text: #!/usr/bin/env python3
  # Copyright (c) 2014-2016 The Bitcoin Core developers
  # Distributed under the MIT software license, see the accompanying
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  """Helpful routines for regression testing."""
  
  from base64 import b64encode
  from binascii import hexlify, unhexlify
  from decimal import Decimal, ROUND_DOWN
  import json
  import logging
  import os
  import random
  import re
  import time
  
  from . import coverage
  from .authproxy import AuthServiceProxy, JSONRPCException
  
  logger = logging.getLogger("TestFramework.utils")
  
  # Assert functions
  ##################
  
  def assert_fee_amount(fee, tx_size, fee_per_kB):
      """Assert the fee was in range"""
      target_fee = tx_size * fee_per_kB / 1000
      if fee < target_fee:
          raise AssertionError("Fee of %s BTC too low! (Should be %s BTC)" % (str(fee), str(target_fee)))
      # allow the wallet's estimation to be at most 2 bytes off
      if fee > (tx_size + 2) * fee_per_kB / 1000:
          raise AssertionError("Fee of %s BTC too high! (Should be %s BTC)" % (str(fee), str(target_fee)))
  
  def assert_equal(thing1, thing2, *args):
      if thing1 != thing2 or any(thing1 != arg for arg in args):
          raise AssertionError("not(%s)" % " == ".join(str(arg) for arg in (thing1, thing2) + args))
  
  def assert_greater_than(thing1, thing2):
      if thing1 <= thing2:
          raise AssertionError("%s <= %s" % (str(thing1), str(thing2)))
  
  def assert_greater_than_or_equal(thing1, thing2):
      if thing1 < thing2:
          raise AssertionError("%s < %s" % (str(thing1), str(thing2)))
  
  def assert_raises(exc, fun, *args, **kwds):
      assert_raises_message(exc, None, fun, *args, **kwds)
  
  def assert_raises_message(exc, message, fun, *args, **kwds):
      try:
          fun(*args, **kwds)
      except exc as e:
          if message is not None and message not in e.error['message']:
              raise AssertionError("Expected substring not found:" + e.error['message'])
      except Exception as e:
          raise AssertionError("Unexpected exception raised: " + type(e).__name__)
      else:
          raise AssertionError("No exception raised")
  
  def assert_raises_jsonrpc(code, message, fun, *args, **kwds):
      """Run an RPC and verify that a specific JSONRPC exception code and message is raised.
  
      Calls function `fun` with arguments `args` and `kwds`. Catches a JSONRPCException
      and verifies that the error code and message are as expected. Throws AssertionError if
      no JSONRPCException was returned or if the error code/message are not as expected.
  
      Args:
          code (int), optional: the error code returned by the RPC call (defined
              in src/rpc/protocol.h). Set to None if checking the error code is not required.
          message (string), optional: [a substring of] the error string returned by the
              RPC call. Set to None if checking the error string is not required
          fun (function): the function to call. This should be the name of an RPC.
          args*: positional arguments for the function.
          kwds**: named arguments for the function.
      """
      try:
          fun(*args, **kwds)
      except JSONRPCException as e:
          # JSONRPCException was thrown as expected. Check the code and message values are correct.
          if (code is not None) and (code != e.error["code"]):
              raise AssertionError("Unexpected JSONRPC error code %i" % e.error["code"])
          if (message is not None) and (message not in e.error['message']):
              raise AssertionError("Expected substring not found:" + e.error['message'])
      except Exception as e:
          raise AssertionError("Unexpected exception raised: " + type(e).__name__)
      else:
          raise AssertionError("No exception raised")
  
  def assert_is_hex_string(string):
      try:
          int(string, 16)
      except Exception as e:
          raise AssertionError(
              "Couldn't interpret %r as hexadecimal; raised: %s" % (string, e))
  
