#!/usr/bin/python2.5

#

# Copyright 2009 the Melange authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#   http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

from __future__ import with_statement

"""Google Summer of Code Melange release script.

This script provides automation for the various tasks involved in

pushing a new release of Melange to the official Google Summer of Code

app engine instance.

It does not provide a turnkey autopilot solution. Notably, each stage

of the release process must be started by a human operator, and some

commands will request confirmation or extra details before

proceeding. It is not a replacement for a cautious human

operator.

Note that this script requires:

 - Python 2.5 or better (for various language features)

 - Subversion 1.5.0 or better (for working copy depth control, which

     cuts down checkout/update times by several orders of

     magnitude).

"""

__authors__ = [

    # alphabetical order by last name, please

    '"David Anderson" <dave@natulte.net>',

    ]

import functools

import os

import re

import subprocess

import sys

import error

import log

import subversion

import util

# Default repository URLs for Melange and the Google release

# repository.

MELANGE_REPOS = 'http://soc.googlecode.com/svn'

GOOGLE_SOC_REPOS = 'https://soc-google.googlecode.com/svn'

# Regular expression matching an apparently well formed Melange

# release number.

MELANGE_RELEASE_RE = re.compile(r'\d-\d-\d{8}p\d+')

class Error(error.Error):

  pass

class AbortedByUser(Error):

  """The operation was aborted by the user."""

class FileAccessError(Error):

  """An error occured while accessing a file."""

def getString(prompt):

  """Prompt for and return a string."""

  prompt += ' '

  log.stdout.write(prompt)

  log.stdout.flush()

  response = sys.stdin.readline()

  log.terminal_echo(prompt + response.strip())

  if not response:

    raise AbortedByUser('Aborted by ctrl+D')

  return response.strip()

def confirm(prompt, default=False):

  """Ask a yes/no question and return the answer.

  Will reprompt the user until one of "yes", "no", "y" or "n" is

  entered. The input is case insensitive.

  Args:

    prompt: The question to ask the user.

    default: The answer to return if the user just hits enter.

  Returns:

    True if the user answered affirmatively, False otherwise.

  """

  if default:

    question = prompt + ' [Yn]'

  else:

    question = prompt + ' [yN]'

  while True:

    answer = getString(question)

    if not answer:

      return default

    elif answer in ('y', 'yes'):

      return True

    elif answer in ('n', 'no'):

      return False

    else:

      log.error('Please answer yes or no.')

def getNumber(prompt):

  """Prompt for and return a number.

  Will reprompt the user until a number is entered.

  """

  while True:

    value_str = getString(prompt)

    try:

      return int(value_str)

    except ValueError:

      log.error('Please enter a number. You entered "%s".' % value_str)

def getChoice(intro, prompt, choices, done=None, suggest=None):

  """Prompt for and return a choice from a menu.

  Will reprompt the user until a valid menu entry is chosen.

  Args:

    intro: Text to print verbatim before the choice menu.

    prompt: The prompt to print right before accepting input.

    choices: The list of string choices to display.

    done: If not None, the list of indices of previously

          selected/completed choices.

    suggest: If not None, the index of the choice to highlight as

             the suggested choice.

  Returns:

    The index in the choices list of the selection the user made.

  """

  done = set(done or [])

  while True:

    print intro

    print

    for i, entry in enumerate(choices):

      done_text = ' (done)' if i in done else ''

      indent = '--> ' if i == suggest else '    '

      print '%s%2d. %s%s' % (indent, i+1, entry, done_text)

    print

    choice = getNumber(prompt)

    if 0 < choice <= len(choices):

      return choice-1

    log.error('%d is not a valid choice between %d and %d' %

              (choice, 1, len(choices)))

    print

def fileToLines(path):

  """Read a file and return it as a list of lines."""

  try:

    with file(path) as f:

      return f.read().split('\n')

  except (IOError, OSError), e:

    raise FileAccessError(str(e))

def linesToFile(path, lines):

  """Write a list of lines to a file."""

  try:

    with file(path, 'w') as f:

      f.write('\n'.join(lines))

  except (IOError, OSError), e:

    raise FileAccessError(str(e))

#

# Decorators for use in ReleaseEnvironment.

#

def pristine_wc(f):

  """A decorator that cleans up the release repository."""

  @functools.wraps(f)

  def revert_wc(self, *args, **kwargs):

    self.wc.revert()

    return f(self, *args, **kwargs)

  return revert_wc

def requires_branch(f):

  """A decorator that checks that a release branch is active."""

