''' pydevd - a debugging daemon
This is the daemon you launch for python remote debugging.

Protocol:
each command has a format:
    id\tsequence-num\ttext
    id: protocol command number
    sequence-num: each request has a sequence number. Sequence numbers
    originating at the debugger are odd, sequence numbers originating
    at the daemon are even. Every response uses the same sequence number
    as the request.
    payload: it is protocol dependent. When response is a complex structure, it
    is returned as XML. Each attribute value is urlencoded, and then the whole
    payload is urlencoded again to prevent stray characters corrupting protocol/xml encodings

    Commands:

    NUMBER   NAME                     FROM*     ARGUMENTS                     RESPONSE      NOTE
100 series: program execution
    101      RUN                      JAVA      -                             -
    102      LIST_THREADS             JAVA                                    RETURN with XML listing of all threads
    103      THREAD_CREATE            PYDB      -                             XML with thread information
    104      THREAD_KILL              JAVA      id (or * to exit)             kills the thread
                                      PYDB      id                            nofies JAVA that thread was killed
    105      THREAD_SUSPEND           JAVA      XML of the stack,             suspends the thread
                                                reason for suspension
                                      PYDB      id                            notifies JAVA that thread was suspended

    106      CMD_THREAD_RUN           JAVA      id                            resume the thread
                                      PYDB      id \t reason                  notifies JAVA that thread was resumed

    107      STEP_INTO                JAVA      thread_id
    108      STEP_OVER                JAVA      thread_id
    109      STEP_RETURN              JAVA      thread_id

    110      GET_VARIABLE             JAVA      thread_id \t frame_id \t      GET_VARIABLE with XML of var content
                                                FRAME|GLOBAL \t attributes*

    111      SET_BREAK                JAVA      file/line of the breakpoint
    112      REMOVE_BREAK             JAVA      file/line of the return
    113      CMD_EVALUATE_EXPRESSION  JAVA      expression                    result of evaluating the expression
    114      CMD_GET_FRAME            JAVA                                    request for frame contents
    115      CMD_EXEC_EXPRESSION      JAVA
    116      CMD_WRITE_TO_CONSOLE     PYDB
    117      CMD_CHANGE_VARIABLE
    118      CMD_RUN_TO_LINE
    119      CMD_RELOAD_CODE
    120      CMD_GET_COMPLETIONS      JAVA

    200      CMD_REDIRECT_OUTPUT      JAVA      streams to redirect as string -
                                                'STDOUT' (redirect only STDOUT)
                                                'STDERR' (redirect only STDERR)
                                                'STDOUT STDERR' (redirect both streams)

500 series diagnostics/ok
    501      VERSION                  either      Version string (1.0)        Currently just used at startup
    502      RETURN                   either      Depends on caller    -

900 series: errors
    901      ERROR                    either      -                           This is reserved for unexpected errors.

    * JAVA - remote debugger, the java end
    * PYDB - pydevd, the python end
'''

import itertools
import linecache
import os

from _pydev_bundle.pydev_imports import _queue
from _pydev_imps._pydev_saved_modules import time
from _pydev_imps._pydev_saved_modules import thread
from _pydev_imps._pydev_saved_modules import threading
from socket import AF_INET, SOCK_STREAM, SHUT_RD, SHUT_WR, SOL_SOCKET, SO_REUSEADDR, SHUT_RDWR
from _pydevd_bundle.pydevd_constants import (DebugInfoHolder, get_thread_id, IS_JYTHON, IS_PY2,
    IS_PY36_OR_GREATER, STATE_RUN, dict_keys, ASYNC_EVAL_TIMEOUT_SEC, GlobalDebuggerHolder,
    get_global_debugger, GetGlobalDebugger, set_global_debugger)  # Keep for backward compatibility @UnusedImport
from _pydev_bundle.pydev_override import overrides
import weakref
from _pydev_bundle._pydev_completer import extract_token_and_qualifier
from _pydevd_bundle._debug_adapter.pydevd_schema import VariablesResponseBody, \
    SetVariableResponseBody
from _pydevd_bundle._debug_adapter import pydevd_base_schema, pydevd_schema
from _pydevd_bundle.pydevd_net_command import NetCommand
from _pydevd_bundle.pydevd_xml import ExceptionOnEvaluate
try:
    from urllib import quote_plus, unquote_plus
except:
    from urllib.parse import quote_plus, unquote_plus  # @Reimport @UnresolvedImport

import pydevconsole
from _pydevd_bundle import pydevd_vars
import pydevd_tracing
from _pydevd_bundle import pydevd_xml
from _pydevd_bundle import pydevd_vm_type
import sys
import traceback
from _pydevd_bundle.pydevd_utils import quote_smart as quote, compare_object_attrs_key
from _pydev_bundle import pydev_log
from _pydev_bundle import _pydev_completer

from pydevd_tracing import get_exception_traceback_str
from _pydevd_bundle import pydevd_console
from _pydev_bundle.pydev_monkey import disable_trace_thread_modules, enable_trace_thread_modules
from socket import socket
try:
    import cStringIO as StringIO  # may not always be available @UnusedImport
except:
    try:
        import StringIO  # @Reimport
    except:
        import io as StringIO

# CMD_XXX constants imported for backward compatibility
from _pydevd_bundle.pydevd_comm_constants import *  # @UnusedWildImport

if IS_JYTHON:
    import org.python.core as JyCore  # @UnresolvedImport


def pydevd_log(level, *args):
    ''' levels are:
        0 most serious warnings/errors
        1 warnings/significant events
        2 informational trace
    '''
    if level <= DebugInfoHolder.DEBUG_TRACE_LEVEL:
        # yes, we can have errors printing if the console of the program has been finished (and we're still trying to print something)
        try:
            sys.stderr.write('%s\n' % (args,))
        except:
            pass


class PyDBDaemonThread(threading.Thread):
    created_pydb_daemon_threads = {}

    def __init__(self, target_and_args=None):
        '''
        :param target_and_args:
            tuple(func, args, kwargs) if this should be a function and args to run.
            -- Note: use through run_as_pydevd_daemon_thread().
        '''
        threading.Thread.__init__(self)
        self.killReceived = False
        mark_as_pydevd_daemon_thread(self)
        self._target_and_args = target_and_args

    def run(self):
        created_pydb_daemon = self.created_pydb_daemon_threads
        created_pydb_daemon[self] = 1
        try:
            try:
                if IS_JYTHON and not isinstance(threading.currentThread(), threading._MainThread):
                    # we shouldn't update sys.modules for the main thread, cause it leads to the second importing 'threading'
                    # module, and the new instance of main thread is created
                    ss = JyCore.PySystemState()
                    # Note: Py.setSystemState() affects only the current thread.
                    JyCore.Py.setSystemState(ss)

