# Copyright 2014-2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

import errno
import io
import functools
import operator
import os

import portage
from portage import _encodings
from portage.dep import Atom
from portage.exception import FileNotFound
from portage.cache.index.IndexStreamIterator import IndexStreamIterator
from portage.cache.index.pkg_desc_index import (
    pkg_desc_index_line_read,
    pkg_desc_index_node,
)
from portage.util.iterators.MultiIterGroupBy import MultiIterGroupBy


class IndexedPortdb:
    """
    A portdbapi interface that uses a package description index to
    improve performance. If the description index is missing for a
    particular repository, then all metadata for that repository is
    obtained using the normal pordbapi.aux_get method.

    For performance reasons, the match method only supports package
    name and version constraints. For the same reason, the xmatch
    method is not implemented.
    """

    # Match returns unordered results.
    match_unordered = True

    _copy_attrs = (
        "cpv_exists",
        "findname",
        "getFetchMap",
        "_aux_cache_keys",
        "_cpv_sort_ascending",
        "_have_root_eclass_dir",
    )

    def __init__(self, portdb):

        self._portdb = portdb

        for k in self._copy_attrs:
            setattr(self, k, getattr(portdb, k))

        self._desc_cache = None
        self._cp_map = None
        self._unindexed_cp_map = None

    def _init_index(self):

        cp_map = {}
        desc_cache = {}
        self._desc_cache = desc_cache
        self._cp_map = cp_map
        index_missing = []

        streams = []
        for repo_path in self._portdb.porttrees:
            outside_repo = os.path.join(
                self._portdb.depcachedir, repo_path.lstrip(os.sep)
            )
            filenames = []
            for parent_dir in (repo_path, outside_repo):
                filenames.append(os.path.join(parent_dir, "metadata", "pkg_desc_index"))

            repo_name = self._portdb.getRepositoryName(repo_path)

            try:
                f = None
                for filename in filenames:
                    try:
                        f = io.open(filename, encoding=_encodings["repo.content"])
                    except IOError as e:
                        if e.errno not in (errno.ENOENT, errno.ESTALE):
                            raise
                    else:
                        break

                if f is None:
                    raise FileNotFound(filename)

                streams.append(
                    iter(
                        IndexStreamIterator(
                            f,
                            functools.partial(pkg_desc_index_line_read, repo=repo_name),
                        )
                    )
                )
            except FileNotFound:
                index_missing.append(repo_path)

        if index_missing:
            self._unindexed_cp_map = {}

            class _NonIndexedStream:
                def __iter__(self_):
                    for cp in self._portdb.cp_all(trees=index_missing):
                        # Don't call cp_list yet, since it's a waste
                        # if the package name does not match the current
                        # search.
                        self._unindexed_cp_map[cp] = index_missing
                        yield pkg_desc_index_node(cp, (), None)

            streams.append(iter(_NonIndexedStream()))

        if streams:
            if len(streams) == 1:
                cp_group_iter = ([node] for node in streams[0])
            else:
                cp_group_iter = MultiIterGroupBy(streams, key=operator.attrgetter("cp"))

            for cp_group in cp_group_iter:

                new_cp = None
                cp_list = cp_map.get(cp_group[0].cp)
                if cp_list is None:
                    new_cp = cp_group[0].cp
                    cp_list = []
                    cp_map[cp_group[0].cp] = cp_list

                for entry in cp_group:
                    cp_list.extend(entry.cpv_list)
                    if entry.desc is not None:
                        for cpv in entry.cpv_list:
                            desc_cache[cpv] = entry.desc

                if new_cp is not None:
                    yield cp_group[0].cp

    def cp_all(self, sort=True):
        """
        Returns an ordered iterator instead of a list, so that search
        results can be displayed incrementally.
        """
        if self._cp_map is None:
            return self._init_index()
        return iter(sorted(self._cp_map)) if sort else iter(self._cp_map)

    def match(self, atom):
        """
        For performance reasons, only package name and version
        constraints are supported, and the returned list is
        unordered.
        """
        if not isinstance(atom, Atom):
            atom = Atom(atom)
        cp_list = self._cp_map.get(atom.cp)
        if cp_list is None:
            return []

        if self._unindexed_cp_map is not None:
            try:
                unindexed = self._unindexed_cp_map.pop(atom.cp)
            except KeyError:
                pass
            else:
                cp_list.extend(self._portdb.cp_list(atom.cp, mytree=unindexed))

        if atom == atom.cp:
            return cp_list[:]
        return portage.match_from_list(atom, cp_list)

    def aux_get(self, cpv, attrs, myrepo=None):
        if len(attrs) == 1 and attrs[0] == "DESCRIPTION":
            try:
                return [self._desc_cache[cpv]]
            except KeyError:
                pass
        return self._portdb.aux_get(cpv, attrs)