#!/usr/bin/env python
"""
Copyright (C) 2014 Analog Devices, Inc.
Author: Paul Cercueil <paul.cercueil@analog.com>

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.
"""

# Imports from package ctypes are not grouped
# pylint: disable=ungrouped-imports
#
# The way the methods and classes are used, violate this, but there
#   isn't a good way to do things otherwise
# pylint: disable=protected-access
from ctypes import (
    Structure,
    c_char_p,
    c_uint,
    c_int,
    c_long,
    c_longlong,
    c_size_t,
    c_ssize_t,
    c_char,
    c_void_p,
    c_bool,
    create_string_buffer,
    c_double,
    cast,
    POINTER as _POINTER,
    CDLL as _cdll,
    memmove as _memmove,
    byref as _byref,
)
from ctypes.util import find_library
from enum import Enum
from os import strerror as _strerror
from platform import system as _system
import weakref
import abc

if "Windows" in _system():
    from ctypes import get_last_error
else:
    from ctypes import get_errno
# pylint: enable=ungrouped-imports

# ctypes requires the errcheck to take three arguments, but we don't use them
# pylint: disable=unused-argument


def _check_null(result, func, arguments):
    if result:
        return result
    err = get_last_error() if "Windows" in _system() else get_errno()
    raise OSError(err, _strerror(err))


def _check_negative(result, func, arguments):
    if result >= 0:
        return result
    raise OSError(-result, _strerror(-result))


# pylint: enable=unused-argument

# Python 2 and Python 3 compatible _isstring function.
# pylint: disable=basestring-builtin
def _isstring(argument):
    try:
        # attempt to evaluate basestring (Python 2)
        return isinstance(argument, basestring)
    except NameError:
        # No basestring --> Python 3
        return isinstance(argument, str)


# pylint: enable=basestring-builtin


class _ScanContext(Structure):
    pass


class _ContextInfo(Structure):
    pass


class _Context(Structure):
    pass


class _Device(Structure):
    pass


class _Channel(Structure):
    pass


class _Buffer(Structure):
    pass


class DataFormat(Structure):
    """Represents the data format of an IIO channel."""

    _fields_ = [
        ("length", c_uint),
        ("bits", c_uint),
        ("shift", c_uint),
        ("is_signed", c_bool),
        ("is_fully_defined", c_bool),
        ("is_be", c_bool),
        ("with_scale", c_bool),
        ("scale", c_double),
        ("repeat", c_uint),
    ]


class ChannelModifier(Enum):
    """Contains the modifier type of an IIO channel."""

    IIO_NO_MOD = 0
    IIO_MOD_X = 1
    IIO_MOD_Y = 2
    IIO_MOD_Z = 3
    IIO_MOD_X_AND_Y = 4
    IIO_MOD_X_AND_Z = 5
    IIO_MOD_Y_AND_Z = 6
    IIO_MOD_X_AND_Y_AND_Z = 7
    IIO_MOD_X_OR_Y = 8
    IIO_MOD_X_OR_Z = 9
    IIO_MOD_Y_OR_Z = 10
    IIO_MOD_X_OR_Y_OR_Z = 11
    IIO_MOD_LIGHT_BOTH = 12
    IIO_MOD_LIGHT_IR = 13
    IIO_MOD_ROOT_SUM_SQUARED_X_Y = 14
    IIO_MOD_SUM_SQUARED_X_Y_Z = 15
    IIO_MOD_LIGHT_CLEAR = 16
    IIO_MOD_LIGHT_RED = 17
    IIO_MOD_LIGHT_GREEN = 18
    IIO_MOD_LIGHT_BLUE = 19
    IIO_MOD_QUATERNION = 20
    IIO_MOD_TEMP_AMBIENT = 21
    IIO_MOD_TEMP_OBJECT = 22
    IIO_MOD_NORTH_MAGN = 23
    IIO_MOD_NORTH_TRUE = 24
    IIO_MOD_NORTH_MAGN_TILT_COMP = 25
    IIO_MOD_NORTH_TRUE_TILT_COMP = 26
    IIO_MOD_RUNNING = 27
    IIO_MOD_JOGGING = 28
    IIO_MOD_WALKING = 29
    IIO_MOD_STILL = 30
    IIO_MOD_ROOT_SUM_SQUARED_X_Y_Z = 31
    IIO_MOD_I = 32
    IIO_MOD_Q = 33
    IIO_MOD_CO2 = 34
    IIO_MOD_VOC = 35
    IIO_MOD_LIGHT_UV = 36
    IIO_MOD_LIGHT_DUV = 37
    IIO_MOD_PM1 = 38
    IIO_MOD_PM2P5 = 39
    IIO_MOD_PM4 = 40
    IIO_MOD_PM10 = 41
    IIO_MOD_ETHANOL = 42
    IIO_MOD_H2 = 43


class ChannelType(Enum):
    """Contains the type of an IIO channel."""

    IIO_VOLTAGE = 0
    IIO_CURRENT = 1
    IIO_POWER = 2
    IIO_ACCEL = 3
    IIO_ANGL_VEL = 4
    IIO_MAGN = 5
    IIO_LIGHT = 6
    IIO_INTENSITY = 7
    IIO_PROXIMITY = 8
    IIO_TEMP = 9
    IIO_INCLI = 10
    IIO_ROT = 11
    IIO_ANGL = 12
    IIO_TIMESTAMP = 13
    IIO_CAPACITANCE = 14
    IIO_ALTVOLTAGE = 15
    IIO_CCT = 16
    IIO_PRESSURE = 17
    IIO_HUMIDITYRELATIVE = 18
    IIO_ACTIVITY = 19
    IIO_STEPS = 20
    IIO_ENERGY = 21
    IIO_DISTANCE = 22
    IIO_VELOCITY = 23
    IIO_CONCENTRATION = 24
    IIO_RESISTANCE = 25
    IIO_PH = 26
    IIO_UVINDEX = 27
    IIO_ELECTRICALCONDUCTIVITY = 28
    IIO_COUNT = 29
    IIO_INDEX = 30
    IIO_GRAVITY = 31
    IIO_POSITIONRELATIVE = 32
    IIO_PHASE = 33
    IIO_MASSCONCENTRATION = 34
    IIO_CHAN_TYPE_UNKNOWN = 0x7FFFFFFF


