import collections
import logging
import multiprocessing
import os
import shutil
import subprocess

try:
    import rpm
except ImportError:
    rpm = None

from repos_cmp import rpm_ffi

LOG = logging.getLogger(__name__)


class NEVR(collections.namedtuple('NEVR', ['name', 'epoch',
                                           'version', 'release'])):

    if rpm:
        @classmethod
        def from_header(cls, header):
            return cls(header[rpm.RPMTAG_NAME],
                       header[rpm.RPMTAG_EPOCH],
                       header[rpm.RPMTAG_VERSION],
                       header[rpm.RPMTAG_RELEASE])

    @classmethod
    def from_tsv_line(cls, line):
        """Creates a NEVR object from a tab-separated line.

        The line should have the following format:
            name\tepoch\tversion\trelease
        """
        try:
            n, e, v, r = line.split(b'\t')
        except Exception:
            LOG.error("Failed to parse line: %s", line, exc_info=True)
            return None

        if e in ('', '(none)', 'None'):
            e = None
        else:
            try:
                e = int(e)
            except Exception:
                LOG.error("Failed to parse epoch from line: %s",
                          line, exc_info=True)
                return None
        return cls(n, e, v, r)

    def format_evr(self):
        if self.epoch is None:
            return '%s-%s' % (self.version, self.release)
        else:
            return '%s:%s-%s' % (self.epoch, self.version, self.release)

    @property
    def evr(self):
        return self[1:]


def format_evr(nevr):
    return nevr.format_evr() if nevr else 'MISSING'


def _uncompressed(path):
    if not path.endswith('.xz'):
        return open(path, 'rb')
    pixz = shutil.which('pixz')
    if pixz:
        return subprocess.Popen([pixz, '-d', '-i', path, '-o', '/dev/stdout'],
                                stdout=subprocess.PIPE).stdout
    return subprocess.Popen(['xz', '-dc', path], stdout=subprocess.PIPE).stdout


def read_pkglist_headers_rpm(path):
    LOG.info("Reading %s using python-module-rpm", path)
    if not rpm:
        raise RuntimeError('rpm module is not avalable')
    with _uncompressed(path) as input_file:
        return rpm.readHeaderListFromFD(input_file.fileno())


def read_pkglist_heders_for_repo(repo_path, arches, components=None):
    bin_lists = []
    src_lists = []
    seen = set()

    # collect the files
    for arch in arches:
        basedir = os.path.join(repo_path, arch, 'base')
        for pkglist in os.listdir(basedir):
            if pkglist.endswith('.bz2'):
                LOG.info('Ignoring %s/%s', basedir, pkglist)
                continue
            parts = pkglist.split('.', 3)
            if parts[0] not in ('pkglist', 'srclist'):
                continue
            if components is not None and parts[1] not in components:
                continue
            what = basedir, parts[0], parts[1]
            if what in seen:
                LOG.info('Ignoring %s/%s', basedir, pkglist)
                continue
            seen.add(what)
            (src_lists if parts[0] == 'srclist' else bin_lists).append(
                os.path.join(basedir, pkglist))
    with multiprocessing.Pool() as p:
        src_res = p.map_async(read_pkglist_headers_rpm, src_lists)
        bin_res = p.map_async(read_pkglist_headers_rpm, bin_lists)
        return sum(src_res.get(), []), sum(bin_res.get(), [])


def _read_pkglist_rpm(path):
    return (NEVR.from_header(h) for h in read_pkglist_headers_rpm(path))


_PKGLIST_QUERY_FORMAT = '%{NAME}\t%{EPOCH}\t%{VERSION}\t%{RELEASE}\n'


def _read_pkglist_pkglist_query(path):
    LOG.info("Reading %s using pkglist-query", path)
    with _uncompressed(path) as input_file:
        query = subprocess.Popen(
            ["pkglist-query", _PKGLIST_QUERY_FORMAT, '-'],
            stdin=input_file, stdout=subprocess.PIPE)
    return (NEVR.from_tsv_line(line)
            for line in query.communicate()[0].splitlines())


def read_pkglist(path):
    if rpm:
        result = _read_pkglist_rpm(path)
    else:
        result = _read_pkglist_pkglist_query(path)
    return [r for r in result if r]


def read_src_dot_list(repo_path):
    path = os.path.join(repo_path, 'files/list/src.list.xz')
    LOG.info("Reading src.list %s", path)

    result = []
    with _uncompressed(path) as input_file:
        for line in input_file:
            try:
                name, evr = line.split(b'\t', 2)[:2]
                e, v, r = rpm_ffi.parse_evr(evr)
                result.append(NEVR(name, e, v, r))
            except Exception:
                LOG.warning('Failed to parse line %r', line, exc_info=True)
    return frozenset(result)


def read_srclists(prefix, arches):
    result = frozenset()
    for arch in arches:
        srclist = os.path.join(prefix, arch, 'base', 'srclist.classic.xz')
        result = result.union(read_pkglist(srclist))
    if not result:
        raise RuntimeError('Empty lists at %s' % prefix)
    return result


def read_all_srclists(repos):
    return dict((name, read_src_dot_list(v['path']))
                for name, v in repos.items())