                self._stop_trace()
                self._on_run()
            except:
                if sys is not None and traceback is not None:
                    traceback.print_exc()
        finally:
            del created_pydb_daemon[self]

    def _on_run(self):
        if self._target_and_args is not None:
            target, args, kwargs = self._target_and_args
            target(*args, **kwargs)
        else:
            raise NotImplementedError('Should be reimplemented by: %s' % self.__class__)

    def do_kill_pydev_thread(self):
        self.killReceived = True

    def _stop_trace(self):
        if self.pydev_do_not_trace:
            pydevd_tracing.SetTrace(None)  # no debugging on this thread


def mark_as_pydevd_daemon_thread(thread):
    thread.pydev_do_not_trace = True
    thread.is_pydev_daemon_thread = True
    thread.daemon = True


def run_as_pydevd_daemon_thread(func, *args, **kwargs):
    '''
    Runs a function as a pydevd daemon thread (without any tracing in place).
    '''
    t = PyDBDaemonThread(target_and_args=(func, args, kwargs))
    t.name = '%s (pydevd daemon thread)' % (func.__name__,)
    t.start()
    return t


class ReaderThread(PyDBDaemonThread):
    ''' reader thread reads and dispatches commands in an infinite loop '''

    def __init__(self, sock):
        from _pydevd_bundle.pydevd_process_net_command_json import process_net_command_json
        from _pydevd_bundle.pydevd_process_net_command import process_net_command
        PyDBDaemonThread.__init__(self)

        self.sock = sock
        self._buffer = b''
        self.setName("pydevd.Reader")
        self.process_net_command = process_net_command
        self.process_net_command_json = process_net_command_json
        self.global_debugger_holder = GlobalDebuggerHolder

    def do_kill_pydev_thread(self):
        # We must close the socket so that it doesn't stay halted there.
        self.killReceived = True
        try:
            self.sock.shutdown(SHUT_RD)  # shutdown the socket for read
        except:
            # just ignore that
            pass

    def _read(self, size):
        while True:
            buffer_len = len(self._buffer)
            if buffer_len == size:
                ret = self._buffer
                self._buffer = b''
                return ret

            if buffer_len > size:
                ret = self._buffer[:size]
                self._buffer = self._buffer[size:]
                return ret

            r = self.sock.recv(max(size - buffer_len, 1024))
            if not r:
                return b''
            self._buffer += r

    def _read_line(self):
        while True:
            i = self._buffer.find(b'\n')
            if i != -1:
                i += 1  # Add the newline to the return
                ret = self._buffer[:i]
                self._buffer = self._buffer[i:]
                return ret
            else:
                r = self.sock.recv(1024)
                if not r:
                    return b''
                self._buffer += r

    @overrides(PyDBDaemonThread._on_run)
    def _on_run(self):
        try:
            content_len = -1

            while not self.killReceived:
                try:
                    line = self._read_line()

                    if len(line) == 0:
                        self.handle_except()
                        return  # Finished communication.

                    if line.startswith(b'Content-Length:'):
                        content_len = int(line.strip().split(b':', 1)[1])
                        continue

                    if content_len != -1:
                        # If we previously received a content length, read until a '\r\n'.
                        if line == b'\r\n':
                            json_contents = self._read(content_len)
                            content_len = -1

                            if len(json_contents) == 0:
                                self.handle_except()
                                return  # Finished communication.

                            # We just received a json message, let's process it.
                            self.process_net_command_json(self.global_debugger_holder.global_dbg, json_contents)

                        continue
                    else:
                        # No content len, regular line-based protocol message (remove trailing new-line).
                        if line.endswith(b'\n\n'):
                            line = line[:-2]

                        elif line.endswith(b'\n'):
                            line = line[:-1]

                        elif line.endswith(b'\r'):
                            line = line[:-1]
                except:
                    if not self.killReceived:
                        traceback.print_exc()
                        self.handle_except()
                    return  # Finished communication.

                # Note: the java backend is always expected to pass utf-8 encoded strings. We now work with unicode
                # internally and thus, we may need to convert to the actual encoding where needed (i.e.: filenames
                # on python 2 may need to be converted to the filesystem encoding).
                if hasattr(line, 'decode'):
                    line = line.decode('utf-8')

                if DebugInfoHolder.DEBUG_RECORD_SOCKET_READS:
                    sys.stderr.write(u'debugger: received >>%s<<\n' % (line,))
                    sys.stderr.flush()

                args = line.split(u'\t', 2)
                try:
                    cmd_id = int(args[0])
                    pydev_log.debug('Received command: %s %s\n' % (ID_TO_MEANING.get(str(cmd_id), '???'), line,))
                    self.process_command(cmd_id, int(args[1]), args[2])
                except:
                    if traceback is not None and sys is not None:  # Could happen at interpreter shutdown
                        traceback.print_exc()
                        sys.stderr.write("Can't process net command: %s\n" % line)
                        sys.stderr.flush()

        except:
            if not self.killReceived:
                if traceback is not None:  # Could happen at interpreter shutdown
                    traceback.print_exc()
            self.handle_except()

    def handle_except(self):
        self.global_debugger_holder.global_dbg.finish_debugging_session()

    def process_command(self, cmd_id, seq, text):
        self.process_net_command(self.global_debugger_holder.global_dbg, cmd_id, seq, text)


class WriterThread(PyDBDaemonThread):
    ''' writer thread writes out the commands in an infinite loop '''

    def __init__(self, sock):
        PyDBDaemonThread.__init__(self)
        self.sock = sock
        self.setName("pydevd.Writer")
        self.cmdQueue = _queue.Queue()
        if pydevd_vm_type.get_vm_type() == 'python':
            self.timeout = 0
        else:
            self.timeout = 0.1

    def add_command(self, cmd):
        ''' cmd is NetCommand '''
        if not self.killReceived:  # we don't take new data after everybody die
            self.cmdQueue.put(cmd)

    @overrides(PyDBDaemonThread._on_run)
    def _on_run(self):
        ''' just loop and write responses '''

        try:
            while True:
                try:
                    try:
                        cmd = self.cmdQueue.get(1, 0.1)
                    except _queue.Empty:
                        if self.killReceived:
                            try:
                                self.sock.shutdown(SHUT_WR)
                                self.sock.close()
                            except:
                                pass

