text: #!/usr/bin/env python
  #
  # Electrum - lightweight Bitcoin client
  # Copyright (C) 2012 thomasv@gitorious
  #
  # 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 socket
  import time
  from enum import IntEnum
  from typing import Tuple
  
  from PyQt5.QtCore import Qt, pyqtSignal, QThread
  from PyQt5.QtWidgets import (QTreeWidget, QTreeWidgetItem, QMenu, QGridLayout, QComboBox,
                               QLineEdit, QDialog, QVBoxLayout, QHeaderView, QCheckBox,
                               QTabWidget, QWidget, QLabel)
  from PyQt5.QtGui import QFontMetrics
  
  from electrum_ltc.i18n import _
  from electrum_ltc import constants, blockchain
  from electrum_ltc.interface import serialize_server, deserialize_server
  from electrum_ltc.network import Network
  from electrum_ltc.logging import get_logger
  
  from .util import Buttons, CloseButton, HelpButton, read_QIcon, char_width_in_lineedit
  
  
  _logger = get_logger(__name__)
  
  protocol_names = ['TCP', 'SSL']
  protocol_letters = 'ts'
  
  class NetworkDialog(QDialog):
      def __init__(self, network, config, network_updated_signal_obj):
          QDialog.__init__(self)
          self.setWindowTitle(_('Network'))
          self.setMinimumSize(500, 300)
          self.nlayout = NetworkChoiceLayout(network, config)
          self.network_updated_signal_obj = network_updated_signal_obj
          vbox = QVBoxLayout(self)
          vbox.addLayout(self.nlayout.layout())
          vbox.addLayout(Buttons(CloseButton(self)))
          self.network_updated_signal_obj.network_updated_signal.connect(
              self.on_update)
          network.register_callback(self.on_network, ['network_updated'])
  
      def on_network(self, event, *args):
          self.network_updated_signal_obj.network_updated_signal.emit(event, args)
  
      def on_update(self):
          self.nlayout.update()
  
  
  
  class NodesListWidget(QTreeWidget):
  
      def __init__(self, parent):
          QTreeWidget.__init__(self)
          self.parent = parent
          self.setHeaderLabels([_('Connected node'), _('Height')])
          self.setContextMenuPolicy(Qt.CustomContextMenu)
          self.customContextMenuRequested.connect(self.create_menu)
  
      def create_menu(self, position):
          item = self.currentItem()
          if not item:
              return
          is_server = not bool(item.data(0, Qt.UserRole))
          menu = QMenu()
          if is_server:
              server = item.data(1, Qt.UserRole)
              menu.addAction(_("Use as server"), lambda: self.parent.follow_server(server))
          else:
              chain_id = item.data(1, Qt.UserRole)
              menu.addAction(_("Follow this branch"), lambda: self.parent.follow_branch(chain_id))
          menu.exec_(self.viewport().mapToGlobal(position))
  
      def keyPressEvent(self, event):
          if event.key() in [ Qt.Key_F2, Qt.Key_Return ]:
              self.on_activated(self.currentItem(), self.currentColumn())
          else:
              QTreeWidget.keyPressEvent(self, event)
  
      def on_activated(self, item, column):
          # on 'enter' we show the menu
          pt = self.visualItemRect(item).bottomLeft()
          pt.setX(50)
          self.customContextMenuRequested.emit(pt)
  
      def update(self, network: Network):
          self.clear()
          self.addChild = self.addTopLevelItem
          chains = network.get_blockchains()
          n_chains = len(chains)
          for chain_id, interfaces in chains.items():
              b = blockchain.blockchains.get(chain_id)
              if b is None: continue
              name = b.get_name()
              if n_chains > 1:
                  x = QTreeWidgetItem([name + '@%d'%b.get_max_forkpoint(), '%d'%b.height()])
                  x.setData(0, Qt.UserRole, 1)
                  x.setData(1, Qt.UserRole, b.get_id())
              else:
                  x = self
              for i in interfaces:
                  star = ' *' if i == network.interface else ''
                  item = QTreeWidgetItem([i.host + star, '%d'%i.tip])
                  item.setData(0, Qt.UserRole, 0)
                  item.setData(1, Qt.UserRole, i.server)
                  x.addChild(item)
              if n_chains > 1:
                  self.addTopLevelItem(x)
                  x.setExpanded(True)
  
          h = self.header()
          h.setStretchLastSection(False)
          h.setSectionResizeMode(0, QHeaderView.Stretch)
          h.setSectionResizeMode(1, QHeaderView.ResizeToContents)
  
          super().update()
  
  
  class ServerListWidget(QTreeWidget):
      class Columns(IntEnum):
          HOST = 0
          PORT = 1
  
