"""Utilities related to the Cast branching scheme."""

from __future__ import absolute_import
import re

RELEASE_BRANCH_PATTERN = r'(?P<major>\d+)\.(?P<minor>\d+)(?P<version>.+)?'
# See go/nest-tv-branch-strategy.
ANDROID_TV_RELEASE_BRANCH_PATTERN = (r'^android(\d+)-(\d+\.\d+)-(.+)'
                                     r'-(factory|ota)(|\d+)$')


def parse_release_branch(branch_name):
  """Converts string branch_name to tuple (int major, int minor, version)."""
  match = re.match(RELEASE_BRANCH_PATTERN, branch_name)
  if not match:
    raise ValueError('Invalid branch name: {}'.format(branch_name))
  major = int(match.group('major'))
  minor = int(match.group('minor'))
  version = match.group('version')
  try:
    version = int(version)
  except (TypeError, ValueError):
    pass
  return major, minor, version


def is_release_branch(branch):
  """Returns True if |branch| matching release branch patterns."""
  return (branch and
          (re.match(RELEASE_BRANCH_PATTERN, branch) or
           re.match(ANDROID_TV_RELEASE_BRANCH_PATTERN, branch)))


def is_master_branch(branch):
  """Returns True if |branch| is a master branch."""
  return branch == 'master'


def is_branch_equal_to_or_later_than(branch, threshold):
  """Returns True if |branch| is at least as new as |threshold|.

  Returns False if |branch| is older than |threshold|. Returns True if
  |branch| is newer than |threshold|, matches |threshold|, or is 'master'.

  Args:
    branch: A Cast branch, of the form X.YY{a-d} or 'master'.
    threshold: A Cast branch, of the form X.YY{a-d} or 'master'.

  Returns:
    True if |branch| is at least as new as |threshold|.

  Raises:
    ValueError: if either |branch| or |threshold| is poorly-formed.
  """
  if is_master_branch(branch):
    return True
  # This means it is a named branch. Usually a bringup branch so we should run
  # everything.
  if not is_release_branch(branch):
    return True
  # Exclude Android TV release branch from version comparison.
  if re.match(ANDROID_TV_RELEASE_BRANCH_PATTERN, branch):
    return True
  if threshold == 'master':
    return False
  if threshold is None:
    return True

  t_major, t_minor, t_ver = parse_release_branch(threshold)
  major, minor, ver = parse_release_branch(branch)
  t_ver = t_ver if t_ver is not None else -1
  ver = ver if ver is not None else -1
  # If the version is a string for one of them we need to compare both as
  # strings.
  if any(isinstance(v, str) for v in (t_ver, ver)):
    t_ver = str(t_ver)
    ver = str(ver)
  return (major > t_major or
          (major == t_major and minor > t_minor) or
          (major == t_major and minor == t_minor and ver >= t_ver))