text: #!/usr/bin/env python
  #
  # Electrum - lightweight Bitcoin client
  # Copyright (C) 2014 Thomas Voegtlin
  #
  # Permission is hereby granted, free of charge, to any person
  # obtaining a copy of this software and associated documentation files
  # (the "Software"), to deal in the Software without restriction,
  # including without limitation the rights to use, copy, modify, merge,
  # publish, distribute, sublicense, and/or sell copies of the Software,
  # and to permit persons to whom the Software is furnished to do so,
  # subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be
  # included in all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  # BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  # SOFTWARE.
  import asyncio
  import hashlib
  from typing import Dict, List, TYPE_CHECKING, Tuple, Set
  from collections import defaultdict
  import logging
  
  from aiorpcx import TaskGroup, run_in_thread, RPCError
  
  from . import util
  from .transaction import Transaction, PartialTransaction
  from .util import bh2u, make_aiohttp_session, NetworkJobOnDefaultServer, random_shuffled_copy
  from .bitcoin import address_to_scripthash, is_address
  from .logging import Logger
  from .interface import GracefulDisconnect, NetworkTimeout
  
  if TYPE_CHECKING:
      from .network import Network
      from .address_synchronizer import AddressSynchronizer
  
  
  class SynchronizerFailure(Exception): pass
  
  
  def history_status(h):
      if not h:
          return None
      status = ''
      for tx_hash, height in h:
          status += tx_hash + ':%d:' % height
      return bh2u(hashlib.sha256(status.encode('ascii')).digest())
  
  
  class SynchronizerBase(NetworkJobOnDefaultServer):
      """Subscribe over the network to a set of addresses, and monitor their statuses.
      Every time a status changes, run a coroutine provided by the subclass.
      """
      def __init__(self, network: 'Network'):
          self.asyncio_loop = network.asyncio_loop
          self._reset_request_counters()
  
          NetworkJobOnDefaultServer.__init__(self, network)
  
      def _reset(self):
          super()._reset()
          self.requested_addrs = set()
          self.scripthash_to_address = {}
          self._processed_some_notifications = False  # so that we don't miss them
          self._reset_request_counters()
          # Queues
          self.add_queue = asyncio.Queue()
          self.status_queue = asyncio.Queue()
  
      async def _run_tasks(self, *, taskgroup):
          await super()._run_tasks(taskgroup=taskgroup)
          try:
              async with taskgroup as group:
                  await group.spawn(self.send_subscriptions())
                  await group.spawn(self.handle_status())
                  await group.spawn(self.main())
          finally:
              # we are being cancelled now
              self.session.unsubscribe(self.status_queue)
  
      def _reset_request_counters(self):
          self._requests_sent = 0
          self._requests_answered = 0
  
      def add(self, addr):
          asyncio.run_coroutine_threadsafe(self._add_address(addr), self.asyncio_loop)
  
      async def _add_address(self, addr: str):
          # note: this method is async as add_queue.put_nowait is not thread-safe.
          if not is_address(addr): raise ValueError(f"invalid fujicoin address {addr}")
          if addr in self.requested_addrs: return
          self.requested_addrs.add(addr)
          self.add_queue.put_nowait(addr)
  
      async def _on_address_status(self, addr, status):
          """Handle the change of the status of an address."""
          raise NotImplementedError()  # implemented by subclasses
  
      async def send_subscriptions(self):
          async def subscribe_to_address(addr):
              h = address_to_scripthash(addr)
              self.scripthash_to_address[h] = addr
              self._requests_sent += 1
              try:
                  async with self._network_request_semaphore:
                      await self.session.subscribe('blockchain.scripthash.subscribe', [h], self.status_queue)
              except RPCError as e:
                  if e.message == 'history too large':  # no unique error code
                      raise GracefulDisconnect(e, log_level=logging.ERROR) from e
                  raise
              self._requests_answered += 1
              self.requested_addrs.remove(addr)
  
