# Copyright (C) 2009 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""Routines for reading/writing a marks file."""


import re
from bzrlib.trace import warning


def import_marks(filename):
    """Read the mapping of marks to revision-ids from a file.

    :param filename: the file to read from
    :return: None if an error is encountered or (revision_ids, branch_names)
      where
      * revision_ids is a dictionary with marks as keys and revision-ids
        as values
      * branch_names is a dictionary mapping branch names to some magic #
    """
    # Check that the file is readable and in the right format
    try:
        f = file(filename)
    except IOError:
        warning("Could not import marks file %s - not importing marks",
            filename)
        return None
    firstline = f.readline()
    match = re.match(r'^format=(\d+)$', firstline)
    if not match:
        warning("%r doesn't look like a marks file - not importing marks",
            filename)
        return None
    elif match.group(1) != '1':
        warning('format version in marks file %s not supported - not importing'
            'marks', filename)
        return None

    # Read the branch info
    branch_names = {}
    for string in f.readline().rstrip('\n').split('\0'):
        if not string:
            continue
        name, integer = string.rsplit('.', 1)
        branch_names[name] = int(integer)
 
    # Read the revision info
    revision_ids = {}
    for line in f:
        line = line.rstrip('\n')
        mark, revid = line.split(' ', 1)
        revision_ids[mark] = revid
    f.close()
    return (revision_ids, branch_names)


def export_marks(filename, revision_ids, branch_names=None):
    """Save marks to a file.

    :param filename: filename to save data to
    :param revision_ids: dictionary mapping marks -> bzr revision-ids
    :param branch_names: dictionary mapping branch names to some magic #
    """
    try:
        f = file(filename, 'w')
    except IOError:
        warning("Could not open export-marks file %s - not exporting marks",
            filename)
        return
    f.write('format=1\n')

    # Write the branch names line
    if branch_names:
        branch_names = [ '%s.%d' % x for x in branch_names.iteritems() ]
        f.write('\0'.join(branch_names) + '\n')
    else:
        f.write('\0tmp.0\n')

    # Write the revision info
    for mark, revid in revision_ids.iteritems():
        f.write('%s %s\n' % (mark, revid))
    f.close()