#!/usr/bin/python
#
# Copyright (c) 2010 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.

"""Generates a pinned solutions file with relative git repository URLs.

make_relative_solution reads a pinned solution file generated by
'gclient revinfo --snapshot' and writes to stdout a pinned solution file
with relative git repository URLs.


The resulting solution file can be used to check out a fixed version of
a gclient set of repositories.  The base URL to fetch from can be changed
by editing one line in the generated solution file.
"""

import optparse
import sys


def ReadSnapshot(filename):
  """Reads a gclient revinfo snapshot file.

  Minimal verification of the structure of the file is performed.

  Args:
    filename: The name of a snapshot file to read.

  Returns:
    The solutions array parsed from the snapshot file.
  """

  env = {}
  execfile(filename, env)

  assert 'solutions' in env
  assert env['solutions']

  return env['solutions']


def BaseRepository(url):
  """Finds the base repository path.

  This only works if the top level repository is not in a subdirectory relative
  to the other repositories on the server.

  Args:
    url: git repository url

  Returns:
    The prefix of the URL that does not contain the repository name and SHA.
  """

  base, versioned_repository = url.rsplit('/', 1)

  assert base and versioned_repository
  return base


def WriteBaseURL(base, solution):
  print '  "%s": "%s",' % (solution['name'], base)


def IsRelativeRepository(base, url):
  return url.startswith(base)


def RelativeRepository(base, url):
  if IsRelativeRepository(base, url):
    return url[len(base):]
  else:
    return url


def RelativeDep(base, dep):
  path, repository = dep

  return (path,
          RelativeRepository(base, repository),
          IsRelativeRepository(base, repository))


def RelativeDeps(base, solution):
  return [RelativeDep(base, dep) for dep in solution['custom_deps'].items()]


def WritePinnedDep(name, dep, indent):
  """Writes a pinned dep.

  The output is indented so that the URLs all line up for ease of reading.  If
  the dep is for a relative git repository then we emit the base_url lookup as
  well.

  Args:
    name:   The name of the solution that is being written out.
    dep:    The relative dep that is to be written out.
    indent: The total number of characters to use for the path component.

  Returns:
    Nothing
  """

  path, repository, relative = dep
  remainder = path.partition('/')[2]
  spaces = indent - len(path)

  if remainder == 'deps':
    return

  if relative:
    print '      "%s": %*sbase_url["%s"] + "%s",' % (path,
                                                     spaces, '',
                                                     name,
                                                     repository)
  else:
    print '      "%s": %*s"%s",' % (path,
                                    spaces, '',
                                    repository)


def WritePinnedSolution(solution):
  """Writes out a pinned and solution file with relative repository paths.

  The relative repository paths make it easier for a user to modify where
  they are pulling source from.

  Args:
    solution: gclient solution object.

  Returns:
    Nothing
  """

  base = BaseRepository(solution['url'])
  url = RelativeRepository(base, solution['url'])
  deps = RelativeDeps(base, solution)
  indent = max(len(dep[0]) for dep in deps)

  deps.sort(key=lambda dep: dep[1])

  print ('  { "name"        : "%s",\n'
         '    "url"         : base_url["%s"] + "%s",\n'
         '    "custom_deps" : {') % (solution['name'],
                                     solution['name'],
                                     url)

  for dep in deps:
    WritePinnedDep(solution['name'], dep, indent)

  print ('    },\n'
         '  },')


def main(argv):
  usage = 'Usage: %prog [options] filename'
  option_parser = optparse.OptionParser(usage=usage)
  option_parser.disable_interspersed_args()
  option_parser.add_option('-s', '--substitute',
                           action='store_true',
                           dest='substitute',
                           default=False,
                           help='substitute a new base git URL')
  option_parser.add_option('-b', '--base',
                           dest='base',
                           default='http://src.chromium.org/git',
                           metavar='URL',
                           help='base git URL to substitute [%default]')

  options, args = option_parser.parse_args(argv[1:])

  if len(args) != 1:
    option_parser.print_help()
    return 1

  filename = args.pop(0)
  solutions = ReadSnapshot(filename)

  print ('#\n'
         '# Autogenerated pinned gclient solution file.  This file was\n'
         '# created by running make_relative_solution.\n'
         '#\n'
         '\n'
         'base_url = {')

  for solution in solutions:
    if options.substitute:
      base = options.base
    else:
      base = BaseRepository(solution['url'])

    WriteBaseURL(base, solution)

  print ('}\n'
         '\n'
         'solutions = [')

  for solution in solutions:
    WritePinnedSolution(solution)

  print ']\n'


if __name__ == '__main__':
  main(sys.argv)