# vim: set fileencoding=utf-8 :
#
# (C) 2011 Guido Günther <agx@sigxcpu.org>
#    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
"""A Debian Changelog"""

import email
import os
import subprocess

class NoChangeLogError(Exception):
    """No changelog found"""
    pass

class ParseChangeLogError(Exception):
    """Problem parsing changelog"""
    pass


class ChangeLogSection(object):
    """A section in the changelog describing one particular version"""
    def __init__(self, package, version):
        self._package = package
        self._version = version

    @property
    def package(self):
        return self._package

    @property
    def version(self):
        return self._version

    @classmethod
    def parse(klass, section):
        """
        Parse one changelog section

        @param section: a changelog section
        @type section: C{str}
        @returns: the parse changelog section
        @rtype: L{ChangeLogSection}
        """
        header = section.split('\n')[0]
        package = header.split()[0]
        version = header.split()[1][1:-1]
        return klass(package, version)


class ChangeLog(object):
    """A Debian changelog"""

    def __init__(self, contents=None, filename=None):
        """
        @param contents: the contents of the changelog
        @type contents: C{str}
        @param filename: the filename of the changelog
        @param filename: C{str}
        """
        self._contents = ''
        self._cp = None
        self._filename = filename

        # Check that either contents or filename is passed (but not both)
        if (not filename and not contents) or (filename and contents):
            raise Exception("Either filename or contents must be passed")

        if filename and not os.access(filename, os.F_OK):
            raise NoChangeLogError, "Changelog %s not found" % (filename, )

        if contents:
            self._contents = contents[:]
        else:
            self._read()
        self._parse()

    def _parse(self):
        """Parse a changelog based on the already read contents."""
        cmd = subprocess.Popen(['dpkg-parsechangelog', '-l-'],
                                stdin=subprocess.PIPE,
                                stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE)
        (output, errors) = cmd.communicate(self._contents)
        if cmd.returncode:
            raise ParseChangeLogError("Failed to parse changelog. "
                                      "dpkg-parsechangelog said:\n%s" % (errors, ))
        # Parse the result of dpkg-parsechangelog (which looks like
        # email headers)
        cp = email.message_from_string(output)
        try:
            if ':' in cp['Version']:
                cp['Epoch'], cp['NoEpoch-Version'] = cp['Version'].split(':', 1)
            else:
                cp['NoEpoch-Version'] = cp['Version']
            if '-' in cp['NoEpoch-Version']:
                cp['Upstream-Version'], cp['Debian-Version'] = cp['NoEpoch-Version'].rsplit('-', 1)
            else:
                cp['Debian-Version'] = cp['NoEpoch-Version']
        except TypeError:
            raise ParseChangeLogError, output.split('\n')[0]

        self._cp = cp

    def _read(self):
            with file(self.filename) as f:
                self._contents = f.read()

    def __getitem__(self, item):
        return self._cp[item]

    def __setitem__(self, item, value):
        self._cp[item] = value

    @property
    def filename(self):
        """The filename (path) of the changelog"""
        return self._filename

    @property
    def name(self):
        """The packges name"""
        return self._cp['Source']

    @property
    def version(self):
       """The full version string"""
       return self._cp['Version']

    @property
    def upstream_version(self):
        """The upstream version"""
        return self._cp['Upstream-Version']

    @property
    def debian_version(self):
        """The Debian part of the version number"""
        return self._cp['Debian-Version']

    @property
    def epoch(self):
        """The package's epoch"""
        return self._cp['Epoch']

    @property
    def noepoch(self):
        """The version string without the epoch"""
        return self._cp['NoEpoch-Version']

    def has_epoch(self):
        """
        Whether the version has an epoch

        @return: C{True} if the version has an epoch, C{False} otherwise
        @rtype: C{bool}
        """
        return self._cp.has_key('Epoch')

    def is_native(self):
        """
        Whether this is a native Debian package
        """
        return not '-' in self.version

    @property
    def author(self):
        """
        The author of the last modification
        """
        return email.Utils.parseaddr(self._cp['Maintainer'])[0]

    @property
    def email(self):
        """
        The author's email
        """
        return email.Utils.parseaddr(self._cp['Maintainer'])[1]

    @property
    def date(self):
        """
        The date of the last modification as rfc822 date
        """
        return self._cp['Date']

    @property
    def sections_iter(self):
        """
        Iterate over sections in the changelog
        """
        section = ''
        for line in self._contents.split('\n'):
            if line and line[0] not in [ ' ', '\t' ]:
                section += line
            else:
                if section:
                    yield ChangeLogSection.parse(section)
                    section = ''

    @property
    def sections(self):
        """
        Get sections in the changelog
        """
        return list(self.sections_iter)