#!/usr/bin/env python3
# Copyright (c) 2010 ArtForz -- public domain half-a-node
# Copyright (c) 2012 Jeff Garzik
# Copyright (c) 2010-2020 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Bitcoin P2P network half-a-node.

This python code was modified from ArtForz' public domain half-a-node, as
found in the mini-node branch of http://github.com/jgarzik/pynode.

P2PConnection: A low-level connection object to a node's P2P interface
P2PInterface: A high-level interface object for communicating to a node over P2P
P2PDataStore: A p2p interface class that keeps a store of transactions and blocks
              and can respond correctly to getdata and getheaders messages
P2PTxInvStore: A p2p interface class that inherits from P2PDataStore, and keeps
              a count of how many times each txid has been announced."""

import asyncio
from collections import defaultdict
from io import BytesIO
import logging
import struct
import sys
import threading

from test_framework.messages import (
    CBlockHeader,
    MIN_VERSION_SUPPORTED,
    msg_addr,
    msg_block,
    MSG_BLOCK,
    msg_blocktxn,
    msg_cmpctblock,
    msg_feefilter,
    msg_filteradd,
    msg_filterclear,
    msg_filterload,
    msg_getaddr,
    msg_getblocks,
    msg_getblocktxn,
    msg_getdata,
    msg_getheaders,
    msg_headers,
    msg_inv,
    msg_mempool,
    msg_merkleblock,
    msg_notfound,
    msg_ping,
    msg_pong,
    msg_sendcmpct,
    msg_sendheaders,
    msg_tx,
    MSG_TX,
    MSG_TYPE_MASK,
    msg_verack,
    msg_version,
    NODE_NETWORK,
    NODE_WITNESS,
    sha256,
)
from test_framework.util import wait_until

logger = logging.getLogger("TestFramework.mininode")

MESSAGEMAP = {
    b"addr": msg_addr,
    b"block": msg_block,
    b"blocktxn": msg_blocktxn,
    b"cmpctblock": msg_cmpctblock,
    b"feefilter": msg_feefilter,
    b"filteradd": msg_filteradd,
    b"filterclear": msg_filterclear,
    b"filterload": msg_filterload,
    b"getaddr": msg_getaddr,
    b"getblocks": msg_getblocks,
    b"getblocktxn": msg_getblocktxn,
    b"getdata": msg_getdata,
    b"getheaders": msg_getheaders,
    b"headers": msg_headers,
    b"inv": msg_inv,
    b"mempool": msg_mempool,
    b"merkleblock": msg_merkleblock,
    b"notfound": msg_notfound,
    b"ping": msg_ping,
    b"pong": msg_pong,
    b"sendcmpct": msg_sendcmpct,
    b"sendheaders": msg_sendheaders,
    b"tx": msg_tx,
    b"verack": msg_verack,
    b"version": msg_version,
}

MAGIC_BYTES = {
    "mainnet": b"\xf9\xbe\xb4\xd9",   # mainnet
    "testnet3": b"\x0b\x11\x09\x07",  # testnet3
    "regtest": b"\xfa\xbf\xb5\xda",   # regtest
}


class P2PConnection(asyncio.Protocol):
    """A low-level connection object to a node's P2P interface.

    This class is responsible for:

    - opening and closing the TCP connection to the node
    - reading bytes from and writing bytes to the socket
    - deserializing and serializing the P2P message header
    - logging messages as they are sent and received

    This class contains no logic for handing the P2P message payloads. It must be
    sub-classed and the on_message() callback overridden."""

    def __init__(self):
        # The underlying transport of the connection.
        # Should only call methods on this from the NetworkThread, c.f. call_soon_threadsafe
        self._transport = None

    @property
    def is_connected(self):
        return self._transport is not None

    def peer_connect(self, dstaddr, dstport, *, net):
        assert not self.is_connected
        self.dstaddr = dstaddr
        self.dstport = dstport
        # The initial message to send after the connection was made:
        self.on_connection_send_msg = None
        self.recvbuf = b""
        self.magic_bytes = MAGIC_BYTES[net]
        logger.debug('Connecting to Bitcoin Node: %s:%d' % (self.dstaddr, self.dstport))

        loop = NetworkThread.network_event_loop
        conn_gen_unsafe = loop.create_connection(lambda: self, host=self.dstaddr, port=self.dstport)
        conn_gen = lambda: loop.call_soon_threadsafe(loop.create_task, conn_gen_unsafe)
        return conn_gen

    def peer_disconnect(self):
        # Connection could have already been closed by other end.
        NetworkThread.network_event_loop.call_soon_threadsafe(lambda: self._transport and self._transport.abort())