                            return  # break if queue is empty and killReceived
                        else:
                            continue
                except:
                    # pydevd_log(0, 'Finishing debug communication...(1)')
                    # when liberating the thread here, we could have errors because we were shutting down
                    # but the thread was still not liberated
                    return
                cmd.send(self.sock)

                if cmd.id == CMD_EXIT:
                    break
                if time is None:
                    break  # interpreter shutdown
                time.sleep(self.timeout)
        except Exception:
            GlobalDebuggerHolder.global_dbg.finish_debugging_session()
            if DebugInfoHolder.DEBUG_TRACE_LEVEL >= 0:
                traceback.print_exc()

    def empty(self):
        return self.cmdQueue.empty()


def start_server(port):
    ''' binds to a port, waits for the debugger to connect '''
    s = socket(AF_INET, SOCK_STREAM)
    s.settimeout(None)

    try:
        from socket import SO_REUSEPORT
        s.setsockopt(SOL_SOCKET, SO_REUSEPORT, 1)
    except ImportError:
        s.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)

    s.bind(('', port))
    pydevd_log(1, "Bound to port ", str(port))

    try:
        s.listen(1)
        newSock, _addr = s.accept()
        pydevd_log(1, "Connection accepted")
        # closing server socket is not necessary but we don't need it
        s.shutdown(SHUT_RDWR)
        s.close()
        return newSock

    except:
        sys.stderr.write("Could not bind to port: %s\n" % (port,))
        sys.stderr.flush()
        traceback.print_exc()


def start_client(host, port):
    ''' connects to a host/port '''
    pydevd_log(1, "Connecting to ", host, ":", str(port))

    s = socket(AF_INET, SOCK_STREAM)

    #  Set TCP keepalive on an open socket.
    #  It activates after 1 second (TCP_KEEPIDLE,) of idleness,
    #  then sends a keepalive ping once every 3 seconds (TCP_KEEPINTVL),
    #  and closes the connection after 5 failed ping (TCP_KEEPCNT), or 15 seconds
    try:
        from socket import IPPROTO_TCP, SO_KEEPALIVE, TCP_KEEPIDLE, TCP_KEEPINTVL, TCP_KEEPCNT
        s.setsockopt(SOL_SOCKET, SO_KEEPALIVE, 1)
        s.setsockopt(IPPROTO_TCP, TCP_KEEPIDLE, 1)
        s.setsockopt(IPPROTO_TCP, TCP_KEEPINTVL, 3)
        s.setsockopt(IPPROTO_TCP, TCP_KEEPCNT, 5)
    except ImportError:
        pass  # May not be available everywhere.

    try:
        # 10 seconds default timeout
        timeout = int(os.environ.get('PYDEVD_CONNECT_TIMEOUT', 10))
        s.settimeout(timeout)
        s.connect((host, port))
        s.settimeout(None)  # no timeout after connected
        pydevd_log(1, "Connected.")
        return s
    except:
        sys.stderr.write("Could not connect to %s: %s\n" % (host, port))
        sys.stderr.flush()
        traceback.print_exc()
        raise


INTERNAL_TERMINATE_THREAD = 1
INTERNAL_SUSPEND_THREAD = 2


class InternalThreadCommand(object):
    ''' internal commands are generated/executed by the debugger.

    The reason for their existence is that some commands have to be executed
    on specific threads. These are the InternalThreadCommands that get
    get posted to PyDB.cmdQueue.
    '''

    def __init__(self, thread_id, method=None, *args, **kwargs):
        self.thread_id = thread_id
        self.method = method
        self.args = args
        self.kwargs = kwargs

    def can_be_executed_by(self, thread_id):
        '''By default, it must be in the same thread to be executed
        '''
        return self.thread_id == thread_id or self.thread_id.endswith('|' + thread_id)

    def do_it(self, dbg):
        try:
            if self.method is not None:
                self.method(dbg, *self.args, **self.kwargs)
            else:
                raise NotImplementedError("you have to override do_it")
        finally:
            self.args = None
            self.kwargs = None


class InternalThreadCommandForAnyThread(InternalThreadCommand):

    def __init__(self, thread_id, method=None, *args, **kwargs):
        assert thread_id == '*'

        InternalThreadCommand.__init__(self, thread_id, method, *args, **kwargs)

        self.executed = False
        self.lock = thread.allocate_lock()

    def can_be_executed_by(self, thread_id):
        return True  # Can be executed by any thread.

    def do_it(self, dbg):
        self.lock.acquire()
        try:
            if self.executed:
                return
            self.executed = True
        finally:
            self.lock.release()
        InternalThreadCommand.do_it(self, dbg)


def internal_reload_code(dbg, seq, module_name):
    module_name = module_name
    if module_name not in sys.modules:
        if '.' in module_name:
            new_module_name = module_name.split('.')[-1]
            if new_module_name in sys.modules:
                module_name = new_module_name

    reloaded_ok = False

    if module_name not in sys.modules:
        sys.stderr.write('pydev debugger: Unable to find module to reload: "' + module_name + '".\n')
        # Too much info...
        # sys.stderr.write('pydev debugger: This usually means you are trying to reload the __main__ module (which cannot be reloaded).\n')

    else:
        sys.stderr.write('pydev debugger: Start reloading module: "' + module_name + '" ... \n')
        from _pydevd_bundle import pydevd_reload
        if pydevd_reload.xreload(sys.modules[module_name]):
            sys.stderr.write('pydev debugger: reload finished\n')
            reloaded_ok = True
        else:
            sys.stderr.write('pydev debugger: reload finished without applying any change\n')

    cmd = dbg.cmd_factory.make_reloaded_code_message(seq, reloaded_ok)
    dbg.writer.add_command(cmd)


class InternalGetThreadStack(InternalThreadCommand):
    '''
    This command will either wait for a given thread to be paused to get its stack or will provide
    it anyways after a timeout (in which case the stack will be gotten but local variables won't
    be available and it'll not be possible to interact with the frame as it's not actually
    stopped in a breakpoint).
    '''

    def __init__(self, seq, thread_id, py_db, set_additional_thread_info, fmt, timeout=.5):
        InternalThreadCommand.__init__(self, thread_id)
        self._py_db = weakref.ref(py_db)
        self._timeout = time.time() + timeout
        self.seq = seq
        self._cmd = None
        self._fmt = fmt

        # Note: receives set_additional_thread_info to avoid a circular import
        # in this module.
        self._set_additional_thread_info = set_additional_thread_info

