERS['Y'])
        self._append_header(chain_z, self.HEADERS['Z'])

        self.assertEqual(chain_z, chain_u.parent)
        self.assertEqual(chain_z, chain_l.parent)
        self.assertEqual(None,    chain_z.parent)

        self._append_header(chain_u, self.HEADERS['R'])
        self._append_header(chain_u, self.HEADERS['S'])
        self._append_header(chain_u, self.HEADERS['T'])
        self._append_header(chain_u, self.HEADERS['U'])

        self.assertEqual(chain_z, chain_u.parent)
        self.assertEqual(chain_z, chain_l.parent)
        self.assertEqual(None,    chain_z.parent)

    def test_forking_and_swapping(self):
        blockchain.blockchains[constants.net.GENESIS] = chain_u = Blockchain(
            config=self.config, forkpoint=0, parent=None,
            forkpoint_hash=constants.net.GENESIS, prev_hash=None)
        open(chain_u.path(), 'w+').close()

        self._append_header(chain_u, self.HEADERS['A'])
        self._append_header(chain_u, self.HEADERS['B'])
        self._append_header(chain_u, self.HEADERS['C'])
        self._append_header(chain_u, self.HEADERS['D'])
        self._append_header(chain_u, self.HEADERS['E'])
        self._append_header(chain_u, self.HEADERS['F'])
        self._append_header(chain_u, self.HEADERS['O'])
        self._append_header(chain_u, self.HEADERS['P'])
        self._append_header(chain_u, self.HEADERS['Q'])
        self._append_header(chain_u, self.HEADERS['R'])

        chain_l = chain_u.fork(self.HEADERS['G'])
        self._append_header(chain_l, self.HEADERS['H'])
        self._append_header(chain_l, self.HEADERS['I'])
        self._append_header(chain_l, self.HEADERS['J'])

        # do checks
        self.assertEqual(2, len(blockchain.blockchains))
        self.assertEqual(1, len(os.listdir(os.path.join(self.data_dir, "forks"))))
        self.assertEqual(0, chain_u.forkpoint)
        self.assertEqual(None, chain_u.parent)
        self.assertEqual(constants.net.GENESIS, chain_u._forkpoint_hash)
        self.assertEqual(None, chain_u._prev_hash)
        self.assertEqual(os.path.join(self.data_dir, "blockchain_headers"), chain_u.path())
        self.assertEqual(10 * 80, os.stat(chain_u.path()).st_size)
        self.assertEqual(6, chain_l.forkpoint)
        self.assertEqual(chain_u, chain_l.parent)
        self.assertEqual(hash_header(self.HEADERS['G']), chain_l._forkpoint_hash)
        self.assertEqual(hash_header(self.HEADERS['F']), chain_l._prev_hash)
        self.assertEqual(os.path.join(self.data_dir, "forks", "fork2_6_5c400c7966145d56291080b6482716a16aa644eefe590f984c1da0ee46ed33b8_711a2e2a701354121a33660f45c9f9f3c4bbdb4441114c39ca837f6e7f689ee1"), chain_l.path())
        self.assertEqual(4 * 80, os.stat(chain_l.path()).st_size)

        self._append_header(chain_l, self.HEADERS['K'])

        # chains were swapped, do checks
        self.assertEqual(2, len(blockchain.blockchains))
        self.assertEqual(1, len(os.listdir(os.path.join(self.data_dir, "forks"))))
        self.assertEqual(6, chain_u.forkpoint)
        self.assertEqual(chain_l, chain_u.parent)
        self.assertEqual(hash_header(self.HEADERS['O']), chain_u._forkpoint_hash)
        self.assertEqual(hash_header(self.HEADERS['F']), chain_u._prev_hash)
        self.assertEqual(os.path.join(self.data_dir, "forks", "fork2_6_5c400c7966145d56291080b6482716a16aa644eefe590f984c1da0ee46ed33b8_aff81830e28e01ef7d23277c56779a6b93f251a2d50dcc09d7c87d119e1e8ab"), chain_u.path())
        self.assertEqual(4 * 80, os.stat(chain_u.path()).st_size)
        self.assertEqual(0, chain_l.forkpoint)
        self.assertEqual(None, chain_l.parent)
        self.assertEqual(constants.net.GENESIS, chain_l._forkpoint_hash)
        self.assertEqual(None, chain_l._prev_hash)
        self.assertEqual(os.path.join(self.data_dir, "blockchain_headers"), chain_l.path())
        self.assertEqual(11 * 80, os.stat(chain_l.path()).st_size)
        for b in (chain_u, chain_l):
            self.assertTrue(all([b.can_connect(b.read_header(i), False) for i in range(b.height())]))

