#!/usr/bin/env python3
#
# Test bitmap-sync backups (incremental, differential, and partials)
#
# Copyright (c) 2019 John Snow for Red Hat, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# owner=jsnow@redhat.com

import math
import os

import iotests
from iotests import log, qemu_img

SIZE = 64 * 1024 * 1024
GRANULARITY = 64 * 1024


class Pattern:
    def __init__(self, byte, offset, size=GRANULARITY):
        self.byte = byte
        self.offset = offset
        self.size = size

    def bits(self, granularity):
        lower = self.offset // granularity
        upper = (self.offset + self.size - 1) // granularity
        return set(range(lower, upper + 1))


class PatternGroup:
    """Grouping of Pattern objects. Initialize with an iterable of Patterns."""
    def __init__(self, patterns):
        self.patterns = patterns

    def bits(self, granularity):
        """Calculate the unique bits dirtied by this pattern grouping"""
        res = set()
        for pattern in self.patterns:
            res |= pattern.bits(granularity)
        return res


GROUPS = [
    PatternGroup([
        # Batch 0: 4 clusters
        Pattern('0x49', 0x0000000),
        Pattern('0x6c', 0x0100000),   # 1M
        Pattern('0x6f', 0x2000000),   # 32M
        Pattern('0x76', 0x3ff0000)]), # 64M - 64K
    PatternGroup([
        # Batch 1: 6 clusters (3 new)
        Pattern('0x65', 0x0000000),   # Full overwrite
        Pattern('0x77', 0x00f8000),   # Partial-left (1M-32K)
        Pattern('0x72', 0x2008000),   # Partial-right (32M+32K)
        Pattern('0x69', 0x3fe0000)]), # Adjacent-left (64M - 128K)
    PatternGroup([
        # Batch 2: 7 clusters (3 new)
        Pattern('0x74', 0x0010000),   # Adjacent-right
        Pattern('0x69', 0x00e8000),   # Partial-left  (1M-96K)
        Pattern('0x6e', 0x2018000),   # Partial-right (32M+96K)
        Pattern('0x67', 0x3fe0000,
                2*GRANULARITY)]),     # Overwrite [(64M-128K)-64M)
    PatternGroup([
        # Batch 3: 8 clusters (5 new)
        # Carefully chosen such that nothing re-dirties the one cluster
        # that copies out successfully before failure in Group #1.
        Pattern('0xaa', 0x0010000,
                3*GRANULARITY),       # Overwrite and 2x Adjacent-right
        Pattern('0xbb', 0x00d8000),   # Partial-left (1M-160K)
        Pattern('0xcc', 0x2028000),   # Partial-right (32M+160K)
        Pattern('0xdd', 0x3fc0000)]), # New; leaving a gap to the right
]


class EmulatedBitmap:
    def __init__(self, granularity=GRANULARITY):
        self._bits = set()
        self.granularity = granularity

    def dirty_bits(self, bits):
        self._bits |= set(bits)

    def dirty_group(self, n):
        self.dirty_bits(GROUPS[n].bits(self.granularity))

    def clear(self):
        self._bits = set()

    def clear_bits(self, bits):
        self._bits -= set(bits)

    def clear_bit(self, bit):
        self.clear_bits({bit})

    def clear_group(self, n):
        self.clear_bits(GROUPS[n].bits(self.granularity))

    @property
    def first_bit(self):
        return sorted(self.bits)[0]

    @property
    def bits(self):
        return self._bits

    @property
    def count(self):
        return len(self.bits)

    def compare(self, qmp_bitmap):
        """
        Print a nice human-readable message checking that a bitmap as reported
        by the QMP interface has as many bits set as we expect it to.
        """

        name = qmp_bitmap.get('name', '(anonymous)')
        log("= Checking Bitmap {:s} =".format(name))

        want = self.count
        have = qmp_bitmap['count'] // qmp_bitmap['granularity']

        log("expecting {:d} dirty sectors; have {:d}. {:s}".format(
            want, have, "OK!" if want == have else "ERROR!"))
        log('')


class Drive:
    """Represents, vaguely, a drive attached to a VM.
    Includes format, graph, and device information."""

