BaseClasses.py

from __future__ import annotations

import collections
import itertools
import functools
import logging
import random
import secrets
import typing  # this can go away when Python 3.8 support is dropped
from argparse import Namespace
from collections import Counter, deque
from collections.abc import Collection, MutableSequence
from enum import IntEnum, IntFlag
from typing import (AbstractSet, Any, Callable, ClassVar, Dict, Iterable, Iterator, List, Mapping, NamedTuple,
                    Optional, Protocol, Set, Tuple, Union, Type)

from typing_extensions import NotRequired, TypedDict

import NetUtils
import Options
import Utils

if typing.TYPE_CHECKING:
    from worlds import AutoWorld


class Group(TypedDict):
    name: str
    game: str
    world: "AutoWorld.World"
    players: AbstractSet[int]
    item_pool: NotRequired[Set[str]]
    replacement_items: NotRequired[Dict[int, Optional[str]]]
    local_items: NotRequired[Set[str]]
    non_local_items: NotRequired[Set[str]]
    link_replacement: NotRequired[bool]


class ThreadBarrierProxy:
    """Passes through getattr while passthrough is True"""
    def __init__(self, obj: object) -> None:
        self.passthrough = True
        self.obj = obj

    def __getattr__(self, name: str) -> Any:
        if self.passthrough:
            return getattr(self.obj, name)
        else:
            raise RuntimeError("You are in a threaded context and global random state was removed for your safety. "
                               "Please use multiworld.per_slot_randoms[player] or randomize ahead of output.")


class HasNameAndPlayer(Protocol):
    name: str
    player: int


class MultiWorld():
    debug_types = False
    player_name: Dict[int, str]
    plando_texts: List[Dict[str, str]]
    plando_items: List[List[Dict[str, Any]]]
    plando_connections: List
    worlds: Dict[int, "AutoWorld.World"]
    groups: Dict[int, Group]
    regions: RegionManager
    itempool: List[Item]
    is_race: bool = False
    precollected_items: Dict[int, List[Item]]
    state: CollectionState

    plando_options: PlandoOptions
    early_items: Dict[int, Dict[str, int]]
    local_early_items: Dict[int, Dict[str, int]]
    local_items: Dict[int, Options.LocalItems]
    non_local_items: Dict[int, Options.NonLocalItems]
    progression_balancing: Dict[int, Options.ProgressionBalancing]
    completion_condition: Dict[int, Callable[[CollectionState], bool]]
    indirect_connections: Dict[Region, Set[Entrance]]
    exclude_locations: Dict[int, Options.ExcludeLocations]
    priority_locations: Dict[int, Options.PriorityLocations]
    start_inventory: Dict[int, Options.StartInventory]
    start_hints: Dict[int, Options.StartHints]
    start_location_hints: Dict[int, Options.StartLocationHints]
    item_links: Dict[int, Options.ItemLinks]

    game: Dict[int, str]

    random: random.Random
    per_slot_randoms: Utils.DeprecateDict[int, random.Random]
    """Deprecated. Please use `self.random` instead."""

    class AttributeProxy():
        def __init__(self, rule):
            self.rule = rule

        def __getitem__(self, player) -> bool:
            return self.rule(player)

    class RegionManager:
        region_cache: Dict[int, Dict[str, Region]]
        entrance_cache: Dict[int, Dict[str, Entrance]]
        location_cache: Dict[int, Dict[str, Location]]

        def __init__(self, players: int):
            self.region_cache = {player: {} for player in range(1, players+1)}
            self.entrance_cache = {player: {} for player in range(1, players+1)}
            self.location_cache = {player: {} for player in range(1, players+1)}

        def __iadd__(self, other: Iterable[Region]):
            self.extend(other)
            return self

        def append(self, region: Region):
            assert region.name not in self.region_cache[region.player], \
                f"{region.name} already exists in region cache."
            self.region_cache[region.player][region.name] = region

        def extend(self, regions: Iterable[Region]):
            for region in regions:
                assert region.name not in self.region_cache[region.player], \
                    f"{region.name} already exists in region cache."
                self.region_cache[region.player][region.name] = region

        def add_group(self, new_id: int):
            self.region_cache[new_id] = {}
            self.entrance_cache[new_id] = {}
            self.location_cache[new_id] = {}

        def __iter__(self) -> Iterator[Region]:
            for regions in self.region_cache.values():
                yield from regions.values()

        def __len__(self):
            return sum(len(regions) for regions in self.region_cache.values())

    def __init__(self, players: int):
        # world-local random state is saved for multiple generations running concurrently
        self.random = ThreadBarrierProxy(random.Random())
        self.players = players
        self.player_types = {player: NetUtils.SlotType.player for player in self.player_ids}
        self.algorithm = 'balanced'
        self.groups = {}
        self.regions = self.RegionManager(players)
        self.shops = []
        self.itempool = []
        self.seed = None
        self.seed_name: str = "Unavailable"
        self.precollected_items = {player: [] for player in self.player_ids}
        self.required_locations = []
        self.light_world_light_cone = False
        self.dark_world_light_cone = False
        self.rupoor_cost = 10
        self.aga_randomness = True
        self.save_and_quit_from_boss = True
        self.custom = False
        self.customitemarray = []
        self.shuffle_ganon = True
        self.spoiler = Spoiler(self)
        self.early_items = {player: {} for player in self.player_ids}
        self.local_early_items = {player: {} for player in self.player_ids}
        self.indirect_connections = {}
        self.start_inventory_from_pool: Dict[int, Options.StartInventoryPool] = {}

        for player in range(1, players + 1):
            def set_player_attr(attr: str, val) -> None:
                self.__dict__.setdefault(attr, {})[player] = val
            set_player_attr('plando_items', [])
            set_player_attr('plando_texts', {})
            set_player_attr('plando_connections', [])
            set_player_attr('game', "Archipelago")
            set_player_attr('completion_condition', lambda state: True)
        self.worlds = {}
        self.per_slot_randoms = Utils.DeprecateDict("Using per_slot_randoms is now deprecated. Please use the "
                                                    "world's random object instead (usually self.random)")
        self.plando_options = PlandoOptions.none

    def get_all_ids(self) -> Tuple[int, ...]:
        return self.player_ids + tuple(self.groups)

    def add_group(self, name: str, game: str, players: AbstractSet[int] = frozenset()) -> Tuple[int, Group]:
        """Create a group with name and return the assigned player ID and group.
        If a group of this name already exists, the set of players is extended instead of creating a new one."""
        from worlds import AutoWorld

        for group_id, group in self.groups.items():
            if group["name"] == name:
                group["players"] |= players
                return group_id, group
        new_id: int = self.players + len(self.groups) + 1

        self.regions.add_group(new_id)
        self.game[new_id] = game
        self.player_types[new_id] = NetUtils.SlotType.group
        world_type = AutoWorld.AutoWorldRegister.world_types[game]
        self.worlds[new_id] = world_type.create_group(self, new_id, players)
        self.worlds[new_id].collect_item = classmethod(AutoWorld.World.collect_item).__get__(self.worlds[new_id])
        self.player_name[new_id] = name