# pylint: disable=invalid-name
_ScanContextPtr = _POINTER(_ScanContext)
_ContextInfoPtr = _POINTER(_ContextInfo)
_ContextPtr = _POINTER(_Context)
_DevicePtr = _POINTER(_Device)
_ChannelPtr = _POINTER(_Channel)
_BufferPtr = _POINTER(_Buffer)
_DataFormatPtr = _POINTER(DataFormat)

if "Windows" in _system():
    _iiolib = "libiio.dll"
else:
    # Non-windows, possibly Posix system
    _iiolib = "iio"

_lib = _cdll(find_library(_iiolib), use_errno=True, use_last_error=True)

_get_backends_count = _lib.iio_get_backends_count
_get_backends_count.restype = c_uint

_get_backend = _lib.iio_get_backend
_get_backend.argtypes = (c_uint,)
_get_backend.restype = c_char_p
_get_backend.errcheck = _check_null

_create_scan_context = _lib.iio_create_scan_context
_create_scan_context.argtypes = (c_char_p, c_uint)
_create_scan_context.restype = _ScanContextPtr
_create_scan_context.errcheck = _check_null

_destroy_scan_context = _lib.iio_scan_context_destroy
_destroy_scan_context.argtypes = (_ScanContextPtr,)

_iio_has_backend = _lib.iio_has_backend
_iio_has_backend.argtypes = (c_char_p,)
_iio_has_backend.restype = c_bool

_iio_strerror = _lib.iio_strerror
_iio_strerror.argtypes = (c_int, c_char_p, c_uint)
_iio_strerror.restype = None

_get_context_info_list = _lib.iio_scan_context_get_info_list
_get_context_info_list.argtypes = (_ScanContextPtr, _POINTER(_POINTER(_ContextInfoPtr)))
_get_context_info_list.restype = c_ssize_t
_get_context_info_list.errcheck = _check_negative

_context_info_list_free = _lib.iio_context_info_list_free
_context_info_list_free.argtypes = (_POINTER(_ContextInfoPtr),)

_context_info_get_description = _lib.iio_context_info_get_description
_context_info_get_description.argtypes = (_ContextInfoPtr,)
_context_info_get_description.restype = c_char_p

_context_info_get_uri = _lib.iio_context_info_get_uri
_context_info_get_uri.argtypes = (_ContextInfoPtr,)
_context_info_get_uri.restype = c_char_p

_new_local = _lib.iio_create_local_context
_new_local.restype = _ContextPtr
_new_local.errcheck = _check_null

_new_xml = _lib.iio_create_xml_context
_new_xml.restype = _ContextPtr
_new_xml.argtypes = (c_char_p,)
_new_xml.errcheck = _check_null

_new_network = _lib.iio_create_network_context
_new_network.restype = _ContextPtr
_new_network.argtypes = (c_char_p,)
_new_network.errcheck = _check_null

_new_default = _lib.iio_create_default_context
_new_default.restype = _ContextPtr
_new_default.errcheck = _check_null

_new_uri = _lib.iio_create_context_from_uri
_new_uri.restype = _ContextPtr
_new_uri.errcheck = _check_null

_destroy = _lib.iio_context_destroy
_destroy.argtypes = (_ContextPtr,)

_get_name = _lib.iio_context_get_name
_get_name.restype = c_char_p
_get_name.argtypes = (_ContextPtr,)
_get_name.errcheck = _check_null

_get_description = _lib.iio_context_get_description
_get_description.restype = c_char_p
_get_description.argtypes = (_ContextPtr,)

_get_xml = _lib.iio_context_get_xml
_get_xml.restype = c_char_p
_get_xml.argtypes = (_ContextPtr,)

_get_library_version = _lib.iio_library_get_version
_get_library_version.argtypes = (
    _POINTER(c_uint),
    _POINTER(c_uint),
    c_char_p,
)

_get_version = _lib.iio_context_get_version
_get_version.restype = c_int
_get_version.argtypes = (
    _ContextPtr,
    _POINTER(c_uint),
    _POINTER(c_uint),
    c_char_p,
)
_get_version.errcheck = _check_negative

_get_attrs_count = _lib.iio_context_get_attrs_count
_get_attrs_count.restype = c_uint
_get_attrs_count.argtypes = (_ContextPtr,)

_get_attr = _lib.iio_context_get_attr
_get_attr.restype = c_int
_get_attr.argtypes = (_ContextPtr, c_uint, _POINTER(c_char_p), _POINTER(c_char_p))
_get_attr.errcheck = _check_negative

_devices_count = _lib.iio_context_get_devices_count
_devices_count.restype = c_uint
_devices_count.argtypes = (_ContextPtr,)

_get_device = _lib.iio_context_get_device
_get_device.restype = _DevicePtr
_get_device.argtypes = (_ContextPtr, c_uint)
_get_device.errcheck = _check_null

_set_timeout = _lib.iio_context_set_timeout
_set_timeout.restype = c_int
_set_timeout.argtypes = (
    _ContextPtr,
    c_uint,
)
_set_timeout.errcheck = _check_negative

_clone = _lib.iio_context_clone
_clone.restype = _ContextPtr
_clone.argtypes = (_ContextPtr,)
_clone.errcheck = _check_null