    @overrides(InternalThreadCommand.can_be_executed_by)
    def can_be_executed_by(self, _thread_id):
        timed_out = time.time() >= self._timeout

        py_db = self._py_db()
        t = pydevd_find_thread_by_id(self.thread_id)
        frame = None
        if t and not getattr(t, 'pydev_do_not_trace', None):
            additional_info = self._set_additional_thread_info(t)
            frame = additional_info.get_topmost_frame(t)
        try:
            self._cmd = py_db.cmd_factory.make_get_thread_stack_message(
                py_db, self.seq, self.thread_id, frame, self._fmt, must_be_suspended=not timed_out)
        finally:
            frame = None
            t = None

        return self._cmd is not None or timed_out

    @overrides(InternalThreadCommand.do_it)
    def do_it(self, dbg):
        if self._cmd is not None:
            dbg.writer.add_command(self._cmd)
            self._cmd = None


class InternalRunThread(InternalThreadCommand):

    def do_it(self, dbg):
        t = pydevd_find_thread_by_id(self.thread_id)
        if t:
            t.additional_info.pydev_step_cmd = -1
            t.additional_info.pydev_step_stop = None
            t.additional_info.pydev_state = STATE_RUN


class InternalStepThread(InternalThreadCommand):

    def __init__(self, thread_id, cmd_id):
        self.thread_id = thread_id
        self.cmd_id = cmd_id

    def do_it(self, dbg):
        t = pydevd_find_thread_by_id(self.thread_id)
        if t:
            t.additional_info.pydev_step_cmd = self.cmd_id
            t.additional_info.pydev_state = STATE_RUN


class InternalSetNextStatementThread(InternalThreadCommand):

    def __init__(self, thread_id, cmd_id, line, func_name, seq=0):
        self.thread_id = thread_id
        self.cmd_id = cmd_id
        self.line = line
        self.seq = seq

        if IS_PY2:
            if isinstance(func_name, unicode):
                # On cython with python 2.X it requires an str, not unicode (but on python 3.3 it should be a str, not bytes).
                func_name = func_name.encode('utf-8')

        self.func_name = func_name

    def do_it(self, dbg):
        t = pydevd_find_thread_by_id(self.thread_id)
        if t:
            t.additional_info.pydev_step_cmd = self.cmd_id
            t.additional_info.pydev_next_line = int(self.line)
            t.additional_info.pydev_func_name = self.func_name
            t.additional_info.pydev_state = STATE_RUN
            t.additional_info.pydev_message = str(self.seq)


def internal_get_variable_json(py_db, request):
    '''
        :param VariablesRequest request:
    '''
    arguments = request.arguments  # : :type arguments: VariablesArguments
    variables_reference = arguments.variablesReference
    fmt = arguments.format
    if hasattr(fmt, 'to_dict'):
        fmt = fmt.to_dict()

    variables = []
    try:
        variable = py_db.suspended_frames_manager.get_variable(variables_reference)
    except KeyError:
        pass
    else:
        for child_var in variable.get_children_variables(fmt=fmt):
            variables.append(child_var.get_var_data(fmt=fmt))

    body = VariablesResponseBody(variables)
    variables_response = pydevd_base_schema.build_response(request, kwargs={'body':body})
    py_db.writer.add_command(NetCommand(CMD_RETURN, 0, variables_response, is_json=True))


class InternalGetVariable(InternalThreadCommand):
    ''' gets the value of a variable '''

    def __init__(self, seq, thread_id, frame_id, scope, attrs):
        self.sequence = seq
        self.thread_id = thread_id
        self.frame_id = frame_id
        self.scope = scope
        self.attributes = attrs

    def do_it(self, dbg):
        ''' Converts request into python variable '''
        try:
            xml = StringIO.StringIO()
            xml.write("<xml>")
            _typeName, val_dict = pydevd_vars.resolve_compound_variable_fields(
                dbg, self.thread_id, self.frame_id, self.scope, self.attributes)
            if val_dict is None:
                val_dict = {}

            # assume properly ordered if resolver returns 'OrderedDict'
            # check type as string to support OrderedDict backport for older Python
            keys = dict_keys(val_dict)
            if not (_typeName == "OrderedDict" or val_dict.__class__.__name__ == "OrderedDict" or IS_PY36_OR_GREATER):
                keys.sort(key=compare_object_attrs_key)

            for k in keys:
                val = val_dict[k]
                evaluate_full_value = pydevd_xml.should_evaluate_full_value(val)
                xml.write(pydevd_xml.var_to_xml(val, k, evaluate_full_value=evaluate_full_value))

            xml.write("</xml>")
            cmd = dbg.cmd_factory.make_get_variable_message(self.sequence, xml.getvalue())
            xml.close()
            dbg.writer.add_command(cmd)
        except Exception:
            cmd = dbg.cmd_factory.make_error_message(
                self.sequence, "Error resolving variables %s" % (get_exception_traceback_str(),))
            dbg.writer.add_command(cmd)


class InternalGetArray(InternalThreadCommand):

    def __init__(self, seq, roffset, coffset, rows, cols, format, thread_id, frame_id, scope, attrs):
        self.sequence = seq
        self.thread_id = thread_id
        self.frame_id = frame_id
        self.scope = scope
        self.name = attrs.split("\t")[-1]
        self.attrs = attrs
        self.roffset = int(roffset)
        self.coffset = int(coffset)
        self.rows = int(rows)
        self.cols = int(cols)
        self.format = format

    def do_it(self, dbg):
        try:
            frame = dbg.find_frame(self.thread_id, self.frame_id)
            var = pydevd_vars.eval_in_context(self.name, frame.f_globals, frame.f_locals)
            xml = pydevd_vars.table_like_struct_to_xml(var, self.name, self.roffset, self.coffset, self.rows, self.cols, self.format)
            cmd = dbg.cmd_factory.make_get_array_message(self.sequence, xml)
            dbg.writer.add_command(cmd)
        except:
            cmd = dbg.cmd_factory.make_error_message(self.sequence, "Error resolving array: " + get_exception_traceback_str())
            dbg.writer.add_command(cmd)


def internal_change_variable(dbg, seq, thread_id, frame_id, scope, attr, value):
    ''' Changes the value of a variable '''
    try:
        frame = dbg.find_frame(thread_id, frame_id)
        if frame is not None:
            result = pydevd_vars.change_attr_expression(frame, attr, value, dbg)
        else:
            result = None
        xml = "<xml>"
        xml += pydevd_xml.var_to_xml(result, "")
        xml += "</xml>"
        cmd = dbg.cmd_factory.make_variable_changed_message(seq, xml)
        dbg.writer.add_command(cmd)
    except Exception:
        cmd = dbg.cmd_factory.make_error_message(seq, "Error changing variable attr:%s expression:%s traceback:%s" % (attr, value, get_exception_traceback_str()))
        dbg.writer.add_command(cmd)


def internal_change_variable_json(py_db, request):
    '''
    The pydevd_vars.change_attr_expression(thread_id, frame_id, attr, value, dbg) can only
    deal with changing at a frame level, so, currently changing the contents of something
    in a different scope is currently not supported.

    TODO: make the resolvers structure resolve the name and change accordingly -- for instance, the
    list resolver should change the value considering the index.