          while True:
              addr = await self.add_queue.get()
              await self.taskgroup.spawn(subscribe_to_address, addr)
  
      async def handle_status(self):
          while True:
              h, status = await self.status_queue.get()
              addr = self.scripthash_to_address[h]
              await self.taskgroup.spawn(self._on_address_status, addr, status)
              self._processed_some_notifications = True
  
      def num_requests_sent_and_answered(self) -> Tuple[int, int]:
          return self._requests_sent, self._requests_answered
  
      async def main(self):
          raise NotImplementedError()  # implemented by subclasses
  
  
  class Synchronizer(SynchronizerBase):
      '''The synchronizer keeps the wallet up-to-date with its set of
      addresses and their transactions.  It subscribes over the network
      to wallet addresses, gets the wallet to generate new addresses
      when necessary, requests the transaction history of any addresses
      we don't have the full history of, and requests binary transaction
      data of any transactions the wallet doesn't have.
      '''
      def __init__(self, wallet: 'AddressSynchronizer'):
          self.wallet = wallet
          SynchronizerBase.__init__(self, wallet.network)
  
      def _reset(self):
          super()._reset()
          self.requested_tx = {}
          self.requested_histories = set()
          self._stale_histories = dict()  # type: Dict[str, asyncio.Task]
  
      def diagnostic_name(self):
          return self.wallet.diagnostic_name()
  
      def is_up_to_date(self):
          return (not self.requested_addrs
                  and not self.requested_histories
                  and not self.requested_tx
                  and not self._stale_histories)
  
      async def _on_address_status(self, addr, status):
          history = self.wallet.db.get_addr_history(addr)
          if history_status(history) == status:
              return
          # No point in requesting history twice for the same announced status.
          # However if we got announced a new status, we should request history again:
          if (addr, status) in self.requested_histories:
              return
          # request address history
          self.requested_histories.add((addr, status))
          self._stale_histories.pop(addr, asyncio.Future()).cancel()
          h = address_to_scripthash(addr)
          self._requests_sent += 1
          async with self._network_request_semaphore:
              result = await self.interface.get_history_for_scripthash(h)
          self._requests_answered += 1
          self.logger.info(f"receiving history {addr} {len(result)}")
          hist = list(map(lambda item: (item['tx_hash'], item['height']), result))
          # tx_fees
          tx_fees = [(item['tx_hash'], item.get('fee')) for item in result]
          tx_fees = dict(filter(lambda x:x[1] is not None, tx_fees))
          # Check that the status corresponds to what was announced
          if history_status(hist) != status:
              # could happen naturally if history changed between getting status and history (race)
              self.logger.info(f"error: status mismatch: {addr}. we'll wait a bit for status update.")
              # The server is supposed to send a new status notification, which will trigger a new
              # get_history. We shall wait a bit for this to happen, otherwise we disconnect.
              async def disconnect_if_still_stale():
                  timeout = self.network.get_network_timeout_seconds(NetworkTimeout.Generic)
                  await asyncio.sleep(timeout)
                  raise SynchronizerFailure(f"timeout reached waiting for addr {addr}: history still stale")
              self._stale_histories[addr] = await self.taskgroup.spawn(disconnect_if_still_stale)
          else:
              self._stale_histories.pop(addr, asyncio.Future()).cancel()
              # Store received history
              self.wallet.receive_history_callback(addr, hist, tx_fees)
              # Request transactions we don't have
              await self._request_missing_txs(hist)
  