      SERVER_STR_ROLE = Qt.UserRole + 100
  
      def __init__(self, parent):
          QTreeWidget.__init__(self)
          self.parent = parent
          self.setHeaderLabels([_('Host'), _('Port')])
          self.setContextMenuPolicy(Qt.CustomContextMenu)
          self.customContextMenuRequested.connect(self.create_menu)
  
      def create_menu(self, position):
          item = self.currentItem()
          if not item:
              return
          menu = QMenu()
          server = item.data(self.Columns.HOST, self.SERVER_STR_ROLE)
          menu.addAction(_("Use as server"), lambda: self.set_server(server))
          menu.exec_(self.viewport().mapToGlobal(position))
  
      def set_server(self, s):
          host, port, protocol = deserialize_server(s)
          self.parent.server_host.setText(host)
          self.parent.server_port.setText(port)
          self.parent.set_server()
  
      def keyPressEvent(self, event):
          if event.key() in [ Qt.Key_F2, Qt.Key_Return ]:
              self.on_activated(self.currentItem(), self.currentColumn())
          else:
              QTreeWidget.keyPressEvent(self, event)
  
      def on_activated(self, item, column):
          # on 'enter' we show the menu
          pt = self.visualItemRect(item).bottomLeft()
          pt.setX(50)
          self.customContextMenuRequested.emit(pt)
  
      def update(self, servers, protocol, use_tor):
          self.clear()
          for _host, d in sorted(servers.items()):
              if _host.endswith('.onion') and not use_tor:
                  continue
              port = d.get(protocol)
              if port:
                  x = QTreeWidgetItem([_host, port])
                  server = serialize_server(_host, port, protocol)
                  x.setData(self.Columns.HOST, self.SERVER_STR_ROLE, server)
                  self.addTopLevelItem(x)
  
          h = self.header()
          h.setStretchLastSection(False)
          h.setSectionResizeMode(self.Columns.HOST, QHeaderView.Stretch)
          h.setSectionResizeMode(self.Columns.PORT, QHeaderView.ResizeToContents)
  
          super().update()
  
  
  class NetworkChoiceLayout(object):
  
      def __init__(self, network: Network, config, wizard=False):
          self.network = network
          self.config = config
          self.protocol = None
          self.tor_proxy = None
  
          self.tabs = tabs = QTabWidget()
          server_tab = QWidget()
          proxy_tab = QWidget()
          blockchain_tab = QWidget()
          tabs.addTab(blockchain_tab, _('Overview'))
          tabs.addTab(server_tab, _('Server'))
          tabs.addTab(proxy_tab, _('Proxy'))
  
          fixed_width_hostname = 24 * char_width_in_lineedit()
          fixed_width_port = 6 * char_width_in_lineedit()
  
          # server tab
          grid = QGridLayout(server_tab)
          grid.setSpacing(8)
  
          self.server_host = QLineEdit()
          self.server_host.setFixedWidth(fixed_width_hostname)
          self.server_port = QLineEdit()
          self.server_port.setFixedWidth(fixed_width_port)
          self.autoconnect_cb = QCheckBox(_('Select server automatically'))
          self.autoconnect_cb.setEnabled(self.config.is_modifiable('auto_connect'))
  
          self.server_host.editingFinished.connect(self.set_server)
          self.server_port.editingFinished.connect(self.set_server)
          self.autoconnect_cb.clicked.connect(self.set_server)
          self.autoconnect_cb.clicked.connect(self.update)
  
          msg = ' '.join([
              _("If auto-connect is enabled, Electrum will always use a server that is on the longest blockchain."),
              _("If it is disabled, you have to choose a server you want to use. Electrum will warn you if your server is lagging.")
          ])
          grid.addWidget(self.autoconnect_cb, 0, 0, 1, 3)
          grid.addWidget(HelpButton(msg), 0, 4)
  
          grid.addWidget(QLabel(_('Server') + ':'), 1, 0)
          grid.addWidget(self.server_host, 1, 1, 1, 2)
          grid.addWidget(self.server_port, 1, 3)
  
          label = _('Server peers') if network.is_connected() else _('Default Servers')
          grid.addWidget(QLabel(label), 2, 0, 1, 5)
          self.servers_list = ServerListWidget(self)
          grid.addWidget(self.servers_list, 3, 0, 1, 5)
  
