#!/usr/bin/env python3
# Copyright (c) 2019-2021 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 that we reject low difficulty headers to prevent our block tree from filling up with useless bloat"""

from test_framework.test_framework import BitcoinTestFramework

from test_framework.p2p import (
    P2PInterface,
)

from test_framework.messages import (
    msg_headers,
)

from test_framework.blocktools import (
    NORMAL_GBT_REQUEST_PARAMS,
    create_block,
)

from test_framework.util import assert_equal

NODE1_BLOCKS_REQUIRED = 15
NODE2_BLOCKS_REQUIRED = 2047


class RejectLowDifficultyHeadersTest(BitcoinTestFramework):
    def set_test_params(self):
        self.setup_clean_chain = True
        self.num_nodes = 3
        # Node0 has no required chainwork; node1 requires 15 blocks on top of the genesis block; node2 requires 2047
        self.extra_args = [["-minimumchainwork=0x0"], ["-minimumchainwork=0x1f"], ["-minimumchainwork=0x1000"]]

    def setup_network(self):
        self.setup_nodes()
        self.connect_nodes(0, 1)
        self.connect_nodes(0, 2)
        self.sync_all()

    def disconnect_all(self):
        self.disconnect_nodes(0, 1)
        self.disconnect_nodes(0, 2)

    def test_chains_sync_when_long_enough(self):
        self.log.info("Generate blocks on the node with no required chainwork, and verify nodes 1 and 2 have no new headers in their headers tree")
        with self.nodes[1].assert_debug_log(expected_msgs=["[net] Ignoring low-work chain (height=14)"]), self.nodes[2].assert_debug_log(expected_msgs=["[net] Ignoring low-work chain (height=14)"]):
            self.generate(self.nodes[0], NODE1_BLOCKS_REQUIRED-1, sync_fun=self.no_op)

        for node in self.nodes[1:]:
            chaintips = node.getchaintips()
            assert(len(chaintips) == 1)
            assert {
                'height': 0,
                'hash': '0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206',
                'branchlen': 0,
                'status': 'active',
            } in chaintips

        self.log.info("Generate more blocks to satisfy node1's minchainwork requirement, and verify node2 still has no new headers in headers tree")
        with self.nodes[2].assert_debug_log(expected_msgs=["[net] Ignoring low-work chain (height=15)"]):
            self.generate(self.nodes[0], NODE1_BLOCKS_REQUIRED - self.nodes[0].getblockcount(), sync_fun=self.no_op)
        self.sync_blocks(self.nodes[0:2])

        assert {
            'height': 0,
            'hash': '0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206',
            'branchlen': 0,
            'status': 'active',
        } in self.nodes[2].getchaintips()

        assert(len(self.nodes[2].getchaintips()) == 1)

        self.log.info("Generate long chain for node0/node1")
        self.generate(self.nodes[0], NODE2_BLOCKS_REQUIRED-self.nodes[0].getblockcount(), sync_fun=self.no_op)

        self.log.info("Verify that node2 will sync the chain when it gets long enough")
        self.sync_blocks()

    def test_peerinfo_includes_headers_presync_height(self):
        self.log.info("Test that getpeerinfo() includes headers presync height")

        # Disconnect network, so that we can find our own peer connection more
        # easily
        self.disconnect_all()

        p2p = self.nodes[0].add_p2p_connection(P2PInterface())
        node = self.nodes[0]

        # Ensure we have a long chain already
        current_height = self.nodes[0].getblockcount()
        if (current_height < 3000):
            self.generate(node, 3000-current_height, sync_fun=self.no_op)

        # Send a group of 2000 headers, forking from genesis.
        new_blocks = []
        hashPrevBlock = int(node.getblockhash(0), 16)
        for i in range(2000):
            block = create_block(hashprev = hashPrevBlock, tmpl=node.getblocktemplate(NORMAL_GBT_REQUEST_PARAMS))
            block.solve()
            new_blocks.append(block)
            hashPrevBlock = block.sha256

        headers_message = msg_headers(headers=new_blocks)
        p2p.send_and_ping(headers_message)

        # getpeerinfo should show a sync in progress
        assert_equal(node.getpeerinfo()[0]['presynced_headers'], 2000)

    def run_test(self):
        self.test_chains_sync_when_long_enough()

        self.test_peerinfo_includes_headers_presync_height()


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