  @functools.wraps(f)

  def check_branch(self, *args, **kwargs):

    if self.branch is None:

      raise error.ExpectationFailed(

        'This operation requires an active release branch')

    return f(self, *args, **kwargs)

  return check_branch

class ReleaseEnvironment(util.Paths):

  """Encapsulates the state of a Melange release rolling environment.

  This class contains the actual releasing logic, and makes use of

  the previously defined utility classes to carry out user commands.

  Attributes:

    release_repos: The URL to the Google release repository root.

    upstream_repos: The URL to the Melange upstream repository root.

    wc: A Subversion object encapsulating a Google SoC working copy.

  """

  BRANCH_FILE = 'BRANCH'

  def __init__(self, root, release_repos, upstream_repos):

    """Initializer.

    Args:

      root: The root of the release environment.

      release_repos: The URL to the Google release repository root.

      upstream_repos: The URL to the Melange upstream repository root.

    """

    util.Paths.__init__(self, root)

    self.wc = subversion.WorkingCopy(self.path('google-soc'))

    self.release_repos = release_repos.strip('/')

    self.upstream_repos = upstream_repos.strip('/')

    if not self.wc.exists():

      self._InitializeWC()

    else:

      self.wc.revert()

      if self.exists(self.BRANCH_FILE):

        branch = fileToLines(self.path(self.BRANCH_FILE))[0]

        self._switchBranch(branch)

      else:

        self._switchBranch(None)

  def _InitializeWC(self):

    """Check out the initial release repository.

    Will also select the latest release branch, if any, so that

    the end state is a fully ready to function release

    environment.

    """

    log.info('Checking out the release repository')

    # Check out a sparse view of the relevant repository paths.

    self.wc.checkout(self.release_repos, depth='immediates')

    self.wc.update('vendor', depth='immediates')

    self.wc.update('branches', depth='immediates')

    self.wc.update('tags', depth='immediates')

    # Locate the most recent release branch, if any, and switch

    # the release environment to it.

    branches = self._listBranches()

    if not branches:

      self._switchBranch(None)

    else:

      self._switchBranch(branches[-1])

  def _listBranches(self):

    """Return a list of available Melange release branches.

    Branches are returned in sorted order, from least recent to

    most recent in release number ordering.

    """

    assert self.wc.exists('branches')

    branches = self.wc.ls('branches')

    # Some early release branches used a different naming scheme

    # that doesn't sort properly with new-style release names. We

    # filter those out here, along with empty lines.

    branches = [b.strip('/') for b in branches

          if MELANGE_RELEASE_RE.match(b.strip('/'))]

    return sorted(branches)

  def _switchBranch(self, release):

    """Activate the branch matching the given release.

    Once activated, this branch is the target of future release

    operations.

    None can be passed as the release. The result is that no

    branch is active, and all operations that require an active

    branch will fail until a branch is activated again. This is

    used only at initialization, when it is detected that there

    are no available release branches to activate.

    Args:

      release: The version number of a Melange release already

           imported in the release repository, or None to

           activate no branch.

    """

    if release is None:

      self.branch = None

      self.branch_dir = None

      log.info('No release branch available')

    else:

      self.wc.update()

      assert self.wc.exists('branches/' + release)

      linesToFile(self.path(self.BRANCH_FILE), [release])

      self.branch = release

      self.branch_dir = 'branches/' + release

      self.wc.update(self.branch_dir, depth='infinity')

      log.info('Working on branch ' + self.branch)

  def _branchPath(self, path):

    """Return the given path with the release branch path prepended."""

    assert self.branch_dir is not None

    return os.path.join(self.branch_dir, path)

  #

  # Release engineering commands. See further down for their

  # integration into a commandline interface.

  #

  @pristine_wc

  def update(self):

    """Update and clean the release repository"""

    self.wc.update()

  @pristine_wc

  def switchToBranch(self):

    """Switch to another Melange release branch"""

    branches = self._listBranches()

    if not branches:

      raise error.ExpectationFailed(

        'No branches available. Please import one.')

    choice = getChoice('Available release branches:',

               'Your choice?',

               branches,

               suggest=len(branches)-1)

    self._switchBranch(branches[choice])

  def _addAppYaml(self):

    """Create a Google production app.yaml configuration.

    The file is copied and modified from the upstream

    app.yaml.template, configure for Google's Summer of Code App

    Engine instance, and committed.