    def __init__(self, path, vm=None):
        self.path = path
        self.vm = vm
        self.fmt = None
        self.size = None
        self.node = None

    def img_create(self, fmt, size):
        self.fmt = fmt
        self.size = size
        iotests.qemu_img_create('-f', self.fmt, self.path, str(self.size))

    def create_target(self, name, fmt, size):
        basename = os.path.basename(self.path)
        file_node_name = "file_{}".format(basename)
        vm = self.vm

        log(vm.command('blockdev-create', job_id='bdc-file-job',
                       options={
                           'driver': 'file',
                           'filename': self.path,
                           'size': 0,
                       }))
        vm.run_job('bdc-file-job')
        log(vm.command('blockdev-add', driver='file',
                       node_name=file_node_name, filename=self.path))

        log(vm.command('blockdev-create', job_id='bdc-fmt-job',
                       options={
                           'driver': fmt,
                           'file': file_node_name,
                           'size': size,
                       }))
        vm.run_job('bdc-fmt-job')
        log(vm.command('blockdev-add', driver=fmt,
                       node_name=name,
                       file=file_node_name))
        self.fmt = fmt
        self.size = size
        self.node = name

def blockdev_backup(vm, device, target, sync, **kwargs):
    # Strip any arguments explicitly nulled by the caller:
    kwargs = {key: val for key, val in kwargs.items() if val is not None}
    result = vm.qmp_log('blockdev-backup',
                        device=device,
                        target=target,
                        sync=sync,
                        filter_node_name='backup-top',
                        **kwargs)
    return result

def blockdev_backup_mktarget(drive, target_id, filepath, sync, **kwargs):
    target_drive = Drive(filepath, vm=drive.vm)
    target_drive.create_target(target_id, drive.fmt, drive.size)
    blockdev_backup(drive.vm, drive.node, target_id, sync, **kwargs)

def reference_backup(drive, n, filepath):
    log("--- Reference Backup #{:d} ---\n".format(n))
    target_id = "ref_target_{:d}".format(n)
    job_id = "ref_backup_{:d}".format(n)
    blockdev_backup_mktarget(drive, target_id, filepath, "full",
                             job_id=job_id)
    drive.vm.run_job(job_id, auto_dismiss=True)
    log('')

def backup(drive, n, filepath, sync, **kwargs):
    log("--- Test Backup #{:d} ---\n".format(n))
    target_id = "backup_target_{:d}".format(n)
    job_id = "backup_{:d}".format(n)
    kwargs.setdefault('auto-finalize', False)
    blockdev_backup_mktarget(drive, target_id, filepath, sync,
                             job_id=job_id, **kwargs)
    return job_id

def perform_writes(drive, n, filter_node_name=None):
    log("--- Write #{:d} ---\n".format(n))
    for pattern in GROUPS[n].patterns:
        cmd = "write -P{:s} 0x{:07x} 0x{:x}".format(
            pattern.byte,
            pattern.offset,
            pattern.size)
        log(cmd)
        log(drive.vm.hmp_qemu_io(filter_node_name or drive.node, cmd))
    bitmaps = drive.vm.query_bitmaps()
    log({'bitmaps': bitmaps}, indent=2)
    log('')
    return bitmaps


def compare_images(image, reference, baseimg=None, expected_match=True):
    """
    Print a nice human-readable message comparing these images.
    """
    expected_ret = 0 if expected_match else 1
    if baseimg:
        assert qemu_img("rebase", "-u", "-b", baseimg, '-F', iotests.imgfmt,
                        image) == 0
    ret = qemu_img("compare", image, reference)
    log('qemu_img compare "{:s}" "{:s}" ==> {:s}, {:s}'.format(
        image, reference,
        "Identical" if ret == 0 else "Mismatch",
        "OK!" if ret == expected_ret else "ERROR!"),
        filters=[iotests.filter_testfiles])

def test_bitmap_sync(bsync_mode, msync_mode='bitmap', failure=None):
    """
    Test bitmap backup routines.

    :param bsync_mode: Is the Bitmap Sync mode, and can be any of:
        - on-success: This is the "incremental" style mode. Bitmaps are
                      synchronized to what was copied out only on success.
                      (Partial images must be discarded.)
        - never:      This is the "differential" style mode.
                      Bitmaps are never synchronized.
        - always:     This is a "best effort" style mode.
                      Bitmaps are always synchronized, regardless of failure.
                      (Partial images must be kept.)

    :param msync_mode: The mirror sync mode to use for the first backup.
                       Can be any one of:
        - bitmap: Backups based on bitmap manifest.
        - full:   Full backups.
        - top:    Full backups of the top layer only.