_d_get_id = _lib.iio_device_get_id
_d_get_id.restype = c_char_p
_d_get_id.argtypes = (_DevicePtr,)
_d_get_id.errcheck = _check_null

_d_get_name = _lib.iio_device_get_name
_d_get_name.restype = c_char_p
_d_get_name.argtypes = (_DevicePtr,)

_d_attr_count = _lib.iio_device_get_attrs_count
_d_attr_count.restype = c_uint
_d_attr_count.argtypes = (_DevicePtr,)

_d_get_attr = _lib.iio_device_get_attr
_d_get_attr.restype = c_char_p
_d_get_attr.argtypes = (_DevicePtr,)
_d_get_attr.errcheck = _check_null

_d_read_attr = _lib.iio_device_attr_read
_d_read_attr.restype = c_ssize_t
_d_read_attr.argtypes = (_DevicePtr, c_char_p, c_char_p, c_size_t)
_d_read_attr.errcheck = _check_negative

_d_write_attr = _lib.iio_device_attr_write
_d_write_attr.restype = c_ssize_t
_d_write_attr.argtypes = (_DevicePtr, c_char_p, c_char_p)
_d_write_attr.errcheck = _check_negative

_d_debug_attr_count = _lib.iio_device_get_debug_attrs_count
_d_debug_attr_count.restype = c_uint
_d_debug_attr_count.argtypes = (_DevicePtr,)

_d_get_debug_attr = _lib.iio_device_get_debug_attr
_d_get_debug_attr.restype = c_char_p
_d_get_debug_attr.argtypes = (_DevicePtr,)
_d_get_debug_attr.errcheck = _check_null

_d_read_debug_attr = _lib.iio_device_debug_attr_read
_d_read_debug_attr.restype = c_ssize_t
_d_read_debug_attr.argtypes = (_DevicePtr, c_char_p, c_char_p, c_size_t)
_d_read_debug_attr.errcheck = _check_negative

_d_write_debug_attr = _lib.iio_device_debug_attr_write
_d_write_debug_attr.restype = c_ssize_t
_d_write_debug_attr.argtypes = (_DevicePtr, c_char_p, c_char_p)
_d_write_debug_attr.errcheck = _check_negative

_d_buffer_attr_count = _lib.iio_device_get_buffer_attrs_count
_d_buffer_attr_count.restype = c_uint
_d_buffer_attr_count.argtypes = (_DevicePtr,)

_d_get_buffer_attr = _lib.iio_device_get_buffer_attr
_d_get_buffer_attr.restype = c_char_p
_d_get_buffer_attr.argtypes = (_DevicePtr,)
_d_get_buffer_attr.errcheck = _check_null

_d_read_buffer_attr = _lib.iio_device_buffer_attr_read
_d_read_buffer_attr.restype = c_ssize_t
_d_read_buffer_attr.argtypes = (_DevicePtr, c_char_p, c_char_p, c_size_t)
_d_read_buffer_attr.errcheck = _check_negative

_d_write_buffer_attr = _lib.iio_device_buffer_attr_write
_d_write_buffer_attr.restype = c_ssize_t
_d_write_buffer_attr.argtypes = (_DevicePtr, c_char_p, c_char_p)
_d_write_buffer_attr.errcheck = _check_negative

_d_get_context = _lib.iio_device_get_context
_d_get_context.restype = _ContextPtr
_d_get_context.argtypes = (_DevicePtr,)

_d_reg_write = _lib.iio_device_reg_write
_d_reg_write.restype = c_int
_d_reg_write.argtypes = (_DevicePtr, c_uint, c_uint)
_d_reg_write.errcheck = _check_negative

_d_reg_read = _lib.iio_device_reg_read
_d_reg_read.restype = c_int
_d_reg_read.argtypes = (_DevicePtr, c_uint, _POINTER(c_uint))
_d_reg_read.errcheck = _check_negative

_channels_count = _lib.iio_device_get_channels_count
_channels_count.restype = c_uint
_channels_count.argtypes = (_DevicePtr,)

_get_channel = _lib.iio_device_get_channel
_get_channel.restype = _ChannelPtr
_get_channel.argtypes = (_DevicePtr, c_uint)
_get_channel.errcheck = _check_null

_get_sample_size = _lib.iio_device_get_sample_size
_get_sample_size.restype = c_int
_get_sample_size.argtypes = (_DevicePtr,)
_get_sample_size.errcheck = _check_negative

_d_is_trigger = _lib.iio_device_is_trigger
_d_is_trigger.restype = c_bool
_d_is_trigger.argtypes = (_DevicePtr,)

_d_get_trigger = _lib.iio_device_get_trigger
_d_get_trigger.restype = c_int
_d_get_trigger.argtypes = (
    _DevicePtr,
    _DevicePtr,
)
_d_get_trigger.errcheck = _check_negative

_d_set_trigger = _lib.iio_device_set_trigger
_d_set_trigger.restype = c_int
_d_set_trigger.argtypes = (
    _DevicePtr,
    _DevicePtr,
)
_d_set_trigger.errcheck = _check_negative

_d_set_buffers_count = _lib.iio_device_set_kernel_buffers_count
_d_set_buffers_count.restype = c_int
_d_set_buffers_count.argtypes = (_DevicePtr, c_uint)
_d_set_buffers_count.errcheck = _check_negative

_c_get_id = _lib.iio_channel_get_id
_c_get_id.restype = c_char_p
_c_get_id.argtypes = (_ChannelPtr,)
_c_get_id.errcheck = _check_null

_c_get_name = _lib.iio_channel_get_name
_c_get_name.restype = c_char_p
_c_get_name.argtypes = (_ChannelPtr,)