          # Proxy tab
          grid = QGridLayout(proxy_tab)
          grid.setSpacing(8)
  
          # proxy setting
          self.proxy_cb = QCheckBox(_('Use proxy'))
          self.proxy_cb.clicked.connect(self.check_disable_proxy)
          self.proxy_cb.clicked.connect(self.set_proxy)
  
          self.proxy_mode = QComboBox()
          self.proxy_mode.addItems(['SOCKS4', 'SOCKS5'])
          self.proxy_host = QLineEdit()
          self.proxy_host.setFixedWidth(fixed_width_hostname)
          self.proxy_port = QLineEdit()
          self.proxy_port.setFixedWidth(fixed_width_port)
          self.proxy_user = QLineEdit()
          self.proxy_user.setPlaceholderText(_("Proxy user"))
          self.proxy_password = QLineEdit()
          self.proxy_password.setPlaceholderText(_("Password"))
          self.proxy_password.setEchoMode(QLineEdit.Password)
          self.proxy_password.setFixedWidth(fixed_width_port)
  
          self.proxy_mode.currentIndexChanged.connect(self.set_proxy)
          self.proxy_host.editingFinished.connect(self.set_proxy)
          self.proxy_port.editingFinished.connect(self.set_proxy)
          self.proxy_user.editingFinished.connect(self.set_proxy)
          self.proxy_password.editingFinished.connect(self.set_proxy)
  
          self.proxy_mode.currentIndexChanged.connect(self.proxy_settings_changed)
          self.proxy_host.textEdited.connect(self.proxy_settings_changed)
          self.proxy_port.textEdited.connect(self.proxy_settings_changed)
          self.proxy_user.textEdited.connect(self.proxy_settings_changed)
          self.proxy_password.textEdited.connect(self.proxy_settings_changed)
  
          self.tor_cb = QCheckBox(_("Use Tor Proxy"))
          self.tor_cb.setIcon(read_QIcon("tor_logo.png"))
          self.tor_cb.hide()
          self.tor_cb.clicked.connect(self.use_tor_proxy)
  
          grid.addWidget(self.tor_cb, 1, 0, 1, 3)
          grid.addWidget(self.proxy_cb, 2, 0, 1, 3)
          grid.addWidget(HelpButton(_('Proxy settings apply to all connections: with Electrum servers, but also with third-party services.')), 2, 4)
          grid.addWidget(self.proxy_mode, 4, 1)
          grid.addWidget(self.proxy_host, 4, 2)
          grid.addWidget(self.proxy_port, 4, 3)
          grid.addWidget(self.proxy_user, 5, 2)
          grid.addWidget(self.proxy_password, 5, 3)
          grid.setRowStretch(7, 1)
  
          # Blockchain Tab
          grid = QGridLayout(blockchain_tab)
          msg =  ' '.join([
              _("Electrum connects to several nodes in order to download block headers and find out the longest blockchain."),
              _("This blockchain is used to verify the transactions sent by your transaction server.")
          ])
          self.status_label = QLabel('')
          grid.addWidget(QLabel(_('Status') + ':'), 0, 0)
          grid.addWidget(self.status_label, 0, 1, 1, 3)
          grid.addWidget(HelpButton(msg), 0, 4)
  
          self.server_label = QLabel('')
          msg = _("Electrum sends your wallet addresses to a single server, in order to receive your transaction history.")
          grid.addWidget(QLabel(_('Server') + ':'), 1, 0)
          grid.addWidget(self.server_label, 1, 1, 1, 3)
          grid.addWidget(HelpButton(msg), 1, 4)
  
