# -*- coding: utf-8 -*-
"""Conversion tool from EDF, EDF+, BDF to FIF."""

# Authors: Teon Brooks <teon.brooks@gmail.com>
#          Martin Billinger <martin.billinger@tugraz.at>
#          Nicolas Barascud <nicolas.barascud@ens.fr>
#          Stefan Appelhoff <stefan.appelhoff@mailbox.org>
#
# License: BSD (3-clause)

import calendar
import datetime
import os
import re

import numpy as np
from io import open as io_open  # python 2 backward compatible open

from ...utils import verbose, logger, warn
from ..utils import _blk_read_lims, _synthesize_stim_channel
from ..base import BaseRaw, _check_update_montage
from ..meas_info import _empty_info, DATE_NONE
from ..constants import FIFF
from ...filter import resample
from ...externals.six.moves import zip
from ...utils import copy_function_doc_to_method_doc
from ...annotations import Annotations, events_from_annotations


def find_edf_events(raw):
    """Get original EDF events as read from the header.

    For GDF, the values are returned in form
    [n_events, pos, typ, chn, dur]
    where:

    ========  ===================================  =======
    name      description                          type
    ========  ===================================  =======
    n_events  The number of all events             integer
    pos       Beginnning of the events in samples  array
    typ       The event identifiers                array
    chn       The associated channels (0 for all)  array
    dur       The durations of the events          array
    ========  ===================================  =======

    For EDF+, the values are returned in form
    n_events * [onset, dur, desc]
    where:

    ========  ===================================  =======
    name      description                          type
    ========  ===================================  =======
    onset     Onset of the event in seconds        float
    dur       Duration of the event in seconds     float
    desc      Description of the event             str
    ========  ===================================  =======

    Parameters
    ----------
    raw : Instance of RawEDF
        The raw object for finding the events.

    Returns
    -------
    events : ndarray
        The events as they are in the file header.
    """
    return raw.find_edf_events()


def _edf_events_from_annotations(raw, event_id):
    """Modify events_from_annotaitons for EDF specifics.

    Modify events_from_annotaitons so that events[:,1] corresponds to
    the duration of the events instead of the id of the previous event.
    """
    events, event_id_ = events_from_annotations(raw, event_id=event_id,
                                                use_rounding=False)
    durations = raw.annotations.duration
    durations = np.array(durations * raw.info['sfreq'], int)

    # XXX see discussion gh-5574, this is necessary due to the fact
    # that stim channel cannot two consecutive events unless they are
    # at least one sample apart (so that stim_ch can go from evnt_id to 0
    # and back to evnt_id).
    durations[durations != 0] -= 1

    events[:, 1] = durations
    return events, event_id_


class RawEDF(BaseRaw):
    """Raw object from EDF, EDF+, BDF file.

    Parameters
    ----------
    input_fname : str
        Path to the EDF+,BDF file.
    montage : str | None | instance of Montage
        Path or instance of montage containing electrode positions.
        If None, sensor locations are (0,0,0). See the documentation of
        :func:`mne.channels.read_montage` for more information.
    eog : list or tuple
        Names of channels or list of indices that should be designated
        EOG channels. Values should correspond to the electrodes in the
        edf file. Default is None.
    misc : list or tuple
        Names of channels or list of indices that should be designated
        MISC channels. Values should correspond to the electrodes in the
        edf file. Default is None.
    stim_channel : str | int | 'auto' | False
        The channel name or channel index (starting at 0). -1 corresponds to
        the last channel. If False, there will be no stim channel added. If
        'auto' (default), the stim channel will be added as the last channel if
        the header contains ``'EDF Annotations'`` or GDF events (otherwise stim
        channel will not be added). None is accepted as an alias for False.

        .. warning:: This defaults to 'auto' in 0.17 but will default to False
                     in 0.18 (when no stim channel synthesis will be allowed)
                     and will be removed in 0.19; migrate code to use
                     :func:`mne.events_from_annotations` instead.

    annot : str | None
        Path to annotation file.
        If None, no derived stim channel will be added (for files requiring
        annotation file to interpret stim channel).
        This was deprecated in 0.17 and will be removed in 0.18.
    annotmap : str | None
        Path to annotation map file containing mapping from label to trigger.
        Must be specified if annot is not None.
        This was deprecated in 0.17 and will be removed in 0.18.
    exclude : list of str
        Channel names to exclude. This can help when reading data with
        different sampling rates to avoid unnecessary resampling.
    preload : bool or str (default False)
        Preload data into memory for data manipulation and faster indexing.
        If True, the data will be preloaded into memory (fast, requires
        large amount of memory). If preload is a string, preload is the
        file name of a memory-mapped file which is used to store the data
        on the hard drive (slower, requires less memory).
    verbose : bool, str, int, or None
        If not None, override default verbose level (see :func:`mne.verbose`
        and :ref:`Logging documentation <tut_logging>` for more).

    Notes
    -----
    Biosemi devices trigger codes are encoded in 16-bit format, whereas system
    codes (CMS in/out-of range, battery low, etc.) are coded in bits 16-23 of
    the status channel (see http://www.biosemi.com/faq/trigger_signals.htm).
    To retrieve correct event values (bits 1-16), one could do:

        >>> events = mne.find_events(...)  # doctest:+SKIP
        >>> events[:, 2] &= (2**16 - 1)  # doctest:+SKIP

    The above operation can be carried out directly in :func:`mne.find_events`
    using the ``mask`` and ``mask_type`` parameters
    (see :func:`mne.find_events` for more details).

    It is also possible to retrieve system codes, but no particular effort has
    been made to decode these in MNE. In case it is necessary, for instance to
    check the CMS bit, the following operation can be carried out:

        >>> cms_bit = 20  # doctest:+SKIP
        >>> cms_high = (events[:, 2] & (1 << cms_bit)) != 0  # doctest:+SKIP

    It is worth noting that in some special cases, it may be necessary to
    shift the event values in order to retrieve correct event triggers. This
    depends on the triggering device used to perform the synchronization.
    For instance, some GDF files need a 8 bits shift:

        >>> events[:, 2] >>= 8  # doctest:+SKIP

    In addition, for GDF files, the stimulus channel is constructed from the
    events in the header. The id numbers of overlapping events are simply
    combined through addition. To get the original events from the header,
    use function :func:`mne.io.find_edf_events`.