    :param SetVariableRequest request:
    '''
    # : :type arguments: SetVariableArguments
    arguments = request.arguments
    variables_reference = arguments.variablesReference
    fmt = arguments.format
    if hasattr(fmt, 'to_dict'):
        fmt = fmt.to_dict()

    # : :type frame: _FrameVariable
    frame_variable = py_db.suspended_frames_manager.get_variable(variables_reference)
    if hasattr(frame_variable, 'frame'):
        frame = frame_variable.frame

        pydevd_vars.change_attr_expression(frame, arguments.name, arguments.value, py_db)

        for child_var in frame_variable.get_children_variables(fmt=fmt):
            if child_var.get_name() == arguments.name:
                var_data = child_var.get_var_data(fmt=fmt)
                body = SetVariableResponseBody(
                    value=var_data['value'],
                    type=var_data['type'],
                    variablesReference=var_data.get('variablesReference'),
                    namedVariables=var_data.get('namedVariables'),
                    indexedVariables=var_data.get('indexedVariables'),
                )
                variables_response = pydevd_base_schema.build_response(request, kwargs={'body':body})
                py_db.writer.add_command(NetCommand(CMD_RETURN, 0, variables_response, is_json=True))
                break

    # If it's gotten here we haven't been able to evaluate it properly. Let the client know.
    body = SetVariableResponseBody('')
    variables_response = pydevd_base_schema.build_response(
        request,
        kwargs={
            'body':body,
            'success': False,
            'message': 'Unable to change: %s.' % (arguments.name,)
    })
    return NetCommand(CMD_RETURN, 0, variables_response, is_json=True)


def internal_get_frame(dbg, seq, thread_id, frame_id):
    ''' Converts request into python variable '''
    try:
        frame = dbg.find_frame(thread_id, frame_id)
        if frame is not None:
            hidden_ns = pydevconsole.get_ipython_hidden_vars()
            xml = "<xml>"
            xml += pydevd_xml.frame_vars_to_xml(frame.f_locals, hidden_ns)
            del frame
            xml += "</xml>"
            cmd = dbg.cmd_factory.make_get_frame_message(seq, xml)
            dbg.writer.add_command(cmd)
        else:
            # pydevd_vars.dump_frames(thread_id)
            # don't print this error: frame not found: means that the client is not synchronized (but that's ok)
            cmd = dbg.cmd_factory.make_error_message(seq, "Frame not found: %s from thread: %s" % (frame_id, thread_id))
            dbg.writer.add_command(cmd)
    except:
        cmd = dbg.cmd_factory.make_error_message(seq, "Error resolving frame: %s from thread: %s" % (frame_id, thread_id))
        dbg.writer.add_command(cmd)


def internal_get_next_statement_targets(dbg, seq, thread_id, frame_id):
    ''' gets the valid line numbers for use with set next statement '''
    try:
        frame = dbg.find_frame(thread_id, frame_id)
        if frame is not None:
            code = frame.f_code
            xml = "<xml>"
            if hasattr(code, 'co_lnotab'):
                lineno = code.co_firstlineno
                lnotab = code.co_lnotab
                for i in itertools.islice(lnotab, 1, len(lnotab), 2):
                    if isinstance(i, int):
                        lineno = lineno + i
                    else:
                        # in python 2 elements in co_lnotab are of type str
                        lineno = lineno + ord(i)
                    xml += "<line>%d</line>" % (lineno,)
            else:
                xml += "<line>%d</line>" % (frame.f_lineno,)
            del frame
            xml += "</xml>"
            cmd = dbg.cmd_factory.make_get_next_statement_targets_message(seq, xml)
            dbg.writer.add_command(cmd)
        else:
            cmd = dbg.cmd_factory.make_error_message(seq, "Frame not found: %s from thread: %s" % (frame_id, thread_id))
            dbg.writer.add_command(cmd)
    except:
        cmd = dbg.cmd_factory.make_error_message(seq, "Error resolving frame: %s from thread: %s" % (frame_id, thread_id))
        dbg.writer.add_command(cmd)


def _evaluate_response(py_db, request, result, error_message=''):
    is_error = isinstance(result, ExceptionOnEvaluate)
    if is_error:
        result = result.result
    if not error_message:
        body = pydevd_schema.EvaluateResponseBody(result=result, variablesReference=0)
        variables_response = pydevd_base_schema.build_response(request, kwargs={'body':body})
        py_db.writer.add_command(NetCommand(CMD_RETURN, 0, variables_response, is_json=True))
    else:
        body = pydevd_schema.EvaluateResponseBody(result='', variablesReference=0)
        variables_response = pydevd_base_schema.build_response(request, kwargs={
            'body':body, 'success':False, 'message': error_message})
        py_db.writer.add_command(NetCommand(CMD_RETURN, 0, variables_response, is_json=True))


def internal_evaluate_expression_json(py_db, request, thread_id):
    '''
    :param EvaluateRequest request:
    '''
    # : :type arguments: EvaluateArguments

    arguments = request.arguments
    expression = arguments.expression
    frame_id = arguments.frameId
    context = arguments.context
    fmt = arguments.format
    if hasattr(fmt, 'to_dict'):
        fmt = fmt.to_dict()

    if IS_PY2 and isinstance(expression, unicode):
        try:
            expression = expression.encode('utf-8')
        except:
            _evaluate_response(py_db, request, '', error_message='Expression is not valid utf-8.')
            raise

    frame = py_db.find_frame(thread_id, frame_id)
    result = pydevd_vars.evaluate_expression(py_db, frame, expression, is_exec=False)
    is_error = isinstance(result, ExceptionOnEvaluate)

    if is_error:
        if context == 'hover':
            _evaluate_response(py_db, request, result='')
            return

        elif context == 'repl':
            try:
                pydevd_vars.evaluate_expression(py_db, frame, expression, is_exec=True)
            except Exception as ex:
                err = ''.join(traceback.format_exception_only(type(ex), ex))
                _evaluate_response(py_db, request, result='', error_message=err)
                return
            # No result on exec.
            _evaluate_response(py_db, request, result='')
            return

    # Ok, we have the result (could be an error), let's put it into the saved variables.
    frame_tracker = py_db.suspended_frames_manager.get_frame_tracker(thread_id)
    if frame_tracker is None:
        # This is not really expected.
        _evaluate_response(py_db, request, result, error_message='Thread id: %s is not current thread id.' % (thread_id,))
        return

    variable = frame_tracker.obtain_as_variable(expression, result)
    var_data = variable.get_var_data(fmt=fmt)

    body = pydevd_schema.EvaluateResponseBody(
        result=var_data['value'],
        variablesReference=var_data.get('variablesReference', 0),
        type=var_data.get('type'),
        presentationHint=var_data.get('presentationHint'),
        namedVariables=var_data.get('namedVariables'),
        indexedVariables=var_data.get('indexedVariables'),
    )
    variables_response = pydevd_base_schema.build_response(request, kwargs={'body':body})
    py_db.writer.add_command(NetCommand(CMD_RETURN, 0, variables_response, is_json=True))