        new_group = self.groups[new_id] = Group(name=name, game=game, players=players,
                                                world=self.worlds[new_id])

        return new_id, new_group

    def get_player_groups(self, player: int) -> Set[int]:
        return {group_id for group_id, group in self.groups.items() if player in group["players"]}

    def set_seed(self, seed: Optional[int] = None, secure: bool = False, name: Optional[str] = None):
        assert not self.worlds, "seed needs to be initialized before Worlds"
        self.seed = get_seed(seed)
        if secure:
            self.secure()
        else:
            self.random.seed(self.seed)
        self.seed_name = name if name else str(self.seed)

    def set_options(self, args: Namespace) -> None:
        # TODO - remove this section once all worlds use options dataclasses
        from worlds import AutoWorld

        all_keys: Set[str] = {key for player in self.player_ids for key in
                              AutoWorld.AutoWorldRegister.world_types[self.game[player]].options_dataclass.type_hints}
        for option_key in all_keys:
            option = Utils.DeprecateDict(f"Getting options from multiworld is now deprecated. "
                                         f"Please use `self.options.{option_key}` instead.")
            option.update(getattr(args, option_key, {}))
            setattr(self, option_key, option)

        for player in self.player_ids:
            world_type = AutoWorld.AutoWorldRegister.world_types[self.game[player]]
            self.worlds[player] = world_type(self, player)
            options_dataclass: typing.Type[Options.PerGameCommonOptions] = world_type.options_dataclass
            self.worlds[player].options = options_dataclass(**{option_key: getattr(args, option_key)[player]
                                                               for option_key in options_dataclass.type_hints})

    def set_item_links(self):
        from worlds import AutoWorld

        item_links = {}
        replacement_prio = [False, True, None]
        for player in self.player_ids:
            for item_link in self.worlds[player].options.item_links.value:
                if item_link["name"] in item_links:
                    if item_links[item_link["name"]]["game"] != self.game[player]:
                        raise Exception(f"Cannot ItemLink across games. Link: {item_link['name']}")
                    current_link = item_links[item_link["name"]]
                    current_link["players"][player] = item_link["replacement_item"]
                    current_link["item_pool"] &= set(item_link["item_pool"])
                    current_link["exclude"] |= set(item_link.get("exclude", []))
                    current_link["local_items"] &= set(item_link.get("local_items", []))
                    current_link["non_local_items"] &= set(item_link.get("non_local_items", []))
                    current_link["link_replacement"] = min(current_link["link_replacement"],
                                                           replacement_prio.index(item_link["link_replacement"]))
                else:
                    if item_link["name"] in self.player_name.values():
                        raise Exception(f"Cannot name a ItemLink group the same as a player ({item_link['name']}) "
                                        f"({self.get_player_name(player)}).")
                    item_links[item_link["name"]] = {
                        "players": {player: item_link["replacement_item"]},
                        "item_pool": set(item_link["item_pool"]),
                        "exclude": set(item_link.get("exclude", [])),
                        "game": self.game[player],
                        "local_items": set(item_link.get("local_items", [])),
                        "non_local_items": set(item_link.get("non_local_items", [])),
                        "link_replacement": replacement_prio.index(item_link["link_replacement"]),
                    }

        for _name, item_link in item_links.items():
            current_item_name_groups = AutoWorld.AutoWorldRegister.world_types[item_link["game"]].item_name_groups
            pool = set()
            local_items = set()
            non_local_items = set()
            for item in item_link["item_pool"]:
                pool |= current_item_name_groups.get(item, {item})
            for item in item_link["exclude"]:
                pool -= current_item_name_groups.get(item, {item})
            for item in item_link["local_items"]:
                local_items |= current_item_name_groups.get(item, {item})
            for item in item_link["non_local_items"]:
                non_local_items |= current_item_name_groups.get(item, {item})
            local_items &= pool
            non_local_items &= pool
            item_link["item_pool"] = pool
            item_link["local_items"] = local_items
            item_link["non_local_items"] = non_local_items

        for group_name, item_link in item_links.items():
            game = item_link["game"]
            group_id, group = self.add_group(group_name, game, set(item_link["players"]))

            group["item_pool"] = item_link["item_pool"]
            group["replacement_items"] = item_link["players"]
            group["local_items"] = item_link["local_items"]
            group["non_local_items"] = item_link["non_local_items"]
            group["link_replacement"] = replacement_prio[item_link["link_replacement"]]

    def link_items(self) -> None:
        """Called to link together items in the itempool related to the registered item link groups."""
        from worlds import AutoWorld

        for group_id, group in self.groups.items():
            def find_common_pool(players: Set[int], shared_pool: Set[str]) -> Tuple[
                Optional[Dict[int, Dict[str, int]]], Optional[Dict[str, int]]
            ]:
                classifications: Dict[str, int] = collections.defaultdict(int)
                counters = {player: {name: 0 for name in shared_pool} for player in players}
                for item in self.itempool:
                    if item.player in counters and item.name in shared_pool:
                        counters[item.player][item.name] += 1
                        classifications[item.name] |= item.classification

                for player in players.copy():
                    if all([counters[player][item] == 0 for item in shared_pool]):
                        players.remove(player)
                        del (counters[player])

                if not players:
                    return None, None

                for item in shared_pool:
                    count = min(counters[player][item] for player in players)
                    if count:
                        for player in players:
                            counters[player][item] = count
                    else:
                        for player in players:
                            del (counters[player][item])
                return counters, classifications

            common_item_count, classifications = find_common_pool(group["players"], group["item_pool"])
            if not common_item_count:
                continue

            new_itempool: List[Item] = []
            for item_name, item_count in next(iter(common_item_count.values())).items():
                for _ in range(item_count):
                    new_item = group["world"].create_item(item_name)
                    # mangle together all original classification bits
                    new_item.classification |= classifications[item_name]
                    new_itempool.append(new_item)

            region = Region("Menu", group_id, self, "ItemLink")
            self.regions.append(region)
            locations = region.locations
            for item in self.itempool:
                count = common_item_count.get(item.player, {}).get(item.name, 0)
                if count:
                    loc = Location(group_id, f"Item Link: {item.name} -> {self.player_name[item.player]} {count}",
                        None, region)
                    loc.access_rule = lambda state, item_name = item.name, group_id_ = group_id, count_ = count: \
                        state.has(item_name, group_id_, count_)

                    locations.append(loc)
                    loc.place_locked_item(item)
                    common_item_count[item.player][item.name] -= 1
                else:
                    new_itempool.append(item)

            itemcount = len(self.itempool)
            self.itempool = new_itempool

            while itemcount > len(self.itempool):
                items_to_add = []
                for player in group["players"]:
                    if group["link_replacement"]:
                        item_player = group_id
                    else:
                        item_player = player
                    if group["replacement_items"][player]:
                        items_to_add.append(AutoWorld.call_single(self, "create_item", item_player,
                            group["replacement_items"][player]))
                    else:
                        items_to_add.append(AutoWorld.call_single(self, "create_filler", item_player))
                self.random.shuffle(items_to_add)
                self.itempool.extend(items_to_add[:itemcount - len(self.itempool)])

    def secure(self):
        self.random = ThreadBarrierProxy(secrets.SystemRandom())
        self.is_race = True