        self._append_header(chain_u, self.HEADERS['S'])
        self._append_header(chain_u, self.HEADERS['T'])
        self._append_header(chain_u, self.HEADERS['U'])
        self._append_header(chain_l, self.HEADERS['L'])

        chain_z = chain_l.fork(self.HEADERS['M'])
        self._append_header(chain_z, self.HEADERS['N'])
        self._append_header(chain_z, self.HEADERS['X'])
        self._append_header(chain_z, self.HEADERS['Y'])
        self._append_header(chain_z, self.HEADERS['Z'])

        # chain_z became best chain, do checks
        self.assertEqual(3, len(blockchain.blockchains))
        self.assertEqual(2, len(os.listdir(os.path.join(self.data_dir, "forks"))))
        self.assertEqual(0, chain_z.forkpoint)
        self.assertEqual(None, chain_z.parent)
        self.assertEqual(constants.net.GENESIS, chain_z._forkpoint_hash)
        self.assertEqual(None, chain_z._prev_hash)
        self.assertEqual(os.path.join(self.data_dir, "blockchain_headers"), chain_z.path())
        self.assertEqual(14 * 80, os.stat(chain_z.path()).st_size)
        self.assertEqual(9, chain_l.forkpoint)
        self.assertEqual(chain_z, chain_l.parent)
        self.assertEqual(hash_header(self.HEADERS['J']), chain_l._forkpoint_hash)
        self.assertEqual(hash_header(self.HEADERS['I']), chain_l._prev_hash)
        self.assertEqual(os.path.join(self.data_dir, "forks", "fork2_9_2874a1277687ab8042eff9916256b860a5b0a08b0038456c5a4a37d3bdf3656a_6e1acd473503ce0ee3cee916ca07db2f656b48baf8968f999189545316423bbb"), chain_l.path())
        self.assertEqual(3 * 80, os.stat(chain_l.path()).st_size)
        self.assertEqual(6, chain_u.forkpoint)
        self.assertEqual(chain_z, chain_u.parent)
        self.assertEqual(hash_header(self.HEADERS['O']), chain_u._forkpoint_hash)
        self.assertEqual(hash_header(self.HEADERS['F']), chain_u._prev_hash)
        self.assertEqual(os.path.join(self.data_dir, "forks", "fork2_6_5c400c7966145d56291080b6482716a16aa644eefe590f984c1da0ee46ed33b8_aff81830e28e01ef7d23277c56779a6b93f251a2d50dcc09d7c87d119e1e8ab"), chain_u.path())
        self.assertEqual(7 * 80, os.stat(chain_u.path()).st_size)
        for b in (chain_u, chain_l, chain_z):
            self.assertTrue(all([b.can_connect(b.read_header(i), False) for i in range(b.height())]))

        self.assertEqual(constants.net.GENESIS, chain_z.get_hash(0))
        self.assertEqual(hash_header(self.HEADERS['F']), chain_z.get_hash(5))
        self.assertEqual(hash_header(self.HEADERS['G']), chain_z.get_hash(6))
        self.assertEqual(hash_header(self.HEADERS['I']), chain_z.get_hash(8))
        self.assertEqual(hash_header(self.HEADERS['M']), chain_z.get_hash(9))
        self.assertEqual(hash_header(self.HEADERS['Z']), chain_z.get_hash(13))