          self.height_label = QLabel('')
          msg = _('This is the height of your local copy of the blockchain.')
          grid.addWidget(QLabel(_('Blockchain') + ':'), 2, 0)
          grid.addWidget(self.height_label, 2, 1)
          grid.addWidget(HelpButton(msg), 2, 4)
  
          self.split_label = QLabel('')
          grid.addWidget(self.split_label, 3, 0, 1, 3)
  
          self.nodes_list_widget = NodesListWidget(self)
          grid.addWidget(self.nodes_list_widget, 5, 0, 1, 5)
  
          vbox = QVBoxLayout()
          vbox.addWidget(tabs)
          self.layout_ = vbox
          # tor detector
          self.td = td = TorDetector()
          td.found_proxy.connect(self.suggest_proxy)
          td.start()
  
          self.fill_in_proxy_settings()
          self.update()
  
      def check_disable_proxy(self, b):
          if not self.config.is_modifiable('proxy'):
              b = False
          for w in [self.proxy_mode, self.proxy_host, self.proxy_port, self.proxy_user, self.proxy_password]:
              w.setEnabled(b)
  
      def enable_set_server(self):
          if self.config.is_modifiable('server'):
              enabled = not self.autoconnect_cb.isChecked()
              self.server_host.setEnabled(enabled)
              self.server_port.setEnabled(enabled)
              self.servers_list.setEnabled(enabled)
          else:
              for w in [self.autoconnect_cb, self.server_host, self.server_port, self.servers_list]:
                  w.setEnabled(False)
  
      def update(self):
          net_params = self.network.get_parameters()
          host, port, protocol = net_params.host, net_params.port, net_params.protocol
          proxy_config, auto_connect = net_params.proxy, net_params.auto_connect
          if not self.server_host.hasFocus() and not self.server_port.hasFocus():
              self.server_host.setText(host)
              self.server_port.setText(str(port))
          self.autoconnect_cb.setChecked(auto_connect)
  
          interface = self.network.interface
          host = interface.host if interface else _('None')
          self.server_label.setText(host)
  
          self.set_protocol(protocol)
          self.servers = self.network.get_servers()
          self.servers_list.update(self.servers, self.protocol, self.tor_cb.isChecked())
          self.enable_set_server()
  
          height_str = "%d "%(self.network.get_local_height()) + _('blocks')
          self.height_label.setText(height_str)
          n = len(self.network.get_interfaces())
          status = _("Connected to {0} nodes.").format(n) if n else _("Not connected")
          self.status_label.setText(status)
          chains = self.network.get_blockchains()
          if len(chains) > 1:
              chain = self.network.blockchain()
              forkpoint = chain.get_max_forkpoint()
              name = chain.get_name()
              msg = _('Chain split detected at block {0}').format(forkpoint) + '\n'
              msg += (_('You are following branch') if auto_connect else _('Your server is on branch'))+ ' ' + name
              msg += ' (%d %s)' % (chain.get_branch_size(), _('blocks'))
          else:
              msg = ''
          self.split_label.setText(msg)
          self.nodes_list_widget.update(self.network)
  
      def fill_in_proxy_settings(self):
          proxy_config = self.network.get_parameters().proxy
          if not proxy_config:
              proxy_config = {"mode": "none", "host": "localhost", "port": "9050"}
  
          b = proxy_config.get('mode') != "none"
          self.check_disable_proxy(b)
          if b:
              self.proxy_cb.setChecked(True)
              self.proxy_mode.setCurrentIndex(
                  self.proxy_mode.findText(str(proxy_config.get("mode").upper())))
  
          self.proxy_host.setText(proxy_config.get("host"))
          self.proxy_port.setText(proxy_config.get("port"))
          self.proxy_user.setText(proxy_config.get("user", ""))
          self.proxy_password.setText(proxy_config.get("password", ""))
  
      def layout(self):
          return self.layout_
  
      def set_protocol(self, protocol):
          if protocol != self.protocol:
              self.protocol = protocol
  
      def change_protocol(self, use_ssl):
          p = 's' if use_ssl else 't'
          host = self.server_host.text()
          pp = self.servers.get(host, constants.net.DEFAULT_PORTS)
          if p not in pp.keys():
              p = list(pp.keys())[0]
          port = pp[p]
          self.server_host.setText(host)
          self.server_port.setText(port)
          self.set_protocol(p)
          self.set_server()
  
