#
# Copyright (c) 2021 Nutanix Inc. All rights reserved.
#
# Authors: Thanos Makatos <thanos@nutanix.com>
#
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#  modification, are permitted provided that the following conditions are met:
#      * Redistributions of source code must retain the above copyright
#        notice, this list of conditions and the following disclaimer.
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#        used to endorse or promote products derived from this software without
#        specific prior written permission.
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#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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#

from libvfio_user import *
import ctypes as c
import errno
from unittest.mock import patch

ctx = None
sock = 0


def setup_function(function):
    global ctx, sock

    ctx = vfu_create_ctx(flags=LIBVFIO_USER_FLAG_ATTACH_NB)
    assert ctx is not None

    ret = vfu_setup_region(ctx, index=VFU_PCI_DEV_MIGR_REGION_IDX, size=0x2000,
                           flags=VFU_REGION_FLAG_RW)
    assert ret == 0

    ret = vfu_setup_device_migration_callbacks(ctx)
    assert ret == 0

    vfu_setup_device_quiesce_cb(ctx)

    ret = vfu_realize_ctx(ctx)
    assert ret == 0

    sock = connect_client(ctx)


def teardown_function(function):
    global ctx
    vfu_destroy_ctx(ctx)


@patch('libvfio_user.quiesce_cb')
@patch('libvfio_user.migr_trans_cb')
def test_migration_bad_access(mock_trans, mock_quiesce):
    """
    Tests that attempting to access the migration state register in an
    non-aligned manner fails.

    This test is important because we tell whether we need to quiesce by
    checking for a register-sized access, otherwise we'll change migration
    state without having quiesced.
    """
    global ctx, sock

    data = VFIO_DEVICE_STATE_V1_SAVING.to_bytes(c.sizeof(c.c_int), 'little')
    write_region(ctx, sock, VFU_PCI_DEV_MIGR_REGION_IDX, offset=0,
                 count=len(data)-1, data=data, expect=errno.EINVAL)

    mock_trans.assert_not_called()


@patch('libvfio_user.quiesce_cb')
@patch('libvfio_user.migr_trans_cb', return_value=0)
def test_migration_trans_sync(mock_trans, mock_quiesce):
    """
    Tests transitioning to the saving state.
    """

    global ctx, sock

    data = VFIO_DEVICE_STATE_V1_SAVING.to_bytes(c.sizeof(c.c_int), 'little')
    write_region(ctx, sock, VFU_PCI_DEV_MIGR_REGION_IDX, offset=0,
                 count=len(data), data=data)

    ret = vfu_run_ctx(ctx)
    assert ret == 0


@patch('libvfio_user.migr_trans_cb', side_effect=fail_with_errno(errno.EPERM))
def test_migration_trans_sync_err(mock_trans):
    """
    Tests the device returning an error when the migration state is written to.
    """

    global ctx, sock

    data = VFIO_DEVICE_STATE_V1_SAVING.to_bytes(c.sizeof(c.c_int), 'little')
    write_region(ctx, sock, VFU_PCI_DEV_MIGR_REGION_IDX, offset=0,
                 count=len(data), data=data, expect=errno.EPERM)

    ret = vfu_run_ctx(ctx)
    assert ret == 0


@patch('libvfio_user.quiesce_cb', side_effect=fail_with_errno(errno.EBUSY))
@patch('libvfio_user.migr_trans_cb', return_value=0)
def test_migration_trans_async(mock_trans, mock_quiesce):
    """
    Tests transitioning to the saving state where the device is initially busy
    quiescing.
    """

    global ctx, sock
    mock_quiesce

    data = VFIO_DEVICE_STATE_V1_SAVING.to_bytes(c.sizeof(c.c_int), 'little')
    write_region(ctx, sock, VFU_PCI_DEV_MIGR_REGION_IDX, offset=0,
                 count=len(data), data=data, rsp=False,
                 busy=True)

    ret = vfu_device_quiesced(ctx, 0)
    assert ret == 0

    get_reply(sock)

    ret = vfu_run_ctx(ctx)
    assert ret == 0


@patch('libvfio_user.quiesce_cb', side_effect=fail_with_errno(errno.EBUSY))
@patch('libvfio_user.migr_trans_cb', side_effect=fail_with_errno(errno.ENOTTY))
def test_migration_trans_async_err(mock_trans, mock_quiesce):
    """
    Tests writing to the migration state register, the device not being able to
    immediately quiesce, and then finally the device failing to transition to
    the new migration state.
    """

    global ctx, sock

    data = VFIO_DEVICE_STATE_V1_RUNNING.to_bytes(c.sizeof(c.c_int), 'little')
    write_region(ctx, sock, VFU_PCI_DEV_MIGR_REGION_IDX, offset=0,
                 count=len(data), data=data, rsp=False,
                 busy=True)

    ret = vfu_device_quiesced(ctx, 0)
    assert ret == 0

    print("waiting for reply")
    get_reply(sock, errno.ENOTTY)
    print("received reply")

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