    See Also
    --------
    mne.io.Raw : Documentation of attribute and methods.
    """

    @verbose
    def __init__(self, input_fname, montage, eog=None, misc=None,
                 stim_channel='', annot=None, annotmap=None, exclude=(),
                 preload=False, verbose=None):  # noqa: D102
        logger.info('Extracting EDF parameters from %s...' % input_fname)
        input_fname = os.path.abspath(input_fname)
        info, edf_info, orig_units = _get_info(input_fname, stim_channel,
                                               annot, annotmap, eog, misc,
                                               exclude, preload)
        logger.info('Creating raw.info structure...')
        _check_update_montage(info, montage)

        if bool(annot) != bool(annotmap):
            warn("Stimulus channel will not be annotated. Both 'annot' and "
                 "'annotmap' must be specified.")

        if annot or annotmap:
            warn("'annot' and 'annotmap' parameters are deprecated and will be"
                 " removed in 0.18", DeprecationWarning)

        # Raw attributes
        last_samps = [edf_info['nsamples'] - 1]
        super(RawEDF, self).__init__(
            info, preload, filenames=[input_fname], raw_extras=[edf_info],
            last_samps=last_samps, orig_format='int', orig_units=orig_units,
            verbose=verbose)

    @verbose
    def _read_segment_file(self, data, idx, fi, start, stop, cals, mult):
        """Read a chunk of raw data."""
        from scipy.interpolate import interp1d
        if mult is not None:
            # XXX "cals" here does not function the same way as in RawFIF,
            # and for efficiency we want to be able to combine mult and cals
            # so proj support will have to wait until this is resolved
            raise NotImplementedError('mult is not supported yet')
        n_samps = self._raw_extras[fi]['n_samps']
        buf_len = int(self._raw_extras[fi]['max_samp'])
        sfreq = self.info['sfreq']
        dtype = self._raw_extras[fi]['dtype_np']
        dtype_byte = self._raw_extras[fi]['dtype_byte']
        data_offset = self._raw_extras[fi]['data_offset']
        stim_channel = self._raw_extras[fi]['stim_channel']
        tal_sel = self._raw_extras[fi]['tal_sel']
        orig_sel = self._raw_extras[fi]['sel']
        annot = self._raw_extras[fi]['annot']
        annotmap = self._raw_extras[fi]['annotmap']
        subtype = self._raw_extras[fi]['subtype']
        stim_data = self._raw_extras[fi].get('stim_data', None)  # for GDF

        if np.size(dtype_byte) > 1:
            if len(np.unique(dtype_byte)) > 1:
                warn("Multiple data type not supported")
            dtype = dtype[0]
            dtype_byte = dtype_byte[0]

        # gain constructor
        physical_range = np.array([ch['range'] for ch in self.info['chs']])
        cal = np.array([ch['cal'] for ch in self.info['chs']])
        assert cal.shape == (len(self.info['chs']),)
        cal = np.atleast_2d(physical_range / cal)  # physical / digital
        gains = np.atleast_2d(self._raw_extras[fi]['units'])

        # physical dimension in uV
        physical_min = self._raw_extras[fi]['physical_min']
        digital_min = self._raw_extras[fi]['digital_min']

        offsets = np.atleast_2d(physical_min - (digital_min * cal)).T
        offsets[np.in1d(orig_sel, tal_sel)] = 0
        this_sel = orig_sel[idx]

        # We could read this one EDF block at a time, which would be this:
        ch_offsets = np.cumsum(np.concatenate([[0], n_samps]), dtype=np.int64)
        block_start_idx, r_lims, d_lims = _blk_read_lims(start, stop, buf_len)
        # But to speed it up, we really need to read multiple blocks at once,
        # Otherwise we can end up with e.g. 18,181 chunks for a 20 MB file!
        # Let's do ~10 MB chunks:
        n_per = max(10 * 1024 * 1024 // (ch_offsets[-1] * dtype_byte), 1)
        with open(self._filenames[fi], 'rb', buffering=0) as fid:

            # Extract data
            start_offset = (data_offset +
                            block_start_idx * ch_offsets[-1] * dtype_byte)
            for ai in range(0, len(r_lims), n_per):
                block_offset = ai * ch_offsets[-1] * dtype_byte
                n_read = min(len(r_lims) - ai, n_per)
                fid.seek(start_offset + block_offset, 0)
                # Read and reshape to (n_chunks_read, ch0_ch1_ch2_ch3...)
                many_chunk = _read_ch(fid, subtype, ch_offsets[-1] * n_read,
                                      dtype_byte, dtype).reshape(n_read, -1)
                for ii, ci in enumerate(this_sel):
                    # This now has size (n_chunks_read, n_samp[ci])
                    ch_data = many_chunk[:, ch_offsets[ci]:ch_offsets[ci + 1]]
                    r_sidx = r_lims[ai][0]
                    r_eidx = (buf_len * (n_read - 1) +
                              r_lims[ai + n_read - 1][1])
                    d_sidx = d_lims[ai][0]
                    d_eidx = d_lims[ai + n_read - 1][1]
                    if n_samps[ci] != buf_len:
                        if ci in tal_sel:
                            # don't resample tal_channels, zero-pad instead.
                            if n_samps[ci] < buf_len:
                                z = np.zeros((len(ch_data),
                                              buf_len - n_samps[ci]))
                                ch_data = np.append(ch_data, z, -1)
                            else:
                                ch_data = ch_data[:, :buf_len]
                        elif ci == stim_channel:
                            if (annot and annotmap or stim_data is not None or
                                    len(tal_sel) > 0):
                                # don't resample, it gets overwritten later
                                ch_data = np.zeros((len(ch_data), buf_len))
                            else:
                                # Stim channel will be interpolated
                                old = np.linspace(0, 1, n_samps[ci] + 1, True)
                                new = np.linspace(0, 1, buf_len, False)
                                ch_data = np.append(
                                    ch_data, np.zeros((len(ch_data), 1)), -1)
                                ch_data = interp1d(old, ch_data,
                                                   kind='zero', axis=-1)(new)
                        else:
                            # XXX resampling each chunk isn't great,
                            # it forces edge artifacts to appear at
                            # each buffer boundary :(
                            # it can also be very slow...
                            ch_data = resample(ch_data, buf_len, n_samps[ci],
                                               npad=0, axis=-1)
                    assert ch_data.shape == (len(ch_data), buf_len)
                    data[ii, d_sidx:d_eidx] = ch_data.ravel()[r_sidx:r_eidx]

        # only try to read the stim channel if it's not None and it's
        # actually one of the requested channels
        idx = np.arange(self.info['nchan'])[idx]  # slice -> ints
        read_size = len(r_lims) * buf_len
        stim_channel_idx = np.where(idx == stim_channel)[0]

        if subtype == 'bdf':
            # do not scale stim channel (see gh-5160)
            stim_idx = np.where(np.arange(self.info['nchan']) == stim_channel)
            cal[0, stim_idx[0]] = 1
            offsets[stim_idx[0], 0] = 0
            gains[0, stim_idx[0]] = 1
        data *= cal.T[idx]
        data += offsets[idx]
        data *= gains.T[idx]

        if stim_channel is not None and len(stim_channel_idx) > 0:
            if annot and annotmap:
                evts = _read_annot(annot, annotmap, sfreq,
                                   self._last_samps[fi] + 1)
                data[stim_channel_idx, :] = evts[start:stop]
            elif len(tal_sel) > 0:
                tal_channel_idx = np.in1d(orig_sel[idx], tal_sel)
                annotations_data = np.atleast_2d(data[tal_channel_idx])
                onset, duration, desc = _read_annotations_edf(annotations_data)

                evts = (onset, duration, desc)
                self._raw_extras[fi]['events'] = np.column_stack(evts)

                self.set_annotations(Annotations(onset=onset,
                                                 duration=duration,
                                                 description=desc,
                                                 orig_time=None))
                event_id = _get_edf_default_event_id(desc)
                events, _ = _edf_events_from_annotations(self,
                                                         event_id=event_id)

                self._check_events(events, read_size)
                stim = self._create_event_ch(events, read_size)
                data[stim_channel_idx, :] = stim[start:stop]

            elif stim_data is not None:  # GDF events
                data[stim_channel_idx, :] = stim_data[start:stop]
            else:
                stim = np.bitwise_and(data[stim_channel_idx].astype(int),
                                      2**17 - 1)
                data[stim_channel_idx, :] = stim