def internal_evaluate_expression(dbg, seq, thread_id, frame_id, expression, is_exec, trim_if_too_big, attr_to_set_result):
    ''' gets the value of a variable '''
    try:
        frame = dbg.find_frame(thread_id, frame_id)
        if frame is not None:
            result = pydevd_vars.evaluate_expression(dbg, frame, expression, is_exec)
            if attr_to_set_result != "":
                pydevd_vars.change_attr_expression(frame, attr_to_set_result, expression, dbg, result)
        else:
            result = None

        xml = "<xml>"
        xml += pydevd_xml.var_to_xml(result, expression, trim_if_too_big)
        xml += "</xml>"
        cmd = dbg.cmd_factory.make_evaluate_expression_message(seq, xml)
        dbg.writer.add_command(cmd)
    except:
        exc = get_exception_traceback_str()
        cmd = dbg.cmd_factory.make_error_message(seq, "Error evaluating expression " + exc)
        dbg.writer.add_command(cmd)


def _set_expression_response(py_db, request, result, error_message):
    body = pydevd_schema.SetExpressionResponseBody(result='', variablesReference=0)
    variables_response = pydevd_base_schema.build_response(request, kwargs={
        'body':body, 'success':False, 'message': error_message})
    py_db.writer.add_command(NetCommand(CMD_RETURN, 0, variables_response, is_json=True))


def internal_set_expression_json(py_db, request, thread_id):
    # : :type arguments: SetExpressionArguments

    arguments = request.arguments
    expression = arguments.expression
    frame_id = arguments.frameId
    value = arguments.value
    fmt = arguments.format
    if hasattr(fmt, 'to_dict'):
        fmt = fmt.to_dict()

    if IS_PY2 and isinstance(expression, unicode):
        try:
            expression = expression.encode('utf-8')
        except:
            _evaluate_response(py_db, request, '', error_message='Expression is not valid utf-8.')
            raise
    if IS_PY2 and isinstance(value, unicode):
        try:
            value = value.encode('utf-8')
        except:
            _evaluate_response(py_db, request, '', error_message='Value is not valid utf-8.')
            raise

    frame = py_db.find_frame(thread_id, frame_id)
    exec_code = '%s = (%s)' % (expression, value)
    result = pydevd_vars.evaluate_expression(py_db, frame, exec_code, is_exec=True)
    is_error = isinstance(result, ExceptionOnEvaluate)

    if is_error:
        _set_expression_response(py_db, request, result, error_message='Error executing: %s' % (exec_code,))
        return

    # Ok, we have the result (could be an error), let's put it into the saved variables.
    frame_tracker = py_db.suspended_frames_manager.get_frame_tracker(thread_id)
    if frame_tracker is None:
        # This is not really expected.
        _set_expression_response(py_db, request, result, error_message='Thread id: %s is not current thread id.' % (thread_id,))
        return

    # Now that the exec is done, get the actual value changed to return.
    result = pydevd_vars.evaluate_expression(py_db, frame, expression, is_exec=False)
    variable = frame_tracker.obtain_as_variable(expression, result)
    var_data = variable.get_var_data(fmt=fmt)

    body = pydevd_schema.SetExpressionResponseBody(
        value=var_data['value'],
        variablesReference=var_data.get('variablesReference', 0),
        type=var_data.get('type'),
        presentationHint=var_data.get('presentationHint'),
        namedVariables=var_data.get('namedVariables'),
        indexedVariables=var_data.get('indexedVariables'),
    )
    variables_response = pydevd_base_schema.build_response(request, kwargs={'body':body})
    py_db.writer.add_command(NetCommand(CMD_RETURN, 0, variables_response, is_json=True))


def internal_get_completions(dbg, seq, thread_id, frame_id, act_tok, line=-1, column=-1):
    '''
    Note that if the column is >= 0, the act_tok is considered text and the actual
    activation token/qualifier is computed in this command.
    '''
    try:
        remove_path = None
        try:
            qualifier = u''
            if column >= 0:
                token_and_qualifier = extract_token_and_qualifier(act_tok, line, column)
                act_tok = token_and_qualifier[0]
                if act_tok:
                    act_tok += u'.'
                qualifier = token_and_qualifier[1]

            frame = dbg.find_frame(thread_id, frame_id)
            if frame is not None:
                if IS_PY2:
                    if not isinstance(act_tok, bytes):
                        act_tok = act_tok.encode('utf-8')
                    if not isinstance(qualifier, bytes):
                        qualifier = qualifier.encode('utf-8')

                completions = _pydev_completer.generate_completions(frame, act_tok)

                # Note that qualifier and start are only actually valid for the
                # Debug Adapter Protocol (for the line-based protocol, the IDE
                # is required to filter the completions returned).
                cmd = dbg.cmd_factory.make_get_completions_message(
                    seq, completions, qualifier, start=column - len(qualifier))
                dbg.writer.add_command(cmd)
            else:
                cmd = dbg.cmd_factory.make_error_message(seq, "internal_get_completions: Frame not found: %s from thread: %s" % (frame_id, thread_id))
                dbg.writer.add_command(cmd)

        finally:
            if remove_path is not None:
                sys.path.remove(remove_path)

    except:
        exc = get_exception_traceback_str()
        sys.stderr.write('%s\n' % (exc,))
        cmd = dbg.cmd_factory.make_error_message(seq, "Error evaluating expression " + exc)
        dbg.writer.add_command(cmd)


def internal_get_description(dbg, seq, thread_id, frame_id, expression):
    ''' Fetch the variable description stub from the debug console
    '''
    try:
        frame = dbg.find_frame(thread_id, frame_id)
        description = pydevd_console.get_description(frame, thread_id, frame_id, expression)
        description = pydevd_xml.make_valid_xml_value(quote(description, '/>_= \t'))
        description_xml = '<xml><var name="" type="" value="%s"/></xml>' % description
        cmd = dbg.cmd_factory.make_get_description_message(seq, description_xml)
        dbg.writer.add_command(cmd)
    except:
        exc = get_exception_traceback_str()
        cmd = dbg.cmd_factory.make_error_message(seq, "Error in fetching description" + exc)
        dbg.writer.add_command(cmd)


def internal_get_exception_details_json(dbg, request, thread_id, max_frames, set_additional_thread_info=None, iter_visible_frames_info=None):
    ''' Fetch exception details
    '''
    try:
        thread = pydevd_find_thread_by_id(thread_id)
        additional_info = set_additional_thread_info(thread)
        topmost_frame = additional_info.get_topmost_frame(thread)

        frames = []
        exc_type = None
        exc_desc = None
        if topmost_frame is not None:
            frame_id_to_lineno = {}
            try:
                trace_obj = None
                frame = topmost_frame
                while frame is not None:
                    if frame.f_code.co_name == 'do_wait_suspend' and frame.f_code.co_filename.endswith('pydevd.py'):
                        arg = frame.f_locals.get('arg', None)
                        if arg is not None:
                            exc_type, exc_desc, trace_obj = arg
                            break
                    frame = frame.f_back

                while trace_obj.tb_next is not None:
                    trace_obj = trace_obj.tb_next

                info = dbg.suspended_frames_manager.get_topmost_frame_and_frame_id_to_line(thread_id)
                if info is not None:
                    topmost_frame, frame_id_to_lineno = info

                if trace_obj is not None:
                    for frame_id, frame, method_name, filename_in_utf8, lineno in iter_visible_frames_info(
                            dbg, trace_obj.tb_frame, frame_id_to_lineno):

