import re

from datetime import datetime, timedelta

from peewee import IntegrityError, fn
from jsonschema import ValidationError

from data.database import (RepoMirrorConfig, RepoMirrorRule, RepoMirrorRuleType, RepoMirrorStatus,
                           RepositoryState, Repository, uuid_generator, db_transaction)
from data.fields import DecryptedValue
from data.model import DataModelException
from util.names import parse_robot_username


# TODO: Move these to the configuration
MAX_SYNC_RETRIES = 3
MAX_SYNC_DURATION = 60*60*2  # 2 Hours


def get_eligible_mirrors():
  """
  Returns the RepoMirrorConfig that are ready to run now. This includes those that are:
  1. Not currently syncing but whose start time is in the past
  2. Status of "sync now"
  3. Currently marked as syncing but whose expiration time is in the past
  """
  now = datetime.utcnow()
  immediate_candidates_filter = ((RepoMirrorConfig.sync_status == RepoMirrorStatus.SYNC_NOW) &
                                 (RepoMirrorConfig.sync_expiration_date >> None))

  ready_candidates_filter = ((RepoMirrorConfig.sync_start_date <= now) &
                             (RepoMirrorConfig.sync_retries_remaining > 0) &
                             (RepoMirrorConfig.sync_status != RepoMirrorStatus.SYNCING) &
                             (RepoMirrorConfig.sync_expiration_date >> None) &
                             (RepoMirrorConfig.is_enabled == True))

  expired_candidates_filter = ((RepoMirrorConfig.sync_start_date <= now) &
                               (RepoMirrorConfig.sync_retries_remaining > 0) &
                               (RepoMirrorConfig.sync_status == RepoMirrorStatus.SYNCING) &
                               (RepoMirrorConfig.sync_expiration_date <= now) &
                               (RepoMirrorConfig.is_enabled == True))

  return (RepoMirrorConfig
          .select()
          .join(Repository)
          .where(Repository.state == RepositoryState.MIRROR)
          .where(immediate_candidates_filter | ready_candidates_filter | expired_candidates_filter)
          .order_by(RepoMirrorConfig.sync_start_date.asc()))


def get_max_id_for_repo_mirror_config():
  """ Gets the maximum id for repository mirroring """
  return RepoMirrorConfig.select(fn.Max(RepoMirrorConfig.id)).scalar()


def get_min_id_for_repo_mirror_config():
  """ Gets the minimum id for a repository mirroring """
  return RepoMirrorConfig.select(fn.Min(RepoMirrorConfig.id)).scalar()


def claim_mirror(mirror):
  """
  Attempt to create an exclusive lock on the RepoMirrorConfig and return it.
  If unable to create the lock, `None` will be returned.
  """

  # Attempt to update the RepoMirrorConfig to mark it as "claimed"
  now = datetime.utcnow()
  expiration_date = now + timedelta(seconds=MAX_SYNC_DURATION)
  query = (RepoMirrorConfig
           .update(sync_status=RepoMirrorStatus.SYNCING,
                   sync_expiration_date=expiration_date,
                   sync_transaction_id=uuid_generator())
           .where(RepoMirrorConfig.id == mirror.id,
                  RepoMirrorConfig.sync_transaction_id == mirror.sync_transaction_id))

  # If the update was successful, then it was claimed. Return the updated instance.
  if query.execute():
    return RepoMirrorConfig.get_by_id(mirror.id)

  return None  # Another process must have claimed the mirror faster.


def release_mirror(mirror, sync_status):
  """
  Return a mirror to the queue and update its status.

  Upon success, move next sync to be at the next interval in the future. Failures remain with
  current date to ensure they are picked up for repeat attempt. After MAX_SYNC_RETRIES,
  the next sync will be moved ahead as if it were a success. This is to allow a daily sync,
  for example, to retry the next day. Without this, users would need to manually run syncs
  to clear failure state.
  """
  if sync_status == RepoMirrorStatus.FAIL:
    retries = max(0, mirror.sync_retries_remaining - 1)

  if sync_status == RepoMirrorStatus.SUCCESS or retries < 1:
    now = datetime.utcnow()
    delta = now - mirror.sync_start_date
    delta_seconds = (delta.days * 24 * 60 * 60) + delta.seconds
    next_start_date = now + timedelta(seconds=mirror.sync_interval - (delta_seconds % mirror.sync_interval))
    retries = MAX_SYNC_RETRIES
  else:
    next_start_date = mirror.sync_start_date

  query = (RepoMirrorConfig
           .update(sync_transaction_id=uuid_generator(),
                   sync_status=sync_status,
                   sync_start_date=next_start_date,
                   sync_expiration_date=None,
                   sync_retries_remaining=retries)
           .where(RepoMirrorConfig.id == mirror.id,
                  RepoMirrorConfig.sync_transaction_id == mirror.sync_transaction_id))

  if query.execute():
    return RepoMirrorConfig.get_by_id(mirror.id)