    @copy_function_doc_to_method_doc(find_edf_events)
    def find_edf_events(self):
        return self._raw_extras[0]['events']

    def _create_event_ch(self, events, n_samples=None):
        """Create the event channel."""
        if n_samples is None:
            n_samples = self.last_samp - self.first_samp + 1
        events = np.array(events, int)
        if events.ndim != 2 or events.shape[1] != 3:
            raise ValueError("[n_events x 3] shaped array required")
        # update events
        self._event_ch = _synthesize_stim_channel(events, n_samples)
        return self._event_ch

    def _check_events(self, events, read_size):
        """Emit warnings based on events.

        Check for:
        - Overlapping events
        - Events that expand over the read buffer

        XXX: This can be vectorized
        """
        stim = np.zeros(read_size)
        for n_start, n_duration, description in events:
            n_stop = n_duration + n_start
            # make sure events without duration get one sample
            n_stop = n_stop if n_stop > n_start else n_start + 1
            if any(stim[n_start:n_stop]):
                warn('EDF+ with overlapping events are not fully supported')
            if n_start >= read_size:  # event out of bounds
                warn('Event "{}" (with onset {}) is out of'
                     ' bounds, it cannot be added to the stim channel.'
                     ' Use find_edf_events to get a list of all EDF '
                     'events as stored in the '
                     'file.'.format(description, n_start))
            stim[n_start:n_stop] += 1


def _read_ch(fid, subtype, samp, dtype_byte, dtype=None):
    """Read a number of samples for a single channel."""
    # BDF
    if subtype == 'bdf':
        ch_data = np.fromfile(fid, dtype=dtype, count=samp * dtype_byte)
        ch_data = ch_data.reshape(-1, 3).astype(np.int32)
        ch_data = ((ch_data[:, 0]) +
                   (ch_data[:, 1] << 8) +
                   (ch_data[:, 2] << 16))
        # 24th bit determines the sign
        ch_data[ch_data >= (1 << 23)] -= (1 << 24)

    # GDF data and EDF data
    else:
        ch_data = np.fromfile(fid, dtype=dtype, count=samp)

    return ch_data


def _get_info(fname, stim_channel, annot, annotmap, eog, misc, exclude,
              preload):
    """Extract all the information from the EDF+, BDF or GDF file."""
    # backward compat aliasing; code below wants to see None but in 0.18
    # we allow/prefer False for consistency with BV/EEGLAB
    stim_channel = None if stim_channel is False else stim_channel
    if stim_channel == '':
        warn('stim_channel will default to "auto" in 0.17 but change to False '
             'in 0.18, and will be removed in 0.19', DeprecationWarning)
        stim_channel = 'auto'
    if eog is None:
        eog = []
    if misc is None:
        misc = []

    # Read header from file
    ext = os.path.splitext(fname)[1][1:].lower()
    logger.info('%s file detected' % ext.upper())
    if ext in ('bdf', 'edf'):
        edf_info, orig_units = _read_edf_header(fname, annot, annotmap,
                                                exclude)
    elif ext in ('gdf'):
        if annot is not None:
            warn('Annotations not yet supported for GDF files.')
        edf_info = _read_gdf_header(fname, stim_channel, exclude)

        # orig_units not yet implemented for gdf
        orig_units = None

        if 'stim_data' not in edf_info and stim_channel == 'auto':
            stim_channel = None  # Cannot construct stim channel.
    else:
        raise NotImplementedError(
            'Only GDF, EDF, and BDF files are supported, got %s.' % ext)

    sel = edf_info['sel']
    ch_names = edf_info['ch_names']
    n_samps = edf_info['n_samps'][sel]
    nchan = edf_info['nchan']
    physical_ranges = edf_info['physical_max'] - edf_info['physical_min']
    cals = edf_info['digital_max'] - edf_info['digital_min']
    bad_idx = np.where((~np.isfinite(cals)) | (cals == 0))[0]
    if len(bad_idx) > 0:
        warn('Scaling factor is not defined in following channels:\n' +
             ', '.join(ch_names[i] for i in bad_idx))
        cals[bad_idx] = 1
    bad_idx = np.where(physical_ranges == 0)[0]
    if len(bad_idx) > 0:
        warn('Physical range is not defined in following channels:\n' +
             ', '.join(ch_names[i] for i in bad_idx))
        physical_ranges[bad_idx] = 1
    if 'stim_data' in edf_info and stim_channel == 'auto':  # For GDF events.
        cals = np.append(cals, 1)
    if stim_channel is not None:
        stim_channel = _check_stim_channel(stim_channel, ch_names, sel)

    # Annotations
    tal_ch_name = 'EDF Annotations'
    tal_chs = np.where(np.array(ch_names) == tal_ch_name)[0]
    if len(tal_chs) > 0:
        logger.info('EDF annotations detected (consider using '
                    'raw.find_edf_events() to extract them)')
        if len(tal_chs) > 1:
            warn('Channel names are not unique, found duplicates for: %s. '
                 'Adding running numbers to duplicate channel names.'
                 % tal_ch_name)
        for idx, tal_ch in enumerate(tal_chs, 1):
            ch_names[tal_ch] = ch_names[tal_ch] + '-%s' % idx
    tal_sel = edf_info['sel'][tal_chs]
    edf_info['tal_sel'] = tal_sel

    if len(tal_sel) > 0 and stim_channel is not None and not preload:
        raise RuntimeError('%s' % ('EDF+ Annotations (TAL) channel needs to be'
                                   ' parsed completely on loading.'
                                   ' You must set preload parameter to True.'))

