""" Testing mio5_utils Cython module

"""
import sys

from io import BytesIO

import numpy as np

from numpy.testing import assert_array_equal, assert_equal, assert_
from pytest import raises as assert_raises

import scipy.io.matlab._byteordercodes as boc
import scipy.io.matlab._streams as streams
import scipy.io.matlab._mio5_params as mio5p
import scipy.io.matlab._mio5_utils as m5u


def test_byteswap():
    for val in (
        1,
        0x100,
        0x10000):
        a = np.array(val, dtype=np.uint32)
        b = a.byteswap()
        c = m5u.byteswap_u4(a)
        assert_equal(b.item(), c)
        d = m5u.byteswap_u4(c)
        assert_equal(a.item(), d)


def _make_tag(base_dt, val, mdtype, sde=False):
    ''' Makes a simple matlab tag, full or sde '''
    base_dt = np.dtype(base_dt)
    bo = boc.to_numpy_code(base_dt.byteorder)
    byte_count = base_dt.itemsize
    if not sde:
        udt = bo + 'u4'
        padding = 8 - (byte_count % 8)
        all_dt = [('mdtype', udt),
                  ('byte_count', udt),
                  ('val', base_dt)]
        if padding:
            all_dt.append(('padding', 'u1', padding))
    else:  # is sde
        udt = bo + 'u2'
        padding = 4-byte_count
        if bo == '<':  # little endian
            all_dt = [('mdtype', udt),
                      ('byte_count', udt),
                      ('val', base_dt)]
        else:  # big endian
            all_dt = [('byte_count', udt),
                      ('mdtype', udt),
                      ('val', base_dt)]
        if padding:
            all_dt.append(('padding', 'u1', padding))
    tag = np.zeros((1,), dtype=all_dt)
    tag['mdtype'] = mdtype
    tag['byte_count'] = byte_count
    tag['val'] = val
    return tag


def _write_stream(stream, *strings):
    stream.truncate(0)
    stream.seek(0)
    for s in strings:
        stream.write(s)
    stream.seek(0)


def _make_readerlike(stream, byte_order=boc.native_code):
    class R:
        pass
    r = R()
    r.mat_stream = stream
    r.byte_order = byte_order
    r.struct_as_record = True
    r.uint16_codec = sys.getdefaultencoding()
    r.chars_as_strings = False
    r.mat_dtype = False
    r.squeeze_me = False
    return r


def test_read_tag():
    # mainly to test errors
    # make reader-like thing
    str_io = BytesIO()
    r = _make_readerlike(str_io)
    c_reader = m5u.VarReader5(r)
    # This works for StringIO but _not_ BytesIO
    assert_raises(OSError, c_reader.read_tag)
    # bad SDE
    tag = _make_tag('i4', 1, mio5p.miINT32, sde=True)
    tag['byte_count'] = 5
    _write_stream(str_io, tag.tobytes())
    assert_raises(ValueError, c_reader.read_tag)


def test_read_stream():
    tag = _make_tag('i4', 1, mio5p.miINT32, sde=True)
    tag_str = tag.tobytes()
    str_io = BytesIO(tag_str)
    st = streams.make_stream(str_io)
    s = streams._read_into(st, tag.itemsize)
    assert_equal(s, tag.tobytes())


def test_read_numeric():
    # make reader-like thing
    str_io = BytesIO()
    r = _make_readerlike(str_io)
    # check simplest of tags
    for base_dt, val, mdtype in (('u2', 30, mio5p.miUINT16),
                                 ('i4', 1, mio5p.miINT32),
                                 ('i2', -1, mio5p.miINT16)):
        for byte_code in ('<', '>'):
            r.byte_order = byte_code
            c_reader = m5u.VarReader5(r)
            assert_equal(c_reader.little_endian, byte_code == '<')
            assert_equal(c_reader.is_swapped, byte_code != boc.native_code)
            for sde_f in (False, True):
                dt = np.dtype(base_dt).newbyteorder(byte_code)
                a = _make_tag(dt, val, mdtype, sde_f)
                a_str = a.tobytes()
                _write_stream(str_io, a_str)
                el = c_reader.read_numeric()
                assert_equal(el, val)
                # two sequential reads
                _write_stream(str_io, a_str, a_str)
                el = c_reader.read_numeric()
                assert_equal(el, val)
                el = c_reader.read_numeric()
                assert_equal(el, val)


def test_read_numeric_writeable():
    # make reader-like thing
    str_io = BytesIO()
    r = _make_readerlike(str_io, '<')
    c_reader = m5u.VarReader5(r)
    dt = np.dtype('<u2')
    a = _make_tag(dt, 30, mio5p.miUINT16, 0)
    a_str = a.tobytes()
    _write_stream(str_io, a_str)
    el = c_reader.read_numeric()
    assert_(el.flags.writeable is True)


def test_zero_byte_string():
    # Tests hack to allow chars of non-zero length, but 0 bytes
    # make reader-like thing
    str_io = BytesIO()
    r = _make_readerlike(str_io, boc.native_code)
    c_reader = m5u.VarReader5(r)
    tag_dt = np.dtype([('mdtype', 'u4'), ('byte_count', 'u4')])
    tag = np.zeros((1,), dtype=tag_dt)
    tag['mdtype'] = mio5p.miINT8
    tag['byte_count'] = 1
    hdr = m5u.VarHeader5()
    # Try when string is 1 length
    hdr.set_dims([1,])
    _write_stream(str_io, tag.tobytes() + b'        ')
    str_io.seek(0)
    val = c_reader.read_char(hdr)
    assert_equal(val, ' ')
    # Now when string has 0 bytes 1 length
    tag['byte_count'] = 0
    _write_stream(str_io, tag.tobytes())
    str_io.seek(0)
    val = c_reader.read_char(hdr)
    assert_equal(val, ' ')
    # Now when string has 0 bytes 4 length
    str_io.seek(0)
    hdr.set_dims([4,])
    val = c_reader.read_char(hdr)
    assert_array_equal(val, [' '] * 4)