    # Connection and disconnection methods

    def connection_made(self, transport):
        """asyncio callback when a connection is opened."""
        assert not self._transport
        logger.debug("Connected & Listening: %s:%d" % (self.dstaddr, self.dstport))
        self._transport = transport
        if self.on_connection_send_msg:
            self.send_message(self.on_connection_send_msg)
            self.on_connection_send_msg = None  # Never used again
        self.on_open()

    def connection_lost(self, exc):
        """asyncio callback when a connection is closed."""
        if exc:
            logger.warning("Connection lost to {}:{} due to {}".format(self.dstaddr, self.dstport, exc))
        else:
            logger.debug("Closed connection to: %s:%d" % (self.dstaddr, self.dstport))
        self._transport = None
        self.recvbuf = b""
        self.on_close()

    # Socket read methods

    def data_received(self, t):
        """asyncio callback when data is read from the socket."""
        if len(t) > 0:
            self.recvbuf += t
            self._on_data()

    def _on_data(self):
        """Try to read P2P messages from the recv buffer.

        This method reads data from the buffer in a loop. It deserializes,
        parses and verifies the P2P header, then passes the P2P payload to
        the on_message callback for processing."""
        try:
            while True:
                if len(self.recvbuf) < 4:
                    return
                if self.recvbuf[:4] != self.magic_bytes:
                    raise ValueError("magic bytes mismatch: {} != {}".format(repr(self.magic_bytes), repr(self.recvbuf)))
                if len(self.recvbuf) < 4 + 12 + 4 + 4:
                    return
                msgtype = self.recvbuf[4:4+12].split(b"\x00", 1)[0]
                msglen = struct.unpack("<i", self.recvbuf[4+12:4+12+4])[0]
                checksum = self.recvbuf[4+12+4:4+12+4+4]
                if len(self.recvbuf) < 4 + 12 + 4 + 4 + msglen:
                    return
                msg = self.recvbuf[4+12+4+4:4+12+4+4+msglen]
                th = sha256(msg)
                h = sha256(th)
                if checksum != h[:4]:
                    raise ValueError("got bad checksum " + repr(self.recvbuf))
                self.recvbuf = self.recvbuf[4+12+4+4+msglen:]
                if msgtype not in MESSAGEMAP:
                    raise ValueError("Received unknown msgtype from %s:%d: '%s' %s" % (self.dstaddr, self.dstport, msgtype, repr(msg)))
                f = BytesIO(msg)
                t = MESSAGEMAP[msgtype]()
                t.deserialize(f)
                self._log_message("receive", t)
                self.on_message(t)
        except Exception as e:
            logger.exception('Error reading message:', repr(e))
            raise

    def on_message(self, message):
        """Callback for processing a P2P payload. Must be overridden by derived class."""
        raise NotImplementedError

    # Socket write methods

    def send_message(self, message):
        """Send a P2P message over the socket.

        This method takes a P2P payload, builds the P2P header and adds
        the message to the send buffer to be sent over the socket."""
        tmsg = self.build_message(message)
        self._log_message("send", message)
        return self.send_raw_message(tmsg)

    def send_raw_message(self, raw_message_bytes):
        if not self.is_connected:
            raise IOError('Not connected')

        def maybe_write():
            if not self._transport:
                return
            if self._transport.is_closing():
                return
            self._transport.write(raw_message_bytes)
        NetworkThread.network_event_loop.call_soon_threadsafe(maybe_write)

    # Class utility methods

    def build_message(self, message):
        """Build a serialized P2P message"""
        msgtype = message.msgtype
        data = message.serialize()
        tmsg = self.magic_bytes
        tmsg += msgtype
        tmsg += b"\x00" * (12 - len(msgtype))
        tmsg += struct.pack("<I", len(data))
        th = sha256(data)
        h = sha256(th)
        tmsg += h[:4]
        tmsg += data
        return tmsg

    def _log_message(self, direction, msg):
        """Logs a message being sent or received over the connection."""
        if direction == "send":
            log_message = "Send message to "
        elif direction == "receive":
            log_message = "Received message from "
        log_message += "%s:%d: %s" % (self.dstaddr, self.dstport, repr(msg)[:500])
        if len(log_message) > 500:
            log_message += "... (msg truncated)"
        logger.debug(log_message)


class P2PInterface(P2PConnection):
    """A high-level P2P interface class for communicating with a Bitcoin node.