    @functools.cached_property
    def player_ids(self) -> Tuple[int, ...]:
        return tuple(range(1, self.players + 1))

    @Utils.cache_self1
    def get_game_players(self, game_name: str) -> Tuple[int, ...]:
        return tuple(player for player in self.player_ids if self.game[player] == game_name)

    @Utils.cache_self1
    def get_game_groups(self, game_name: str) -> Tuple[int, ...]:
        return tuple(group_id for group_id in self.groups if self.game[group_id] == game_name)

    @Utils.cache_self1
    def get_game_worlds(self, game_name: str):
        return tuple(world for player, world in self.worlds.items() if
                     player not in self.groups and self.game[player] == game_name)

    def get_name_string_for_object(self, obj: HasNameAndPlayer) -> str:
        return obj.name if self.players == 1 else f'{obj.name} ({self.get_player_name(obj.player)})'

    def get_player_name(self, player: int) -> str:
        return self.player_name[player]

    def get_file_safe_player_name(self, player: int) -> str:
        return Utils.get_file_safe_name(self.get_player_name(player))

    def get_out_file_name_base(self, player: int) -> str:
        """ the base name (without file extension) for each player's output file for a seed """
        return f"AP_{self.seed_name}_P{player}_{self.get_file_safe_player_name(player).replace(' ', '_')}"

    @functools.cached_property
    def world_name_lookup(self):
        return {self.player_name[player_id]: player_id for player_id in self.player_ids}

    def get_regions(self, player: Optional[int] = None) -> Collection[Region]:
        return self.regions if player is None else self.regions.region_cache[player].values()

    def get_region(self, region_name: str, player: int) -> Region:
        return self.regions.region_cache[player][region_name]

    def get_entrance(self, entrance_name: str, player: int) -> Entrance:
        return self.regions.entrance_cache[player][entrance_name]

    def get_location(self, location_name: str, player: int) -> Location:
        return self.regions.location_cache[player][location_name]

    def get_all_state(self, use_cache: bool) -> CollectionState:
        cached = getattr(self, "_all_state", None)
        if use_cache and cached:
            return cached.copy()

        ret = CollectionState(self)

        for item in self.itempool:
            self.worlds[item.player].collect(ret, item)
        for player in self.player_ids:
            subworld = self.worlds[player]
            for item in subworld.get_pre_fill_items():
                subworld.collect(ret, item)
        ret.sweep_for_advancements()

        if use_cache:
            self._all_state = ret
        return ret

    def get_items(self) -> List[Item]:
        return [loc.item for loc in self.get_filled_locations()] + self.itempool

    def find_item_locations(self, item: str, player: int, resolve_group_locations: bool = False) -> List[Location]:
        if resolve_group_locations:
            player_groups = self.get_player_groups(player)
            return [location for location in self.get_locations() if
                    location.item and location.item.name == item and location.player not in player_groups and
                    (location.item.player == player or location.item.player in player_groups)]
        return [location for location in self.get_locations() if
                location.item and location.item.name == item and location.item.player == player]

    def find_item(self, item: str, player: int) -> Location:
        return next(location for location in self.get_locations() if
                    location.item and location.item.name == item and location.item.player == player)

    def find_items_in_locations(self, items: Set[str], player: int, resolve_group_locations: bool = False) -> List[Location]:
        if resolve_group_locations:
            player_groups = self.get_player_groups(player)
            return [location for location in self.get_locations() if
                    location.item and location.item.name in items and location.player not in player_groups and
                    (location.item.player == player or location.item.player in player_groups)]
        return [location for location in self.get_locations() if
                location.item and location.item.name in items and location.item.player == player]

    def create_item(self, item_name: str, player: int) -> Item:
        return self.worlds[player].create_item(item_name)

    def push_precollected(self, item: Item):
        self.precollected_items[item.player].append(item)
        self.state.collect(item, True)

    def push_item(self, location: Location, item: Item, collect: bool = True):
        location.item = item
        item.location = location
        if collect:
            self.state.collect(item, location.advancement, location)

        logging.debug('Placed %s at %s', item, location)

    def get_entrances(self, player: Optional[int] = None) -> Iterable[Entrance]:
        if player is not None:
            return self.regions.entrance_cache[player].values()
        return Utils.RepeatableChain(tuple(self.regions.entrance_cache[player].values()
                                           for player in self.regions.entrance_cache))

    def register_indirect_condition(self, region: Region, entrance: Entrance):
        """Report that access to this Region can result in unlocking this Entrance,
        state.can_reach(Region) in the Entrance's traversal condition, as opposed to pure transition logic."""
        self.indirect_connections.setdefault(region, set()).add(entrance)

    def get_locations(self, player: Optional[int] = None) -> Iterable[Location]:
        if player is not None:
            return self.regions.location_cache[player].values()
        return Utils.RepeatableChain(tuple(self.regions.location_cache[player].values()
                                           for player in self.regions.location_cache))

    def get_unfilled_locations(self, player: Optional[int] = None) -> List[Location]:
        return [location for location in self.get_locations(player) if location.item is None]

    def get_filled_locations(self, player: Optional[int] = None) -> List[Location]:
        return [location for location in self.get_locations(player) if location.item is not None]

    def get_reachable_locations(self, state: Optional[CollectionState] = None, player: Optional[int] = None) -> List[Location]:
        state: CollectionState = state if state else self.state
        return [location for location in self.get_locations(player) if location.can_reach(state)]

    def get_placeable_locations(self, state=None, player=None) -> List[Location]:
        state: CollectionState = state if state else self.state
        return [location for location in self.get_locations(player) if location.item is None and location.can_reach(state)]

    def get_unfilled_locations_for_players(self, location_names: List[str], players: Iterable[int]):
        for player in players:
            if not location_names:
                valid_locations = [location.name for location in self.get_unfilled_locations(player)]
            else:
                valid_locations = location_names
            relevant_cache = self.regions.location_cache[player]
            for location_name in valid_locations:
                location = relevant_cache.get(location_name, None)
                if location and location.item is None:
                    yield location

    def unlocks_new_location(self, item: Item) -> bool:
        temp_state = self.state.copy()
        temp_state.collect(item, True)

        for location in self.get_unfilled_locations(item.player):
            if temp_state.can_reach(location) and not self.state.can_reach(location):
                return True

        return False

    def has_beaten_game(self, state: CollectionState, player: Optional[int] = None) -> bool:
        if player:
            return self.completion_condition[player](state)
        else:
            return all((self.has_beaten_game(state, p) for p in range(1, self.players + 1)))

    def can_beat_game(self, starting_state: Optional[CollectionState] = None) -> bool:
        if starting_state:
            if self.has_beaten_game(starting_state):
                return True
            state = starting_state.copy()
        else:
            state = CollectionState(self)
            if self.has_beaten_game(state):
                return True
        prog_locations = {location for location in self.get_locations() if location.item
                          and location.item.advancement and location not in state.locations_checked}

        while prog_locations:
            sphere: Set[Location] = set()
            # build up spheres of collection radius.
            # Everything in each sphere is independent from each other in dependencies and only depends on lower spheres
            for location in prog_locations:
                if location.can_reach(state):
                    sphere.add(location)

            if not sphere:
                # ran out of places and did not finish yet, quit
                return False

            for location in sphere:
                state.collect(location.item, True, location)
            prog_locations -= sphere

            if self.has_beaten_game(state):
                return True

        return False

    def get_spheres(self) -> Iterator[Set[Location]]:
        """
        yields a set of locations for each logical sphere

