# SPDX-License-Identifier: BSD-2-Clause
""" This module provides specification items and an item cache. """

# Copyright (C) 2019, 2020 embedded brains GmbH (http://www.embedded-brains.de)
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

# pylint: disable=useless-object-inheritance

import os
import pickle
import stat
from typing import Any, List, Dict
import yaml

from rtemsqual.content import SphinxContent

ItemList = List["Item"]
ItemMap = Dict[str, "Item"]


class Item(object):
    """ Objects of this class represent a specification item. """
    def __init__(self, uid: str, data: Any):
        self._uid = uid
        self._data = data
        self._links = []  # type: ItemList
        self._children = []  # type: ItemList

    def __getitem__(self, name: str) -> Any:
        return self._data[name]

    @property
    def uid(self) -> str:
        """ Returns the UID of the item. """
        return self._uid

    @property
    def parents(self) -> ItemList:
        """ Returns the list of parents of this items. """
        return self._links

    @property
    def children(self) -> ItemList:
        """ Returns the list of children of this items. """
        return self._children

    def init_parents(self, item_cache: "ItemCache"):
        """ Initializes the list of parents of this items. """
        for link in self._data["links"]:
            self._links.append(item_cache[list(link.keys())[0]])

    def add_child(self, child: "Item"):
        """ Adds a child to this item. """
        self._children.append(child)

    def register_license_and_copyrights(self, content: SphinxContent):
        """ Registers the license and copyrights of this item. """
        content.register_license(self["SPDX-License-Identifier"])
        for statement in self["copyrights"]:
            content.register_copyright(statement)


def _is_one_item_newer(path: str, mtime: float) -> bool:
    for name in os.listdir(path):
        path2 = os.path.join(path, name)
        if name.endswith(".yml") and not name.startswith("."):
            mtime2 = os.path.getmtime(path2)
            if mtime <= mtime2:
                return True
        else:
            mode = os.lstat(path2).st_mode
            if stat.S_ISDIR(mode) and _is_one_item_newer(path2, mtime):
                return True
    return False


def _must_update_item_cache(path: str, cache_file: str) -> bool:
    try:
        mtime = os.path.getmtime(cache_file)
        return _is_one_item_newer(path, mtime)
    except FileNotFoundError:
        return True


def _load_from_yaml(data_by_uid: Dict[str, Any], path: str) -> None:
    for name in os.listdir(path):
        path2 = os.path.join(path, name)
        if name.endswith(".yml") and not name.startswith("."):
            uid = os.path.basename(name).replace(".yml", "")
            with open(path2, "r") as src:
                data_by_uid[uid] = yaml.safe_load(src.read())
        else:
            mode = os.lstat(path2).st_mode
            if stat.S_ISDIR(mode):
                _load_from_yaml(data_by_uid, path2)


class ItemCache(object):
    """ This class provides a cache of specification items. """
    def __init__(self, config: Any):
        self._items = {}  # type: ItemMap
        self._top_level = {}  # type: ItemMap
        self._load_items(config)

    def __getitem__(self, uid: str) -> Item:
        return self._items[uid]

    @property
    def top_level(self) -> ItemMap:
        """ Returns the list of top-level specification items. """
        return self._top_level

    def _load_items_in_path(self, path: str, cache_file: str) -> None:
        data_by_uid = {}  # type: Dict[str, Any]
        if _must_update_item_cache(path, cache_file):
            _load_from_yaml(data_by_uid, path)
            with open(cache_file, "wb") as out:
                pickle.dump(data_by_uid, out)
        else:
            with open(cache_file, "rb") as out:
                data_by_uid = pickle.load(out)
        for uid, data in data_by_uid.items():
            item = Item(uid, data)
            self._items[uid] = item
            if not item["links"]:
                self._top_level[uid] = item

    def _init_parents(self) -> None:
        for item in self._items.values():
            item.init_parents(self)

    def _init_children(self) -> None:
        for item in self._items.values():
            for parent in item.parents:
                parent.add_child(item)

    def _load_items(self, config: Any) -> None:
        cache_file = config["cache-file"]
        for path in config["paths"]:
            self._load_items_in_path(path, cache_file)
        self._init_parents()
        self._init_children()