    :param failure: Is the (optional) failure mode, and can be any of:
        - None:         No failure. Test the normative path. Default.
        - simulated:    Cancel the job right before it completes.
                        This also tests writes "during" the job.
        - intermediate: This tests a job that fails mid-process and produces
                        an incomplete backup. Testing limitations prevent
                        testing competing writes.
    """
    with iotests.FilePath(
            'img', 'bsync1', 'bsync2', 'fbackup0', 'fbackup1', 'fbackup2') as \
            (img_path, bsync1, bsync2, fbackup0, fbackup1, fbackup2), \
         iotests.VM() as vm:

        mode = "Mode {:s}; Bitmap Sync {:s}".format(msync_mode, bsync_mode)
        preposition = "with" if failure else "without"
        cond = "{:s} {:s}".format(preposition,
                                  "{:s} failure".format(failure) if failure
                                  else "failure")
        log("\n=== {:s} {:s} ===\n".format(mode, cond))

        log('--- Preparing image & VM ---\n')
        drive0 = Drive(img_path, vm=vm)
        drive0.img_create(iotests.imgfmt, SIZE)
        vm.add_device("{},id=scsi0".format(iotests.get_virtio_scsi_device()))
        vm.launch()

        file_config = {
            'driver': 'file',
            'filename': drive0.path
        }

        if failure == 'intermediate':
            file_config = {
                'driver': 'blkdebug',
                'image': file_config,
                'set-state': [{
                    'event': 'flush_to_disk',
                    'state': 1,
                    'new_state': 2
                }, {
                    'event': 'read_aio',
                    'state': 2,
                    'new_state': 3
                }],
                'inject-error': [{
                    'event': 'read_aio',
                    'errno': 5,
                    'state': 3,
                    'immediately': False,
                    'once': True
                }]
            }

        drive0.node = 'drive0'
        vm.qmp_log('blockdev-add',
                   filters=[iotests.filter_qmp_testfiles],
                   node_name=drive0.node,
                   driver=drive0.fmt,
                   file=file_config)
        log('')

        # 0 - Writes and Reference Backup
        perform_writes(drive0, 0)
        reference_backup(drive0, 0, fbackup0)
        log('--- Add Bitmap ---\n')
        vm.qmp_log("block-dirty-bitmap-add", node=drive0.node,
                   name="bitmap0", granularity=GRANULARITY)
        log('')
        ebitmap = EmulatedBitmap()

        # 1 - Writes and Reference Backup
        bitmaps = perform_writes(drive0, 1)
        ebitmap.dirty_group(1)
        bitmap = vm.get_bitmap(drive0.node, 'bitmap0', bitmaps=bitmaps)
        ebitmap.compare(bitmap)
        reference_backup(drive0, 1, fbackup1)

        # 1 - Test Backup (w/ Optional induced failure)
        if failure == 'intermediate':
            # Activate blkdebug induced failure for second-to-next read
            log(vm.hmp_qemu_io(drive0.node, 'flush'))
            log('')
        job = backup(drive0, 1, bsync1, msync_mode,
                     bitmap="bitmap0", bitmap_mode=bsync_mode)

        def _callback():
            """Issue writes while the job is open to test bitmap divergence."""
            # Note: when `failure` is 'intermediate', this isn't called.
            log('')
            bitmaps = perform_writes(drive0, 2, filter_node_name='backup-top')
            # Named bitmap (static, should be unchanged)
            ebitmap.compare(vm.get_bitmap(drive0.node, 'bitmap0',
                                          bitmaps=bitmaps))
            # Anonymous bitmap (dynamic, shows new writes)
            anonymous = EmulatedBitmap()
            anonymous.dirty_group(2)
            anonymous.compare(vm.get_bitmap(drive0.node, '', recording=True,
                                            bitmaps=bitmaps))

            # Simulate the order in which this will happen:
            # group 1 gets cleared first, then group two gets written.
            if ((bsync_mode == 'on-success' and not failure) or
                (bsync_mode == 'always')):
                ebitmap.clear()
            ebitmap.dirty_group(2)

        vm.run_job(job, auto_dismiss=True, auto_finalize=False,
                   pre_finalize=_callback,
                   cancel=(failure == 'simulated'))
        bitmaps = vm.query_bitmaps()
        log({'bitmaps': bitmaps}, indent=2)
        log('')

        if bsync_mode == 'always' and failure == 'intermediate':
            # TOP treats anything allocated as dirty, expect to see:
            if msync_mode == 'top':
                ebitmap.dirty_group(0)

            # We manage to copy one sector (one bit) before the error.
            ebitmap.clear_bit(ebitmap.first_bit)

            # Full returns all bits set except what was copied/skipped
            if msync_mode == 'full':
                fail_bit = ebitmap.first_bit
                ebitmap.clear()
                ebitmap.dirty_bits(range(fail_bit, SIZE // GRANULARITY))

        ebitmap.compare(vm.get_bitmap(drive0.node, 'bitmap0', bitmaps=bitmaps))

        # 2 - Writes and Reference Backup
        bitmaps = perform_writes(drive0, 3)
        ebitmap.dirty_group(3)
        ebitmap.compare(vm.get_bitmap(drive0.node, 'bitmap0', bitmaps=bitmaps))
        reference_backup(drive0, 2, fbackup2)

