"""Callbacks available from R's C-API.

The callbacks make available in R's C-API can be specified as
Python functions, with the module providing the adapter code
that makes it possible."""

from contextlib import contextmanager
import logging
import sys
import typing
import warnings
import os
from rpy2.rinterface_lib import openrlib
from rpy2.rinterface_lib import ffi_proxy
from rpy2.rinterface_lib import conversion

logger = logging.getLogger(__name__)

_CCHAR_ENCODING = sys.getdefaultencoding()
_READCONSOLE_EXCEPTION_LOG = (
    'R callback read-console: {exception} {exc_value} {traceback}'
)
_WRITECONSOLE_EXCEPTION_LOG = (
    'R callback write-console: {exception} {exc_value} {traceback}'
)
_POLLEDEVENTS_EXCEPTION_LOG = (
    'R callback polled-events: {exception} {exc_value} {traceback}'
)


# TODO: rename to "replace_in_module"
@contextmanager
def obj_in_module(module, name: str, obj: typing.Any):
    warnings.warn(
        '"obj_in_module" was renamed to "replace_in_module".',
        DeprecationWarning
    )
    obj_orig = getattr(module, name)
    setattr(module, name, obj)
    try:
        yield
    finally:
        setattr(module, name, obj_orig)


@contextmanager
def replace_in_module(module, name: str, obj: typing.Any):
    obj_orig = getattr(module, name)
    setattr(module, name, obj)
    try:
        yield
    finally:
        setattr(module, name, obj_orig)


def handler_callback_error(log_template):
    def func(exception, exc_value, traceback):
        logger.error(
            log_template.format(
                exception=exception,
                exc_value=exc_value,
                traceback=traceback
            )
        )
    return func


def consoleflush():
    pass


_FLUSHCONSOLE_EXCEPTION_LOG = 'R[flush console]: %s'


@ffi_proxy.callback(ffi_proxy._consoleflush_def,
                    openrlib._rinterface_cffi)
def _consoleflush() -> None:
    try:
        with openrlib.rlock:
            consoleflush()
    except Exception as e:
        logger.error(_FLUSHCONSOLE_EXCEPTION_LOG, str(e))


def consoleread(prompt: str) -> str:
    """Read input for the R console.

    :param prompt: The message prompted.
    :return: A string with the input returned by the user.
    """
    return input(prompt)


@ffi_proxy.callback(ffi_proxy._consoleread_def,
                    openrlib._rinterface_cffi,
                    error=0,
                    onerror=handler_callback_error(_READCONSOLE_EXCEPTION_LOG))
def _consoleread(prompt, buf, n: int, addtohistory) -> int:
    success = None
    s = conversion._cchar_to_str(prompt, _CCHAR_ENCODING)
    with openrlib.rlock:
        reply = consoleread(s)

    # TODO: Should the coding be dynamically extracted from
    # elsewhere ?
    reply_b = reply.encode('utf-8')
    reply_n = min(n, len(reply_b))
    pybuf = bytearray(n)
    pybuf[:reply_n] = reply_b[:reply_n]
    pybuf[reply_n] = ord('\n')
    pybuf[reply_n+1] = 0
    openrlib.ffi.memmove(buf,
                         pybuf,
                         n)
    if reply_n == 0:
        success = 0
    else:
        success = 1
    return success


def consolereset() -> None:
    pass


_RESETCONSOLE_EXCEPTION_LOG = 'R[reset console]: %s'


@ffi_proxy.callback(ffi_proxy._consolereset_def,
                    openrlib._rinterface_cffi)
def _consolereset() -> None:
    try:
        with openrlib.rlock:
            consolereset()
    except Exception as e:
        logger.error(_RESETCONSOLE_EXCEPTION_LOG, str(e))


def consolewrite_print(s: str) -> None:
    """R writing to the console/terminal.

    :param s: the data to write to the console/terminal.
    """
    # TODO: is the callback for flush working with Linux ?
    print(s, end='', flush=True)


def consolewrite_warnerror(s: str) -> None:
    # TODO: use an rpy2/R-specific warning instead of UserWarning.
    logger.warning(
        _WRITECONSOLE_EXCEPTION_LOG.format(
            exception=s,
            exc_value='',
            traceback=''
        )
    )


@ffi_proxy.callback(ffi_proxy._consolewrite_ex_def,
                    openrlib._rinterface_cffi,
                    error=None,
                    onerror=handler_callback_error(_WRITECONSOLE_EXCEPTION_LOG))
def _consolewrite_ex(buf, n: int, otype: int) -> None:
    s = conversion._cchar_to_str_with_maxlen(buf, n, _CCHAR_ENCODING)
    with openrlib.rlock:
        if otype == 0:
            consolewrite_print(s)
        else:
            consolewrite_warnerror(s)


def showmessage(s: str) -> None:
    print('R wants to show a message')
    print(s)


_SHOWMESSAGE_EXCEPTION_LOG = 'R[show message]: %s'


@ffi_proxy.callback(ffi_proxy._showmessage_def,
                    openrlib._rinterface_cffi)
def _showmessage(buf):
    s = conversion._cchar_to_str(buf, _CCHAR_ENCODING)
    try:
        with openrlib.rlock:
            showmessage(s)
    except Exception as e:
        logger.error(_SHOWMESSAGE_EXCEPTION_LOG, str(e))


def choosefile(new):
    return input('Enter file name:')


_CHOOSEFILE_EXCEPTION_LOG = 'R[choose file]: %s'


@ffi_proxy.callback(ffi_proxy._choosefile_def,
                    openrlib._rinterface_cffi)
def _choosefile(new, buf, n: int) -> int:
    try:
        with openrlib.rlock:
            res = choosefile(new)
    except Exception as e:
        logger.error(_CHOOSEFILE_EXCEPTION_LOG, str(e))
        res = None

    if res is None:
        return 0

    res_cdata = conversion._str_to_cchar(res)
    openrlib.ffi.memmove(buf, res_cdata, len(res_cdata))
    return len(res_cdata)


def showfiles(filenames: typing.Tuple[str, ...],
              headers: typing.Tuple[str, ...],
              wtitle: typing.Optional[str],
              pager: typing.Optional[str]) -> None:
    """R showing files.