    # Creates a list of dicts of eeg channels for raw.info
    logger.info('Setting channel info structure...')
    chs = list()
    pick_mask = np.ones(len(ch_names))
    for idx, ch_info in enumerate(zip(ch_names, physical_ranges, cals)):
        ch_name, physical_range, cal = ch_info
        chan_info = {}
        logger.debug('  %s: range=%s cal=%s' % (ch_name, physical_range, cal))
        chan_info['cal'] = cal
        chan_info['logno'] = idx + 1
        chan_info['scanno'] = idx + 1
        chan_info['range'] = physical_range
        chan_info['unit_mul'] = 0.
        chan_info['ch_name'] = ch_name
        chan_info['unit'] = FIFF.FIFF_UNIT_V
        chan_info['coord_frame'] = FIFF.FIFFV_COORD_HEAD
        chan_info['coil_type'] = FIFF.FIFFV_COIL_EEG
        chan_info['kind'] = FIFF.FIFFV_EEG_CH
        chan_info['loc'] = np.zeros(12)
        if ch_name in eog or idx in eog or idx - nchan in eog:
            chan_info['coil_type'] = FIFF.FIFFV_COIL_NONE
            chan_info['kind'] = FIFF.FIFFV_EOG_CH
            pick_mask[idx] = False
        if ch_name in misc or idx in misc or idx - nchan in misc:
            chan_info['coil_type'] = FIFF.FIFFV_COIL_NONE
            chan_info['kind'] = FIFF.FIFFV_MISC_CH
            pick_mask[idx] = False
        check1 = stim_channel == ch_name
        check2 = stim_channel == idx
        check3 = nchan > 1
        stim_check = np.logical_and(np.logical_or(check1, check2), check3)
        if stim_check:
            chan_info['coil_type'] = FIFF.FIFFV_COIL_NONE
            chan_info['unit'] = FIFF.FIFF_UNIT_NONE
            chan_info['kind'] = FIFF.FIFFV_STIM_CH
            pick_mask[idx] = False
            chan_info['ch_name'] = 'STI 014'
            ch_names[idx] = chan_info['ch_name']
            edf_info['units'][idx] = 1
            if isinstance(stim_channel, str):
                stim_channel = idx
        if edf_info['sel'][idx] in tal_sel:
            chan_info['range'] = 1
            chan_info['cal'] = 1
            chan_info['coil_type'] = FIFF.FIFFV_COIL_NONE
            chan_info['unit'] = FIFF.FIFF_UNIT_NONE
            chan_info['kind'] = FIFF.FIFFV_STIM_CH
            pick_mask[idx] = False
        chs.append(chan_info)
    edf_info['stim_channel'] = stim_channel

    if any(pick_mask):
        picks = [item for item, mask in zip(range(nchan), pick_mask) if mask]
        edf_info['max_samp'] = max_samp = n_samps[picks].max()
    else:
        edf_info['max_samp'] = max_samp = n_samps.max()

    # Info structure
    # -------------------------------------------------------------------------

    # sfreq defined as the max sampling rate of eeg (stim_ch not included)
    if stim_channel is None:
        data_samps = n_samps
    else:
        data_samps = np.delete(n_samps, slice(stim_channel, stim_channel + 1))
    sfreq = data_samps.max() * \
        edf_info['record_length'][1] / edf_info['record_length'][0]

    info = _empty_info(sfreq)
    info['meas_date'] = edf_info['meas_date']
    info['chs'] = chs
    info['ch_names'] = ch_names

    # Filter settings
    highpass = edf_info['highpass']
    lowpass = edf_info['lowpass']
    if highpass.size == 0:
        pass
    elif all(highpass):
        if highpass[0] == 'NaN':
            pass  # Placeholder for future use. Highpass set in _empty_info.
        elif highpass[0] == 'DC':
            info['highpass'] = 0.
        else:
            hp = highpass[0]
            try:
                hp = float(hp)
            except Exception:
                hp = 0.
            info['highpass'] = hp
    else:
        info['highpass'] = float(np.max(highpass))
        warn('Channels contain different highpass filters. Highest filter '
             'setting will be stored.')
    if np.isnan(info['highpass']):
        info['highpass'] = 0.
    if lowpass.size == 0:
        pass  # Placeholder for future use. Lowpass set in _empty_info.
    elif all(lowpass):
        if lowpass[0] == 'NaN':
            pass  # Placeholder for future use. Lowpass set in _empty_info.
        else:
            info['lowpass'] = float(lowpass[0])
    else:
        info['lowpass'] = float(np.min(lowpass))
        warn('Channels contain different lowpass filters. Lowest filter '
             'setting will be stored.')
    if np.isnan(info['lowpass']):
        info['lowpass'] = info['sfreq'] / 2.

    # Some keys to be consistent with FIF measurement info
    info['description'] = None
    edf_info['nsamples'] = int(edf_info['n_records'] * max_samp)

    # These are the conditions under which a stim channel will be interpolated
    if stim_channel is not None and not (annot and annotmap) and \
            len(tal_sel) == 0 and n_samps[stim_channel] != int(max_samp):
        warn('Interpolating stim channel. Events may jitter.')
    info._update_redundant()

    return info, edf_info, orig_units


def _read_edf_header(fname, annot, annotmap, exclude):
    """Read header information from EDF+ or BDF file."""
    edf_info = dict()
    edf_info.update(annot=annot, annotmap=annotmap, events=[])

    with open(fname, 'rb') as fid:

        fid.read(8)  # version (unused here)

        # patient ID
        pid = fid.read(80).decode()
        pid = pid.split(' ', 2)
        patient = {}
        if len(pid) >= 2:
            patient['id'] = pid[0]
            patient['name'] = pid[1]

        # Recording ID
        meas_id = {}
        meas_id['recording_id'] = fid.read(80).decode().strip(' \x00')

        day, month, year = [int(x) for x in
                            re.findall(r'(\d+)', fid.read(8).decode())]
        hour, minute, sec = [int(x) for x in
                             re.findall(r'(\d+)', fid.read(8).decode())]
        century = 2000 if year < 50 else 1900
        date = datetime.datetime(year + century, month, day, hour, minute, sec)
        meas_date = (calendar.timegm(date.utctimetuple()), 0)

        header_nbytes = int(fid.read(8).decode())

        # The following 44 bytes sometimes identify the file type, but this is
        # not guaranteed. Therefore, we skip this field and use the file
        # extension to determine the subtype (EDF or BDF, which differ in the
        # number of bytes they use for the data records; EDF uses 2 bytes
        # whereas BDF uses 3 bytes).
        fid.read(44)
        subtype = os.path.splitext(fname)[1][1:].lower()

        n_records = int(fid.read(8).decode())
        record_length = fid.read(8).decode().strip('\x00').strip()
        record_length = np.array([float(record_length), 1.])  # in seconds
        if record_length[0] == 0:
            record_length = record_length[0] = 1.
            warn('Header information is incorrect for record length. Default '
                 'record length set to 1.')