  def assert_is_hash_string(string, length=64):
      if not isinstance(string, str):
          raise AssertionError("Expected a string, got type %r" % type(string))
      elif length and len(string) != length:
          raise AssertionError(
              "String of length %d expected; got %d" % (length, len(string)))
      elif not re.match('[abcdef0-9]+$', string):
          raise AssertionError(
              "String %r contains invalid characters for a hash." % string)
  
  def assert_array_result(object_array, to_match, expected, should_not_find=False):
      """
          Pass in array of JSON objects, a dictionary with key/value pairs
          to match against, and another dictionary with expected key/value
          pairs.
          If the should_not_find flag is true, to_match should not be found
          in object_array
          """
      if should_not_find:
          assert_equal(expected, {})
      num_matched = 0
      for item in object_array:
          all_match = True
          for key, value in to_match.items():
              if item[key] != value:
                  all_match = False
          if not all_match:
              continue
          elif should_not_find:
              num_matched = num_matched + 1
          for key, value in expected.items():
              if item[key] != value:
                  raise AssertionError("%s : expected %s=%s" % (str(item), str(key), str(value)))
              num_matched = num_matched + 1
      if num_matched == 0 and not should_not_find:
          raise AssertionError("No objects matched %s" % (str(to_match)))
      if num_matched > 0 and should_not_find:
          raise AssertionError("Objects were found %s" % (str(to_match)))
  
  # Utility functions
  ###################
  
  def check_json_precision():
      """Make sure json library being used does not lose precision converting BTC values"""
      n = Decimal("20000000.00000003")
      satoshis = int(json.loads(json.dumps(float(n))) * 1.0e8)
      if satoshis != 2000000000000003:
          raise RuntimeError("JSON encode/decode loses precision")
  
  def count_bytes(hex_string):
      return len(bytearray.fromhex(hex_string))
  
  def bytes_to_hex_str(byte_str):
      return hexlify(byte_str).decode('ascii')
  
  def hex_str_to_bytes(hex_str):
      return unhexlify(hex_str.encode('ascii'))
  
  def str_to_b64str(string):
      return b64encode(string.encode('utf-8')).decode('ascii')
  
  def satoshi_round(amount):
      return Decimal(amount).quantize(Decimal('0.00000001'), rounding=ROUND_DOWN)
  
  # RPC/P2P connection constants and functions
  ############################################
  
  # The maximum number of nodes a single test can spawn
  MAX_NODES = 8
  # Don't assign rpc or p2p ports lower than this
  PORT_MIN = 11000
  # The number of ports to "reserve" for p2p and rpc, each
  PORT_RANGE = 5000
  
  class PortSeed:
      # Must be initialized with a unique integer for each process
      n = None
  
  def get_rpc_proxy(url, node_number, timeout=None, coveragedir=None):
      """
      Args:
          url (str): URL of the RPC server to call
          node_number (int): the node number (or id) that this calls to
  
      Kwargs:
          timeout (int): HTTP timeout in seconds
  
      Returns:
          AuthServiceProxy. convenience object for making RPC calls.
  
      """
      proxy_kwargs = {}
      if timeout is not None:
          proxy_kwargs['timeout'] = timeout
  
      proxy = AuthServiceProxy(url, **proxy_kwargs)
      proxy.url = url  # store URL on proxy for info
  
      coverage_logfile = coverage.get_filename(
          coveragedir, node_number) if coveragedir else None
  
      return coverage.AuthServiceProxyWrapper(proxy, coverage_logfile)
  
  def p2p_port(n):
      assert(n <= MAX_NODES)
      return PORT_MIN + n + (MAX_NODES * PortSeed.n) % (PORT_RANGE - 1 - MAX_NODES)
  
  def rpc_port(n):
      return PORT_MIN + PORT_RANGE + n + (MAX_NODES * PortSeed.n) % (PORT_RANGE - 1 - MAX_NODES)
  
  def rpc_url(datadir, i, rpchost=None):
      rpc_u, rpc_p = get_auth_cookie(datadir, i)
      host = '127.0.0.1'
      port = rpc_port(i)
      if rpchost:
          parts = rpchost.split(':')
          if len(parts) == 2:
              host, port = parts
          else:
              host = rpchost
      return "http://%s:%s@%s:%d" % (rpc_u, rpc_p, host, int(port))
  
