# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.


import logging, re
import deduping_scheduler, forgiving_config_parser
from distutils import version
from constants import Labels


class MalformedConfigEntry(Exception):
    """Raised to indicate a failure to parse a Task out of a config."""
    pass


BARE_BRANCHES = ['factory', 'firmware']


def PickBranchName(type, milestone):
    if type in BARE_BRANCHES:
        return type
    return milestone


class Task(object):
    """Represents an entry from the scheduler config.  Can schedule itself.

    Each entry from the scheduler config file maps one-to-one to a
    Task.  Each instance has enough info to schedule itself
    on-demand with the AFE.

    This class also overrides __hash__() and all comparitor methods to enable
    correct use in dicts, sets, etc.
    """


    @staticmethod
    def CreateFromConfigSection(config, section):
        """Create a Task from a section of a config file.

        The section to parse should look like this:
        [TaskName]
        suite: suite_to_run  # Required
        run_on: event_on which to run  # Required
        branch_specs: factory,firmware,>=R12  # Optional
        pool: pool_of_devices  # Optional

        By default, Tasks run on all release branches, not factory or firmware.

        @param config: a ForgivingConfigParser.
        @param section: the section to parse into a Task.
        @return keyword, Task object pair.  One or both will be None on error.
        @raise MalformedConfigEntry if there's a problem parsing |section|.
        """
        if not config.has_section(section):
            raise MalformedConfigEntry('unknown section %s' % section)

        allowed = set(['suite', 'run_on', 'branch_specs', 'pool'])
        # The parameter of union() is the keys under the section in the config
        # The union merges this with the allowed set, so if any optional keys
        # are omitted, then they're filled in. If any extra keys are present,
        # then they will expand unioned set, causing it to fail the following
        # comparison against the allowed set.
        section_headers = allowed.union(dict(config.items(section)).keys())
        if allowed != section_headers:
            raise MalformedConfigEntry('unknown entries: %s' %
                      ", ".join(map(str, section_headers.difference(allowed))))

        keyword = config.getstring(section, 'run_on')
        suite = config.getstring(section, 'suite')
        branches = config.getstring(section, 'branch_specs')
        pool = config.getstring(section, 'pool')
        if not keyword:
            raise MalformedConfigEntry('No event to |run_on|.')
        if not suite:
            raise MalformedConfigEntry('No |suite|')
        specs = []
        if branches:
            specs = re.split('\s*,\s*', branches)
            Task.CheckBranchSpecs(specs)
        return keyword, Task(section, suite, specs, pool)


    @staticmethod
    def CheckBranchSpecs(branch_specs):
        """Make sure entries in the list branch_specs are correctly formed.

        We accept any of BARE_BRANCHES in |branch_specs|, as
        well as _one_ string of the form '>=RXX', where 'RXX' is a
        CrOS milestone number.

        @param branch_specs: an iterable of branch specifiers.
        @raise MalformedConfigEntry if there's a problem parsing |branch_specs|.
        """
        have_seen_numeric_constraint = False
        for branch in branch_specs:
            if branch in BARE_BRANCHES:
                continue
            if branch.startswith('>=R') and not have_seen_numeric_constraint:
                have_seen_numeric_constraint = True
                continue
            raise MalformedConfigEntry("%s isn't a valid branch spec." % branch)


    def __init__(self, name, suite, branch_specs, pool=None):
        """Constructor

        Given an iterable in |branch_specs|, pre-vetted using CheckBranchSpecs,
        we'll store them such that _FitsSpec() can be used to check whether a
        given branch 'fits' with the specifications passed in here.
        For example, given branch_specs = ['factory', '>=R18'], we'd set things
        up so that _FitsSpec() would return True for 'factory', or 'RXX'
        where XX is a number >= 18.

        Given branch_specs = ['factory', 'firmware'], _FitsSpec()
        would pass only those two specific strings.

        Example usage:
          t = Task('Name', 'suite', ['factory', '>=R18'])
          t._FitsSpec('factory')  # True
          t._FitsSpec('R19')  # True
          t._FitsSpec('R17')  # False
          t._FitsSpec('firmware')  # False
          t._FitsSpec('goober')  # False

        @param suite: the name of the suite to run, e.g. 'bvt'
        @param branch_specs: a pre-vetted iterable of branch specifiers,
                             e.g. ['>=R18', 'factory']
        @param pool: the pool of machines to use for scheduling purposes.
                     Default: None
        """
        self._name = name
        self._suite = suite
        self._branch_specs = branch_specs
        self._pool = pool

        self._bare_branches = []
        if not branch_specs:
            # Any milestone is OK.
            self._numeric_constraint = version.LooseVersion('0')
        else:
            self._numeric_constraint = None
            for spec in branch_specs:
                if spec.startswith('>='):
                    self._numeric_constraint = version.LooseVersion(
                        spec.lstrip('>=R'))
                else:
                    self._bare_branches.append(spec)
        # Since we expect __hash__() and other comparitor methods to be used
        # frequently by set operations, and they use str() a lot, pre-compute
        # the string representation of this object.
        self._str = '%s: %s on %s with pool %s' % (self.__class__.__name__,
                                                   suite, branch_specs, pool)


    def _FitsSpec(self, branch):
        """Checks if a branch is deemed OK by this instance's branch specs.