        If there are unreachable locations, the last sphere of reachable
        locations is followed by an empty set, and then a set of all of the
        unreachable locations.
        """
        state = CollectionState(self)
        locations = set(self.get_filled_locations())

        while locations:
            sphere: Set[Location] = set()

            for location in locations:
                if location.can_reach(state):
                    sphere.add(location)
            yield sphere
            if not sphere:
                if locations:
                    yield locations  # unreachable locations
                break

            for location in sphere:
                state.collect(location.item, True, location)
            locations -= sphere

    def fulfills_accessibility(self, state: Optional[CollectionState] = None):
        """Check if accessibility rules are fulfilled with current or supplied state."""
        if not state:
            state = CollectionState(self)
        players: Dict[str, Set[int]] = {
            "minimal": set(),
            "items": set(),
            "full": set()
        }
        for player, world in self.worlds.items():
            players[world.options.accessibility.current_key].add(player)

        beatable_fulfilled = False

        def location_condition(location: Location) -> bool:
            """Determine if this location has to be accessible, location is already filtered by location_relevant"""
            return location.player in players["full"] or \
                (location.item and location.item.player not in players["minimal"])

        def location_relevant(location: Location) -> bool:
            """Determine if this location is relevant to sweep."""
            return location.player in players["full"] or location.advancement

        def all_done() -> bool:
            """Check if all access rules are fulfilled"""
            if not beatable_fulfilled:
                return False
            if any(location_condition(location) for location in locations):
                return False  # still locations required to be collected
            return True

        locations = [location for location in self.get_locations() if location_relevant(location)]

        while locations:
            sphere: List[Location] = []
            for n in range(len(locations) - 1, -1, -1):
                if locations[n].can_reach(state):
                    sphere.append(locations.pop(n))

            if not sphere:
                # ran out of places and did not finish yet, quit
                logging.warning(f"Could not access required locations for accessibility check."
                                f" Missing: {locations}")
                return False

            for location in sphere:
                if location.item:
                    state.collect(location.item, True, location)

            if self.has_beaten_game(state):
                beatable_fulfilled = True

            if all_done():
                return True

        return False


PathValue = Tuple[str, Optional["PathValue"]]


class CollectionState():
    prog_items: Dict[int, Counter[str]]
    multiworld: MultiWorld
    reachable_regions: Dict[int, Set[Region]]
    blocked_connections: Dict[int, Set[Entrance]]
    advancements: Set[Location]
    path: Dict[Union[Region, Entrance], PathValue]
    locations_checked: Set[Location]
    stale: Dict[int, bool]
    additional_init_functions: List[Callable[[CollectionState, MultiWorld], None]] = []
    additional_copy_functions: List[Callable[[CollectionState, CollectionState], CollectionState]] = []

    def __init__(self, parent: MultiWorld):
        self.prog_items = {player: Counter() for player in parent.get_all_ids()}
        self.multiworld = parent
        self.reachable_regions = {player: set() for player in parent.get_all_ids()}
        self.blocked_connections = {player: set() for player in parent.get_all_ids()}
        self.advancements = set()
        self.path = {}
        self.locations_checked = set()
        self.stale = {player: True for player in parent.get_all_ids()}
        for function in self.additional_init_functions:
            function(self, parent)
        for items in parent.precollected_items.values():
            for item in items:
                self.collect(item, True)

    def update_reachable_regions(self, player: int):
        self.stale[player] = False
        reachable_regions = self.reachable_regions[player]
        blocked_connections = self.blocked_connections[player]
        queue = deque(self.blocked_connections[player])
        start = self.multiworld.get_region("Menu", player)

        # init on first call - this can't be done on construction since the regions don't exist yet
        if start not in reachable_regions:
            reachable_regions.add(start)
            blocked_connections.update(start.exits)
            queue.extend(start.exits)

        # run BFS on all connections, and keep track of those blocked by missing items
        while queue:
            connection = queue.popleft()
            new_region = connection.connected_region
            if new_region in reachable_regions:
                blocked_connections.remove(connection)
            elif connection.can_reach(self):
                assert new_region, f"tried to search through an Entrance \"{connection}\" with no Region"
                reachable_regions.add(new_region)
                blocked_connections.remove(connection)
                blocked_connections.update(new_region.exits)
                queue.extend(new_region.exits)
                self.path[new_region] = (new_region.name, self.path.get(connection, None))

                # Retry connections if the new region can unblock them
                for new_entrance in self.multiworld.indirect_connections.get(new_region, set()):
                    if new_entrance in blocked_connections and new_entrance not in queue:
                        queue.append(new_entrance)

    def copy(self) -> CollectionState:
        ret = CollectionState(self.multiworld)
        ret.prog_items = {player: counter.copy() for player, counter in self.prog_items.items()}
        ret.reachable_regions = {player: region_set.copy() for player, region_set in
                                 self.reachable_regions.items()}
        ret.blocked_connections = {player: entrance_set.copy() for player, entrance_set in
                                   self.blocked_connections.items()}
        ret.advancements = self.advancements.copy()
        ret.path = self.path.copy()
        ret.locations_checked = self.locations_checked.copy()
        for function in self.additional_copy_functions:
            ret = function(self, ret)
        return ret

    def can_reach(self,
                  spot: Union[Location, Entrance, Region, str],
                  resolution_hint: Optional[str] = None,
                  player: Optional[int] = None) -> bool:
        if isinstance(spot, str):
            assert isinstance(player, int), "can_reach: player is required if spot is str"
            # try to resolve a name
            if resolution_hint == 'Location':
                return self.can_reach_location(spot, player)
            elif resolution_hint == 'Entrance':
                return self.can_reach_entrance(spot, player)
            else:
                # default to Region
                return self.can_reach_region(spot, player)
        return spot.can_reach(self)

    def can_reach_location(self, spot: str, player: int) -> bool:
        return self.multiworld.get_location(spot, player).can_reach(self)

    def can_reach_entrance(self, spot: str, player: int) -> bool:
        return self.multiworld.get_entrance(spot, player).can_reach(self)

    def can_reach_region(self, spot: str, player: int) -> bool:
        return self.multiworld.get_region(spot, player).can_reach(self)

    def sweep_for_events(self, locations: Optional[Iterable[Location]] = None) -> None:
        Utils.deprecate("sweep_for_events has been renamed to sweep_for_advancements. The functionality is the same. "
                        "Please switch over to sweep_for_advancements.")
        return self.sweep_for_advancements(locations)

    def sweep_for_advancements(self, locations: Optional[Iterable[Location]] = None) -> None:
        if locations is None:
            locations = self.multiworld.get_filled_locations()
        reachable_advancements = True
        # since the loop has a good chance to run more than once, only filter the advancements once
        locations = {location for location in locations if location.advancement and location not in self.advancements}

        while reachable_advancements:
            reachable_advancements = {location for location in locations if location.can_reach(self)}
            locations -= reachable_advancements
            for advancement in reachable_advancements:
                self.advancements.add(advancement)
                assert isinstance(advancement.item, Item), "tried to collect Event with no Item"
                self.collect(advancement.item, True, advancement)