                        line_text = linecache.getline(filename_in_utf8, lineno)

                        # Never filter out plugin frames!
                        if not getattr(frame, 'IS_PLUGIN_FRAME', False):
                            if not dbg.in_project_scope(filename_in_utf8):
                                if not dbg.get_use_libraries_filter():
                                    continue
                        frames.append((filename_in_utf8, lineno, method_name, line_text))
            finally:
                topmost_frame = None

        name = 'exception: type unknown'
        if exc_type is not None:
            try:
                name = exc_type.__qualname__
            except:
                try:
                    name = exc_type.__name__
                except:
                    try:
                        name = str(exc_type)
                    except:
                        pass

        description = 'exception: no description'
        if exc_desc is not None:
            try:
                description = str(exc_desc)
            except:
                pass

        stack_str = ''.join(traceback.format_list(frames[-max_frames:]))

        # This is an extra bit of data used by Visual Studio
        source_path = frames[0][0] if frames else ''

        if thread.stop_reason == CMD_STEP_CAUGHT_EXCEPTION:
            break_mode = pydevd_schema.ExceptionBreakMode.ALWAYS
        else:
            break_mode = pydevd_schema.ExceptionBreakMode.UNHANDLED

        response = pydevd_schema.ExceptionInfoResponse(
            request_seq=request.seq,
            success=True,
            command='exceptionInfo',
            body=pydevd_schema.ExceptionInfoResponseBody(
                exceptionId=name,
                description=description,
                breakMode=break_mode,
                details=pydevd_schema.ExceptionDetails(
                    message=description,
                    typeName=name,
                    stackTrace=stack_str,
                    source=source_path
                )
            )
        )
    except:
        exc = get_exception_traceback_str()
        response = pydevd_base_schema.build_response(request, kwargs={
            'success': False,
            'message': exc,
            'body':{}
        })
    dbg.writer.add_command(NetCommand(CMD_RETURN, 0, response, is_json=True))


class InternalGetBreakpointException(InternalThreadCommand):
    ''' Send details of exception raised while evaluating conditional breakpoint '''

    def __init__(self, thread_id, exc_type, stacktrace):
        self.sequence = 0
        self.thread_id = thread_id
        self.stacktrace = stacktrace
        self.exc_type = exc_type

    def do_it(self, dbg):
        try:
            callstack = "<xml>"

            makeValid = pydevd_xml.make_valid_xml_value

            for filename, line, methodname, methodobj in self.stacktrace:
                if not filesystem_encoding_is_utf8 and hasattr(filename, "decode"):
                    # filename is a byte string encoded using the file system encoding
                    # convert it to utf8
                    filename = filename.decode(file_system_encoding).encode("utf-8")

                callstack += '<frame thread_id = "%s" file="%s" line="%s" name="%s" obj="%s" />' \
                                    % (self.thread_id, makeValid(filename), line, makeValid(methodname), makeValid(methodobj))
            callstack += "</xml>"

            cmd = dbg.cmd_factory.make_send_breakpoint_exception_message(self.sequence, self.exc_type + "\t" + callstack)
            dbg.writer.add_command(cmd)
        except:
            exc = get_exception_traceback_str()
            sys.stderr.write('%s\n' % (exc,))
            cmd = dbg.cmd_factory.make_error_message(self.sequence, "Error Sending Exception: " + exc)
            dbg.writer.add_command(cmd)


class InternalSendCurrExceptionTrace(InternalThreadCommand):
    ''' Send details of the exception that was caught and where we've broken in.
    '''

    def __init__(self, thread_id, arg, curr_frame_id):
        '''
        :param arg: exception type, description, traceback object
        '''
        self.sequence = 0
        self.thread_id = thread_id
        self.curr_frame_id = curr_frame_id
        self.arg = arg

    def do_it(self, dbg):
        try:
            cmd = dbg.cmd_factory.make_send_curr_exception_trace_message(self.sequence, self.thread_id, self.curr_frame_id, *self.arg)
            del self.arg
            dbg.writer.add_command(cmd)
        except:
            exc = get_exception_traceback_str()
            sys.stderr.write('%s\n' % (exc,))
            cmd = dbg.cmd_factory.make_error_message(self.sequence, "Error Sending Current Exception Trace: " + exc)
            dbg.writer.add_command(cmd)


class InternalSendCurrExceptionTraceProceeded(InternalThreadCommand):
    ''' Send details of the exception that was caught and where we've broken in.
    '''

    def __init__(self, thread_id):
        self.sequence = 0
        self.thread_id = thread_id

    def do_it(self, dbg):
        try:
            cmd = dbg.cmd_factory.make_send_curr_exception_trace_proceeded_message(self.sequence, self.thread_id)
            dbg.writer.add_command(cmd)
        except:
            exc = get_exception_traceback_str()
            sys.stderr.write('%s\n' % (exc,))
            cmd = dbg.cmd_factory.make_error_message(self.sequence, "Error Sending Current Exception Trace Proceeded: " + exc)
            dbg.writer.add_command(cmd)


class InternalEvaluateConsoleExpression(InternalThreadCommand):
    ''' Execute the given command in the debug console '''

    def __init__(self, seq, thread_id, frame_id, line, buffer_output=True):
        self.sequence = seq
        self.thread_id = thread_id
        self.frame_id = frame_id
        self.line = line
        self.buffer_output = buffer_output

    def do_it(self, dbg):
        ''' Create an XML for console output, error and more (true/false)
        <xml>
            <output message=output_message></output>
            <error message=error_message></error>
            <more>true/false</more>
        </xml>
        '''
        try:
            frame = dbg.find_frame(self.thread_id, self.frame_id)
            if frame is not None:
                console_message = pydevd_console.execute_console_command(
                    frame, self.thread_id, self.frame_id, self.line, self.buffer_output)

                cmd = dbg.cmd_factory.make_send_console_message(self.sequence, console_message.to_xml())
            else:
                from _pydevd_bundle.pydevd_console import ConsoleMessage
                console_message = ConsoleMessage()
                console_message.add_console_message(
                    pydevd_console.CONSOLE_ERROR,
                    "Select the valid frame in the debug view (thread: %s, frame: %s invalid)" % (self.thread_id, self.frame_id),
                )
                cmd = dbg.cmd_factory.make_error_message(self.sequence, console_message.to_xml())
        except:
            exc = get_exception_traceback_str()
            cmd = dbg.cmd_factory.make_error_message(self.sequence, "Error evaluating expression " + exc)
        dbg.writer.add_command(cmd)