    def test_doing_multiple_swaps_after_single_new_header(self):
        blockchain.blockchains[constants.net.GENESIS] = chain_u = Blockchain(
            config=self.config, forkpoint=0, parent=None,
            forkpoint_hash=constants.net.GENESIS, prev_hash=None)
        open(chain_u.path(), 'w+').close()

        self._append_header(chain_u, self.HEADERS['A'])
        self._append_header(chain_u, self.HEADERS['B'])
        self._append_header(chain_u, self.HEADERS['C'])
        self._append_header(chain_u, self.HEADERS['D'])
        self._append_header(chain_u, self.HEADERS['E'])
        self._append_header(chain_u, self.HEADERS['F'])
        self._append_header(chain_u, self.HEADERS['O'])
        self._append_header(chain_u, self.HEADERS['P'])
        self._append_header(chain_u, self.HEADERS['Q'])
        self._append_header(chain_u, self.HEADERS['R'])
        self._append_header(chain_u, self.HEADERS['S'])

        self.assertEqual(1, len(blockchain.blockchains))
        self.assertEqual(0, len(os.listdir(os.path.join(self.data_dir, "forks"))))

        chain_l = chain_u.fork(self.HEADERS['G'])
        self._append_header(chain_l, self.HEADERS['H'])
        self._append_header(chain_l, self.HEADERS['I'])
        self._append_header(chain_l, self.HEADERS['J'])
        self._append_header(chain_l, self.HEADERS['K'])
        # now chain_u is best chain, but it's tied with chain_l

        self.assertEqual(2, len(blockchain.blockchains))
        self.assertEqual(1, len(os.listdir(os.path.join(self.data_dir, "forks"))))

        chain_z = chain_l.fork(self.HEADERS['M'])
        self._append_header(chain_z, self.HEADERS['N'])
        self._append_header(chain_z, self.HEADERS['X'])

        self.assertEqual(3, len(blockchain.blockchains))
        self.assertEqual(2, len(os.listdir(os.path.join(self.data_dir, "forks"))))

        # chain_z became best chain, do checks
        self.assertEqual(0, chain_z.forkpoint)
        self.assertEqual(None, chain_z.parent)
        self.assertEqual(constants.net.GENESIS, chain_z._forkpoint_hash)
        self.assertEqual(None, chain_z._prev_hash)
        self.assertEqual(os.path.join(self.data_dir, "blockchain_headers"), chain_z.path())
        self.assertEqual(12 * 80, os.stat(chain_z.path()).st_size)
        self.assertEqual(9, chain_l.forkpoint)
        self.assertEqual(chain_z, chain_l.parent)
        self.assertEqual(hash_header(self.HEADERS['J']), chain_l._forkpoint_hash)
        self.assertEqual(hash_header(self.HEADERS['I']), chain_l._prev_hash)
        self.assertEqual(os.path.join(self.data_dir, "forks", "fork2_9_2874a1277687ab8042eff9916256b860a5b0a08b0038456c5a4a37d3bdf3656a_6e1acd473503ce0ee3cee916ca07db2f656b48baf8968f999189545316423bbb"), chain_l.path())
        self.assertEqual(2 * 80, os.stat(chain_l.path()).st_size)
        self.assertEqual(6, chain_u.forkpoint)
        self.assertEqual(chain_z, chain_u.parent)
        self.assertEqual(hash_header(self.HEADERS['O']), chain_u._forkpoint_hash)
        self.assertEqual(hash_header(self.HEADERS['F']), chain_u._prev_hash)
        self.assertEqual(os.path.join(self.data_dir, "forks", "fork2_6_5c400c7966145d56291080b6482716a16aa644eefe590f984c1da0ee46ed33b8_aff81830e28e01ef7d23277c56779a6b93f251a2d50dcc09d7c87d119e1e8ab"), chain_u.path())
        self.assertEqual(5 * 80, os.stat(chain_u.path()).st_size)