        nchan = int(fid.read(4).decode())
        channels = list(range(nchan))
        ch_names = [fid.read(16).strip().decode() for ch in channels]
        exclude = _find_exclude_idx(ch_names, exclude)
        sel = np.setdiff1d(np.arange(len(ch_names)), exclude)
        for ch in channels:
            fid.read(80)  # transducer
        units = [fid.read(8).strip().decode() for ch in channels]
        orig_units = dict(zip(ch_names, units))
        edf_info['units'] = list()
        for i, unit in enumerate(units):
            if i in exclude:
                continue
            if unit == 'uV':
                edf_info['units'].append(1e-6)
            else:
                edf_info['units'].append(1)
        ch_names = [ch_names[idx] for idx in sel]

        physical_min = np.array([float(fid.read(8).decode())
                                 for ch in channels])[sel]
        physical_max = np.array([float(fid.read(8).decode())
                                 for ch in channels])[sel]
        digital_min = np.array([float(fid.read(8).decode())
                                for ch in channels])[sel]
        digital_max = np.array([float(fid.read(8).decode())
                                for ch in channels])[sel]
        prefiltering = [fid.read(80).decode().strip(' \x00')
                        for ch in channels][:-1]
        highpass = np.ravel([re.findall(r'HP:\s+(\w+)', filt)
                             for filt in prefiltering])
        lowpass = np.ravel([re.findall(r'LP:\s+(\w+)', filt)
                            for filt in prefiltering])

        # number of samples per record
        n_samps = np.array([int(fid.read(8).decode()) for ch
                            in channels])

        # Populate edf_info
        edf_info.update(
            ch_names=ch_names, data_offset=header_nbytes,
            digital_max=digital_max, digital_min=digital_min,
            highpass=highpass, sel=sel, lowpass=lowpass, meas_date=meas_date,
            n_records=n_records, n_samps=n_samps, nchan=nchan,
            subject_info=patient, physical_max=physical_max,
            physical_min=physical_min, record_length=record_length,
            subtype=subtype)

        fid.read(32 * nchan).decode()  # reserved
        assert fid.tell() == header_nbytes

        fid.seek(0, 2)
        n_bytes = fid.tell()
        n_data_bytes = n_bytes - header_nbytes
        total_samps = (n_data_bytes // 3 if subtype == 'bdf'
                       else n_data_bytes // 2)
        read_records = total_samps // np.sum(n_samps)
        if n_records != read_records:
            warn('Number of records from the header does not match the file '
                 'size (perhaps the recording was not stopped before exiting).'
                 ' Inferring from the file size.')
            edf_info['n_records'] = n_records = read_records

        if subtype == 'bdf':
            edf_info['dtype_byte'] = 3  # 24-bit (3 byte) integers
            edf_info['dtype_np'] = np.uint8
        else:
            edf_info['dtype_byte'] = 2  # 16-bit (2 byte) integers
            edf_info['dtype_np'] = np.int16

    return edf_info, orig_units


def _read_gdf_header(fname, stim_channel, exclude):
    """Read GDF 1.x and GDF 2.x header info."""
    edf_info = dict()
    events = []
    edf_info['annot'] = None
    edf_info['annotmap'] = None
    with open(fname, 'rb') as fid:

        version = fid.read(8).decode()

        gdftype_np = (None, np.int8, np.uint8, np.int16, np.uint16, np.int32,
                      np.uint32, np.int64, np.uint64, None, None, None, None,
                      None, None, None, np.float32, np.float64)
        gdftype_byte = [np.dtype(x).itemsize if x is not None else 0
                        for x in gdftype_np]
        assert sum(gdftype_byte) == 42

        edf_info['type'] = edf_info['subtype'] = version[:3]
        edf_info['number'] = float(version[4:])
        meas_date = DATE_NONE

        # GDF 1.x
        # ---------------------------------------------------------------------
        if edf_info['number'] < 1.9:

            # patient ID
            pid = fid.read(80).decode('latin-1')
            pid = pid.split(' ', 2)
            patient = {}
            if len(pid) >= 2:
                patient['id'] = pid[0]
                patient['name'] = pid[1]

            # Recording ID
            meas_id = {}
            meas_id['recording_id'] = fid.read(80).decode().strip(' \x00')

            # date
            tm = fid.read(16).decode().strip(' \x00')
            try:
                if tm[14:16] == '  ':
                    tm = tm[:14] + '00' + tm[16:]
                date = datetime.datetime(int(tm[0:4]), int(tm[4:6]),
                                         int(tm[6:8]), int(tm[8:10]),
                                         int(tm[10:12]), int(tm[12:14]),
                                         int(tm[14:16]) * pow(10, 4))
                meas_date = (calendar.timegm(date.utctimetuple()), 0)
            except Exception:
                pass

            header_nbytes = np.fromfile(fid, np.int64, 1)[0]
            meas_id['equipment'] = np.fromfile(fid, np.uint8, 8)[0]
            meas_id['hospital'] = np.fromfile(fid, np.uint8, 8)[0]
            meas_id['technician'] = np.fromfile(fid, np.uint8, 8)[0]
            fid.seek(20, 1)    # 20bytes reserved

            n_records = np.fromfile(fid, np.int64, 1)[0]
            # record length in seconds
            record_length = np.fromfile(fid, np.uint32, 2)
            if record_length[0] == 0:
                record_length[0] = 1.
                warn('Header information is incorrect for record length. '
                     'Default record length set to 1.')
            nchan = np.fromfile(fid, np.uint32, 1)[0]
            channels = list(range(nchan))
            ch_names = [fid.read(16).decode('latin-1').strip(' \x00')
                        for ch in channels]
            fid.seek(80 * len(channels), 1)  # transducer
            units = [fid.read(8).decode('latin-1').strip(' \x00')
                     for ch in channels]
            exclude = _find_exclude_idx(ch_names, exclude)
            sel = list()
            for i, unit in enumerate(units):
                if unit[:2] == 'uV':
                    units[i] = 1e-6
                else:
                    units[i] = 1
                sel.append(i)

            ch_names = [ch_names[idx] for idx in sel]
            physical_min = np.fromfile(fid, np.float64, len(channels))
            physical_max = np.fromfile(fid, np.float64, len(channels))
            digital_min = np.fromfile(fid, np.int64, len(channels))
            digital_max = np.fromfile(fid, np.int64, len(channels))
            prefiltering = [fid.read(80).decode().strip(' \x00')
                            for ch in channels][:-1]
            highpass = np.ravel([re.findall(r'HP:\s+(\w+)', filt)
                                 for filt in prefiltering])
            lowpass = np.ravel([re.findall('LP:\\s+(\\w+)', filt)
                                for filt in prefiltering])

            # n samples per record
            n_samps = np.fromfile(fid, np.int32, len(channels))

            # channel data type
            dtype = np.fromfile(fid, np.int32, len(channels))

            # total number of bytes for data
            bytes_tot = np.sum([gdftype_byte[t] * n_samps[i]
                                for i, t in enumerate(dtype)])