        When called on a branch name, will return whether that branch
        'fits' the specifications stored in self._bare_branches and
        self._numeric_constraint.

        @param branch: the branch to check.
        @return True if b 'fits' with stored specs, False otherwise.
        """
        if branch in BARE_BRANCHES:
            return branch in self._bare_branches
        return (self._numeric_constraint and
                version.LooseVersion(branch) >= self._numeric_constraint)


    @property
    def suite(self):
        return self._suite


    @property
    def branch_specs(self):
        return self._branch_specs


    @property
    def pool(self):
        return self._pool


    def __str__(self):
        return self._str


    def __lt__(self, other):
        return str(self) < str(other)


    def __le__(self, other):
        return str(self) <= str(other)


    def __eq__(self, other):
        return str(self) == str(other)


    def __ne__(self, other):
        return str(self) != str(other)


    def __gt__(self, other):
        return str(self) > str(other)


    def __ge__(self, other):
        return str(self) >= str(other)


    def __hash__(self):
        """Allows instances to be correctly deduped when used in a set."""
        return hash(str(self))


    def AvailableHosts(self, scheduler, board):
        """Query what hosts are able to run a test on a board and pool
        combination.

        @param scheduler: an instance of DedupingScheduler, as defined in
                          deduping_scheduler.py
        @param board: the board against which one wants to run the test.
        @return The list of hosts meeting the board and pool requirements,
                or None if no hosts were found."""
        labels = [Labels.BOARD_PREFIX + board]
        if self._pool:
            labels.append(Labels.POOL_PREFIX + self._pool)

        return scheduler.GetHosts(multiple_labels=labels)


    def ShouldHaveAvailableHosts(self):
        """As a sanity check, return true if we know for certain that
        we should be able to schedule this test. If we claim this test
        should be able to run, and it ends up not being scheduled, then
        a warning will be reported.

        @return True if this test should be able to run, False otherwise.
        """
        return self._pool == 'bvt'


    def Run(self, scheduler, branch_builds, board, force=False):
        """Run this task.  Returns False if it should be destroyed.

        Execute this task.  Attempt to schedule the associated suite.
        Return True if this task should be kept around, False if it
        should be destroyed.  This allows for one-shot Tasks.

        @param scheduler: an instance of DedupingScheduler, as defined in
                          deduping_scheduler.py
        @param branch_builds: a dict mapping branch name to the build(s) to
                              install for that branch, e.g.
                              {'R18': ['x86-alex-release/R18-1655.0.0'],
                               'R19': ['x86-alex-release/R19-2077.0.0']}
        @param board: the board against which to run self._suite.
        @param force: Always schedule the suite.
        @return True if the task should be kept, False if not
        """
        logging.info('Running %s on %s', self._name, board)
        builds = []
        for branch, build in branch_builds.iteritems():
            logging.info('Checking if %s fits spec %r',
                         branch, self.branch_specs)
            if self._FitsSpec(branch):
                builds.extend(build)
        for build in builds:
            try:
                if not scheduler.ScheduleSuite(self._suite, board, build,
                                               self._pool, force):
                    logging.info('Skipping scheduling %s on %s for %s',
                                 self._suite, build, board)
            except deduping_scheduler.DedupingSchedulerException as e:
                logging.error(e)
        return True


class OneShotTask(Task):
    """A Task that can be run only once.  Can schedule itself."""


    def Run(self, scheduler, branch_builds, board, force=False):
        """Run this task.  Returns False, indicating it should be destroyed.

        Run this task.  Attempt to schedule the associated suite.
        Return False, indicating to the caller that it should discard this task.

        @param scheduler: an instance of DedupingScheduler, as defined in
                          deduping_scheduler.py
        @param branch_builds: a dict mapping branch name to the build(s) to
                              install for that branch, e.g.
                              {'R18': ['x86-alex-release/R18-1655.0.0'],
                               'R19': ['x86-alex-release/R19-2077.0.0']}
        @param board: the board against which to run self._suite.
        @param force: Always schedule the suite.
        @return False
        """
        super(OneShotTask, self).Run(scheduler, branch_builds, board, force)
        return False