"""The IPython kernel implementation"""

import asyncio
import builtins
from contextlib import contextmanager
from functools import partial
import getpass
import signal
import sys

from IPython.core import release
from IPython.utils.tokenutil import token_at_cursor, line_at_cursor
from traitlets import Instance, Type, Any, List, Bool, observe, observe_compat
from zmq.eventloop.zmqstream import ZMQStream

from .comm import CommManager
from .kernelbase import Kernel as KernelBase
from .zmqshell import ZMQInteractiveShell
from .eventloops import _use_appnope
from .debugger import Debugger
from .compiler import XCachingCompiler

try:
    from IPython.core.interactiveshell import _asyncio_runner
except ImportError:
    _asyncio_runner = None

try:
    from IPython.core.completer import (
        rectify_completions as _rectify_completions,
        provisionalcompleter as _provisionalcompleter,
    )
    _use_experimental_60_completion = True
except ImportError:
    _use_experimental_60_completion = False

_EXPERIMENTAL_KEY_NAME = '_jupyter_types_experimental'


class IPythonKernel(KernelBase):
    shell = Instance('IPython.core.interactiveshell.InteractiveShellABC',
                     allow_none=True)
    shell_class = Type(ZMQInteractiveShell)

    use_experimental_completions = Bool(True,
        help="Set this flag to False to deactivate the use of experimental IPython completion APIs.",
    ).tag(config=True)

    debugpy_stream = Instance(ZMQStream, allow_none=True)

    user_module = Any()
    @observe('user_module')
    @observe_compat
    def _user_module_changed(self, change):
        if self.shell is not None:
            self.shell.user_module = change['new']

    user_ns = Instance(dict, args=None, allow_none=True)
    @observe('user_ns')
    @observe_compat
    def _user_ns_changed(self, change):
        if self.shell is not None:
            self.shell.user_ns = change['new']
            self.shell.init_user_ns()

    # A reference to the Python builtin 'raw_input' function.
    # (i.e., __builtin__.raw_input for Python 2.7, builtins.input for Python 3)
    _sys_raw_input = Any()
    _sys_eval_input = Any()

    def __init__(self, **kwargs):
        super(IPythonKernel, self).__init__(**kwargs)

        # Initialize the Debugger
        self.debugger = Debugger(self.log,
                                 self.debugpy_stream,
                                 self._publish_debug_event,
                                 self.debug_shell_socket,
                                 self.session)

        # Initialize the InteractiveShell subclass
        self.shell = self.shell_class.instance(parent=self,
            profile_dir = self.profile_dir,
            user_module = self.user_module,
            user_ns     = self.user_ns,
            kernel      = self,
            compiler_class = XCachingCompiler,
        )
        self.shell.displayhook.session = self.session
        self.shell.displayhook.pub_socket = self.iopub_socket
        self.shell.displayhook.topic = self._topic('execute_result')
        self.shell.display_pub.session = self.session
        self.shell.display_pub.pub_socket = self.iopub_socket

        self.comm_manager = CommManager(parent=self, kernel=self)

        self.shell.configurables.append(self.comm_manager)
        comm_msg_types = [ 'comm_open', 'comm_msg', 'comm_close' ]
        for msg_type in comm_msg_types:
            self.shell_handlers[msg_type] = getattr(self.comm_manager, msg_type)

        if _use_appnope() and self._darwin_app_nap:
            # Disable app-nap as the kernel is not a gui but can have guis
            import appnope
            appnope.nope()

    help_links = List([
        {
            'text': "Python Reference",
            'url': "https://docs.python.org/%i.%i" % sys.version_info[:2],
        },
        {
            'text': "IPython Reference",
            'url': "https://ipython.org/documentation.html",
        },
        {
            'text': "NumPy Reference",
            'url': "https://docs.scipy.org/doc/numpy/reference/",
        },
        {
            'text': "SciPy Reference",
            'url': "https://docs.scipy.org/doc/scipy/reference/",
        },
        {
            'text': "Matplotlib Reference",
            'url': "https://matplotlib.org/contents.html",
        },
        {
            'text': "SymPy Reference",
            'url': "http://docs.sympy.org/latest/index.html",
        },
        {
            'text': "pandas Reference",
            'url': "https://pandas.pydata.org/pandas-docs/stable/",
        },
    ]).tag(config=True)