    This class provides high-level callbacks for processing P2P message
    payloads, as well as convenience methods for interacting with the
    node over P2P.

    Individual testcases should subclass this and override the on_* methods
    if they want to alter message handling behaviour."""
    def __init__(self):
        super().__init__()

        # Track number of messages of each type received and the most recent
        # message of each type
        self.message_count = defaultdict(int)
        self.last_message = {}

        # A count of the number of ping messages we've sent to the node
        self.ping_counter = 1

        # The network services received from the peer
        self.nServices = 0

    def peer_connect(self, *args, services=NODE_NETWORK|NODE_WITNESS, send_version=True, **kwargs):
        create_conn = super().peer_connect(*args, **kwargs)

        if send_version:
            # Send a version msg
            vt = msg_version()
            vt.nServices = services
            vt.addrTo.ip = self.dstaddr
            vt.addrTo.port = self.dstport
            vt.addrFrom.ip = "0.0.0.0"
            vt.addrFrom.port = 0
            self.on_connection_send_msg = vt  # Will be sent soon after connection_made

        return create_conn

    # Message receiving methods

    def on_message(self, message):
        """Receive message and dispatch message to appropriate callback.

        We keep a count of how many of each message type has been received
        and the most recent message of each type."""
        with mininode_lock:
            try:
                msgtype = message.msgtype.decode('ascii')
                self.message_count[msgtype] += 1
                self.last_message[msgtype] = message
                getattr(self, 'on_' + msgtype)(message)
            except:
                print("ERROR delivering %s (%s)" % (repr(message), sys.exc_info()[0]))
                raise

    # Callback methods. Can be overridden by subclasses in individual test
    # cases to provide custom message handling behaviour.

    def on_open(self):
        pass

    def on_close(self):
        pass

    def on_addr(self, message): pass
    def on_block(self, message): pass
    def on_blocktxn(self, message): pass
    def on_cmpctblock(self, message): pass
    def on_feefilter(self, message): pass
    def on_filteradd(self, message): pass
    def on_filterclear(self, message): pass
    def on_filterload(self, message): pass
    def on_getaddr(self, message): pass
    def on_getblocks(self, message): pass
    def on_getblocktxn(self, message): pass
    def on_getdata(self, message): pass
    def on_getheaders(self, message): pass
    def on_headers(self, message): pass
    def on_mempool(self, message): pass
    def on_merkleblock(self, message): pass
    def on_notfound(self, message): pass
    def on_pong(self, message): pass
    def on_sendcmpct(self, message): pass
    def on_sendheaders(self, message): pass
    def on_tx(self, message): pass

    def on_inv(self, message):
        want = msg_getdata()
        for i in message.inv:
            if i.type != 0:
                want.inv.append(i)
        if len(want.inv):
            self.send_message(want)

    def on_ping(self, message):
        self.send_message(msg_pong(message.nonce))

    def on_verack(self, message):
        pass

    def on_version(self, message):
        assert message.nVersion >= MIN_VERSION_SUPPORTED, "Version {} received. Test framework only supports versions greater than {}".format(message.nVersion, MIN_VERSION_SUPPORTED)
        self.send_message(msg_verack())
        self.nServices = message.nServices

    # Connection helper methods

    def wait_for_disconnect(self, timeout=60):
        test_function = lambda: not self.is_connected
        wait_until(test_function, timeout=timeout, lock=mininode_lock)

    # Message receiving helper methods

    def wait_for_tx(self, txid, timeout=60):
        def test_function():
            assert self.is_connected
            if not self.last_message.get('tx'):
                return False
            return self.last_message['tx'].tx.rehash() == txid

        wait_until(test_function, timeout=timeout, lock=mininode_lock)

    def wait_for_block(self, blockhash, timeout=60):
        def test_function():
            assert self.is_connected
            return self.last_message.get("block") and self.last_message["block"].block.rehash() == blockhash

        wait_until(test_function, timeout=timeout, lock=mininode_lock)

    def wait_for_header(self, blockhash, timeout=60):
        def test_function():
            assert self.is_connected
            last_headers = self.last_message.get('headers')
            if not last_headers:
                return False
            return last_headers.headers[0].rehash() == int(blockhash, 16)

        wait_until(test_function, timeout=timeout, lock=mininode_lock)

    def wait_for_merkleblock(self, blockhash, timeout=60):
        def test_function():
            assert self.is_connected
            last_filtered_block = self.last_message.get('merkleblock')
            if not last_filtered_block:
                return False
            return last_filtered_block.merkleblock.header.rehash() == int(blockhash, 16)

        wait_until(test_function, timeout=timeout, lock=mininode_lock)

    def wait_for_getdata(self, hash_list, timeout=60):
        """Waits for a getdata message.

