# -*- coding: utf-8 -*-
#
# License: BSD (3-clause)

import os
from xml.dom.minidom import parse
import re

import numpy as np


def _extract(tags, filepath=None, obj=None):
    """Extract info from XML."""
    if obj is not None:
        fileobj = obj
    elif filepath is not None:
        fileobj = parse(filepath)
    else:
        raise ValueError('There is not object or file to extract data')
    infoxml = dict()
    for tag in tags:
        value = fileobj.getElementsByTagName(tag)
        infoxml[tag] = []
        for i in range(len(value)):
            infoxml[tag].append(value[i].firstChild.data)
    return infoxml


def _get_gains(filepath):
    """Parse gains."""
    file_obj = parse(filepath)
    objects = file_obj.getElementsByTagName('calibration')
    gains = dict()
    for ob in objects:
        value = ob.getElementsByTagName('type')
        if value[0].firstChild.data == 'GCAL':
            data_g = _extract(['ch'], obj=ob)['ch']
            gains.update(gcal=np.asarray(data_g, dtype=np.float64))
        elif value[0].firstChild.data == 'ICAL':
            data_g = _extract(['ch'], obj=ob)['ch']
            gains.update(ical=np.asarray(data_g, dtype=np.float64))
    return gains


def _get_ep_info(filepath):
    """Get epoch info."""
    epochfile = filepath + '/epochs.xml'
    epochlist = parse(epochfile)
    epochs = epochlist.getElementsByTagName('epoch')
    epoch_info = list()
    for epoch in epochs:
        ep_begin = int(epoch.getElementsByTagName('beginTime')[0]
                       .firstChild.data)
        ep_end = int(epoch.getElementsByTagName('endTime')[0].firstChild.data)
        first_block = int(epoch.getElementsByTagName('firstBlock')[0]
                          .firstChild.data)
        last_block = int(epoch.getElementsByTagName('lastBlock')[0]
                         .firstChild.data)
        epoch_info.append({'first_samp': ep_begin,
                           'last_samp': ep_end,
                           'first_block': first_block,
                           'last_block': last_block})
    return epoch_info


def _get_blocks(filepath):
    """Get info from meta data blocks."""
    binfile = os.path.join(filepath)
    n_blocks = 0
    samples_block = []
    header_sizes = []
    n_channels = []
    sfreq = []
    # Meta data consists of:
    # * 1 byte of flag (1 for meta data, 0 for data)
    # * 1 byte of header size
    # * 1 byte of block size
    # * 1 byte of n_channels
    # * n_channels bytes of offsets
    # * n_channels bytes of sigfreqs?
    with open(binfile, 'rb') as fid:
        fid.seek(0, 2)  # go to end of file
        file_length = fid.tell()
        block_size = file_length
        fid.seek(0)
        position = 0
        while position < file_length:
            block = _block_r(fid)
            if block is None:
                samples_block.append(samples_block[n_blocks - 1])
                n_blocks += 1
                fid.seek(block_size, 1)
                position = fid.tell()
                continue
            block_size = block['block_size']
            header_size = block['header_size']
            header_sizes.append(header_size)
            samples_block.append(block['nsamples'])
            n_blocks += 1
            fid.seek(block_size, 1)
            sfreq.append(block['sfreq'])
            n_channels.append(block['nc'])
            position = fid.tell()

    if any([n != n_channels[0] for n in n_channels]):
        raise RuntimeError("All the blocks don't have the same amount of "
                           "channels.")
    if any([f != sfreq[0] for f in sfreq]):
        raise RuntimeError("All the blocks don't have the same sampling "
                           "frequency.")
    samples_block = np.array(samples_block)
    signal_blocks = dict(n_channels=n_channels[0], sfreq=sfreq[0],
                         n_blocks=n_blocks, samples_block=samples_block,
                         header_sizes=header_sizes)
    return signal_blocks


def _get_signalfname(filepath):
    """Get filenames."""
    listfiles = os.listdir(filepath)
    binfiles = list(f for f in listfiles if 'signal' in f and
                    f[-4:] == '.bin' and f[0] != '.')
    all_files = {}
    for binfile in binfiles:
        bin_num_str = re.search(r'\d+', binfile).group()
        infofile = 'info' + bin_num_str + '.xml'
        infobjfile = os.path.join(filepath, infofile)
        infobj = parse(infobjfile)
        if len(infobj.getElementsByTagName('EEG')):
            signal_type = 'EEG'
        elif len(infobj.getElementsByTagName('PNSData')):
            signal_type = 'PNS'
        all_files[signal_type] = {
            'signal': 'signal{}.bin'.format(bin_num_str),
            'info': infofile}
    return all_files


def _block_r(fid):
    """Read meta data."""
    if np.fromfile(fid, dtype=np.dtype('i4'), count=1)[0] != 1:  # not metadata
        return None
    header_size = np.fromfile(fid, dtype=np.dtype('i4'), count=1)[0]
    block_size = np.fromfile(fid, dtype=np.dtype('i4'), count=1)[0]
    hl = int(block_size / 4)
    nc = np.fromfile(fid, dtype=np.dtype('i4'), count=1)[0]
    nsamples = int(hl / nc)
    np.fromfile(fid, dtype=np.dtype('i4'), count=nc)  # sigoffset
    sigfreq = np.fromfile(fid, dtype=np.dtype('i4'), count=nc)
    depth = sigfreq[0] & 0xFF
    if depth != 32:
        raise ValueError('I do not know how to read this MFF (depth != 32)')
    sfreq = sigfreq[0] >> 8
    count = int(header_size / 4 - (4 + 2 * nc))
    np.fromfile(fid, dtype=np.dtype('i4'), count=count)  # sigoffset
    block = dict(nc=nc,
                 hl=hl,
                 nsamples=nsamples,
                 block_size=block_size,
                 header_size=header_size,
                 sfreq=sfreq)
    return block