    """

    if self.wc.exists(self._branchPath('app/app.yaml')):

      raise ObstructionError('app/app.yaml exists already')

    yaml_path = self._branchPath('app/app.yaml')

    self.wc.copy(yaml_path + '.template', yaml_path)

    yaml = fileToLines(self.wc.path(yaml_path))

    out = []

    for i, line in enumerate(yaml):

      stripped_line = line.strip()

      if 'TODO' in stripped_line:

        continue

      elif stripped_line == '# application: FIXME':

        out.append('application: socghop')

      elif stripped_line.startswith('version:'):

        out.append(line.lstrip() + 'g0')

        out.append('# * initial Google fork of Melange ' +

               self.branch)

      else:

        out.append(line)

    linesToFile(self.wc.path(yaml_path), out)

    self.wc.commit('Create app.yaml with Google patch version g0 '

             'in branch ' + self.branch)

  def _applyGooglePatches(self):

    """Apply Google-specific patches to a vanilla Melange release.

    Each patch is applied and committed in turn.

    """

    # Edit the base template to point users to the Google fork

    # of the Melange codebase instead of the vanilla release.

    tmpl_file = self.wc.path(

      self._branchPath('app/soc/templates/soc/base.html'))

    tmpl = fileToLines(tmpl_file)

    for i, line in enumerate(tmpl):

      if 'http://code.google.com/p/soc/source/browse/tags/' in line:

        tmpl[i] = line.replace('/p/soc/', '/p/soc-google/')

        break

    else:

      raise error.ExpectationFailed(

        'No source code link found in base.html')

    linesToFile(tmpl_file, tmpl)

    self.wc.commit(

      'Customize the Melange release link in the sidebar menu')

  @pristine_wc

  def importTag(self):

    """Import a new Melange release"""

    release = getString('Enter the Melange release to import:')

    if not release:

      AbortedByUser('No release provided, import aborted')

    branch_dir = 'branches/' + release

    if self.wc.exists(branch_dir):

      raise ObstructionError('Release %s already imported' % release)

    tag_url = '%s/tags/%s' % (self.upstream_repos, release)

    release_rev = subversion.find_tag_rev(tag_url)

    if confirm('Confirm import of release %s, tagged at r%d?' %

           (release, release_rev)):

      # Add an entry to the vendor externals for the Melange

      # release.

      externals = self.wc.propget('svn:externals', 'vendor/soc')

      externals.append('%s -r %d %s' % (release, release_rev, tag_url))

      self.wc.propset('svn:externals', '\n'.join(externals), 'vendor/soc')

      self.wc.commit('Add svn:externals entry to pull in Melange '

               'release %s at r%d.' % (release, release_rev))

      # Export the tag into the release repository's branches

      subversion.export(tag_url, release_rev, self.wc.path(branch_dir))

      # Add and commit the branch add (very long operation!)

      self.wc.add([branch_dir])

      self.wc.commit('Branch of Melange release %s' % release,

               branch_dir)

      self._switchBranch(release)

      # Commit the production GSoC configuration and

      # google-specific patches.

      self._addAppYaml()

      self._applyGooglePatches()

      # All done!

      log.info('Melange release %s imported and googlified' % self.branch)

  @requires_branch

  @pristine_wc

  def cherryPickChange(self):

    """Cherry-pick a change from the Melange trunk"""

    rev = getNumber('Revision number to cherry-pick:')

    bug = getNumber('Issue fixed by this change:')

    diff = subversion.diff(self.upstream_repos + '/trunk', rev)

    if not diff.strip():

      raise error.ExpectationFailed(

        'Retrieved diff is empty. '

        'Did you accidentally cherry-pick a branch change?')

    util.run(['patch', '-p0'], cwd=self.wc.path(self.branch_dir),

         stdin=diff)

    self.wc.addRemove(self.branch_dir)

    yaml_path = self.wc.path(self._branchPath('app/app.yaml'))

    out = []

    updated_patchlevel = False

    for line in fileToLines(yaml_path):

      if line.strip().startswith('version: '):

        version = line.strip().split()[-1]

        base, patch = line.rsplit('g', 1)

        new_version = '%sg%d' % (base, int(patch) + 1)

        message = ('Cherry-picked r%d from /p/soc/ to fix issue %d' %

               (rev, bug))

        out.append('version: ' + new_version)

        out.append('# * ' + message)

        updated_patchlevel = True

      else:

        out.append(line)

    if not updated_patchlevel:

      log.error('Failed to update Google patch revision')

      log.error('Cherry-picking failed')

    linesToFile(yaml_path, out)

    log.info('Check the diff about to be committed with:')

    log.info('svn diff ' + self.wc.path(self.branch_dir))

    if not confirm('Commit this change?'):

      raise AbortedByUser('Cherry-pick aborted')

    self.wc.commit(message)

    log.info('Cherry-picked r%d from the Melange trunk.' % rev)

  MENU_ORDER = [

    update,

    switchToBranch,

    importTag,

    cherryPickChange,

    ]

  MENU_STRINGS = [d.__doc__ for d in MENU_ORDER]