_c_is_output = _lib.iio_channel_is_output
_c_is_output.restype = c_bool
_c_is_output.argtypes = (_ChannelPtr,)

_c_is_scan_element = _lib.iio_channel_is_scan_element
_c_is_scan_element.restype = c_bool
_c_is_scan_element.argtypes = (_ChannelPtr,)

_c_attr_count = _lib.iio_channel_get_attrs_count
_c_attr_count.restype = c_uint
_c_attr_count.argtypes = (_ChannelPtr,)

_c_get_attr = _lib.iio_channel_get_attr
_c_get_attr.restype = c_char_p
_c_get_attr.argtypes = (_ChannelPtr,)
_c_get_attr.errcheck = _check_null

_c_get_filename = _lib.iio_channel_attr_get_filename
_c_get_filename.restype = c_char_p
_c_get_filename.argtypes = (
    _ChannelPtr,
    c_char_p,
)
_c_get_filename.errcheck = _check_null

_c_read_attr = _lib.iio_channel_attr_read
_c_read_attr.restype = c_ssize_t
_c_read_attr.argtypes = (_ChannelPtr, c_char_p, c_char_p, c_size_t)
_c_read_attr.errcheck = _check_negative

_c_write_attr = _lib.iio_channel_attr_write
_c_write_attr.restype = c_ssize_t
_c_write_attr.argtypes = (_ChannelPtr, c_char_p, c_char_p)
_c_write_attr.errcheck = _check_negative

_c_enable = _lib.iio_channel_enable
_c_enable.argtypes = (_ChannelPtr,)

_c_disable = _lib.iio_channel_disable
_c_disable.argtypes = (_ChannelPtr,)

_c_is_enabled = _lib.iio_channel_is_enabled
_c_is_enabled.restype = c_bool
_c_is_enabled.argtypes = (_ChannelPtr,)

_c_read = _lib.iio_channel_read
_c_read.restype = c_ssize_t
_c_read.argtypes = (
    _ChannelPtr,
    _BufferPtr,
    c_void_p,
    c_size_t,
)

_c_read_raw = _lib.iio_channel_read_raw
_c_read_raw.restype = c_ssize_t
_c_read_raw.argtypes = (
    _ChannelPtr,
    _BufferPtr,
    c_void_p,
    c_size_t,
)

_c_write = _lib.iio_channel_write
_c_write.restype = c_ssize_t
_c_write.argtypes = (
    _ChannelPtr,
    _BufferPtr,
    c_void_p,
    c_size_t,
)

_c_write_raw = _lib.iio_channel_write_raw
_c_write_raw.restype = c_ssize_t
_c_write_raw.argtypes = (
    _ChannelPtr,
    _BufferPtr,
    c_void_p,
    c_size_t,
)

_channel_get_device = _lib.iio_channel_get_device
_channel_get_device.restype = _DevicePtr
_channel_get_device.argtypes = (_ChannelPtr,)

_channel_get_index = _lib.iio_channel_get_index
_channel_get_index.restype = c_long
_channel_get_index.argtypes = (_ChannelPtr,)

_channel_get_data_format = _lib.iio_channel_get_data_format
_channel_get_data_format.restype = _DataFormatPtr
_channel_get_data_format.argtypes = (_ChannelPtr,)

_channel_get_modifier = _lib.iio_channel_get_modifier
_channel_get_modifier.restype = c_int
_channel_get_modifier.argtypes = (_ChannelPtr,)

_channel_get_type = _lib.iio_channel_get_type
_channel_get_type.restype = c_int
_channel_get_type.argtypes = (_ChannelPtr,)

_channel_convert = _lib.iio_channel_convert
_channel_convert.restype = None
_channel_convert.argtypes = (_ChannelPtr, c_void_p, c_void_p)

_channel_convert_inverse = _lib.iio_channel_convert_inverse
_channel_convert_inverse.restype = None
_channel_convert_inverse.argtypes = (_ChannelPtr, c_void_p, c_void_p)

_create_buffer = _lib.iio_device_create_buffer
_create_buffer.restype = _BufferPtr
_create_buffer.argtypes = (
    _DevicePtr,
    c_size_t,
    c_bool,
)
_create_buffer.errcheck = _check_null

_buffer_destroy = _lib.iio_buffer_destroy
_buffer_destroy.argtypes = (_BufferPtr,)

_buffer_refill = _lib.iio_buffer_refill
_buffer_refill.restype = c_ssize_t
_buffer_refill.argtypes = (_BufferPtr,)
_buffer_refill.errcheck = _check_negative

_buffer_push_partial = _lib.iio_buffer_push_partial
_buffer_push_partial.restype = c_ssize_t
_buffer_push_partial.argtypes = (
    _BufferPtr,
    c_uint,
)
_buffer_push_partial.errcheck = _check_negative

_buffer_start = _lib.iio_buffer_start
_buffer_start.restype = c_void_p
_buffer_start.argtypes = (_BufferPtr,)

_buffer_end = _lib.iio_buffer_end
_buffer_end.restype = c_void_p
_buffer_end.argtypes = (_BufferPtr,)

_buffer_cancel = _lib.iio_buffer_cancel
_buffer_cancel.restype = c_void_p
_buffer_cancel.argtypes = (_BufferPtr,)

_buffer_get_device = _lib.iio_buffer_get_device
_buffer_get_device.restype = _DevicePtr
_buffer_get_device.argtypes = (_BufferPtr,)

_buffer_get_poll_fd = _lib.iio_buffer_get_poll_fd
_buffer_get_poll_fd.restype = c_int
_buffer_get_poll_fd.argtypes = (_BufferPtr,)

_buffer_step = _lib.iio_buffer_step
_buffer_step.restype = c_longlong
_buffer_step.argtypes = (_BufferPtr,)