          # Remove request; this allows up_to_date to be True
          self.requested_histories.discard((addr, status))
  
      async def _request_missing_txs(self, hist, *, allow_server_not_finding_tx=False):
          # "hist" is a list of [tx_hash, tx_height] lists
          transaction_hashes = []
          for tx_hash, tx_height in hist:
              if tx_hash in self.requested_tx:
                  continue
              tx = self.wallet.db.get_transaction(tx_hash)
              if tx and not isinstance(tx, PartialTransaction):
                  continue  # already have complete tx
              transaction_hashes.append(tx_hash)
              self.requested_tx[tx_hash] = tx_height
  
          if not transaction_hashes: return
          async with TaskGroup() as group:
              for tx_hash in transaction_hashes:
                  await group.spawn(self._get_transaction(tx_hash, allow_server_not_finding_tx=allow_server_not_finding_tx))
  
      async def _get_transaction(self, tx_hash, *, allow_server_not_finding_tx=False):
          self._requests_sent += 1
          try:
              async with self._network_request_semaphore:
                  raw_tx = await self.interface.get_transaction(tx_hash)
          except RPCError as e:
              # most likely, "No such mempool or blockchain transaction"
              if allow_server_not_finding_tx:
                  self.requested_tx.pop(tx_hash)
                  return
              else:
                  raise
          finally:
              self._requests_answered += 1
          tx = Transaction(raw_tx)
          if tx_hash != tx.txid():
              raise SynchronizerFailure(f"received tx does not match expected txid ({tx_hash} != {tx.txid()})")
          tx_height = self.requested_tx.pop(tx_hash)
          self.wallet.receive_tx_callback(tx_hash, tx, tx_height)
          self.logger.info(f"received tx {tx_hash} height: {tx_height} bytes: {len(raw_tx)}")
          # callbacks
          util.trigger_callback('new_transaction', self.wallet, tx)
  
      async def main(self):
          self.wallet.set_up_to_date(False)
          # request missing txns, if any
          for addr in random_shuffled_copy(self.wallet.db.get_history()):
              history = self.wallet.db.get_addr_history(addr)
              # Old electrum servers returned ['*'] when all history for the address
              # was pruned. This no longer happens but may remain in old wallets.
              if history == ['*']: continue
              await self._request_missing_txs(history, allow_server_not_finding_tx=True)
          # add addresses to bootstrap
          for addr in random_shuffled_copy(self.wallet.get_addresses()):
              await self._add_address(addr)
          # main loop
          while True:
              await asyncio.sleep(0.1)
              await run_in_thread(self.wallet.synchronize)
              up_to_date = self.is_up_to_date()
              if (up_to_date != self.wallet.is_up_to_date()
                      or up_to_date and self._processed_some_notifications):
                  self._processed_some_notifications = False
                  if up_to_date:
                      self._reset_request_counters()
                  self.wallet.set_up_to_date(up_to_date)
                  util.trigger_callback('wallet_updated', self.wallet)
  
  
  class Notifier(SynchronizerBase):
      """Watch addresses. Every time the status of an address changes,
      an HTTP POST is sent to the corresponding URL.
      """
      def __init__(self, network):
          SynchronizerBase.__init__(self, network)
          self.watched_addresses = defaultdict(list)  # type: Dict[str, List[str]]
          self._start_watching_queue = asyncio.Queue()  # type: asyncio.Queue[Tuple[str, str]]
  
      async def main(self):
          # resend existing subscriptions if we were restarted
          for addr in self.watched_addresses:
              await self._add_address(addr)
          # main loop
          while True:
              addr, url = await self._start_watching_queue.get()
              self.watched_addresses[addr].append(url)
              await self._add_address(addr)
  
      async def start_watching_addr(self, addr: str, url: str):
          await self._start_watching_queue.put((addr, url))
  
      async def stop_watching_addr(self, addr: str):
          self.watched_addresses.pop(addr, None)
          # TODO blockchain.scripthash.unsubscribe
  
      async def _on_address_status(self, addr, status):
          if addr not in self.watched_addresses:
              return
          self.logger.info(f'new status for addr {addr}')
          headers = {'content-type': 'application/json'}
          data = {'address': addr, 'status': status}
          for url in self.watched_addresses[addr]:
              try:
                  async with make_aiohttp_session(proxy=self.network.proxy, headers=headers) as session:
                      async with session.post(url, json=data, headers=headers) as resp:
                          await resp.text()
              except Exception as e:
                  self.logger.info(repr(e))
              else:
                  self.logger.info(f'Got Response for {addr}')
  