class InternalRunCustomOperation(InternalThreadCommand):
    ''' Run a custom command on an expression
    '''

    def __init__(self, seq, thread_id, frame_id, scope, attrs, style, encoded_code_or_file, fnname):
        self.sequence = seq
        self.thread_id = thread_id
        self.frame_id = frame_id
        self.scope = scope
        self.attrs = attrs
        self.style = style
        self.code_or_file = unquote_plus(encoded_code_or_file)
        self.fnname = fnname

    def do_it(self, dbg):
        try:
            res = pydevd_vars.custom_operation(dbg, self.thread_id, self.frame_id, self.scope, self.attrs,
                                              self.style, self.code_or_file, self.fnname)
            resEncoded = quote_plus(res)
            cmd = dbg.cmd_factory.make_custom_operation_message(self.sequence, resEncoded)
            dbg.writer.add_command(cmd)
        except:
            exc = get_exception_traceback_str()
            cmd = dbg.cmd_factory.make_error_message(self.sequence, "Error in running custom operation" + exc)
            dbg.writer.add_command(cmd)


class InternalConsoleGetCompletions(InternalThreadCommand):
    ''' Fetch the completions in the debug console
    '''

    def __init__(self, seq, thread_id, frame_id, act_tok):
        self.sequence = seq
        self.thread_id = thread_id
        self.frame_id = frame_id
        self.act_tok = act_tok

    def do_it(self, dbg):
        ''' Get completions and write back to the client
        '''
        try:
            frame = dbg.find_frame(self.thread_id, self.frame_id)
            completions_xml = pydevd_console.get_completions(frame, self.act_tok)
            cmd = dbg.cmd_factory.make_send_console_message(self.sequence, completions_xml)
            dbg.writer.add_command(cmd)
        except:
            exc = get_exception_traceback_str()
            cmd = dbg.cmd_factory.make_error_message(self.sequence, "Error in fetching completions" + exc)
            dbg.writer.add_command(cmd)


class InternalConsoleExec(InternalThreadCommand):
    ''' gets the value of a variable '''

    def __init__(self, seq, thread_id, frame_id, expression):
        self.sequence = seq
        self.thread_id = thread_id
        self.frame_id = frame_id
        self.expression = expression

    def do_it(self, dbg):
        ''' Converts request into python variable '''
        try:
            try:
                # don't trace new threads created by console command
                disable_trace_thread_modules()

                result = pydevconsole.console_exec(self.thread_id, self.frame_id, self.expression, dbg)
                xml = "<xml>"
                xml += pydevd_xml.var_to_xml(result, "")
                xml += "</xml>"
                cmd = dbg.cmd_factory.make_evaluate_expression_message(self.sequence, xml)
                dbg.writer.add_command(cmd)
            except:
                exc = get_exception_traceback_str()
                sys.stderr.write('%s\n' % (exc,))
                cmd = dbg.cmd_factory.make_error_message(self.sequence, "Error evaluating console expression " + exc)
                dbg.writer.add_command(cmd)
        finally:
            enable_trace_thread_modules()

            sys.stderr.flush()
            sys.stdout.flush()


class InternalLoadFullValue(InternalThreadCommand):
    '''
    Loads values asynchronously
    '''

    def __init__(self, seq, thread_id, frame_id, vars):
        self.sequence = seq
        self.thread_id = thread_id
        self.frame_id = frame_id
        self.vars = vars

    def do_it(self, dbg):
        '''Starts a thread that will load values asynchronously'''
        try:
            var_objects = []
            for variable in self.vars:
                variable = variable.strip()
                if len(variable) > 0:
                    if '\t' in variable:  # there are attributes beyond scope
                        scope, attrs = variable.split('\t', 1)
                        name = attrs[0]
                    else:
                        scope, attrs = (variable, None)
                        name = scope
                    var_obj = pydevd_vars.getVariable(dbg, self.thread_id, self.frame_id, scope, attrs)
                    var_objects.append((var_obj, name))

            t = GetValueAsyncThreadDebug(dbg, self.sequence, var_objects)
            t.start()
        except:
            exc = get_exception_traceback_str()
            sys.stderr.write('%s\n' % (exc,))
            cmd = dbg.cmd_factory.make_error_message(self.sequence, "Error evaluating variable %s " % exc)
            dbg.writer.add_command(cmd)


class AbstractGetValueAsyncThread(PyDBDaemonThread):
    '''
    Abstract class for a thread, which evaluates values for async variables
    '''

    def __init__(self, frame_accessor, seq, var_objects):
        PyDBDaemonThread.__init__(self)
        self.frame_accessor = frame_accessor
        self.seq = seq
        self.var_objs = var_objects
        self.cancel_event = threading.Event()

    def send_result(self, xml):
        raise NotImplementedError()

    @overrides(PyDBDaemonThread._on_run)
    def _on_run(self):
        start = time.time()
        xml = StringIO.StringIO()
        xml.write("<xml>")
        for (var_obj, name) in self.var_objs:
            current_time = time.time()
            if current_time - start > ASYNC_EVAL_TIMEOUT_SEC or self.cancel_event.is_set():
                break
            xml.write(pydevd_xml.var_to_xml(var_obj, name, evaluate_full_value=True))
        xml.write("</xml>")
        self.send_result(xml)
        xml.close()


class GetValueAsyncThreadDebug(AbstractGetValueAsyncThread):
    '''
    A thread for evaluation async values, which returns result for debugger
    Create message and send it via writer thread
    '''

    def send_result(self, xml):
        if self.frame_accessor is not None:
            cmd = self.frame_accessor.cmd_factory.make_load_full_value_message(self.seq, xml.getvalue())
            self.frame_accessor.writer.add_command(cmd)


class GetValueAsyncThreadConsole(AbstractGetValueAsyncThread):
    '''
    A thread for evaluation async values, which returns result for Console
    Send result directly to Console's server
    '''

    def send_result(self, xml):
        if self.frame_accessor is not None:
            self.frame_accessor.ReturnFullValue(self.seq, xml.getvalue())


def pydevd_find_thread_by_id(thread_id):
    try:
        # there was a deadlock here when I did not remove the tracing function when thread was dead
        threads = threading.enumerate()
        for i in threads:
            tid = get_thread_id(i)
            if thread_id == tid or thread_id.endswith('|' + tid):
                return i

        # This can happen when a request comes for a thread which was previously removed.
        pydevd_log(1, "Could not find thread %s\n" % (thread_id,))
        pydevd_log(1, "Available: %s\n" % ([get_thread_id(t) for t in threads],))
    except:
        traceback.print_exc()

    return None