        # 2 - Bitmap Backup (In failure modes, this is a recovery.)
        job = backup(drive0, 2, bsync2, "bitmap",
                     bitmap="bitmap0", bitmap_mode=bsync_mode)
        vm.run_job(job, auto_dismiss=True, auto_finalize=False)
        bitmaps = vm.query_bitmaps()
        log({'bitmaps': bitmaps}, indent=2)
        log('')
        if bsync_mode != 'never':
            ebitmap.clear()
        ebitmap.compare(vm.get_bitmap(drive0.node, 'bitmap0', bitmaps=bitmaps))

        log('--- Cleanup ---\n')
        vm.qmp_log("block-dirty-bitmap-remove",
                   node=drive0.node, name="bitmap0")
        bitmaps = vm.query_bitmaps()
        log({'bitmaps': bitmaps}, indent=2)
        vm.shutdown()
        log('')

        log('--- Verification ---\n')
        # 'simulated' failures will actually all pass here because we canceled
        # while "pending". This is actually undefined behavior,
        # don't rely on this to be true!
        compare_images(bsync1, fbackup1, baseimg=fbackup0,
                       expected_match=failure != 'intermediate')
        if not failure or bsync_mode == 'always':
            # Always keep the last backup on success or when using 'always'
            base = bsync1
        else:
            base = fbackup0
        compare_images(bsync2, fbackup2, baseimg=base)
        compare_images(img_path, fbackup2)
        log('')

def test_backup_api():
    """
    Test malformed and prohibited invocations of the backup API.
    """
    with iotests.FilePath('img', 'bsync1') as (img_path, backup_path), \
         iotests.VM() as vm:

        log("\n=== API failure tests ===\n")
        log('--- Preparing image & VM ---\n')
        drive0 = Drive(img_path, vm=vm)
        drive0.img_create(iotests.imgfmt, SIZE)
        vm.add_device("{},id=scsi0".format(iotests.get_virtio_scsi_device()))
        vm.launch()

        file_config = {
            'driver': 'file',
            'filename': drive0.path
        }

        drive0.node = 'drive0'
        vm.qmp_log('blockdev-add',
                   filters=[iotests.filter_qmp_testfiles],
                   node_name=drive0.node,
                   driver=drive0.fmt,
                   file=file_config)
        log('')

        target0 = Drive(backup_path, vm=vm)
        target0.create_target("backup_target", drive0.fmt, drive0.size)
        log('')

        vm.qmp_log("block-dirty-bitmap-add", node=drive0.node,
                   name="bitmap0", granularity=GRANULARITY)
        log('')

        log('-- Testing invalid QMP commands --\n')

        error_cases = {
            'incremental': {
                None:        ['on-success', 'always', 'never', None],
                'bitmap404': ['on-success', 'always', 'never', None],
                'bitmap0':   ['always', 'never']
            },
            'bitmap': {
                None:        ['on-success', 'always', 'never', None],
                'bitmap404': ['on-success', 'always', 'never', None],
                'bitmap0':   [None],
            },
            'full': {
                None:        ['on-success', 'always', 'never'],
                'bitmap404': ['on-success', 'always', 'never', None],
                'bitmap0':   ['never', None],
            },
            'top': {
                None:        ['on-success', 'always', 'never'],
                'bitmap404': ['on-success', 'always', 'never', None],
                'bitmap0':   ['never', None],
            },
            'none': {
                None:        ['on-success', 'always', 'never'],
                'bitmap404': ['on-success', 'always', 'never', None],
                'bitmap0':   ['on-success', 'always', 'never', None],
            }
        }

        # Dicts, as always, are not stably-ordered prior to 3.7, so use tuples:
        for sync_mode in ('incremental', 'bitmap', 'full', 'top', 'none'):
            log("-- Sync mode {:s} tests --\n".format(sync_mode))
            for bitmap in (None, 'bitmap404', 'bitmap0'):
                for policy in error_cases[sync_mode][bitmap]:
                    blockdev_backup(drive0.vm, drive0.node, "backup_target",
                                    sync_mode, job_id='api_job',
                                    bitmap=bitmap, bitmap_mode=policy)
                    log('')


def main():
    for bsync_mode in ("never", "on-success", "always"):
        for failure in ("simulated", "intermediate", None):
            test_bitmap_sync(bsync_mode, "bitmap", failure)

    for sync_mode in ('full', 'top'):
        for bsync_mode in ('on-success', 'always'):
            for failure in ('simulated', 'intermediate', None):
                test_bitmap_sync(bsync_mode, sync_mode, failure)

    test_backup_api()

if __name__ == '__main__':
    iotests.script_main(main, supported_fmts=['qcow2'],
                        supported_protocols=['file'])