text: ﻿"""Provides the wrapper for a Comsol client instance."""
  __license__ = 'MIT'
  
  
  ########################################
  # Components                           #
  ########################################
  from . import discovery                # back-end discovery
  from .model import Model               # model class
  from .config import option             # configuration
  
  
  ########################################
  # Dependencies                         #
  ########################################
  import jpype                           # Java bridge
  import jpype.imports                   # Java object imports
  import platform                        # platform information
  import os                              # operating system
  from pathlib import Path               # file-system paths
  from logging import getLogger          # event logging
  
  
  ########################################
  # Globals                              #
  ########################################
  logger = getLogger(__package__)        # event logger
  
  
  ########################################
  # Client                               #
  ########################################
  class Client:
      """
      Manages the Comsol client instance.
  
      A client can either be a stand-alone instance or it could connect
      to a Comsol server instance started independently, possibly on a
      different machine on the network.
  
      Example:
      ```python
          import mph
          client = mph.Client(cores=1)
          model = client.load('model.mph')
          model.solve()
          model.save()
          client.remove(model)
      ```
  
      Due to limitations of the Java bridge, provided by the JPype
      library, only one client can be instantiated at a time. This is
      because JPype cannot manage more than one Java virtual machine
      within the same Python session. Separate Python processes would
      have to be started, or spawned, to work around this limitation.
      `NotImplementedError` is therefore raised if another client is
      already running.
  
      The number of `cores` (threads) the client instance uses can
      be restricted by specifying a number. Otherwise all available
      cores are used.
  
      A specific Comsol `version` can be selected if several are
      installed, for example `version='5.3a'`. Otherwise the latest
      version is used, and reported via the `.version` attribute.
  
      Initializes a stand-alone Comsol session if no `port` number is
      specified. Otherwise tries to connect to the Comsol server
      listening at the given port for client connections. The `host`
      address defaults to `'localhost'`, but could be any domain name
      or IP address.
  
      Internally, the client is a wrapper around the `ModelUtil` object
      provided by Comsol's Java API, which may also be accessed directly
      via the instance attribute `.java`.
      """
  
      def __init__(self, cores=None, version=None, port=None, host='localhost'):
  
          # Make sure this is the one and only client.
          if jpype.isJVMStarted():
              error = 'Only one client can be instantiated at a time.'
              logger.critical(error)
              raise NotImplementedError(error)
  
          # Discover Comsol back-end.
          backend = discovery.backend(version)
  
          # Instruct Comsol to limit number of processor cores to use.
          if cores:
              os.environ['COMSOL_NUM_THREADS'] = str(cores)
  
          # Start the Java virtual machine.
          logger.info(f'JPype version is {jpype.__version__}.')
          logger.info('Starting Java virtual machine.')
          jpype.startJVM(str(backend['jvm']),
                         classpath=str(backend['root']/'plugins'/'*'),
                         convertStrings=False)
          logger.info('Java virtual machine has started.')
  
          # Initialize a stand-alone client if no server port given.
          from com.comsol.model.util import ModelUtil as java
          if port is None:
              logger.info('Initializing stand-alone client.')
              check_environment(backend)
              graphics = True
              java.initStandalone(graphics)
              logger.info('Stand-alone client initialized.')
          # Otherwise skip stand-alone initialization and connect to server.
          else:
              logger.info(f'Connecting to server "{host}" at port {port}.')
              java.connect(host, port)
  
          # Log number of used processor cores as reported by Comsol instance.
          cores = java.getPreference('cluster.processor.numberofprocessors')
          cores = int(str(cores))
          noun = 'core' if cores == 1 else 'cores'
          logger.info(f'Running on {cores} processor {noun}.')
  
          # Load Comsol settings from disk so as to not just use defaults.
          java.loadPreferences()
  
          # Override certain settings not useful in headless operation.
          java.setPreference('updates.update.check', 'off')
          java.setPreference('tempfiles.saving.warnifoverwriteolder', 'off')
          java.setPreference('tempfiles.recovery.autosave', 'off')
          try:
              java.setPreference('tempfiles.recovery.checkforrecoveries', 'off')
          except Exception:
              logger.warning('Could not turn off check for recovery files.')
          java.setPreference('tempfiles.saving.optimize', 'filesize')
  
          # Save useful information in instance attributes.
          self.version = backend['name']
          self.cores   = cores
          self.host    = host
          self.port    = port
          self.java    = java
  
      def load(self, file):
          """Loads a model from the given `file` and returns it."""
          file = Path(file).resolve()
          if self.caching() and file in self.files():
              logger.info(f'Retrieving "{file.name}" from cache.')
              return self.models()[self.files().index(file)]
          tag = self.java.uniquetag('model')
          logger.info(f'Loading model "{file.name}".')
          model = Model(self.java.load(tag, str(file)))
          logger.info('Finished loading model.')
          return model
  
      def caching(self, state=None):
          """
          Enables or disables caching of previously loaded models.
  