        self.assertEqual(constants.net.GENESIS, chain_z.get_hash(0))
        self.assertEqual(hash_header(self.HEADERS['F']), chain_z.get_hash(5))
        self.assertEqual(hash_header(self.HEADERS['G']), chain_z.get_hash(6))
        self.assertEqual(hash_header(self.HEADERS['I']), chain_z.get_hash(8))
        self.assertEqual(hash_header(self.HEADERS['M']), chain_z.get_hash(9))
        self.assertEqual(hash_header(self.HEADERS['X']), chain_z.get_hash(11))

        for b in (chain_u, chain_l, chain_z):
            self.assertTrue(all([b.can_connect(b.read_header(i), False) for i in range(b.height())]))

    def get_chains_that_contain_header_helper(self, header: dict):
        height = header['block_height']
        header_hash = hash_header(header)
        return blockchain.get_chains_that_contain_header(height, header_hash)

    def test_get_chains_that_contain_header(self):
        blockchain.blockchains[constants.net.GENESIS] = chain_u = Blockchain(
            config=self.config, forkpoint=0, parent=None,
            forkpoint_hash=constants.net.GENESIS, prev_hash=None)
        open(chain_u.path(), 'w+').close()
        self._append_header(chain_u, self.HEADERS['A'])
        self._append_header(chain_u, self.HEADERS['B'])
        self._append_header(chain_u, self.HEADERS['C'])
        self._append_header(chain_u, self.HEADERS['D'])
        self._append_header(chain_u, self.HEADERS['E'])
        self._append_header(chain_u, self.HEADERS['F'])
        self._append_header(chain_u, self.HEADERS['O'])
        self._append_header(chain_u, self.HEADERS['P'])
        self._append_header(chain_u, self.HEADERS['Q'])

        chain_l = chain_u.fork(self.HEADERS['G'])
        self._append_header(chain_l, self.HEADERS['H'])
        self._append_header(chain_l, self.HEADERS['I'])
        self._append_header(chain_l, self.HEADERS['J'])
        self._append_header(chain_l, self.HEADERS['K'])
        self._append_header(chain_l, self.HEADERS['L'])

        chain_z = chain_l.fork(self.HEADERS['M'])

        self.assertEqual([chain_l, chain_z, chain_u], self.get_chains_that_contain_header_helper(self.HEADERS['A']))
        self.assertEqual([chain_l, chain_z, chain_u], self.get_chains_that_contain_header_helper(self.HEADERS['C']))
        self.assertEqual([chain_l, chain_z, chain_u], self.get_chains_that_contain_header_helper(self.HEADERS['F']))
        self.assertEqual([chain_l, chain_z], self.get_chains_that_contain_header_helper(self.HEADERS['G']))
        self.assertEqual([chain_l, chain_z], self.get_chains_that_contain_header_helper(self.HEADERS['I']))
        self.assertEqual([chain_z], self.get_chains_that_contain_header_helper(self.HEADERS['M']))
        self.assertEqual([chain_l], self.get_chains_that_contain_header_helper(self.HEADERS['K']))

        self._append_header(chain_z, self.HEADERS['N'])
        self._append_header(chain_z, self.HEADERS['X'])
        self._append_header(chain_z, self.HEADERS['Y'])
        self._append_header(chain_z, self.HEADERS['Z'])

        self.assertEqual([chain_z, chain_l, chain_u], self.get_chains_that_contain_header_helper(self.HEADERS['A']))
        self.assertEqual([chain_z, chain_l, chain_u], self.get_chains_that_contain_header_helper(self.HEADERS['C']))
        self.assertEqual([chain_z, chain_l, chain_u], self.get_chains_that_contain_header_helper(self.HEADERS['F']))
        self.assertEqual([chain_u], self.get_chains_that_contain_header_helper(self.HEADERS['O']))
        self.assertEqual([chain_z, chain_l], self.get_chains_that_contain_header_helper(self.HEADERS['I']))

    def test_target_to_bits(self):
        # https://github.com/bitcoin/bitcoin/blob/7fcf53f7b4524572d1d0c9a5fdc388e87eb02416/src/arith_uint256.h#L269
        self.assertEqual(0x05123456, Blockchain.target_to_bits(0x1234560000))
        self.assertEqual(0x0600c0de, Blockchain.target_to_bits(0xc0de000000))