_buffer_set_blocking_mode = _lib.iio_buffer_set_blocking_mode
_buffer_set_blocking_mode.restype = c_uint
_buffer_set_blocking_mode.argtypes = (_BufferPtr, c_bool)


# pylint: enable=invalid-name


def _get_lib_version():
    major = c_uint()
    minor = c_uint()
    buf = create_string_buffer(8)
    _get_library_version(_byref(major), _byref(minor), buf)
    return (major.value, minor.value, buf.value.decode("ascii"))


def _has_backend(backend):
    b_backend = backend.encode("utf-8")
    return _iio_has_backend(b_backend)


def iio_strerror(err, buf, length):
    """Get a string description of an error code."""
    b_buf = buf.encode("utf-8")
    _iio_strerror(err, b_buf, length)


version = _get_lib_version()
backends = [_get_backend(b).decode("ascii") for b in range(0, _get_backends_count())]


class _Attr(object):
    def __init__(self, name, filename=None):
        self._name = name
        self._name_ascii = name.encode("ascii")
        self._filename = name if filename is None else filename

    def __str__(self):
        return self._name

    @abc.abstractmethod
    def _read(self):
        pass

    @abc.abstractmethod
    def _write(self, value):
        pass

    name = property(
        lambda self: self._name, None, None, "The name of this attribute.\n\ttype=str"
    )
    filename = property(
        lambda self: self._filename,
        None,
        None,
        "The filename in sysfs to which this attribute is bound.\n\ttype=str",
    )
    value = property(
        lambda self: self._read(),
        lambda self, x: self._write(x),
        None,
        "Current value of this attribute.\n\ttype=str",
    )


class ChannelAttr(_Attr):
    """Represents an attribute of a channel."""

    def __init__(self, channel, name):
        """
        Initialize a new instance of the ChannelAttr class.

        :param channel: type=iio.Channel
            A valid instance of the iio.Channel class.
        :param name: type=str
            The channel attribute's name

        returns: type=iio.ChannelAttr
            A new instance of this class
        """
        super(ChannelAttr, self).__init__(
            name, _c_get_filename(channel, name.encode("ascii")).decode("ascii")
        )
        self._channel = channel

    def _read(self):
        buf = create_string_buffer(1024)
        _c_read_attr(self._channel, self._name_ascii, buf, len(buf))
        return buf.value.decode("ascii")

    def _write(self, value):
        _c_write_attr(self._channel, self._name_ascii, value.encode("ascii"))


class DeviceAttr(_Attr):
    """Represents an attribute of an IIO device."""

    def __init__(self, device, name):
        """
        Initialize a new instance of the DeviceAttr class.

        :param device: type=iio.Device
            A valid instance of the iio.Device class.
        :param name: type=str
            The device attribute's name

        returns: type=iio.DeviceAttr
            A new instance of this class
        """
        super(DeviceAttr, self).__init__(name)
        self._device = device

    def _read(self):
        buf = create_string_buffer(1024)
        _d_read_attr(self._device, self._name_ascii, buf, len(buf))
        return buf.value.decode("ascii")

    def _write(self, value):
        _d_write_attr(self._device, self._name_ascii, value.encode("ascii"))


class DeviceDebugAttr(DeviceAttr):
    """Represents a debug attribute of an IIO device."""

    def __init__(self, device, name):
        """
        Initialize a new instance of the DeviceDebugAttr class.

        :param device: type=iio.Device
             A valid instance of the iio.Device class.
        :param name: type=str
             The device debug attribute's name

        returns: type=iio.DeviceDebugAttr
            A new instance of this class
        """
        super(DeviceDebugAttr, self).__init__(device, name)

    def _read(self):
        buf = create_string_buffer(1024)
        _d_read_debug_attr(self._device, self._name_ascii, buf, len(buf))
        return buf.value.decode("ascii")

    def _write(self, value):
        _d_write_debug_attr(self._device, self._name_ascii, value.encode("ascii"))


class DeviceBufferAttr(DeviceAttr):
    """Represents a buffer attribute of an IIO device."""

    def __init__(self, device, name):
        """
        Initialize a new instance of the DeviceBufferAttr class.

        :param device: type=iio.Device
            A valid instance of the iio.Device class.
        :param name: type=str
            The device buffer attribute's name

        returns: type=iio.DeviceBufferAttr
            A new instance of this class
        """
        super(DeviceBufferAttr, self).__init__(device, name)

    def _read(self):
        buf = create_string_buffer(1024)
        _d_read_buffer_attr(self._device, self._name_ascii, buf, len(buf))
        return buf.value.decode("ascii")

    def _write(self, value):
        _d_write_buffer_attr(self._device, self._name_ascii, value.encode("ascii"))


class Channel(object):
    """Represents a channel of an IIO device."""

    def __init__(self, _channel):
        """
        Initialize a new instance of the Channel class.

        :param _channel: type=_ChannelPtr
            Pointer to an IIO Channel.

        returns: type=iio.Channel
            An new instance of this class
        """
        self._channel = _channel
        self._attrs = {
            name: ChannelAttr(_channel, name)
            for name in [
                _c_get_attr(_channel, x).decode("ascii")
                for x in range(0, _c_attr_count(_channel))
            ]
        }
        self._id = _c_get_id(self._channel).decode("ascii")

        name_raw = _c_get_name(self._channel)
        self._name = name_raw.decode("ascii") if name_raw is not None else None
        self._output = _c_is_output(self._channel)
        self._scan_element = _c_is_scan_element(self._channel)

    def read(self, buf, raw=False):
        """
        Extract the samples corresponding to this channel from the given iio.Buffer object.