  # Node functions
  ################
  
  def initialize_datadir(dirname, n):
      datadir = os.path.join(dirname, "node" + str(n))
      if not os.path.isdir(datadir):
          os.makedirs(datadir)
      with open(os.path.join(datadir, "perakcoin.conf"), 'w', encoding='utf8') as f:
          f.write("regtest=1\n")
          f.write("port=" + str(p2p_port(n)) + "\n")
          f.write("rpcport=" + str(rpc_port(n)) + "\n")
          f.write("listenonion=0\n")
      return datadir
  
  def get_datadir_path(dirname, n):
      return os.path.join(dirname, "node" + str(n))
  
  def get_auth_cookie(datadir, n):
      user = None
      password = None
      if os.path.isfile(os.path.join(datadir, "perakcoin.conf")):
          with open(os.path.join(datadir, "perakcoin.conf"), 'r', encoding='utf8') as f:
              for line in f:
                  if line.startswith("rpcuser="):
                      assert user is None  # Ensure that there is only one rpcuser line
                      user = line.split("=")[1].strip("\n")
                  if line.startswith("rpcpassword="):
                      assert password is None  # Ensure that there is only one rpcpassword line
                      password = line.split("=")[1].strip("\n")
      if os.path.isfile(os.path.join(datadir, "regtest", ".cookie")):
          with open(os.path.join(datadir, "regtest", ".cookie"), 'r') as f:
              userpass = f.read()
              split_userpass = userpass.split(':')
              user = split_userpass[0]
              password = split_userpass[1]
      if user is None or password is None:
          raise ValueError("No RPC credentials")
      return user, password
  
  def log_filename(dirname, n_node, logname):
      return os.path.join(dirname, "node" + str(n_node), "regtest", logname)
  
  def get_bip9_status(node, key):
      info = node.getblockchaininfo()
      return info['bip9_softforks'][key]
  
  def set_node_times(nodes, t):
      for node in nodes:
          node.setmocktime(t)
  
  def disconnect_nodes(from_connection, node_num):
      for peer_id in [peer['id'] for peer in from_connection.getpeerinfo() if "testnode%d" % node_num in peer['subver']]:
          from_connection.disconnectnode(nodeid=peer_id)
  
      for _ in range(50):
          if [peer['id'] for peer in from_connection.getpeerinfo() if "testnode%d" % node_num in peer['subver']] == []:
              break
          time.sleep(0.1)
      else:
          raise AssertionError("timed out waiting for disconnect")
  
  def connect_nodes(from_connection, node_num):
      ip_port = "127.0.0.1:" + str(p2p_port(node_num))
      from_connection.addnode(ip_port, "onetry")
      # poll until version handshake complete to avoid race conditions
      # with transaction relaying
      while any(peer['version'] == 0 for peer in from_connection.getpeerinfo()):
          time.sleep(0.1)
  
  def connect_nodes_bi(nodes, a, b):
      connect_nodes(nodes[a], b)
      connect_nodes(nodes[b], a)
  
  def sync_blocks(rpc_connections, *, wait=1, timeout=60):
      """
      Wait until everybody has the same tip.
  