    # item name related
    def has(self, item: str, player: int, count: int = 1) -> bool:
        return self.prog_items[player][item] >= count

    def has_all(self, items: Iterable[str], player: int) -> bool:
        """Returns True if each item name of items is in state at least once."""
        return all(self.prog_items[player][item] for item in items)

    def has_any(self, items: Iterable[str], player: int) -> bool:
        """Returns True if at least one item name of items is in state at least once."""
        return any(self.prog_items[player][item] for item in items)

    def has_all_counts(self, item_counts: Mapping[str, int], player: int) -> bool:
        """Returns True if each item name is in the state at least as many times as specified."""
        return all(self.prog_items[player][item] >= count for item, count in item_counts.items())

    def has_any_count(self, item_counts: Mapping[str, int], player: int) -> bool:
        """Returns True if at least one item name is in the state at least as many times as specified."""
        return any(self.prog_items[player][item] >= count for item, count in item_counts.items())

    def count(self, item: str, player: int) -> int:
        return self.prog_items[player][item]

    def has_from_list(self, items: Iterable[str], player: int, count: int) -> bool:
        """Returns True if the state contains at least `count` items matching any of the item names from a list."""
        found: int = 0
        player_prog_items = self.prog_items[player]
        for item_name in items:
            found += player_prog_items[item_name]
            if found >= count:
                return True
        return False

    def has_from_list_unique(self, items: Iterable[str], player: int, count: int) -> bool:
        """Returns True if the state contains at least `count` items matching any of the item names from a list.
        Ignores duplicates of the same item."""
        found: int = 0
        player_prog_items = self.prog_items[player]
        for item_name in items:
            found += player_prog_items[item_name] > 0
            if found >= count:
                return True
        return False

    def count_from_list(self, items: Iterable[str], player: int) -> int:
        """Returns the cumulative count of items from a list present in state."""
        return sum(self.prog_items[player][item_name] for item_name in items)

    def count_from_list_unique(self, items: Iterable[str], player: int) -> int:
        """Returns the cumulative count of items from a list present in state. Ignores duplicates of the same item."""
        return sum(self.prog_items[player][item_name] > 0 for item_name in items)

    # item name group related
    def has_group(self, item_name_group: str, player: int, count: int = 1) -> bool:
        """Returns True if the state contains at least `count` items present in a specified item group."""
        found: int = 0
        player_prog_items = self.prog_items[player]
        for item_name in self.multiworld.worlds[player].item_name_groups[item_name_group]:
            found += player_prog_items[item_name]
            if found >= count:
                return True
        return False

    def has_group_unique(self, item_name_group: str, player: int, count: int = 1) -> bool:
        """Returns True if the state contains at least `count` items present in a specified item group.
        Ignores duplicates of the same item.
        """
        found: int = 0
        player_prog_items = self.prog_items[player]
        for item_name in self.multiworld.worlds[player].item_name_groups[item_name_group]:
            found += player_prog_items[item_name] > 0
            if found >= count:
                return True
        return False

    def count_group(self, item_name_group: str, player: int) -> int:
        """Returns the cumulative count of items from an item group present in state."""
        player_prog_items = self.prog_items[player]
        return sum(
            player_prog_items[item_name]
            for item_name in self.multiworld.worlds[player].item_name_groups[item_name_group]
        )

    def count_group_unique(self, item_name_group: str, player: int) -> int:
        """Returns the cumulative count of items from an item group present in state.
        Ignores duplicates of the same item."""
        player_prog_items = self.prog_items[player]
        return sum(
            player_prog_items[item_name] > 0
            for item_name in self.multiworld.worlds[player].item_name_groups[item_name_group]
        )

    # Item related
    def collect(self, item: Item, prevent_sweep: bool = False, location: Optional[Location] = None) -> bool:
        if location:
            self.locations_checked.add(location)

        changed = self.multiworld.worlds[item.player].collect(self, item)

        self.stale[item.player] = True

        if changed and not prevent_sweep:
            self.sweep_for_advancements()

        return changed

    def remove(self, item: Item):
        changed = self.multiworld.worlds[item.player].remove(self, item)
        if changed:
            # invalidate caches, nothing can be trusted anymore now
            self.reachable_regions[item.player] = set()
            self.blocked_connections[item.player] = set()
            self.stale[item.player] = True


class Entrance:
    access_rule: Callable[[CollectionState], bool] = staticmethod(lambda state: True)
    hide_path: bool = False
    player: int
    name: str
    parent_region: Optional[Region]
    connected_region: Optional[Region] = None
    # LttP specific, TODO: should make a LttPEntrance
    addresses = None
    target = None

    def __init__(self, player: int, name: str = "", parent: Optional[Region] = None) -> None:
        self.name = name
        self.parent_region = parent
        self.player = player

    def can_reach(self, state: CollectionState) -> bool:
        if self.parent_region.can_reach(state) and self.access_rule(state):
            if not self.hide_path and not self in state.path:
                state.path[self] = (self.name, state.path.get(self.parent_region, (self.parent_region.name, None)))
            return True

        return False

    def connect(self, region: Region, addresses: Any = None, target: Any = None) -> None:
        self.connected_region = region
        self.target = target
        self.addresses = addresses
        region.entrances.append(self)

    def __repr__(self):
        multiworld = self.parent_region.multiworld if self.parent_region else None
        return multiworld.get_name_string_for_object(self) if multiworld else f'{self.name} (Player {self.player})'


class Region:
    name: str
    _hint_text: str
    player: int
    multiworld: Optional[MultiWorld]
    entrances: List[Entrance]
    exits: List[Entrance]
    locations: List[Location]
    entrance_type: ClassVar[Type[Entrance]] = Entrance

    class Register(MutableSequence):
        region_manager: MultiWorld.RegionManager

        def __init__(self, region_manager: MultiWorld.RegionManager):
            self._list = []
            self.region_manager = region_manager

        def __getitem__(self, index: int) -> Location:
            return self._list.__getitem__(index)

        def __setitem__(self, index: int, value: Location) -> None:
            raise NotImplementedError()

        def __len__(self) -> int:
            return self._list.__len__()

        # This seems to not be needed, but that's a bit suspicious.
        # def __del__(self):
        #     self.clear()

        def copy(self):
            return self._list.copy()

    class LocationRegister(Register):
        def __delitem__(self, index: int) -> None:
            location: Location = self._list.__getitem__(index)
            self._list.__delitem__(index)
            del(self.region_manager.location_cache[location.player][location.name])

        def insert(self, index: int, value: Location) -> None:
            assert value.name not in self.region_manager.location_cache[value.player], \
                f"{value.name} already exists in the location cache."
            self._list.insert(index, value)
            self.region_manager.location_cache[value.player][value.name] = value

    class EntranceRegister(Register):
        def __delitem__(self, index: int) -> None:
            entrance: Entrance = self._list.__getitem__(index)
            self._list.__delitem__(index)
            del(self.region_manager.entrance_cache[entrance.player][entrance.name])

        def insert(self, index: int, value: Entrance) -> None:
            assert value.name not in self.region_manager.entrance_cache[value.player], \
                f"{value.name} already exists in the entrance cache."
            self._list.insert(index, value)
            self.region_manager.entrance_cache[value.player][value.name] = value