    # Kernel info fields
    implementation = 'ipython'
    implementation_version = release.version
    language_info = {
        'name': 'python',
        'version': sys.version.split()[0],
        'mimetype': 'text/x-python',
        'codemirror_mode': {
            'name': 'ipython',
            'version': sys.version_info[0]
        },
        'pygments_lexer': 'ipython%d' % 3,
        'nbconvert_exporter': 'python',
        'file_extension': '.py'
    }

    def dispatch_debugpy(self, msg):
        # The first frame is the socket id, we can drop it
        frame = msg[1].bytes.decode('utf-8')
        self.log.debug("Debugpy received: %s", frame)
        self.debugger.tcp_client.receive_dap_frame(frame)

    @property
    def banner(self):
        return self.shell.banner

    def start(self):
        self.shell.exit_now = False
        if self.debugpy_stream is None:
            self.log.warning("debugpy_stream undefined, debugging will not be enabled")
        else:
            self.debugpy_stream.on_recv(self.dispatch_debugpy, copy=False)
        super(IPythonKernel, self).start()

    def set_parent(self, ident, parent, channel='shell'):
        """Overridden from parent to tell the display hook and output streams
        about the parent message.
        """
        super(IPythonKernel, self).set_parent(ident, parent, channel)
        if channel == 'shell':
            self.shell.set_parent(parent)

    def init_metadata(self, parent):
        """Initialize metadata.

        Run at the beginning of each execution request.
        """
        md = super(IPythonKernel, self).init_metadata(parent)
        # FIXME: remove deprecated ipyparallel-specific code
        # This is required for ipyparallel < 5.0
        md.update({
            'dependencies_met' : True,
            'engine' : self.ident,
        })
        return md

    def finish_metadata(self, parent, metadata, reply_content):
        """Finish populating metadata.

        Run after completing an execution request.
        """
        # FIXME: remove deprecated ipyparallel-specific code
        # This is required by ipyparallel < 5.0
        metadata["status"] = reply_content["status"]
        if (
            reply_content["status"] == "error"
            and reply_content["ename"] == "UnmetDependency"
        ):
            metadata["dependencies_met"] = False

        return metadata

    def _forward_input(self, allow_stdin=False):
        """Forward raw_input and getpass to the current frontend.

        via input_request
        """
        self._allow_stdin = allow_stdin

        self._sys_raw_input = builtins.input
        builtins.input = self.raw_input

        self._save_getpass = getpass.getpass
        getpass.getpass = self.getpass

    def _restore_input(self):
        """Restore raw_input, getpass"""
        builtins.input = self._sys_raw_input

        getpass.getpass = self._save_getpass

    @property
    def execution_count(self):
        return self.shell.execution_count

    @execution_count.setter
    def execution_count(self, value):
        # Ignore the incrementing done by KernelBase, in favour of our shell's
        # execution counter.
        pass

    @contextmanager
    def _cancel_on_sigint(self, future):
        """ContextManager for capturing SIGINT and cancelling a future

        SIGINT raises in the event loop when running async code,
        but we want it to halt a coroutine.

        Ideally, it would raise KeyboardInterrupt,
        but this turns it into a CancelledError.
        At least it gets a decent traceback to the user.
        """
        sigint_future = asyncio.Future()

        # whichever future finishes first,
        # cancel the other one
        def cancel_unless_done(f, _ignored):
            if f.cancelled() or f.done():
                return
            f.cancel()

        # when sigint finishes,
        # abort the coroutine with CancelledError
        sigint_future.add_done_callback(
            partial(cancel_unless_done, future)
        )
        # when the main future finishes,
        # stop watching for SIGINT events
        future.add_done_callback(
            partial(cancel_unless_done, sigint_future)
        )

        def handle_sigint(*args):
            def set_sigint_result():
                if sigint_future.cancelled() or sigint_future.done():
                    return
                sigint_future.set_result(1)
            # use add_callback for thread safety
            self.io_loop.add_callback(set_sigint_result)

        # set the custom sigint hander during this context
        save_sigint = signal.signal(signal.SIGINT, handle_sigint)
        try:
            yield
        finally:
            # restore the previous sigint handler
            signal.signal(signal.SIGINT, save_sigint)

    async def do_execute(self, code, silent, store_history=True,
                         user_expressions=None, allow_stdin=False):
        shell = self.shell # we'll need this a lot here

        self._forward_input(allow_stdin)

        reply_content = {}
        if hasattr(shell, 'run_cell_async') and hasattr(shell, 'should_run_async'):
            run_cell = shell.run_cell_async
            should_run_async = shell.should_run_async
        else:
            should_run_async = lambda cell: False
            # older IPython,
            # use blocking run_cell and wrap it in coroutine
            async def run_cell(*args, **kwargs):
                return shell.run_cell(*args, **kwargs)
        try:

            # default case: runner is asyncio and asyncio is already running
            # TODO: this should check every case for "are we inside the runner",
            # not just asyncio
            preprocessing_exc_tuple = None
            try:
                transformed_cell = self.shell.transform_cell(code)
            except Exception:
                transformed_cell = code
                preprocessing_exc_tuple = sys.exc_info()

            if (
                _asyncio_runner
                and shell.loop_runner is _asyncio_runner
                and asyncio.get_event_loop().is_running()
                and should_run_async(
                    code,
                    transformed_cell=transformed_cell,
                    preprocessing_exc_tuple=preprocessing_exc_tuple,
                )
            ):
                coro = run_cell(
                    code,
                    store_history=store_history,
                    silent=silent,
                    transformed_cell=transformed_cell,
                    preprocessing_exc_tuple=preprocessing_exc_tuple
                )
                coro_future = asyncio.ensure_future(coro)

                with self._cancel_on_sigint(coro_future):
                    res = None
                    try:
                        res = await coro_future
                    finally:
                        shell.events.trigger('post_execute')
                        if not silent:
                            shell.events.trigger('post_run_cell', res)
            else:
                # runner isn't already running,
                # make synchronous call,
                # letting shell dispatch to loop runners
                res = shell.run_cell(code, store_history=store_history, silent=silent)
        finally:
            self._restore_input()

        if res.error_before_exec is not None:
            err = res.error_before_exec
        else:
            err = res.error_in_exec

        if res.success:
            reply_content['status'] = 'ok'
        else:
            reply_content['status'] = 'error'

            reply_content.update({
                'traceback': shell._last_traceback or [],
                'ename': str(type(err).__name__),
                'evalue': str(err),
            })

            # FIXME: deprecated piece for ipyparallel (remove in 5.0):
            e_info = dict(engine_uuid=self.ident, engine_id=self.int_id,
                          method='execute')
            reply_content['engine_info'] = e_info


        # Return the execution counter so clients can display prompts
        reply_content['execution_count'] = shell.execution_count - 1

        if 'traceback' in reply_content:
            self.log.info("Exception in execute request:\n%s", '\n'.join(reply_content['traceback']))


        # At this point, we can tell whether the main code execution succeeded
        # or not.  If it did, we proceed to evaluate user_expressions
        if reply_content['status'] == 'ok':
            reply_content['user_expressions'] = \
                         shell.user_expressions(user_expressions or {})
        else:
            # If there was an error, don't even try to compute expressions
            reply_content['user_expressions'] = {}

        # Payloads should be retrieved regardless of outcome, so we can both
        # recover partial output (that could have been generated early in a
        # block, before an error) and always clear the payload system.
        reply_content['payload'] = shell.payload_manager.read_payload()
        # Be aggressive about clearing the payload because we don't want
        # it to sit in memory until the next execute_request comes in.
        shell.payload_manager.clear_payload()

        return reply_content

    def do_complete(self, code, cursor_pos):
        if _use_experimental_60_completion and self.use_experimental_completions:
            return self._experimental_do_complete(code, cursor_pos)

        # FIXME: IPython completers currently assume single line,
        # but completion messages give multi-line context
        # For now, extract line from cell, based on cursor_pos:
        if cursor_pos is None:
            cursor_pos = len(code)
        line, offset = line_at_cursor(code, cursor_pos)
        line_cursor = cursor_pos - offset

        txt, matches = self.shell.complete('', line, line_cursor)
        return {'matches' : matches,
                'cursor_end' : cursor_pos,
                'cursor_start' : cursor_pos - len(txt),
                'metadata' : {},
                'status' : 'ok'}

    async def do_debug_request(self, msg):
        return await self.debugger.process_request(msg)

    def _experimental_do_complete(self, code, cursor_pos):
        """
        Experimental completions from IPython, using Jedi.
        """
        if cursor_pos is None:
            cursor_pos = len(code)
        with _provisionalcompleter():
            raw_completions = self.shell.Completer.completions(code, cursor_pos)
            completions = list(_rectify_completions(code, raw_completions))

            comps = []
            for comp in completions:
                comps.append(dict(
                            start=comp.start,
                            end=comp.end,
                            text=comp.text,
                            type=comp.type,
                ))