  # Unable to release Mirror. Has it been claimed by another process?
  return None


def expire_mirror(mirror):
  """
  Set the mirror to synchronize ASAP and reset its failure count.
  """

  # Set the next-sync date to now
  # TODO: Verify the `where` conditions would not expire a currently syncing mirror.
  query = (RepoMirrorConfig
           .update(sync_transaction_id=uuid_generator(),
                   sync_expiration_date=datetime.utcnow(),
                   sync_retries_remaining=MAX_SYNC_RETRIES)
           .where(RepoMirrorConfig.sync_transaction_id == mirror.sync_transaction_id,
                  RepoMirrorConfig.id == mirror.id,
                  RepoMirrorConfig.state != RepoMirrorStatus.SYNCING))

  # Fetch and return the latest updates
  if query.execute():
    return RepoMirrorConfig.get_by_id(mirror.id)

  # Unable to update expiration date. Perhaps another process has claimed it?
  return None  # TODO: Raise some Exception?


def create_mirroring_rule(repository, rule_value, rule_type=RepoMirrorRuleType.TAG_GLOB_CSV):
  """
  Create a RepoMirrorRule for a given Repository.
  """

  if rule_type != RepoMirrorRuleType.TAG_GLOB_CSV:
    raise ValidationError('validation failed: rule_type must be TAG_GLOB_CSV')

  if not isinstance(rule_value, list) or len(rule_value) < 1:
    raise ValidationError('validation failed: rule_value for TAG_GLOB_CSV must be a list with at least one rule')

  rule = RepoMirrorRule.create(repository=repository, rule_type=rule_type, rule_value=rule_value)
  return rule


def enable_mirroring_for_repository(repository,
                                    root_rule,
                                    internal_robot,
                                    external_reference,
                                    sync_interval,
                                    external_registry_username=None,
                                    external_registry_password=None,
                                    external_registry_config=None,
                                    is_enabled=True,
                                    sync_start_date=None):
  """
  Create a RepoMirrorConfig and set the Repository to the MIRROR state.
  """
  assert internal_robot.robot

  namespace, _ = parse_robot_username(internal_robot.username)
  if namespace != repository.namespace_user.username:
    raise DataModelException('Cannot use robot for mirroring')

  with db_transaction():
    # Create the RepoMirrorConfig
    try:
      username = DecryptedValue(external_registry_username) if external_registry_username else None
      password = DecryptedValue(external_registry_password) if external_registry_password else None
      mirror = RepoMirrorConfig.create(repository=repository,
                                       root_rule=root_rule,
                                       is_enabled=is_enabled,
                                       internal_robot=internal_robot,
                                       external_reference=external_reference,
                                       external_registry_username=username,
                                       external_registry_password=password,
                                       external_registry_config=external_registry_config or {},
                                       sync_interval=sync_interval,
                                       sync_start_date=sync_start_date or datetime.utcnow())
    except IntegrityError:
      return RepoMirrorConfig.get(repository=repository)

    # Change Repository state to mirroring mode as needed
    if repository.state != RepositoryState.MIRROR:
      query = (Repository
               .update(state=RepositoryState.MIRROR)
               .where(Repository.id == repository.id))
      if not query.execute():
        raise DataModelException('Could not change the state of the repository')

    return mirror


def update_sync_status(mirror, sync_status):
  """
  Update the sync status
  """
  query = (RepoMirrorConfig
           .update(sync_transaction_id=uuid_generator(),
                   sync_status=sync_status)
           .where(RepoMirrorConfig.sync_transaction_id == mirror.sync_transaction_id,
                  RepoMirrorConfig.id == mirror.id))
  if query.execute():
    return RepoMirrorConfig.get_by_id(mirror.id)