    _locations: LocationRegister[Location]
    _exits: EntranceRegister[Entrance]

    def __init__(self, name: str, player: int, multiworld: MultiWorld, hint: Optional[str] = None):
        self.name = name
        self.entrances = []
        self._exits = self.EntranceRegister(multiworld.regions)
        self._locations = self.LocationRegister(multiworld.regions)
        self.multiworld = multiworld
        self._hint_text = hint
        self.player = player

    def get_locations(self):
        return self._locations

    def set_locations(self, new):
        if new is self._locations:
            return
        self._locations.clear()
        self._locations.extend(new)

    locations = property(get_locations, set_locations)

    def get_exits(self):
        return self._exits

    def set_exits(self, new):
        if new is self._exits:
            return
        self._exits.clear()
        self._exits.extend(new)

    exits = property(get_exits, set_exits)

    def can_reach(self, state: CollectionState) -> bool:
        if state.stale[self.player]:
            state.update_reachable_regions(self.player)
        return self in state.reachable_regions[self.player]

    @property
    def hint_text(self) -> str:
        return self._hint_text if self._hint_text else self.name

    def get_connecting_entrance(self, is_main_entrance: Callable[[Entrance], bool]) -> Entrance:
        for entrance in self.entrances:
            if is_main_entrance(entrance):
                return entrance
        for entrance in self.entrances:  # BFS might be better here, trying DFS for now.
            return entrance.parent_region.get_connecting_entrance(is_main_entrance)

    def add_locations(self, locations: Dict[str, Optional[int]],
                      location_type: Optional[Type[Location]] = None) -> None:
        """
        Adds locations to the Region object, where location_type is your Location class and locations is a dict of
        location names to address.

        :param locations: dictionary of locations to be created and added to this Region `{name: ID}`
        :param location_type: Location class to be used to create the locations with"""
        if location_type is None:
            location_type = Location
        for location, address in locations.items():
            self.locations.append(location_type(self.player, location, address, self))

    def connect(self, connecting_region: Region, name: Optional[str] = None,
                rule: Optional[Callable[[CollectionState], bool]] = None) -> Entrance:
        """
        Connects this Region to another Region, placing the provided rule on the connection.

        :param connecting_region: Region object to connect to path is `self -> exiting_region`
        :param name: name of the connection being created
        :param rule: callable to determine access of this connection to go from self to the exiting_region"""
        exit_ = self.create_exit(name if name else f"{self.name} -> {connecting_region.name}")
        if rule:
            exit_.access_rule = rule
        exit_.connect(connecting_region)
        return exit_

    def create_exit(self, name: str) -> Entrance:
        """
        Creates and returns an Entrance object as an exit of this region.

        :param name: name of the Entrance being created
        """
        exit_ = self.entrance_type(self.player, name, self)
        self.exits.append(exit_)
        return exit_

    def add_exits(self, exits: Union[Iterable[str], Dict[str, Optional[str]]],
                  rules: Dict[str, Callable[[CollectionState], bool]] = None) -> None:
        """
        Connects current region to regions in exit dictionary. Passed region names must exist first.

        :param exits: exits from the region. format is {"connecting_region": "exit_name"}. if a non dict is provided,
        created entrances will be named "self.name -> connecting_region"
        :param rules: rules for the exits from this region. format is {"connecting_region", rule}
        """
        if not isinstance(exits, Dict):
            exits = dict.fromkeys(exits)
        for connecting_region, name in exits.items():
            self.connect(self.multiworld.get_region(connecting_region, self.player),
                         name,
                         rules[connecting_region] if rules and connecting_region in rules else None)

    def __repr__(self):
        return self.multiworld.get_name_string_for_object(self) if self.multiworld else f'{self.name} (Player {self.player})'


class LocationProgressType(IntEnum):
    DEFAULT = 1
    PRIORITY = 2
    EXCLUDED = 3


class Location:
    game: str = "Generic"
    player: int
    name: str
    address: Optional[int]
    parent_region: Optional[Region]
    locked: bool = False
    show_in_spoiler: bool = True
    progress_type: LocationProgressType = LocationProgressType.DEFAULT
    always_allow: Callable[[CollectionState, Item], bool] = staticmethod(lambda state, item: False)
    access_rule: Callable[[CollectionState], bool] = staticmethod(lambda state: True)
    item_rule: Callable[[Item], bool] = staticmethod(lambda item: True)
    item: Optional[Item] = None

    def __init__(self, player: int, name: str = '', address: Optional[int] = None, parent: Optional[Region] = None):
        self.player = player
        self.name = name
        self.address = address
        self.parent_region = parent

    def can_fill(self, state: CollectionState, item: Item, check_access: bool = True) -> bool:
        return ((
            self.always_allow(state, item)
            and item.name not in state.multiworld.worlds[item.player].options.non_local_items
        ) or (
            (self.progress_type != LocationProgressType.EXCLUDED or not (item.advancement or item.useful))
            and self.item_rule(item)
            and (not check_access or self.can_reach(state))
        ))

    def can_reach(self, state: CollectionState) -> bool:
        # Region.can_reach is just a cache lookup, so placing it first for faster abort on average
        assert self.parent_region, "Can't reach location without region"
        return self.parent_region.can_reach(state) and self.access_rule(state)

    def place_locked_item(self, item: Item):
        if self.item:
            raise Exception(f"Location {self} already filled.")
        self.item = item
        item.location = self
        self.locked = True

    def __repr__(self):
        multiworld = self.parent_region.multiworld if self.parent_region and self.parent_region.multiworld else None
        return multiworld.get_name_string_for_object(self) if multiworld else f'{self.name} (Player {self.player})'

    def __hash__(self):
        return hash((self.name, self.player))

    def __lt__(self, other: Location):
        return (self.player, self.name) < (other.player, other.name)

    @property
    def advancement(self) -> bool:
        return self.item is not None and self.item.advancement

    @property
    def is_event(self) -> bool:
        """Returns True if the address of this location is None, denoting it is an Event Location."""
        return self.address is None

    @property
    def native_item(self) -> bool:
        """Returns True if the item in this location matches game."""
        return self.item is not None and self.item.game == self.game

    @property
    def hint_text(self) -> str:
        return "at " + self.name.replace("_", " ").replace("-", " ")


class ItemClassification(IntFlag):
    filler = 0b0000  # aka trash, as in filler items like ammo, currency etc,
    progression = 0b0001  # Item that is logically relevant
    useful = 0b0010  # Item that is generally quite useful, but not required for anything logical
    trap = 0b0100  # detrimental or entirely useless (nothing) item
    skip_balancing = 0b1000  # should technically never occur on its own
    # Item that is logically relevant, but progression balancing should not touch.
    # Typically currency or other counted items.
    progression_skip_balancing = 0b1001  # only progression gets balanced

    def as_flag(self) -> int:
        """As Network API flag int."""
        return int(self & 0b0111)


class Item:
    game: str = "Generic"
    __slots__ = ("name", "classification", "code", "player", "location")
    name: str
    classification: ItemClassification
    code: Optional[int]
    """an item with code None is called an Event, and does not get written to multidata"""
    player: int
    location: Optional[Location]

    def __init__(self, name: str, classification: ItemClassification, code: Optional[int], player: int):
        self.name = name
        self.classification = classification
        self.player = player
        self.code = code
        self.location = None