        if completions:
            s = completions[0].start
            e = completions[0].end
            matches = [c.text for c in completions]
        else:
            s = cursor_pos
            e = cursor_pos
            matches = []

        return {'matches': matches,
                'cursor_end': e,
                'cursor_start': s,
                'metadata': {_EXPERIMENTAL_KEY_NAME: comps},
                'status': 'ok'}

    def do_inspect(self, code, cursor_pos, detail_level=0):
        name = token_at_cursor(code, cursor_pos)

        reply_content = {'status' : 'ok'}
        reply_content['data'] = {}
        reply_content['metadata'] = {}
        try:
            reply_content['data'].update(
                self.shell.object_inspect_mime(
                    name,
                    detail_level=detail_level
                )
            )
            if not self.shell.enable_html_pager:
                reply_content['data'].pop('text/html')
            reply_content['found'] = True
        except KeyError:
            reply_content['found'] = False

        return reply_content

    def do_history(self, hist_access_type, output, raw, session=0, start=0,
                   stop=None, n=None, pattern=None, unique=False):
        if hist_access_type == 'tail':
            hist = self.shell.history_manager.get_tail(n, raw=raw, output=output,
                                                            include_latest=True)

        elif hist_access_type == 'range':
            hist = self.shell.history_manager.get_range(session, start, stop,
                                                        raw=raw, output=output)

        elif hist_access_type == 'search':
            hist = self.shell.history_manager.search(
                pattern, raw=raw, output=output, n=n, unique=unique)
        else:
            hist = []

        return {
            'status': 'ok',
            'history' : list(hist),
        }

    def do_shutdown(self, restart):
        self.shell.exit_now = True
        return dict(status='ok', restart=restart)

    def do_is_complete(self, code):
        transformer_manager = getattr(self.shell, 'input_transformer_manager', None)
        if transformer_manager is None:
            # input_splitter attribute is deprecated
            transformer_manager = self.shell.input_splitter
        status, indent_spaces = transformer_manager.check_complete(code)
        r = {'status': status}
        if status == 'incomplete':
            r['indent'] = ' ' * indent_spaces
        return r

    def do_apply(self, content, bufs, msg_id, reply_metadata):
        from .serialize import serialize_object, unpack_apply_message
        shell = self.shell
        try:
            working = shell.user_ns

            prefix = "_"+str(msg_id).replace("-","")+"_"

            f,args,kwargs = unpack_apply_message(bufs, working, copy=False)

            fname = getattr(f, '__name__', 'f')

            fname = prefix+"f"
            argname = prefix+"args"
            kwargname = prefix+"kwargs"
            resultname = prefix+"result"

            ns = { fname : f, argname : args, kwargname : kwargs , resultname : None }
            # print ns
            working.update(ns)
            code = "%s = %s(*%s,**%s)" % (resultname, fname, argname, kwargname)
            try:
                exec(code, shell.user_global_ns, shell.user_ns)
                result = working.get(resultname)
            finally:
                for key in ns:
                    working.pop(key)

            result_buf = serialize_object(result,
                buffer_threshold=self.session.buffer_threshold,
                item_threshold=self.session.item_threshold,
            )

        except BaseException as e:
            # invoke IPython traceback formatting
            shell.showtraceback()
            reply_content = {
                "traceback": shell._last_traceback or [],
                "ename": str(type(e).__name__),
                "evalue": str(e),
            }
            # FIXME: deprecated piece for ipyparallel (remove in 5.0):
            e_info = dict(engine_uuid=self.ident, engine_id=self.int_id, method='apply')
            reply_content['engine_info'] = e_info

            self.send_response(self.iopub_socket, 'error', reply_content,
                               ident=self._topic('error'), channel='shell')
            self.log.info("Exception in apply request:\n%s", '\n'.join(reply_content['traceback']))
            result_buf = []
            reply_content['status'] = 'error'
        else:
            reply_content = {'status' : 'ok'}

        return reply_content, result_buf

    def do_clear(self):
        self.shell.reset(False)
        return dict(status='ok')


# This exists only for backwards compatibility - use IPythonKernel instead

class Kernel(IPythonKernel):
    def __init__(self, *args, **kwargs):
        import warnings
        warnings.warn('Kernel is a deprecated alias of ipykernel.ipkernel.IPythonKernel',
                      DeprecationWarning)
        super(Kernel, self).__init__(*args, **kwargs)