      def follow_branch(self, chain_id):
          self.network.run_from_another_thread(self.network.follow_chain_given_id(chain_id))
          self.update()
  
      def follow_server(self, server):
          self.network.run_from_another_thread(self.network.follow_chain_given_server(server))
          self.update()
  
      def server_changed(self, x):
          if x:
              self.change_server(str(x.text(0)), self.protocol)
  
      def change_server(self, host, protocol):
          pp = self.servers.get(host, constants.net.DEFAULT_PORTS)
          if protocol and protocol not in protocol_letters:
              protocol = None
          if protocol:
              port = pp.get(protocol)
              if port is None:
                  protocol = None
          if not protocol:
              if 's' in pp.keys():
                  protocol = 's'
                  port = pp.get(protocol)
              else:
                  protocol = list(pp.keys())[0]
                  port = pp.get(protocol)
          self.server_host.setText(host)
          self.server_port.setText(port)
  
      def accept(self):
          pass
  
      def set_server(self):
          net_params = self.network.get_parameters()
          net_params = net_params._replace(host=str(self.server_host.text()),
                                           port=str(self.server_port.text()),
                                           auto_connect=self.autoconnect_cb.isChecked())
          self.network.run_from_another_thread(self.network.set_parameters(net_params))
  
      def set_proxy(self):
          net_params = self.network.get_parameters()
          if self.proxy_cb.isChecked():
              proxy = { 'mode':str(self.proxy_mode.currentText()).lower(),
                        'host':str(self.proxy_host.text()),
                        'port':str(self.proxy_port.text()),
                        'user':str(self.proxy_user.text()),
                        'password':str(self.proxy_password.text())}
          else:
              proxy = None
              self.tor_cb.setChecked(False)
          net_params = net_params._replace(proxy=proxy)
          self.network.run_from_another_thread(self.network.set_parameters(net_params))
  
      def suggest_proxy(self, found_proxy):
          if found_proxy is None:
              self.tor_cb.hide()
              return
          self.tor_proxy = found_proxy
          self.tor_cb.setText("Use Tor proxy at port " + str(found_proxy[1]))
          if (self.proxy_cb.isChecked()
                  and self.proxy_mode.currentIndex() == self.proxy_mode.findText('SOCKS5')
                  and self.proxy_host.text() == "127.0.0.1"
                  and self.proxy_port.text() == str(found_proxy[1])):
              self.tor_cb.setChecked(True)
          self.tor_cb.show()
  
      def use_tor_proxy(self, use_it):
          if not use_it:
              self.proxy_cb.setChecked(False)
          else:
              socks5_mode_index = self.proxy_mode.findText('SOCKS5')
              if socks5_mode_index == -1:
                  _logger.info("can't find proxy_mode 'SOCKS5'")
                  return
              self.proxy_mode.setCurrentIndex(socks5_mode_index)
              self.proxy_host.setText("127.0.0.1")
              self.proxy_port.setText(str(self.tor_proxy[1]))
              self.proxy_user.setText("")
              self.proxy_password.setText("")
              self.tor_cb.setChecked(True)
              self.proxy_cb.setChecked(True)
          self.check_disable_proxy(use_it)
          self.set_proxy()
  
      def proxy_settings_changed(self):
          self.tor_cb.setChecked(False)
  
  
  class TorDetector(QThread):
      found_proxy = pyqtSignal(object)
  
      def __init__(self):
          QThread.__init__(self)
  
      def run(self):
          # Probable ports for Tor to listen at
          ports = [9050, 9150]
          while True:
              for p in ports:
                  net_addr = ("127.0.0.1", p)
                  if TorDetector.is_tor_port(net_addr):
                      self.found_proxy.emit(net_addr)
                      break
              else:
                  self.found_proxy.emit(None)
              time.sleep(10)
  
      @staticmethod
      def is_tor_port(net_addr: Tuple[str, int]) -> bool:
          try:
              s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
              s.settimeout(0.1)
              s.connect(net_addr)
              # Tor responds uniquely to HTTP-like requests
              s.send(b"GET\n")
              if b"Tor is not an HTTP Proxy" in s.recv(1024):
                  return True
          except socket.error:
              pass
          return False
  