    :param filenames: A tuple of file names.
    :param headers: A tuple of strings (TODO: check what it is)
    :wtitle: Title of the "window" showing the files.
    :pager: Pager to use to show the list of files.
    """
    for fn in filenames:
        print('File: %s' % fn)
        with open(fn) as fh:
            for row in fh:
                print(row)
            print('---')


_SHOWFILE_EXCEPTION_LOG = 'R[show file]: %s'
_SHOWFILE_INTERNAL_EXCEPTION_LOG = ('Internal rpy2 error while '
                                    'showing files for R: %s')


@ffi_proxy.callback(ffi_proxy._showfiles_def,
                    openrlib._rinterface_cffi)
def _showfiles(nfiles: int, files, headers, wtitle, delete, pager) -> int:
    filenames = []
    headers_str = []
    wtitle_str = None
    pager_str = None
    try:
        wtitle_str = conversion._cchar_to_str(wtitle, _CCHAR_ENCODING)
        pager_str = conversion._cchar_to_str(pager, _CCHAR_ENCODING)
        for i in range(nfiles):
            filenames.append(
                conversion._cchar_to_str(files[i],
                                         _CCHAR_ENCODING)
            )
            headers_str.append(
                conversion._cchar_to_str(headers[i],
                                         _CCHAR_ENCODING)
            )
    except Exception as e:
        logger.error(_SHOWFILE_INTERNAL_EXCEPTION_LOG, str(e))

    if len(filenames):
        res = 0
    else:
        res = 1
    try:
        with openrlib.rlock:
            showfiles(tuple(filenames),
                      tuple(headers_str),
                      wtitle_str,
                      pager_str)
    except Exception as e:
        res = 1
        logger.error(_SHOWFILE_EXCEPTION_LOG, str(e))

    return res


def cleanup(saveact, status, runlast):
    pass


_CLEANUP_EXCEPTION_LOG = 'R[cleanup]: %s'


@ffi_proxy.callback(ffi_proxy._cleanup_def,
                    openrlib._rinterface_cffi)
def _cleanup(saveact, status, runlast):
    try:
        with openrlib.rlock:
            cleanup(saveact, status, runlast)
    except Exception as e:
        logger.error(_CLEANUP_EXCEPTION_LOG, str(e))


def processevents() -> None:
    """Process R events.

    This function can be periodically called by R to handle
    events such as window resizing in an interactive graphical
    device."""
    pass


_PROCESSEVENTS_EXCEPTION_LOG = 'R[processevents]: %s'


@ffi_proxy.callback(ffi_proxy._processevents_def,
                    openrlib._rinterface_cffi)
def _processevents() -> None:
    try:
        with openrlib.rlock:
            processevents()
    except KeyboardInterrupt:
        # This function is a Python callback. A keyboard interruption is
        # captured in Python, but R must be notified that an interruption
        # occured so it can handle it.
        rlib = openrlib.rlib
        if os.name == 'nt':
            # On Windows, the global C-level R variable `UserBreak` is set
            # to one to notifying R that a `SIGBREAK` has been sent
            # (see the R source - `src/gnuwin32/embeddedR.c:my_onintr()`).
            rlib.UserBreak = 1
        else:
            # On UNIX-like, R can be notified that a SIGINT has been sent
            # through the C-level R variable `R_interrupts_pending`
            # (see the R source - `src/main/main.c:handleInterrupt()`)
            rlib.R_interrupts_pending = 1
    except Exception as e:
        logger.error(_PROCESSEVENTS_EXCEPTION_LOG, str(e))


def busy(x: int) -> None:
    """R is busy.

    :param x: TODO this is an integer but I do not know what it does.
    """
    pass


_BUSY_EXCEPTION_LOG = 'R[busy]: %s'


@ffi_proxy.callback(ffi_proxy._busy_def,
                    openrlib._rinterface_cffi)
def _busy(which: int) -> None:
    try:
        with openrlib.rlock:
            busy(which)
    except Exception as e:
        logger.error(_BUSY_EXCEPTION_LOG, str(e))


def callback() -> None:
    pass


_CALLBACK_EXCEPTION_LOG = 'R[callback]: %s'


@ffi_proxy.callback(ffi_proxy._callback_def,
                    openrlib._rinterface_cffi)
def _callback() -> None:
    try:
        with openrlib.rlock:
            callback()
    except Exception as e:
        logger.error(_CALLBACK_EXCEPTION_LOG, str(e))


def yesnocancel(question: str) -> int:
    """Asking a user to answer yes, no, or cancel.

    :param question: The question asked to the user
    :return: An integer with the answer.
    """
    return int(input(question))


_YESNOCANCEL_EXCEPTION_LOG = 'R[yesnocancel]: %s'


@ffi_proxy.callback(ffi_proxy._yesnocancel_def,
                    openrlib._rinterface_cffi)
def _yesnocancel(question):
    try:
        q = conversion._cchar_to_str(question, _CCHAR_ENCODING)
        with openrlib.rlock:
            res = yesnocancel(q)
    except Exception as e:
        logger.error(_YESNOCANCEL_EXCEPTION_LOG, str(e))
    return res
