import json
import io
import logging
import re

class TriggerException(Exception):
  pass

class TriggerAuthException(TriggerException):
  pass

class InvalidPayloadException(TriggerException):
  pass

class BuildArchiveException(TriggerException):
  pass

class InvalidServiceException(TriggerException):
  pass

class TriggerActivationException(TriggerException):
  pass

class TriggerDeactivationException(TriggerException):
  pass

class TriggerStartException(TriggerException):
  pass

class ValidationRequestException(TriggerException):
  pass

class SkipRequestException(TriggerException):
  pass

class EmptyRepositoryException(TriggerException):
  pass

class RepositoryReadException(TriggerException):
  pass

class TriggerProviderException(TriggerException):
  pass

logger = logging.getLogger(__name__)

def determine_build_ref(run_parameters, get_branch_sha, get_tag_sha, default_branch):
  run_parameters = run_parameters or {}

  kind = ''
  value = ''

  if 'refs' in run_parameters and run_parameters['refs']:
    kind = run_parameters['refs']['kind']
    value = run_parameters['refs']['name']
  elif 'branch_name' in run_parameters:
    kind = 'branch'
    value = run_parameters['branch_name']

  kind = kind or 'branch'
  value = value or default_branch or 'master'

  ref = 'refs/tags/' + value if kind == 'tag' else 'refs/heads/' + value
  commit_sha = get_tag_sha(value) if kind == 'tag' else get_branch_sha(value)
  return (commit_sha, ref)


def find_matching_branches(config, branches):
  if 'branchtag_regex' in config:
    try:
      regex = re.compile(config['branchtag_regex'])
      return [branch for branch in branches
              if matches_ref('refs/heads/' + branch, regex)]
    except:
      pass

  return branches


def should_skip_commit(metadata):
  if 'commit_info' in metadata:
    message = metadata['commit_info']['message']
    return '[skip build]' in message or '[build skip]' in message
  return False


def raise_if_skipped_build(prepared_build, config):
  """ Raises a SkipRequestException if the given build should be skipped. """
  # Check to ensure we have metadata.
  if not prepared_build.metadata:
    logger.debug('Skipping request due to missing metadata for prepared build')
    raise SkipRequestException()

  # Check the branchtag regex.
  if 'branchtag_regex' in config:
    try:
      regex = re.compile(config['branchtag_regex'])
    except:
      regex = re.compile('.*')

    if not matches_ref(prepared_build.metadata.get('ref'), regex):
      raise SkipRequestException()

  # Check the commit message.
  if should_skip_commit(prepared_build.metadata):
    logger.debug('Skipping request due to commit message request')
    raise SkipRequestException()


def matches_ref(ref, regex):
  match_string = ref.split('/', 1)[1]
  if not regex:
    return False

  m = regex.match(match_string)
  if not m:
    return False

  return len(m.group(0)) == len(match_string)


def raise_unsupported():
  raise io.UnsupportedOperation


def get_trigger_config(trigger):
  try:
    return json.loads(trigger.config)
  except ValueError:
    return {}