        :param buf: type=iio.Buffer
            A valid instance of the iio.Buffer class
        :param raw: type=bool
            If set to True, the samples are not converted from their
            native format to their host format

        returns: type=bytearray
            An array containing the samples for this channel
        """
        array = bytearray(buf._length)
        mytype = c_char * len(array)
        c_array = mytype.from_buffer(array)
        if raw:
            length = _c_read_raw(self._channel, buf._buffer, c_array, len(array))
        else:
            length = _c_read(self._channel, buf._buffer, c_array, len(array))
        return array[:length]

    def write(self, buf, array, raw=False):
        """
        Write the specified array of samples corresponding to this channel into the given iio.Buffer object.

        :param buf: type=iio.Buffer
            A valid instance of the iio.Buffer class
        :param array: type=bytearray
            The array containing the samples to copy
        :param raw: type=bool
            If set to True, the samples are not converted from their
            host format to their native format

        returns: type=int
            The number of bytes written
        """
        mytype = c_char * len(array)
        c_array = mytype.from_buffer(array)
        if raw:
            return _c_write_raw(self._channel, buf._buffer, c_array, len(array))
        return _c_write(self._channel, buf._buffer, c_array, len(array))

    id = property(
        lambda self: self._id,
        None,
        None,
        "An identifier of this channel.\n\tNote that it is possible that two channels have the same ID, if one is an input channel and the other is an output channel.\n\ttype=str",
    )
    name = property(
        lambda self: self._name, None, None, "The name of this channel.\n\ttype=str"
    )
    attrs = property(
        lambda self: self._attrs,
        None,
        None,
        "List of attributes for this channel.\n\ttype=dict of iio.ChannelAttr",
    )
    output = property(
        lambda self: self._output,
        None,
        None,
        "Contains True if the channel is an output channel, False otherwise.\n\ttype=bool",
    )
    scan_element = property(
        lambda self: self._scan_element,
        None,
        None,
        "Contains True if the channel is a scan element, False otherwise.\n\tIf a channel is a scan element, then it is possible to enable it and use it for I/O operations.\n\ttype=bool",
    )
    enabled = property(
        lambda self: _c_is_enabled(self._channel),
        lambda self, x: _c_enable(self._channel) if x else _c_disable(self._channel),
        None,
        "Configured state of the channel\n\ttype=bool",
    )

    @property
    def device(self):
        """
        Corresponding device for the channel.
        type: iio.Device
        """
        c_dev = _channel_get_device(self._channel)
        return Device(_d_get_context(c_dev), c_dev)

    @property
    def index(self):
        """Index for the channel."""
        return _channel_get_index(self._channel)

    @property
    def data_format(self):
        """
        Channel data format.
        type: iio.DataFormat
        """
        return _channel_get_data_format(self._channel).contents

    @property
    def modifier(self):
        """
        Channel modifier.
        type: iio.ChannelModifier(Enum)
        """
        return ChannelModifier(_channel_get_modifier(self._channel))

    @property
    def type(self):
        """
        Type for the channel.
        type: iio.ChannelType(Enum)
        """
        return ChannelType(_channel_get_type(self._channel))

    def convert(self, dst, src):
        """
        Convert src and saves the result in dst, using current channel's data format.

        :param dst: type=list
            The variable where the result is stored.
        :param src: type=list
            Data to be converted.
        """
        src_ptr = cast((c_char * (len(src) * self.data_format.length))(*src), c_void_p)
        dst_ptr = cast((c_char * (len(dst) * self.data_format.length))(*dst), c_void_p)
        _channel_convert(self._channel, src_ptr, dst_ptr)

    def convert_inverse(self, dst, src):
        """
        Convert the sample from host format to hardware format.

        :param dst: type=list
            The variable where the result is stored.
        :param src: type=list
            Data to be converted.
        """
        src_ptr = cast((c_char * (len(src) * self.data_format.length))(*src), c_void_p)
        dst_ptr = cast((c_char * (len(dst) * self.data_format.length))(*dst), c_void_p)
        _channel_convert_inverse(self._channel, src_ptr, dst_ptr)


class Buffer(object):
    """The class used for all I/O operations."""

    def __init__(self, device, samples_count, cyclic=False):
        """
        Initialize a new instance of the Buffer class.

        :param device: type=iio.Device
            The iio.Device object that represents the device where the I/O
            operations will be performed
        :param samples_count: type=int
            The size of the buffer, in samples
        :param circular: type=bool
            If set to True, the buffer is circular

        returns: type=iio.Buffer
            An new instance of this class
        """
        try:
            self._buffer = _create_buffer(device._device, samples_count, cyclic)
        except Exception:
            self._buffer = None
            raise
        self._length = samples_count * device.sample_size
        self._samples_count = samples_count
        self._ctx = device.ctx()
        # Holds a reference to the corresponding IIO Context. This ensures that
        # every iio.Buffer object is destroyed before its corresponding IIO Context.

    def __del__(self):
        """Destroy this buffer."""
        if self._buffer is not None:
            _buffer_destroy(self._buffer)

    def __len__(self):
        """Size of this buffer, in bytes."""
        return self._length

    def refill(self):
        """Fetch a new set of samples from the hardware."""
        _buffer_refill(self._buffer)

    def push(self, samples_count=None):
        """
        Submit the samples contained in this buffer to the hardware.

        :param samples_count: type=int
            The number of samples to submit, default = full buffer
        """
        _buffer_push_partial(self._buffer, samples_count or self._samples_count)

    def read(self):
        """
        Retrieve the samples contained inside the Buffer object.

        returns: type=bytearray
            An array containing the samples
        """
        start = _buffer_start(self._buffer)
        end = _buffer_end(self._buffer)
        array = bytearray(end - start)
        mytype = c_char * len(array)
        c_array = mytype.from_buffer(array)
        _memmove(c_array, start, len(array))
        return array

    def write(self, array):
        """
        Copy the given array of samples inside the Buffer object.