        # tests from https://github.com/bitcoin/bitcoin/blob/a7d17daa5cd8bf6398d5f8d7e77290009407d6ea/src/test/arith_uint256_tests.cpp#L411
        tuples = (
            (0, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x00123456, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x01003456, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x02000056, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x03000000, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x04000000, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x00923456, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x01803456, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x02800056, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x03800000, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x04800000, 0x0000000000000000000000000000000000000000000000000000000000000000, 0),
            (0x01123456, 0x0000000000000000000000000000000000000000000000000000000000000012, 0x01120000),
            (0x02123456, 0x0000000000000000000000000000000000000000000000000000000000001234, 0x02123400),
            (0x03123456, 0x0000000000000000000000000000000000000000000000000000000000123456, 0x03123456),
            (0x04123456, 0x0000000000000000000000000000000000000000000000000000000012345600, 0x04123456),
            (0x05009234, 0x0000000000000000000000000000000000000000000000000000000092340000, 0x05009234),
            (0x20123456, 0x1234560000000000000000000000000000000000000000000000000000000000, 0x20123456),
        )
        for nbits1, target, nbits2 in tuples:
            with self.subTest(original_compact_nbits=nbits1.to_bytes(length=4, byteorder="big").hex()):
                num = Blockchain.bits_to_target(nbits1)
                self.assertEqual(target, num)
                self.assertEqual(nbits2, Blockchain.target_to_bits(num))

        # Make sure that we don't generate compacts with the 0x00800000 bit set
        self.assertEqual(0x02008000, Blockchain.target_to_bits(0x80))

        with self.assertRaises(InvalidHeader):  # target cannot be negative
            Blockchain.bits_to_target(0x01fedcba)
        with self.assertRaises(InvalidHeader):  # target cannot be negative
            Blockchain.bits_to_target(0x04923456)
        with self.assertRaises(InvalidHeader):  # overflow
            Blockchain.bits_to_target(0xff123456)


class TestVerifyHeader(ElectrumTestCase):

    # Data for Bitcoin block header #100.
    valid_header = "0100000095194b8567fe2e8bbda931afd01a7acd399b9325cb54683e64129bcd00000000660802c98f18fd34fd16d61c63cf447568370124ac5f3be626c2e1c3c9f0052d19a76949ffff001d33f3c25d"
    target = Blockchain.bits_to_target(0x1d00ffff)
    prev_hash = "00000000cd9b12643e6854cb25939b39cd7a1ad0af31a9bd8b2efe67854b1995"

    def setUp(self):
        super().setUp()
        self.header = deserialize_header(bfh(self.valid_header), 100)

    def test_valid_header(self):
        Blockchain.verify_header(self.header, self.prev_hash, self.target)

    def test_expected_hash_mismatch(self):
        with self.assertRaises(InvalidHeader):
            Blockchain.verify_header(self.header, self.prev_hash, self.target,
                                     expected_header_hash="foo")

    def test_prev_hash_mismatch(self):
        with self.assertRaises(InvalidHeader):
            Blockchain.verify_header(self.header, "foo", self.target)

    def test_target_mismatch(self):
        with self.assertRaises(InvalidHeader):
            other_target = Blockchain.bits_to_target(0x1d00eeee)
            Blockchain.verify_header(self.header, self.prev_hash, other_target)

    def test_insufficient_pow(self):
        with self.assertRaises(InvalidHeader):
            self.header["nonce"] = 42
            Blockchain.verify_header(self.header, self.prev_hash, self.target)