            # Populate edf_info
            edf_info.update(
                bytes_tot=bytes_tot, ch_names=ch_names,
                data_offset=header_nbytes, digital_min=digital_min,
                digital_max=digital_max,
                dtype_byte=[gdftype_byte[t] for t in dtype],
                dtype_np=[gdftype_np[t] for t in dtype], exclude=exclude,
                highpass=highpass, sel=sel, lowpass=lowpass,
                meas_date=meas_date,
                meas_id=meas_id, n_records=n_records, n_samps=n_samps,
                nchan=nchan, subject_info=patient, physical_max=physical_max,
                physical_min=physical_min, record_length=record_length,
                units=units)

            fid.seek(32 * edf_info['nchan'], 1)  # reserved
            assert fid.tell() == header_nbytes

            # Event table
            # -----------------------------------------------------------------
            etp = header_nbytes + n_records * edf_info['bytes_tot']
            # skip data to go to event table
            fid.seek(etp)
            etmode = np.fromfile(fid, np.uint8, 1)[0]
            if etmode in (1, 3):
                sr = np.fromfile(fid, np.uint8, 3)
                event_sr = sr[0]
                for i in range(1, len(sr)):
                    event_sr = event_sr + sr[i] * 2 ** (i * 8)
                n_events = np.fromfile(fid, np.uint32, 1)[0]
                pos = np.fromfile(fid, np.uint32, n_events) - 1  # 1-based inds
                typ = np.fromfile(fid, np.uint16, n_events)

                if etmode == 3:
                    chn = np.fromfile(fid, np.uint16, n_events)
                    dur = np.fromfile(fid, np.uint32, n_events)
                else:
                    chn = np.zeros(n_events, dtype=np.int32)
                    dur = np.ones(n_events, dtype=np.uint32)
                np.clip(dur, 1, np.inf, out=dur)
                events = [n_events, pos, typ, chn, dur]

        # GDF 2.x
        # ---------------------------------------------------------------------
        else:
            # FIXED HEADER
            handedness = ('Unknown', 'Right', 'Left', 'Equal')
            gender = ('Unknown', 'Male', 'Female')
            scale = ('Unknown', 'No', 'Yes', 'Corrected')

            # date
            pid = fid.read(66).decode()
            pid = pid.split(' ', 2)
            patient = {}
            if len(pid) >= 2:
                patient['id'] = pid[0]
                patient['name'] = pid[1]
            fid.seek(10, 1)  # 10bytes reserved

            # Smoking / Alcohol abuse / drug abuse / medication
            sadm = np.fromfile(fid, np.uint8, 1)[0]
            patient['smoking'] = scale[sadm % 4]
            patient['alcohol_abuse'] = scale[(sadm >> 2) % 4]
            patient['drug_abuse'] = scale[(sadm >> 4) % 4]
            patient['medication'] = scale[(sadm >> 6) % 4]
            patient['weight'] = np.fromfile(fid, np.uint8, 1)[0]
            if patient['weight'] == 0 or patient['weight'] == 255:
                patient['weight'] = None
            patient['height'] = np.fromfile(fid, np.uint8, 1)[0]
            if patient['height'] == 0 or patient['height'] == 255:
                patient['height'] = None

            # Gender / Handedness / Visual Impairment
            ghi = np.fromfile(fid, np.uint8, 1)[0]
            patient['sex'] = gender[ghi % 4]
            patient['handedness'] = handedness[(ghi >> 2) % 4]
            patient['visual'] = scale[(ghi >> 4) % 4]

            # Recording identification
            meas_id = {}
            meas_id['recording_id'] = fid.read(64).decode().strip(' \x00')
            vhsv = np.fromfile(fid, np.uint8, 4)
            loc = {}
            if vhsv[3] == 0:
                loc['vertpre'] = 10 * int(vhsv[0] >> 4) + int(vhsv[0] % 16)
                loc['horzpre'] = 10 * int(vhsv[1] >> 4) + int(vhsv[1] % 16)
                loc['size'] = 10 * int(vhsv[2] >> 4) + int(vhsv[2] % 16)
            else:
                loc['vertpre'] = 29
                loc['horzpre'] = 29
                loc['size'] = 29
            loc['version'] = 0
            loc['latitude'] = \
                float(np.fromfile(fid, np.uint32, 1)[0]) / 3600000
            loc['longitude'] = \
                float(np.fromfile(fid, np.uint32, 1)[0]) / 3600000
            loc['altitude'] = float(np.fromfile(fid, np.int32, 1)[0]) / 100
            meas_id['loc'] = loc

            date = np.fromfile(fid, np.uint64, 1)[0]
            if date != 0:
                date = datetime.datetime(1, 1, 1) + \
                    datetime.timedelta(date * pow(2, -32) - 367)
                meas_date = (calendar.timegm(date.utctimetuple()), 0)

            birthday = np.fromfile(fid, np.uint64, 1).tolist()[0]
            if birthday == 0:
                birthday = datetime.datetime(1, 1, 1)
            else:
                birthday = (datetime.datetime(1, 1, 1) +
                            datetime.timedelta(birthday * pow(2, -32) - 367))
            patient['birthday'] = birthday
            if patient['birthday'] != datetime.datetime(1, 1, 1, 0, 0):
                today = datetime.datetime.today()
                patient['age'] = today.year - patient['birthday'].year
                today = today.replace(year=patient['birthday'].year)
                if today < patient['birthday']:
                    patient['age'] -= 1
            else:
                patient['age'] = None

            header_nbytes = np.fromfile(fid, np.uint16, 1)[0] * 256

            fid.seek(6, 1)  # 6 bytes reserved
            meas_id['equipment'] = np.fromfile(fid, np.uint8, 8)
            meas_id['ip'] = np.fromfile(fid, np.uint8, 6)
            patient['headsize'] = np.fromfile(fid, np.uint16, 3)
            patient['headsize'] = np.asarray(patient['headsize'], np.float32)
            patient['headsize'] = np.ma.masked_array(
                patient['headsize'],
                np.equal(patient['headsize'], 0), None).filled()
            ref = np.fromfile(fid, np.float32, 3)
            gnd = np.fromfile(fid, np.float32, 3)
            n_records = np.fromfile(fid, np.int64, 1)[0]

            # record length in seconds
            record_length = np.fromfile(fid, np.uint32, 2)
            if record_length[0] == 0:
                record_length[0] = 1.
                warn('Header information is incorrect for record length. '
                     'Default record length set to 1.')

            nchan = np.fromfile(fid, np.uint16, 1)[0]
            fid.seek(2, 1)  # 2bytes reserved

            # Channels (variable header)
            channels = list(range(nchan))
            ch_names = [fid.read(16).decode().strip(' \x00')
                        for ch in channels]
            exclude = _find_exclude_idx(ch_names, exclude)

            fid.seek(80 * len(channels), 1)  # reserved space
            fid.seek(6 * len(channels), 1)  # phys_dim, obsolete