      sync_blocks needs to be called with an rpc_connections set that has least
      one node already synced to the latest, stable tip, otherwise there's a
      chance it might return before all nodes are stably synced.
      """
      # Use getblockcount() instead of waitforblockheight() to determine the
      # initial max height because the two RPCs look at different internal global
      # variables (chainActive vs latestBlock) and the former gets updated
      # earlier.
      maxheight = max(x.getblockcount() for x in rpc_connections)
      start_time = cur_time = time.time()
      while cur_time <= start_time + timeout:
          tips = [r.waitforblockheight(maxheight, int(wait * 1000)) for r in rpc_connections]
          if all(t["height"] == maxheight for t in tips):
              if all(t["hash"] == tips[0]["hash"] for t in tips):
                  return
              raise AssertionError("Block sync failed, mismatched block hashes:{}".format(
                                   "".join("\n  {!r}".format(tip) for tip in tips)))
          cur_time = time.time()
      raise AssertionError("Block sync to height {} timed out:{}".format(
                           maxheight, "".join("\n  {!r}".format(tip) for tip in tips)))
  
  def sync_chain(rpc_connections, *, wait=1, timeout=60):
      """
      Wait until everybody has the same best block
      """
      while timeout > 0:
          best_hash = [x.getbestblockhash() for x in rpc_connections]
          if best_hash == [best_hash[0]] * len(best_hash):
              return
          time.sleep(wait)
          timeout -= wait
      raise AssertionError("Chain sync failed: Best block hashes don't match")
  
  def sync_mempools(rpc_connections, *, wait=1, timeout=60):
      """
      Wait until everybody has the same transactions in their memory
      pools
      """
      while timeout > 0:
          pool = set(rpc_connections[0].getrawmempool())
          num_match = 1
          for i in range(1, len(rpc_connections)):
              if set(rpc_connections[i].getrawmempool()) == pool:
                  num_match = num_match + 1
          if num_match == len(rpc_connections):
              return
          time.sleep(wait)
          timeout -= wait
      raise AssertionError("Mempool sync failed")
  
  # Transaction/Block functions
  #############################
  
  def find_output(node, txid, amount):
      """
      Return index to output of txid with value amount
      Raises exception if there is none.
      """
      txdata = node.getrawtransaction(txid, 1)
      for i in range(len(txdata["vout"])):
          if txdata["vout"][i]["value"] == amount:
              return i
      raise RuntimeError("find_output txid %s : %s not found" % (txid, str(amount)))
  
  def gather_inputs(from_node, amount_needed, confirmations_required=1):
      """
      Return a random set of unspent txouts that are enough to pay amount_needed
      """
      assert(confirmations_required >= 0)
      utxo = from_node.listunspent(confirmations_required)
      random.shuffle(utxo)
      inputs = []
      total_in = Decimal("0.00000000")
      while total_in < amount_needed and len(utxo) > 0:
          t = utxo.pop()
          total_in += t["amount"]
          inputs.append({"txid": t["txid"], "vout": t["vout"], "address": t["address"]})
      if total_in < amount_needed:
          raise RuntimeError("Insufficient funds: need %d, have %d" % (amount_needed, total_in))
      return (total_in, inputs)
  
  def make_change(from_node, amount_in, amount_out, fee):
      """
      Create change output(s), return them
      """
      outputs = {}
      amount = amount_out + fee
      change = amount_in - amount
      if change > amount * 2:
          # Create an extra change output to break up big inputs
          change_address = from_node.getnewaddress()
          # Split change in two, being careful of rounding:
          outputs[change_address] = Decimal(change / 2).quantize(Decimal('0.00000001'), rounding=ROUND_DOWN)
          change = amount_in - amount - outputs[change_address]
      if change > 0:
          outputs[from_node.getnewaddress()] = change
      return outputs
  
  def random_transaction(nodes, amount, min_fee, fee_increment, fee_variants):
      """
      Create a random transaction.
      Returns (txid, hex-encoded-transaction-data, fee)
      """
      from_node = random.choice(nodes)
      to_node = random.choice(nodes)
      fee = min_fee + fee_increment * random.randint(0, fee_variants)
  
      (total_in, inputs) = gather_inputs(from_node, amount + fee)
      outputs = make_change(from_node, total_in, amount, fee)
      outputs[to_node.getnewaddress()] = float(amount)
  
      rawtx = from_node.createrawtransaction(inputs, outputs)
      signresult = from_node.signrawtransaction(rawtx)
      txid = from_node.sendrawtransaction(signresult["hex"], True)
  
      return (txid, signresult["hex"], fee)
  