    @property
    def hint_text(self) -> str:
        return getattr(self, "_hint_text", self.name.replace("_", " ").replace("-", " "))

    @property
    def pedestal_hint_text(self) -> str:
        return getattr(self, "_pedestal_hint_text", self.name.replace("_", " ").replace("-", " "))

    @property
    def advancement(self) -> bool:
        return ItemClassification.progression in self.classification

    @property
    def skip_in_prog_balancing(self) -> bool:
        return ItemClassification.progression_skip_balancing in self.classification

    @property
    def useful(self) -> bool:
        return ItemClassification.useful in self.classification

    @property
    def trap(self) -> bool:
        return ItemClassification.trap in self.classification

    @property
    def flags(self) -> int:
        return self.classification.as_flag()

    def __eq__(self, other: object) -> bool:
        if not isinstance(other, Item):
            return NotImplemented
        return self.name == other.name and self.player == other.player

    def __lt__(self, other: object) -> bool:
        if not isinstance(other, Item):
            return NotImplemented
        if other.player != self.player:
            return other.player < self.player
        return self.name < other.name

    def __hash__(self) -> int:
        return hash((self.name, self.player))

    def __repr__(self) -> str:
        if self.location and self.location.parent_region and self.location.parent_region.multiworld:
            return self.location.parent_region.multiworld.get_name_string_for_object(self)
        return f"{self.name} (Player {self.player})"


class EntranceInfo(TypedDict, total=False):
    player: int
    entrance: str
    exit: str
    direction: str


class Spoiler:
    multiworld: MultiWorld
    hashes: Dict[int, str]
    entrances: Dict[Tuple[str, str, int], EntranceInfo]
    playthrough: Dict[str, Union[List[str], Dict[str, str]]]  # sphere "0" is list, others are dict
    unreachables: Set[Location]
    paths: Dict[str, List[Union[Tuple[str, str], Tuple[str, None]]]]  # last step takes no further exits

    def __init__(self, multiworld: MultiWorld) -> None:
        self.multiworld = multiworld
        self.hashes = {}
        self.entrances = {}
        self.playthrough = {}
        self.unreachables = set()
        self.paths = {}

    def set_entrance(self, entrance: str, exit_: str, direction: str, player: int) -> None:
        if self.multiworld.players == 1:
            self.entrances[(entrance, direction, player)] = \
                {"entrance": entrance, "exit": exit_, "direction": direction}
        else:
            self.entrances[(entrance, direction, player)] = \
                {"player": player, "entrance": entrance, "exit": exit_, "direction": direction}

    def create_playthrough(self, create_paths: bool = True) -> None:
        """Destructive to the multiworld while it is run, damage gets repaired afterwards."""
        from itertools import chain
        # get locations containing progress items
        multiworld = self.multiworld
        prog_locations = {location for location in multiworld.get_filled_locations() if location.item.advancement}
        state_cache: List[Optional[CollectionState]] = [None]
        collection_spheres: List[Set[Location]] = []
        state = CollectionState(multiworld)
        sphere_candidates = set(prog_locations)
        logging.debug('Building up collection spheres.')
        while sphere_candidates:

            # build up spheres of collection radius.
            # Everything in each sphere is independent from each other in dependencies and only depends on lower spheres

            sphere = {location for location in sphere_candidates if state.can_reach(location)}

            for location in sphere:
                state.collect(location.item, True, location)

            sphere_candidates -= sphere
            collection_spheres.append(sphere)
            state_cache.append(state.copy())

            logging.debug('Calculated sphere %i, containing %i of %i progress items.', len(collection_spheres),
                          len(sphere),
                          len(prog_locations))
            if not sphere:
                logging.debug('The following items could not be reached: %s', ['%s (Player %d) at %s (Player %d)' % (
                    location.item.name, location.item.player, location.name, location.player) for location in
                                                                               sphere_candidates])
                if any([multiworld.worlds[location.item.player].options.accessibility != 'minimal' for location in sphere_candidates]):
                    raise RuntimeError(f'Not all progression items reachable ({sphere_candidates}). '
                                       f'Something went terribly wrong here.')
                else:
                    self.unreachables = sphere_candidates
                    break

        # in the second phase, we cull each sphere such that the game is still beatable,
        # reducing each range of influence to the bare minimum required inside it
        restore_later: Dict[Location, Item] = {}
        for num, sphere in reversed(tuple(enumerate(collection_spheres))):
            to_delete: Set[Location] = set()
            for location in sphere:
                # we remove the item at location and check if game is still beatable
                logging.debug('Checking if %s (Player %d) is required to beat the game.', location.item.name,
                              location.item.player)
                old_item = location.item
                location.item = None
                if multiworld.can_beat_game(state_cache[num]):
                    to_delete.add(location)
                    restore_later[location] = old_item
                else:
                    # still required, got to keep it around
                    location.item = old_item

            # cull entries in spheres for spoiler walkthrough at end
            sphere -= to_delete

        # second phase, sphere 0
        removed_precollected: List[Item] = []
        for item in (i for i in chain.from_iterable(multiworld.precollected_items.values()) if i.advancement):
            logging.debug('Checking if %s (Player %d) is required to beat the game.', item.name, item.player)
            multiworld.precollected_items[item.player].remove(item)
            multiworld.state.remove(item)
            if not multiworld.can_beat_game():
                multiworld.push_precollected(item)
            else:
                removed_precollected.append(item)

        # we are now down to just the required progress items in collection_spheres. Unfortunately
        # the previous pruning stage could potentially have made certain items dependant on others
        # in the same or later sphere (because the location had 2 ways to access but the item originally
        # used to access it was deemed not required.) So we need to do one final sphere collection pass
        # to build up the correct spheres

        required_locations = {item for sphere in collection_spheres for item in sphere}
        state = CollectionState(multiworld)
        collection_spheres = []
        while required_locations:
            sphere = set(filter(state.can_reach, required_locations))

            for location in sphere:
                state.collect(location.item, True, location)

            collection_spheres.append(sphere)

            logging.debug('Calculated final sphere %i, containing %i of %i progress items.', len(collection_spheres),
                          len(sphere), len(required_locations))

            required_locations -= sphere
            if not sphere:
                raise RuntimeError(f'Not all required items reachable. Unreachable locations: {required_locations}')

        # we can finally output our playthrough
        self.playthrough = {"0": sorted([self.multiworld.get_name_string_for_object(item) for item in
                                         chain.from_iterable(multiworld.precollected_items.values())
                                         if item.advancement])}

        for i, sphere in enumerate(collection_spheres):
            self.playthrough[str(i + 1)] = {
                str(location): str(location.item) for location in sorted(sphere)}
        if create_paths:
            self.create_paths(state, collection_spheres)