            """The Physical Dimensions are encoded as int16, according to:
            - Units codes :
            https://sourceforge.net/p/biosig/svn/HEAD/tree/trunk/biosig/doc/units.csv
            - Decimal factors codes:
            https://sourceforge.net/p/biosig/svn/HEAD/tree/trunk/biosig/doc/DecimalFactors.txt
            """  # noqa
            units = np.fromfile(fid, np.uint16, len(channels)).tolist()
            unitcodes = np.array(units[:])
            sel = list()
            for i, unit in enumerate(units):
                if unit == 4275:  # microvolts
                    units[i] = 1e-6
                elif unit == 512:  # dimensionless
                    units[i] = 1
                elif unit == 0:
                    units[i] = 1  # unrecognized
                else:
                    warn('Unsupported physical dimension for channel %d '
                         '(assuming dimensionless). Please contact the '
                         'MNE-Python developers for support.' % i)
                    units[i] = 1
                sel.append(i)

            ch_names = [ch_names[idx] for idx in sel]
            physical_min = np.fromfile(fid, np.float64, len(channels))
            physical_max = np.fromfile(fid, np.float64, len(channels))
            digital_min = np.fromfile(fid, np.float64, len(channels))
            digital_max = np.fromfile(fid, np.float64, len(channels))

            fid.seek(68 * len(channels), 1)  # obsolete
            lowpass = np.fromfile(fid, np.float32, len(channels))
            highpass = np.fromfile(fid, np.float32, len(channels))
            notch = np.fromfile(fid, np.float32, len(channels))

            # number of samples per record
            n_samps = np.fromfile(fid, np.int32, len(channels))

            # data type
            dtype = np.fromfile(fid, np.int32, len(channels))

            channel = {}
            channel['xyz'] = [np.fromfile(fid, np.float32, 3)[0]
                              for ch in channels]

            if edf_info['number'] < 2.19:
                impedance = np.fromfile(fid, np.uint8,
                                        len(channels)).astype(float)
                impedance[impedance == 255] = np.nan
                channel['impedance'] = pow(2, impedance / 8)
                fid.seek(19 * len(channels), 1)  # reserved
            else:
                tmp = np.fromfile(fid, np.float32, 5 * len(channels))
                tmp = tmp[::5]
                fZ = tmp[:]
                impedance = tmp[:]
                # channels with no voltage (code 4256) data
                ch = [unitcodes & 65504 != 4256][0]
                impedance[np.where(ch)] = None
                # channel with no impedance (code 4288) data
                ch = [unitcodes & 65504 != 4288][0]
                fZ[np.where(ch)[0]] = None

            assert fid.tell() == header_nbytes

            # total number of bytes for data
            bytes_tot = np.sum([gdftype_byte[t] * n_samps[i]
                                for i, t in enumerate(dtype)])

            # Populate edf_info
            edf_info.update(
                bytes_tot=bytes_tot, ch_names=ch_names,
                data_offset=header_nbytes,
                dtype_byte=[gdftype_byte[t] for t in dtype],
                dtype_np=[gdftype_np[t] for t in dtype],
                digital_min=digital_min, digital_max=digital_max,
                exclude=exclude, gnd=gnd, highpass=highpass, sel=sel,
                impedance=impedance, lowpass=lowpass, meas_date=meas_date,
                meas_id=meas_id, n_records=n_records, n_samps=n_samps,
                nchan=nchan, notch=notch, subject_info=patient,
                physical_max=physical_max, physical_min=physical_min,
                record_length=record_length, ref=ref, units=units)

            # EVENT TABLE
            # -----------------------------------------------------------------
            etp = edf_info['data_offset'] + edf_info['n_records'] * \
                edf_info['bytes_tot']
            fid.seek(etp)  # skip data to go to event table
            etmode = fid.read(1).decode()
            if etmode != '':
                etmode = np.fromstring(etmode, np.uint8).tolist()[0]

                if edf_info['number'] < 1.94:
                    sr = np.fromfile(fid, np.uint8, 3)
                    event_sr = sr[0]
                    for i in range(1, len(sr)):
                        event_sr = event_sr + sr[i] * 2**(i * 8)
                    n_events = np.fromfile(fid, np.uint32, 1)[0]
                else:
                    ne = np.fromfile(fid, np.uint8, 3)
                    n_events = ne[0]
                    for i in range(1, len(ne)):
                        n_events = n_events + ne[i] * 2**(i * 8)
                    event_sr = np.fromfile(fid, np.float32, 1)[0]

                pos = np.fromfile(fid, np.uint32, n_events) - 1  # 1-based inds
                typ = np.fromfile(fid, np.uint16, n_events)

                if etmode == 3:
                    chn = np.fromfile(fid, np.uint16, n_events)
                    dur = np.fromfile(fid, np.uint32, n_events)
                else:
                    chn = np.zeros(n_events, dtype=np.uint32)
                    dur = np.ones(n_events, dtype=np.uint32)
                np.clip(dur, 1, np.inf, out=dur)
                events = [n_events, pos, typ, chn, dur]
                edf_info['event_sfreq'] = event_sr

    if stim_channel == 'auto' and edf_info['nchan'] not in exclude:
        if len(events) == 0:
            warn('No events found. Cannot construct a stimulus channel.')
        else:
            edf_info['sel'].append(edf_info['nchan'])
            edf_info['n_samps'] = np.append(edf_info['n_samps'], 0)
            edf_info['units'] = np.append(edf_info['units'], 1)
            edf_info['ch_names'] += [u'STI 014']
            edf_info['physical_min'] = np.append(edf_info['physical_min'], 0)
            edf_info['digital_min'] = np.append(edf_info['digital_min'], 0)
            vmax = np.max(events[2])
            edf_info['physical_max'] = np.append(edf_info['physical_max'],
                                                 vmax)
            edf_info['digital_max'] = np.append(edf_info['digital_max'], vmax)

            data = np.zeros(np.max(n_samps * n_records))
            warn_overlap = False
            for samp, id, dur in zip(events[1], events[2], events[4]):
                if np.sum(data[samp:samp + dur]) > 0:
                    warn_overlap = True  # Warn only once.
                data[samp:samp + dur] += id
            if warn_overlap:
                warn('Overlapping events detected. Use find_edf_events for '
                     'the original events.')
            edf_info['stim_data'] = data
    edf_info.update(events=events, sel=np.arange(len(edf_info['ch_names'])))
    return edf_info


def _read_annot(annot, annotmap, sfreq, data_length):
    """Annotation File Reader.

    Parameters
    ----------
    annot : str
        Path to annotation file.
    annotmap : str
        Path to annotation map file containing mapping from label to trigger.
    sfreq : float
        Sampling frequency.
    data_length : int
        Length of the data file.