  # Helper to create at least "count" utxos
  # Pass in a fee that is sufficient for relay and mining new transactions.
  def create_confirmed_utxos(fee, node, count):
      to_generate = int(0.5 * count) + 101
      while to_generate > 0:
          node.generate(min(25, to_generate))
          to_generate -= 25
      utxos = node.listunspent()
      iterations = count - len(utxos)
      addr1 = node.getnewaddress()
      addr2 = node.getnewaddress()
      if iterations <= 0:
          return utxos
      for i in range(iterations):
          t = utxos.pop()
          inputs = []
          inputs.append({"txid": t["txid"], "vout": t["vout"]})
          outputs = {}
          send_value = t['amount'] - fee
          outputs[addr1] = satoshi_round(send_value / 2)
          outputs[addr2] = satoshi_round(send_value / 2)
          raw_tx = node.createrawtransaction(inputs, outputs)
          signed_tx = node.signrawtransaction(raw_tx)["hex"]
          node.sendrawtransaction(signed_tx)
  
      while (node.getmempoolinfo()['size'] > 0):
          node.generate(1)
  
      utxos = node.listunspent()
      assert(len(utxos) >= count)
      return utxos
  
  # Create large OP_RETURN txouts that can be appended to a transaction
  # to make it large (helper for constructing large transactions).
  def gen_return_txouts():
      # Some pre-processing to create a bunch of OP_RETURN txouts to insert into transactions we create
      # So we have big transactions (and therefore can't fit very many into each block)
      # create one script_pubkey
      script_pubkey = "6a4d0200"  # OP_RETURN OP_PUSH2 512 bytes
      for i in range(512):
          script_pubkey = script_pubkey + "01"
      # concatenate 128 txouts of above script_pubkey which we'll insert before the txout for change
      txouts = "81"
      for k in range(128):
          # add txout value
          txouts = txouts + "0000000000000000"
          # add length of script_pubkey
          txouts = txouts + "fd0402"
          # add script_pubkey
          txouts = txouts + script_pubkey
      return txouts
  
  def create_tx(node, coinbase, to_address, amount):
      inputs = [{"txid": coinbase, "vout": 0}]
      outputs = {to_address: amount}
      rawtx = node.createrawtransaction(inputs, outputs)
      signresult = node.signrawtransaction(rawtx)
      assert_equal(signresult["complete"], True)
      return signresult["hex"]
  
  # Create a spend of each passed-in utxo, splicing in "txouts" to each raw
  # transaction to make it large.  See gen_return_txouts() above.
  def create_lots_of_big_transactions(node, txouts, utxos, num, fee):
      addr = node.getnewaddress()
      txids = []
      for _ in range(num):
          t = utxos.pop()
          inputs = [{"txid": t["txid"], "vout": t["vout"]}]
          outputs = {}
          change = t['amount'] - fee
          outputs[addr] = satoshi_round(change)
          rawtx = node.createrawtransaction(inputs, outputs)
          newtx = rawtx[0:92]
          newtx = newtx + txouts
          newtx = newtx + rawtx[94:]
          signresult = node.signrawtransaction(newtx, None, None, "NONE")
          txid = node.sendrawtransaction(signresult["hex"], True)
          txids.append(txid)
      return txids
  
  def mine_large_block(node, utxos=None):
      # generate a 66k transaction,
      # and 14 of them is close to the 1MB block limit
      num = 14
      txouts = gen_return_txouts()
      utxos = utxos if utxos is not None else []
      if len(utxos) < num:
          utxos.clear()
          utxos.extend(node.listunspent())
      fee = 100 * node.getnetworkinfo()["relayfee"]
      create_lots_of_big_transactions(node, txouts, utxos, num, fee=fee)
      node.generate(1)
  