          Caching means that the `load()` method will check if a model
          has been previously loaded from the same file-system path and,
          if so, return the in-memory model object instead of reloading
          it from disk. By default (at start-up) caching is disabled.
  
          Pass `True` to enable caching, `False` to disable it. If no
          argument is passed, the current state is returned.
          """
          if state is None:
              return option('caching')
          elif state in (True, False):
              option('caching', state)
          else:
              error = 'Caching state can only be set to either True or False.'
              logger.critical(error)
              raise ValueError(error)
  
      def create(self, name):
          """
          Creates and returns a new, empty model with the given `name`.
  
          This is not particularly useful unless you are prepared to
          drop down to the Java layer and add model features on your
          own. It may help to call the returned (Python) model object
          something like `pymodel` and assign the name `model` to
          `pymodel.java`. Then you can just copy-and-paste Java or
          Matlab code from the Comsol programming manual or as exported
          from the Comsol front-end. Python will gracefully overlook
          gratuitous semicolons at the end of statements, so this
          approach would even work for entire blocks of code.
          """
          java = self.java.createUnique('model')
          logger.debug(f'Created model with tag "{java.tag()}".')
          model = Model(java)
          model.rename(name)
          return model
  
      def models(self):
          """Returns all models currently held in memory."""
          return [Model(self.java.model(tag)) for tag in self.java.tags()]
  
      def names(self):
          """Returns the names of all loaded models."""
          return [model.name() for model in self.models()]
  
      def files(self):
          """Returns the file-system paths of all loaded models."""
          return [model.file() for model in self.models()]
  
      def remove(self, model):
          """Removes the given `model` from memory."""
          name = model.name()
          tag  = model.java.tag()
          logger.debug(f'Removing model "{name}" with tag "{tag}".')
          self.java.remove(tag)
  
      def clear(self):
          """Removes all loaded models from memory."""
          logger.debug('Clearing all models from memory.')
          self.java.clear()
  
      def disconnect(self):
          """Disconnects the client from the server."""
          if self.port:
              self.java.disconnect()
              self.host = None
              self.port = None
          else:
              error = 'The client is not connected to a server.'
              logger.critical(error)
              raise RuntimeError(error)
  
  
  ########################################
  # Environment                          #
  ########################################
  
  def check_environment(backend):
      """Checks the process environment required for a stand-alone client."""
      system = platform.system()
      root = backend['root']
      help = 'Refer to chapter "Limitations" in the documentation for help.'
      if system == 'Windows':
          pass
      elif system == 'Linux':
          var = 'LD_LIBRARY_PATH'
          if var not in os.environ:
              error = f'Library search path {var} not set in environment.'
              logger.critical(error)
              raise RuntimeError(error + '\n' + help)
          path = os.environ[var].split(os.pathsep)
          lib = root/'lib'/'glnxa64'
          if str(lib) not in path:
              error = f'Folder "{lib}" missing in library search path.'
              logger.critical(error)
              raise RuntimeError(error + '\n' + help)
          gcc = root/'lib'/'glnxa64'/'gcc'
          if gcc.exists() and str(gcc) not in path:
              logger.warning(f'Folder "{gcc}" missing in library search path.')
          gra = str(root/'ext'/'graphicsmagick'/'glnxa64')
          if str(gra) not in path:
              error = f'Folder "{gra}" missing in library search path.'
              logger.critical(error)
              raise RuntimeError(error + '\n' + help)
          cad = root/'ext'/'cadimport'/'glnxa64'
          if cad.exists() and str(cad) not in path:
              logger.warning(f'Folder "{cad}" missing in library search path.')
      elif system == 'Darwin':
          var = 'DYLD_LIBRARY_PATH'
          if var not in os.environ:
              error = f'Library search path {var} not set in environment.'
              logger.critical(error)
              raise RuntimeError(error + '\n' + help)
          if var in os.environ:
              path = os.environ[var].split(os.pathsep)
          else:
              path = []
          lib = root/'lib'/'maci64'
          if str(lib) not in path:
              error = f'Folder "{lib}" missing in library search path.'
              logger.critical(error)
              raise RuntimeError(error + '\n' + help)
          gra = root/'ext'/'graphicsmagick'/'maci64'
          if str(gra) not in path:
              error = f'Folder "{gra}" missing in library search path.'
              logger.critical(error)
              raise RuntimeError(error + '\n' + help)
          cad = root/'ext'/'cadimport'/'maci64'
          if cad.exists() and str(cad) not in path:
              logger.warning(f'Folder "{cad}" missing in library search path.')
  