    Returns
    -------
    stim_channel : ndarray
        An array containing stimulus trigger events.
    """
    times, durations, descriptions = _read_annotations_edf(annot)
    times = [float(time) * sfreq for time in times]

    pat = r'([\w\s]+):(\d+)'
    with io_open(annotmap) as annotmap_file:
        mappings = re.findall(pat, annotmap_file.read())
    maps = {}
    for mapping in mappings:
        maps[mapping[0]] = mapping[1]
    triggers = [int(maps[value]) for value in descriptions]

    stim_channel = np.zeros(data_length, dtype=int)
    for time, trigger in zip(times, triggers):
        stim_channel[int(time)] = int(trigger)

    return stim_channel


def _check_stim_channel(stim_channel, ch_names, sel):
    """Check that the stimulus channel exists in the current datafile."""
    if isinstance(stim_channel, str):
        if stim_channel == 'auto':
            if 'auto' in ch_names:
                raise ValueError("'auto' exists as a channel name. Change "
                                 "stim_channel parameter!")
            stim_channel = len(sel) - 1
        elif stim_channel not in ch_names:
            err = 'Could not find a channel named "{}" in datafile.' \
                  .format(stim_channel)
            casematch = [ch for ch in ch_names
                         if stim_channel.lower().replace(' ', '') ==
                         ch.lower().replace(' ', '')]
            if casematch:
                err += ' Closest match is "{}".'.format(casematch[0])
            raise ValueError(err)
    else:
        if stim_channel == -1:
            stim_channel = len(sel) - 1
        elif stim_channel > len(ch_names):
            raise ValueError('Requested stim_channel index ({}) exceeds total '
                             'number of channels in datafile ({})'
                             .format(stim_channel, len(ch_names)))

    return stim_channel


def _find_exclude_idx(ch_names, exclude):
    """Find the index of all channels to exclude.

    If there are several channels called "A" and we want to exclude "A",
    then add (the index of) all "A" channels to the exclusion list.
    """
    return [idx for idx, ch in enumerate(ch_names) if ch in exclude]


def read_raw_edf(input_fname, montage=None, eog=None, misc=None,
                 stim_channel='', annot=None, annotmap=None, exclude=(),
                 preload=False, verbose=None):
    """Reader function for EDF+, BDF, GDF conversion to FIF.

    Parameters
    ----------
    input_fname : str
        Path to the EDF+, BDF, or GDF file.
    montage : str | None | instance of Montage
        Path or instance of montage containing electrode positions.
        If None, sensor locations are (0,0,0). See the documentation of
        :func:`mne.channels.read_montage` for more information.
    eog : list or tuple
        Names of channels or list of indices that should be designated
        EOG channels. Values should correspond to the electrodes in the
        edf file. Default is None.
    misc : list or tuple
        Names of channels or list of indices that should be designated
        MISC channels. Values should correspond to the electrodes in the
        edf file. Default is None.
    stim_channel : str | int | 'auto' | False
        The channel name or channel index (starting at 0). -1 corresponds to
        the last channel. If False, there will be no stim channel added. If
        'auto' (default), the stim channel will be added as the last channel if
        the header contains ``'EDF Annotations'`` or GDF events (otherwise stim
        channel will not be added). None is accepted as an alias for False.

        .. warning:: This defaults to 'auto' in 0.17 but will default to False
                     in 0.18 (when no stim channel synthesis will be allowed)
                     and will be removed in 0.19; migrate code to use
                     :func:`mne.events_from_annotations` instead.

    annot : str | None
        Path to annotation file.
        If None, no derived stim channel will be added (for files requiring
        annotation file to interpret stim channel).
        This was deprecated in 0.17 and will be removed in 0.18.
    annotmap : str | None
        Path to annotation map file containing mapping from label to trigger.
        Must be specified if annot is not None.
        This was deprecated in 0.17 and will be removed in 0.18.
    exclude : list of str
        Channel names to exclude. This can help when reading data with
        different sampling rates to avoid unnecessary resampling.
    preload : bool or str (default False)
        Preload data into memory for data manipulation and faster indexing.
        If True, the data will be preloaded into memory (fast, requires
        large amount of memory). If preload is a string, preload is the
        file name of a memory-mapped file which is used to store the data
        on the hard drive (slower, requires less memory).
    verbose : bool, str, int, or None
        If not None, override default verbose level (see :func:`mne.verbose`
        and :ref:`Logging documentation <tut_logging>` for more).

    Returns
    -------
    raw : Instance of RawEDF
        A Raw object containing EDF data.

    Notes
    -----
    Biosemi devices trigger codes are encoded in bits 1-16 of the status
    channel, whereas system codes (CMS in/out-of range, battery low, etc.) are
    coded in bits 16-23 (see http://www.biosemi.com/faq/trigger_signals.htm).
    To retrieve correct event values (bits 1-16), one could do:

        >>> events = mne.find_events(...)  # doctest:+SKIP
        >>> events[:, 2] >>= 8  # doctest:+SKIP

    It is also possible to retrieve system codes, but no particular effort has
    been made to decode these in MNE.

    For GDF files, the stimulus channel is constructed from the events in the
    header. You should use keyword ``stim_channel=-1`` to add it at the end of
    the channel list. The id numbers of overlapping events are simply combined
    through addition. To get the original events from the header, use method
    ``raw.find_edf_events``.

    See Also
    --------
    mne.io.Raw : Documentation of attribute and methods.
    """
    return RawEDF(input_fname=input_fname, montage=montage, eog=eog, misc=misc,
                  stim_channel=stim_channel, annot=annot, annotmap=annotmap,
                  exclude=exclude, preload=preload, verbose=verbose)


def _read_annotations_edf(annotations):
    """Annotation File Reader.

    Parameters
    ----------
    annotations : ndarray (n_chans, n_samples) | str
        Channel data in EDF+ TAL format or path to annotation file.

    Returns
    -------
    onset : array of float, shape (n_annotations,)
        The starting time of annotations in seconds after ``orig_time``.
    duration : array of float, shape (n_annotations,)
        Durations of the annotations in seconds.
    description : array of str, shape (n_annotations,)
        Array of strings containing description for each annotation. If a
        string, all the annotations are given the same description. To reject
        epochs, use description starting with keyword 'bad'. See example above.
    """
    pat = '([+-]\\d+\\.?\\d*)(\x15(\\d+\\.?\\d*))?(\x14.*?)\x14\x00'
    if isinstance(annotations, str):
        with io_open(annotations, encoding='latin-1') as annot_file:
            triggers = re.findall(pat, annot_file.read())
    else:
        tals = bytearray()
        for chan in annotations:
            for s in chan:
                i = int(s)
                tals.extend(np.uint8([i % 256, i // 256]))
        # use of latin-1 because characters are only encoded for the first 256
        # code points and utf-8 can triggers an "invalid continuation byte"
        # error
        triggers = re.findall(pat, tals.decode('latin-1'))

    events = []
    for ev in triggers:
        onset = float(ev[0])
        duration = float(ev[2]) if ev[2] else 0
        for description in ev[3].split('\x14')[1:]:
            if description:
                events.append([onset, duration, description])

    return zip(*events) if events else (list(), list(), list())


def _get_edf_default_event_id(descriptions):
    mapping = dict((a, n) for n, a in
                   enumerate(sorted(set(descriptions)), start=1))
    return mapping