        :param array: type=bytearray
                The array containing the samples to copy

        returns: type=int
            The number of bytes written into the buffer
        """
        start = _buffer_start(self._buffer)
        end = _buffer_end(self._buffer)
        length = end - start
        if length > len(array):
            length = len(array)
        mytype = c_char * len(array)
        c_array = mytype.from_buffer(array)
        _memmove(start, c_array, length)
        return length

    def cancel(self):
        """Cancel the current buffer."""
        _buffer_cancel(self._buffer)

    def set_blocking_mode(self, blocking):
        """
        Set the buffer's blocking mode.

        :param blocking: type=boolean
            True if in blocking_mode else False.

        returns: type=int
            Return code from the C layer.
        """
        return _buffer_set_blocking_mode(self._buffer, c_bool(blocking))

    @property
    def device(self):
        """
        Device for the buffer.
        type: iio.Device
        """
        return Device(self._ctx, _buffer_get_device(self._buffer))

    @property
    def poll_fd(self):
        """
        Poll_fd for the buffer.
        type: int
        """
        return _buffer_get_poll_fd(self._buffer)

    @property
    def step(self):
        """
        Step size for the buffer.
        type: int
        """
        return _buffer_step(self._buffer)


class _DeviceOrTrigger(object):
    def __init__(self, _device):
        self._device = _device
        self._context = _d_get_context(_device)
        self._attrs = {
            name: DeviceAttr(_device, name)
            for name in [
                _d_get_attr(_device, x).decode("ascii")
                for x in range(0, _d_attr_count(_device))
            ]
        }
        self._debug_attrs = {
            name: DeviceDebugAttr(_device, name)
            for name in [
                _d_get_debug_attr(_device, x).decode("ascii")
                for x in range(0, _d_debug_attr_count(_device))
            ]
        }
        self._buffer_attrs = {
            name: DeviceBufferAttr(_device, name)
            for name in [
                _d_get_buffer_attr(_device, x).decode("ascii")
                for x in range(0, _d_buffer_attr_count(_device))
            ]
        }

        # TODO(pcercuei): Use a dictionary for the channels.
        chans = [
            Channel(_get_channel(self._device, x))
            for x in range(0, _channels_count(self._device))
        ]
        self._channels = sorted(chans, key=lambda c: c.id)
        self._id = _d_get_id(self._device).decode("ascii")

        name_raw = _d_get_name(self._device)
        self._name = name_raw.decode("ascii") if name_raw is not None else None

    def reg_write(self, reg, value):
        """
        Set a value to one register of this device.

        :param reg: type=int
            The register address
        :param value: type=int
            The value that will be used for this register
        """
        _d_reg_write(self._device, reg, value)

    def reg_read(self, reg):
        """
        Read the content of a register of this device.

        :param reg: type=int
            The register address

        returns: type=int
            The value of the register
        """
        value = c_uint()
        _d_reg_read(self._device, reg, _byref(value))
        return value.value

    def find_channel(self, name_or_id, is_output=False):
        """

        Find a IIO channel by its name or ID.

        :param name_or_id: type=str
            The name or ID of the channel to find
        :param is_output: type=bool
            Set to True to search for an output channel

        returns: type=iio.Device or type=iio.Trigger
            The IIO Device
        """
        return next(
            (
                x
                for x in self.channels
                if name_or_id == x.name or name_or_id == x.id and x.output == is_output
            ),
            None,
        )

    def set_kernel_buffers_count(self, count):
        """

        Set the number of kernel buffers to use with the specified device.

        :param count: type=int
            The number of kernel buffers

        """
        return _d_set_buffers_count(self._device, count)

    @property
    def sample_size(self):
        """
        Sample size of this device.
        type: int

        The sample size varies each time channels get enabled or disabled.
        """
        return _get_sample_size(self._device)

    id = property(
        lambda self: self._id,
        None,
        None,
        "An identifier of this device, only valid in this IIO context.\n\ttype=str",
    )
    name = property(
        lambda self: self._name, None, None, "The name of this device.\n\ttype=str"
    )
    attrs = property(
        lambda self: self._attrs,
        None,
        None,
        "List of attributes for this IIO device.\n\ttype=dict of iio.DeviceAttr",
    )
    debug_attrs = property(
        lambda self: self._debug_attrs,
        None,
        None,
        "List of debug attributes for this IIO device.\n\ttype=dict of iio.DeviceDebugAttr",
    )
    buffer_attrs = property(
        lambda self: self._buffer_attrs,
        None,
        None,
        "List of buffer attributes for this IIO device.\n\ttype=dict of iio.DeviceBufferAttr",
    )
    channels = property(
        lambda self: self._channels,
        None,
        None,
        "List of channels available with this IIO device.\n\ttype=list of iio.Channel objects",
    )


class Trigger(_DeviceOrTrigger):
    """Contains the representation of an IIO device that can act as a trigger."""

    def __init__(self, _device):
        """
        Initialize a new instance of the Trigger class.

        :param _device: type=iio._DevicePtr
            A pointer to an IIO device.

        returns: type=iio.Trigger
            An new instance of this class
        """
        super(Trigger, self).__init__(_device)

    def _get_rate(self):
        return int(self._attrs["frequency"].value)

    def _set_rate(self, value):
        self._attrs["frequency"].value = str(value)

    frequency = property(
        _get_rate,
        _set_rate,
        None,
        "Configured frequency (in Hz) of this trigger\n\ttype=int",
    )


class Device(_DeviceOrTrigger):
    """Contains the representation of an IIO device."""

    def __init__(self, ctx, _device):
        """
        Initialize a new instance of the Device class.

