import operator
import os
import subprocess
import sys

from xml.dom import minidom

scripts_dir = os.path.dirname(__file__)
base_dir = os.path.dirname(scripts_dir)

_cached_dname, _cached_dversion = None, None
_cached_packages = None
_UNSTABLE_NAMES = {
    'debian': 'unstable',
    'fedora': 'rawhide',
    'mandrivalinux': 'cooker',
    'ubuntu': 'unstable',
    'tuquito':'unstable',
}


def _pipe_lower(args):
    out, err_ = subprocess.Popen(args, stdout=subprocess.PIPE).communicate()
    return out.strip().lower()


def get_distribution():
    global _cached_dname, _cached_dversion

    if _cached_dname:
        return _cached_dname, _cached_dversion

    if 'SJH_DISTRIBUTION' in os.environ:
        _cached_dname, _cached_dversion = \
            os.environ['SJH_DISTRIBUTION'].split('-')
        return _cached_dname, _cached_dversion

    try:
        _cached_dname = _pipe_lower(['lsb_release', '-is'])
        _cached_dversion = _pipe_lower(['lsb_release', '-rs'])

    except OSError:
        sys.stderr.write('ERROR: Could not run lsb_release. Is it installed?\n')

    return _cached_dname, _cached_dversion


def check_package(package):
    name, version_ = get_distribution()
    if name in ['fedora', 'mandrivalinux']:
        ret = subprocess.call(['rpm', '--quiet', '-q', package])
        return ret == 0
    elif name in ['ubuntu', 'debian', 'tuquito']:
        cmd = ["dpkg-query", "-f='${status}'", "-W", package]
        out, err_ = subprocess.Popen(cmd, stdout=subprocess.PIPE).communicate()
        return out.find('install ok installed') != -1

    return None


def _check_suffix(name, suffixes):
    """
    Returns a list of all matching suffixes for <name>.
    """
    return [name for suffix in suffixes if name.endswith(suffix)]


def _parse_dependencies(dname, dversion):
    if not (dname and dversion):
        return []

    suffixes = ['alldistros.xml', '%s-allversions.xml' % (dname, ),
                '%s-%s.xml' % (dname, dversion)]

    dirname = os.path.join(base_dir, 'config', 'sysdeps')
    filenames = [os.path.join(dirname, fname)
        for fname in os.listdir(dirname)
        if _check_suffix(fname, suffixes)]

    # check whether we have a file matching the exact distro version
    if not [name for name in filenames if name.endswith(suffixes[-1])]:
        if dname not in _UNSTABLE_NAMES:
            sys.stderr.write('ERROR: %r is not a supported distro. If you '
                'think it is sufficiently recent to contain everything the '
                'latest development version of Sugar needs and would like to '
                'see it supported, please file a ticket at dev.sugarlabs.org.'
                '\n' % (dname, ))
            return []

        uversion = _UNSTABLE_NAMES[dname]
        if (dversion == uversion):
            # no config for unstable
            return []

        sys.stderr.write('Warning: unknown distro version, automatic fallback '
            'to %s.\n' % (uversion, ))
        return _parse_dependencies(dname, uversion)


    return [minidom.parse(fname)
            for fname in filenames if os.path.exists(fname)]


def get_packages():
    global _cached_packages

    if _cached_packages is not None:
        return _cached_packages

    dname, dversion = get_distribution()
    documents = _parse_dependencies(dname, dversion)
    _cached_packages = []

    if not documents:
        return _cached_packages

    roots = [doc.childNodes[0] for doc in documents]

    for node in reduce(operator.add, [root.childNodes for root in roots]):
        if node.nodeType == node.ELEMENT_NODE:
            if node.nodeName == 'package':
                name = node.getAttribute('name')
                if node.hasAttribute('source'):
                    source = node.getAttribute('source')
                else:
                    source = None

                _cached_packages.append((name, source))

    return _cached_packages