        The object hashes in the inventory vector must match the provided hash_list."""

        def test_function():
            assert self.is_connected
            last_data = self.last_message.get("getdata")
            if not last_data:
                return False
            return [x.hash for x in last_data.inv] == hash_list

        wait_until(test_function, timeout=timeout, lock=mininode_lock)

    def wait_for_getheaders(self, timeout=60):
        """Waits for a getheaders message.

        Receiving any getheaders message will satisfy the predicate. the last_message["getheaders"]
        value must be explicitly cleared before calling this method, or this will return
        immediately with success. TODO: change this method to take a hash value and only
        return true if the correct block header has been requested."""

        def test_function():
            assert self.is_connected
            return self.last_message.get("getheaders")

        wait_until(test_function, timeout=timeout, lock=mininode_lock)

    def wait_for_inv(self, expected_inv, timeout=60):
        """Waits for an INV message and checks that the first inv object in the message was as expected."""
        if len(expected_inv) > 1:
            raise NotImplementedError("wait_for_inv() will only verify the first inv object")

        def test_function():
            assert self.is_connected
            return self.last_message.get("inv") and \
                                self.last_message["inv"].inv[0].type == expected_inv[0].type and \
                                self.last_message["inv"].inv[0].hash == expected_inv[0].hash

        wait_until(test_function, timeout=timeout, lock=mininode_lock)

    def wait_for_verack(self, timeout=60):
        def test_function():
            return self.message_count["verack"]

        wait_until(test_function, timeout=timeout, lock=mininode_lock)

    # Message sending helper functions

    def send_and_ping(self, message, timeout=60):
        self.send_message(message)
        self.sync_with_ping(timeout=timeout)

    # Sync up with the node
    def sync_with_ping(self, timeout=60):
        self.send_message(msg_ping(nonce=self.ping_counter))

        def test_function():
            assert self.is_connected
            return self.last_message.get("pong") and self.last_message["pong"].nonce == self.ping_counter

        wait_until(test_function, timeout=timeout, lock=mininode_lock)
        self.ping_counter += 1


# One lock for synchronizing all data access between the network event loop (see
# NetworkThread below) and the thread running the test logic.  For simplicity,
# P2PConnection acquires this lock whenever delivering a message to a P2PInterface.
# This lock should be acquired in the thread running the test logic to synchronize
# access to any data shared with the P2PInterface or P2PConnection.
mininode_lock = threading.RLock()


class NetworkThread(threading.Thread):
    network_event_loop = None

    def __init__(self):
        super().__init__(name="NetworkThread")
        # There is only one event loop and no more than one thread must be created
        assert not self.network_event_loop

        NetworkThread.network_event_loop = asyncio.new_event_loop()

    def run(self):
        """Start the network thread."""
        self.network_event_loop.run_forever()

    def close(self, timeout=10):
        """Close the connections and network event loop."""
        self.network_event_loop.call_soon_threadsafe(self.network_event_loop.stop)
        wait_until(lambda: not self.network_event_loop.is_running(), timeout=timeout)
        self.network_event_loop.close()
        self.join(timeout)
        # Safe to remove event loop.
        NetworkThread.network_event_loop = None

class P2PDataStore(P2PInterface):
    """A P2P data store class.

    Keeps a block and transaction store and responds correctly to getdata and getheaders requests."""

    def __init__(self):
        super().__init__()
        # store of blocks. key is block hash, value is a CBlock object
        self.block_store = {}
        self.last_block_hash = ''
        # store of txs. key is txid, value is a CTransaction object
        self.tx_store = {}
        self.getdata_requests = []

    def on_getdata(self, message):
        """Check for the tx/block in our stores and if found, reply with an inv message."""
        for inv in message.inv:
            self.getdata_requests.append(inv.hash)
            if (inv.type & MSG_TYPE_MASK) == MSG_TX and inv.hash in self.tx_store.keys():
                self.send_message(msg_tx(self.tx_store[inv.hash]))
            elif (inv.type & MSG_TYPE_MASK) == MSG_BLOCK and inv.hash in self.block_store.keys():
                self.send_message(msg_block(self.block_store[inv.hash]))
            else:
                logger.debug('getdata message type {} received.'.format(hex(inv.type)))

    def on_getheaders(self, message):
        """Search back through our block store for the locator, and reply with a headers message if found."""