  return None


def update_sync_status_to_sync_now(mirror):
  """
  This will change the sync status to SYNC_NOW and set the retries remaining to one, if it is
  less than one. None will be returned in cases where this is not possible, such as if the
  mirror is in the SYNCING state.
  """

  if mirror.sync_status == RepoMirrorStatus.SYNCING:
    return None

  retries = max(mirror.sync_retries_remaining, 1)

  query = (RepoMirrorConfig
           .update(sync_transaction_id=uuid_generator(),
                   sync_status=RepoMirrorStatus.SYNC_NOW,
                   sync_expiration_date=None,
                   sync_retries_remaining=retries)
           .where(RepoMirrorConfig.id == mirror.id,
                  RepoMirrorConfig.sync_transaction_id == mirror.sync_transaction_id))

  if query.execute():
    return RepoMirrorConfig.get_by_id(mirror.id)

  return None


def update_sync_status_to_cancel(mirror):
  """
  If the mirror is SYNCING, it will be force-claimed (ignoring existing transaction id), and the
  state will set to NEVER_RUN. None will be returned in cases where this is not possible, such
  as if the mirror is not in the SYNCING state.
  """

  if mirror.sync_status != RepoMirrorStatus.SYNCING and mirror.sync_status != RepoMirrorStatus.SYNC_NOW:
    return None

  query = (RepoMirrorConfig
           .update(sync_transaction_id=uuid_generator(),
                   sync_status=RepoMirrorStatus.NEVER_RUN,
                   sync_expiration_date=None)
           .where(RepoMirrorConfig.id == mirror.id))

  if query.execute():
    return RepoMirrorConfig.get_by_id(mirror.id)

  return None


def update_with_transaction(mirror, **kwargs):
  """
  Helper function which updates a Repository's RepoMirrorConfig while also rolling its
  sync_transaction_id for locking purposes.
  """

  # RepoMirrorConfig attributes which can be modified
  mutable_attributes = (
    'is_enabled',
    'mirror_type',
    'external_reference',
    'external_registry_username',
    'external_registry_password',
    'external_registry_config',
    'sync_interval',
    'sync_start_date',
    'sync_expiration_date',
    'sync_retries_remaining',
    'sync_status',
    'sync_transaction_id'
  )

  # Key-Value map of changes to make
  filtered_kwargs = {key:kwargs.pop(key) for key in mutable_attributes if key in kwargs}

  # Roll the sync_transaction_id to a new value
  filtered_kwargs['sync_transaction_id'] = uuid_generator()

  # Generate the query to perform the updates
  query = (RepoMirrorConfig
           .update(filtered_kwargs)
           .where(RepoMirrorConfig.sync_transaction_id == mirror.sync_transaction_id,
                  RepoMirrorConfig.id == mirror.id))

  # Apply the change(s) and return the object if successful
  if query.execute():
    return RepoMirrorConfig.get_by_id(mirror.id)
  else:
    return None


def get_mirror(repository):
  """
  Return the RepoMirrorConfig associated with the given Repository, or None if it doesn't exist.
  """
  try:
    return RepoMirrorConfig.get(repository=repository)
  except RepoMirrorConfig.DoesNotExist:
    return None


def enable_mirror(repository):
  """
  Enables a RepoMirrorConfig.
  """
  mirror = get_mirror(repository)
  return bool(update_with_transaction(mirror, is_enabled=True))


def disable_mirror(repository):
  """
  Disables a RepoMirrorConfig.
  """
  mirror = get_mirror(repository)
  return bool(update_with_transaction(mirror, is_enabled=False))


def delete_mirror(repository):
  """
  Delete a Repository Mirroring configuration.
  """
  raise NotImplementedError("TODO: Not Implemented")


def change_remote(repository, remote_repository):
  """
  Update the external repository for Repository Mirroring.
  """
  mirror = get_mirror(repository)
  updates = {
    'external_reference': remote_repository
  }
  return bool(update_with_transaction(mirror, **updates))


def change_credentials(repository, username, password):
  """
  Update the credentials used to access the remote repository.
  """
  mirror = get_mirror(repository)
  updates = {
    'external_registry_username': username,
    'external_registry_password': password,
  }
  return bool(update_with_transaction(mirror, **updates))