        :param ctx: type=iio.Context
            A valid instance of the iio.Context class.
        :param _device: type=_DevicePtr
            A pointer to an IIO device.

        returns: type=iio.Device
            An new instance of this class
        """
        super(Device, self).__init__(_device)
        self.ctx = weakref.ref(ctx)

    def _set_trigger(self, trigger):
        _d_set_trigger(self._device, trigger._device if trigger else None)

    def _get_trigger(self):
        value = _Device()
        _d_get_trigger(self._device, _byref(value))

        for dev in self.ctx()._devices:
            if value == dev._device:
                return dev
        return None

    trigger = property(
        _get_trigger,
        _set_trigger,
        None,
        "Contains the configured trigger for this IIO device.\n\ttype=iio.Trigger",
    )

    @property
    def context(self):
        """
        Context for the device.
        type: iio.Context
        """
        return self.ctx()


class Context(object):
    """Contains the representation of an IIO context."""

    def __init__(self, _context=None):
        """
        Initialize a new instance of the Context class, using the local or the network backend of the IIO library.

        returns: type=iio.Context
            An new instance of this class

        This function will create a network context if the IIOD_REMOTE
        environment variable is set to the hostname where the IIOD server runs.
        If set to an empty string, the server will be discovered using ZeroConf.
        If the environment variable is not set, a local context will be created instead.
        """
        self._context = None

        if _context is None:
            self._context = _new_default()
        elif _isstring(_context):
            self._context = _new_uri(_context.encode("ascii"))
        else:
            self._context = _context

        self._attrs = {}
        for index in range(0, _get_attrs_count(self._context)):
            str1 = c_char_p()
            str2 = c_char_p()
            _get_attr(self._context, index, _byref(str1), _byref(str2))
            self._attrs[str1.value.decode("ascii")] = str2.value.decode("ascii")

        # TODO(pcercuei): Use a dictionary for the devices.
        self._devices = [
            Trigger(dev) if _d_is_trigger(dev) else Device(self, dev)
            for dev in [
                _get_device(self._context, x)
                for x in range(0, _devices_count(self._context))
            ]
        ]
        self._name = _get_name(self._context).decode("ascii")
        self._description = _get_description(self._context).decode("ascii")
        self._xml = _get_xml(self._context).decode("ascii")

        major = c_uint()
        minor = c_uint()
        buf = create_string_buffer(8)
        _get_version(self._context, _byref(major), _byref(minor), buf)
        self._version = (major.value, minor.value, buf.value.decode("ascii"))

    def __del__(self):
        """Destroy this context."""
        if self._context is not None:
            _destroy(self._context)

    def set_timeout(self, timeout):
        """
        Set a timeout for I/O operations.

        :param timeout: type=int
            The timeout value, in milliseconds
        """
        _set_timeout(self._context, timeout)

    def clone(self):
        """
        Clone this instance.

        returns: type=iio.LocalContext
            An new instance of this class
        """
        return Context(_clone(self._context))

    def find_device(self, name_or_id):
        """

        Find a IIO device by its name or ID.

        :param name_or_id: type=str
            The name or ID of the device to find

        returns: type=iio.Device or type=iio.Trigger
            The IIO Device
        """
        return next((x for x in self.devices if name_or_id in [x.name, x.id]), None,)

    name = property(
        lambda self: self._name, None, None, "Name of this IIO context.\n\ttype=str"
    )
    description = property(
        lambda self: self._description,
        None,
        None,
        "Description of this IIO context.\n\ttype=str",
    )
    xml = property(
        lambda self: self._xml,
        None,
        None,
        "XML representation of the current context.\n\ttype=str",
    )
    version = property(
        lambda self: self._version,
        None,
        None,
        "Version of the backend.\n\ttype=(int, int, str)",
    )
    attrs = property(
        lambda self: self._attrs,
        None,
        None,
        "List of context-specific attributes\n\ttype=dict of str objects",
    )
    devices = property(
        lambda self: self._devices,
        None,
        None,
        "List of devices contained in this context.\n\ttype=list of iio.Device and iio.Trigger objects",
    )


class LocalContext(Context):
    """Local IIO Context."""

    def __init__(self):
        """
        Initialize a new instance of the Context class, using the local backend of the IIO library.

        returns: type=iio.LocalContext
            An new instance of this class
        """
        ctx = _new_local()
        super(LocalContext, self).__init__(ctx)


class XMLContext(Context):
    """XML IIO Context."""

    def __init__(self, xmlfile):
        """
        Initialize a new instance of the Context class, using the XML backend of the IIO library.

        :param xmlfile: type=str
            Filename of the XML file to build the context from

        returns: type=iio.XMLContext
            An new instance of this class
        """
        ctx = _new_xml(xmlfile.encode("ascii"))
        super(XMLContext, self).__init__(ctx)


class NetworkContext(Context):
    """Network IIO Context."""

    def __init__(self, hostname=None):
        """
        Initialize a new instance of the Context class, using the network backend of the IIO library.

        :param hostname: type=str
            Hostname, IPv4 or IPv6 address where the IIO Daemon is running

        returns: type=iio.NetworkContext
            An new instance of this class
        """
        ctx = _new_network(hostname.encode("ascii") if hostname is not None else None)
        super(NetworkContext, self).__init__(ctx)


def scan_contexts():
    """Scan Context."""
    scan_ctx = dict()
    ptr = _POINTER(_ContextInfoPtr)()

    ctx = _create_scan_context(None, 0)
    ctx_nb = _get_context_info_list(ctx, _byref(ptr))

    for i in range(0, ctx_nb):
        scan_ctx[
            _context_info_get_uri(ptr[i]).decode("ascii")
        ] = _context_info_get_description(ptr[i]).decode("ascii")

    _context_info_list_free(ptr)
    _destroy_scan_context(ctx)
    return scan_ctx