        locator, hash_stop = message.locator, message.hashstop

        # Assume that the most recent block added is the tip
        if not self.block_store:
            return

        headers_list = [self.block_store[self.last_block_hash]]
        maxheaders = 2000
        while headers_list[-1].sha256 not in locator.vHave:
            # Walk back through the block store, adding headers to headers_list
            # as we go.
            prev_block_hash = headers_list[-1].hashPrevBlock
            if prev_block_hash in self.block_store:
                prev_block_header = CBlockHeader(self.block_store[prev_block_hash])
                headers_list.append(prev_block_header)
                if prev_block_header.sha256 == hash_stop:
                    # if this is the hashstop header, stop here
                    break
            else:
                logger.debug('block hash {} not found in block store'.format(hex(prev_block_hash)))
                break

        # Truncate the list if there are too many headers
        headers_list = headers_list[:-maxheaders - 1:-1]
        response = msg_headers(headers_list)

        if response is not None:
            self.send_message(response)

    def send_blocks_and_test(self, blocks, node, *, success=True, force_send=False, reject_reason=None, expect_disconnect=False, timeout=60):
        """Send blocks to test node and test whether the tip advances.

         - add all blocks to our block_store
         - send a headers message for the final block
         - the on_getheaders handler will ensure that any getheaders are responded to
         - if force_send is False: wait for getdata for each of the blocks. The on_getdata handler will
           ensure that any getdata messages are responded to. Otherwise send the full block unsolicited.
         - if success is True: assert that the node's tip advances to the most recent block
         - if success is False: assert that the node's tip doesn't advance
         - if reject_reason is set: assert that the correct reject message is logged"""

        with mininode_lock:
            for block in blocks:
                self.block_store[block.sha256] = block
                self.last_block_hash = block.sha256

        reject_reason = [reject_reason] if reject_reason else []
        with node.assert_debug_log(expected_msgs=reject_reason):
            if force_send:
                for b in blocks:
                    self.send_message(msg_block(block=b))
            else:
                self.send_message(msg_headers([CBlockHeader(block) for block in blocks]))
                wait_until(lambda: blocks[-1].sha256 in self.getdata_requests, timeout=timeout, lock=mininode_lock)

            if expect_disconnect:
                self.wait_for_disconnect(timeout=timeout)
            else:
                self.sync_with_ping(timeout=timeout)

            if success:
                wait_until(lambda: node.getbestblockhash() == blocks[-1].hash, timeout=timeout)
            else:
                assert node.getbestblockhash() != blocks[-1].hash

    def send_txs_and_test(self, txs, node, *, success=True, expect_disconnect=False, reject_reason=None):
        """Send txs to test node and test whether they're accepted to the mempool.

         - add all txs to our tx_store
         - send tx messages for all txs
         - if success is True/False: assert that the txs are/are not accepted to the mempool
         - if expect_disconnect is True: Skip the sync with ping
         - if reject_reason is set: assert that the correct reject message is logged."""

        with mininode_lock:
            for tx in txs:
                self.tx_store[tx.sha256] = tx

        reject_reason = [reject_reason] if reject_reason else []
        with node.assert_debug_log(expected_msgs=reject_reason):
            for tx in txs:
                self.send_message(msg_tx(tx))

            if expect_disconnect:
                self.wait_for_disconnect()
            else:
                self.sync_with_ping()

            raw_mempool = node.getrawmempool()
            if success:
                # Check that all txs are now in the mempool
                for tx in txs:
                    assert tx.hash in raw_mempool, "{} not found in mempool".format(tx.hash)
            else:
                # Check that none of the txs are now in the mempool
                for tx in txs:
                    assert tx.hash not in raw_mempool, "{} tx found in mempool".format(tx.hash)

class P2PTxInvStore(P2PInterface):
    """A P2PInterface which stores a count of how many times each txid has been announced."""
    def __init__(self):
        super().__init__()
        self.tx_invs_received = defaultdict(int)

    def on_inv(self, message):
        # Store how many times invs have been received for each tx.
        for i in message.inv:
            if i.type == MSG_TX:
                # save txid
                self.tx_invs_received[i.hash] += 1

    def get_invs(self):
        with mininode_lock:
            return list(self.tx_invs_received.keys())