def change_username(repository, username):
  """
  Update the Username used to access the external repository.
  """
  mirror = get_mirror(repository)
  return bool(update_with_transaction(mirror, external_registry_username=username))


def change_sync_interval(repository, interval):
  """
  Update the interval at which a repository will be synchronized.
  """
  mirror = get_mirror(repository)
  return bool(update_with_transaction(mirror, sync_interval=interval))


def change_sync_start_date(repository, dt):
  """
  Specify when the repository should be synchronized next.
  """
  mirror = get_mirror(repository)
  return bool(update_with_transaction(mirror, sync_start_date=dt))


def change_root_rule(repository, rule):
  """
  Specify which rule should be used for repository mirroring.
  """
  assert rule.repository == repository
  mirror = get_mirror(repository)
  return bool(update_with_transaction(mirror, root_rule=rule))


def change_sync_status(repository, sync_status):
  """
  Change Repository's mirroring status.
  """
  mirror = get_mirror(repository)
  return update_with_transaction(mirror, sync_status=sync_status)


def change_retries_remaining(repository, retries_remaining):
  """
  Change the number of retries remaining for mirroring a repository.
  """
  mirror = get_mirror(repository)
  return update_with_transaction(mirror, sync_retries_remaining=retries_remaining)


def change_external_registry_config(repository, config_updates):
  """
  Update the 'external_registry_config' with the passed in fields. Config has:
  verify_tls: True|False
  proxy: JSON fields 'http_proxy', 'https_proxy', andn 'no_proxy'
  """
  mirror = get_mirror(repository)
  external_registry_config = mirror.external_registry_config

  if 'verify_tls' in config_updates:
    external_registry_config['verify_tls'] = config_updates['verify_tls']

  if 'proxy' in config_updates:
    proxy_updates = config_updates['proxy']
    for key in ('http_proxy', 'https_proxy', 'no_proxy'):
      if key in config_updates['proxy']:
        if 'proxy' not in external_registry_config:
          external_registry_config['proxy'] = {}
        else:
          external_registry_config['proxy'][key] = proxy_updates[key]

  return update_with_transaction(mirror, external_registry_config=external_registry_config)


def get_mirroring_robot(repository):
  """
  Return the robot used for mirroring. Returns None if the repository does not have an associated
  RepoMirrorConfig or the robot does not exist.
  """
  mirror = get_mirror(repository)
  if mirror:
    return mirror.internal_robot

  return None


def set_mirroring_robot(repository, robot):
  """
  Sets the mirroring robot for the repository.
  """
  assert robot.robot
  namespace, _ = parse_robot_username(robot.username)
  if namespace != repository.namespace_user.username:
    raise DataModelException('Cannot use robot for mirroring')

  mirror = get_mirror(repository)
  mirror.internal_robot = robot
  mirror.save()


# -------------------- Mirroring Rules --------------------------#


def create_rule(repository, rule_value, rule_type=RepoMirrorRuleType.TAG_GLOB_CSV, left_child=None, right_child=None):
  """
  Create a new Rule for mirroring a Repository
  """

  if rule_type != RepoMirrorRuleType.TAG_GLOB_CSV:
    raise ValidationError('validation failed: rule_type must be TAG_GLOB_CSV')

  if not isinstance(rule_value, list) or len(rule_value) < 1:
    raise ValidationError('validation failed: rule_value for TAG_GLOB_CSV must be a list with at least one rule')

  rule_kwargs = {
    'repository': repository,
    'rule_value': rule_value,
    'rule_type': rule_type,
    'left_child': left_child,
    'right_child': right_child,
  }
  rule = RepoMirrorRule.create(**rule_kwargs)
  return rule


def list_rules(repository):
  """
  Returns all RepoMirrorRules associated with a Repository.
  """
  rules = RepoMirrorRule.select().where(RepoMirrorRule.repository == repository).all()
  return rules


def get_root_rule(repository):
  """
  Return the primary mirroring Rule
  """
  mirror = get_mirror(repository)
  try:
    rule = RepoMirrorRule.get(repository=repository)
    return rule
  except RepoMirrorRule.DoesNotExist:
    return None


def change_rule_value(rule, value):
  """
  Update the value of an existing rule.
  """
  query = (RepoMirrorRule
          .update(rule_value=value)
          .where(RepoMirrorRule.id == rule.id))
  return query.execute()