        # repair the multiworld again
        for location, item in restore_later.items():
            location.item = item

        for item in removed_precollected:
            multiworld.push_precollected(item)

    def create_paths(self, state: CollectionState, collection_spheres: List[Set[Location]]) -> None:
        from itertools import zip_longest
        multiworld = self.multiworld

        def flist_to_iter(path_value: Optional[PathValue]) -> Iterator[str]:
            while path_value:
                region_or_entrance, path_value = path_value
                yield region_or_entrance

        def get_path(state: CollectionState, region: Region) -> List[Union[Tuple[str, str], Tuple[str, None]]]:
            reversed_path_as_flist: PathValue = state.path.get(region, (str(region), None))
            string_path_flat = reversed(list(map(str, flist_to_iter(reversed_path_as_flist))))
            # Now we combine the flat string list into (region, exit) pairs
            pathsiter = iter(string_path_flat)
            pathpairs = zip_longest(pathsiter, pathsiter)
            return list(pathpairs)

        self.paths = {}
        topology_worlds = (player for player in multiworld.player_ids if multiworld.worlds[player].topology_present)
        for player in topology_worlds:
            self.paths.update(
                {str(location): get_path(state, location.parent_region)
                 for sphere in collection_spheres for location in sphere
                 if location.player == player})
            if player in multiworld.get_game_players("A Link to the Past"):
                # If Pyramid Fairy Entrance needs to be reached, also path to Big Bomb Shop
                # Maybe move the big bomb over to the Event system instead?
                if any(exit_path == 'Pyramid Fairy' for path in self.paths.values()
                       for (_, exit_path) in path):
                    if multiworld.worlds[player].options.mode != 'inverted':
                        self.paths[str(multiworld.get_region('Big Bomb Shop', player))] = \
                            get_path(state, multiworld.get_region('Big Bomb Shop', player))
                    else:
                        self.paths[str(multiworld.get_region('Inverted Big Bomb Shop', player))] = \
                            get_path(state, multiworld.get_region('Inverted Big Bomb Shop', player))

    def to_file(self, filename: str) -> None:
        from itertools import chain
        from worlds import AutoWorld
        from Options import Visibility

        def write_option(option_key: str, option_obj: Options.AssembleOptions) -> None:
            res = getattr(self.multiworld.worlds[player].options, option_key)
            if res.visibility & Visibility.spoiler:
                display_name = getattr(option_obj, "display_name", option_key)
                outfile.write(f"{display_name + ':':33}{res.current_option_name}\n")

        with open(filename, 'w', encoding="utf-8-sig") as outfile:
            outfile.write(
                'Archipelago Version %s  -  Seed: %s\n\n' % (
                    Utils.__version__, self.multiworld.seed))
            outfile.write('Filling Algorithm:               %s\n' % self.multiworld.algorithm)
            outfile.write('Players:                         %d\n' % self.multiworld.players)
            outfile.write(f'Plando Options:                  {self.multiworld.plando_options}\n')
            AutoWorld.call_stage(self.multiworld, "write_spoiler_header", outfile)

            for player in range(1, self.multiworld.players + 1):
                if self.multiworld.players > 1:
                    outfile.write('\nPlayer %d: %s\n' % (player, self.multiworld.get_player_name(player)))
                outfile.write('Game:                            %s\n' % self.multiworld.game[player])

                for f_option, option in self.multiworld.worlds[player].options_dataclass.type_hints.items():
                    write_option(f_option, option)

                AutoWorld.call_single(self.multiworld, "write_spoiler_header", player, outfile)

            if self.entrances:
                outfile.write('\n\nEntrances:\n\n')
                outfile.write('\n'.join(['%s%s %s %s' % (f'{self.multiworld.get_player_name(entry["player"])}: '
                                                         if self.multiworld.players > 1 else '', entry['entrance'],
                                                         '<=>' if entry['direction'] == 'both' else
                                                         '<=' if entry['direction'] == 'exit' else '=>',
                                                         entry['exit']) for entry in self.entrances.values()]))

            AutoWorld.call_all(self.multiworld, "write_spoiler", outfile)

            precollected_items = [f"{item.name} ({self.multiworld.get_player_name(item.player)})"
                                  if self.multiworld.players > 1
                                  else item.name
                                  for item in chain.from_iterable(self.multiworld.precollected_items.values())]
            if precollected_items:
                outfile.write("\n\nStarting Items:\n\n")
                outfile.write("\n".join([item for item in precollected_items]))

            locations = [(str(location), str(location.item) if location.item is not None else "Nothing")
                         for location in self.multiworld.get_locations() if location.show_in_spoiler]
            outfile.write('\n\nLocations:\n\n')
            outfile.write('\n'.join(
                ['%s: %s' % (location, item) for location, item in locations]))

            outfile.write('\n\nPlaythrough:\n\n')
            outfile.write('\n'.join(['%s: {\n%s\n}' % (sphere_nr, '\n'.join(
                [f"  {location}: {item}" for (location, item) in sphere.items()] if isinstance(sphere, dict) else
                [f"  {item}" for item in sphere])) for (sphere_nr, sphere) in self.playthrough.items()]))
            if self.unreachables:
                outfile.write('\n\nUnreachable Items:\n\n')
                outfile.write(
                    '\n'.join(['%s: %s' % (unreachable.item, unreachable) for unreachable in self.unreachables]))

            if self.paths:
                outfile.write('\n\nPaths:\n\n')
                path_listings: List[str] = []
                for location, path in sorted(self.paths.items()):
                    path_lines: List[str] = []
                    for region, exit in path:
                        if exit is not None:
                            path_lines.append("{} -> {}".format(region, exit))
                        else:
                            path_lines.append(region)
                    path_listings.append("{}\n        {}".format(location, "\n   =>   ".join(path_lines)))

                outfile.write('\n'.join(path_listings))
            AutoWorld.call_all(self.multiworld, "write_spoiler_end", outfile)


class Tutorial(NamedTuple):
    """Class to build website tutorial pages from a .md file in the world's /docs folder. Order is as follows.
    Name of the tutorial as it will appear on the site. Concise description covering what the guide will entail.
    Language the guide is written in. Name of the file ex 'setup_en.md'. Name of the link on the site; game name is
    filled automatically so 'setup/en' etc. Author or authors."""
    tutorial_name: str
    description: str
    language: str
    file_name: str
    link: str
    authors: List[str]


class PlandoOptions(IntFlag):
    none = 0b0000
    items = 0b0001
    connections = 0b0010
    texts = 0b0100
    bosses = 0b1000

    @classmethod
    def from_option_string(cls, option_string: str) -> PlandoOptions:
        result = cls(0)
        for part in option_string.split(","):
            part = part.strip().lower()
            if part:
                result = cls._handle_part(part, result)
        return result

    @classmethod
    def from_set(cls, option_set: Set[str]) -> PlandoOptions:
        result = cls(0)
        for part in option_set:
            result = cls._handle_part(part, result)
        return result

    @classmethod
    def _handle_part(cls, part: str, base: PlandoOptions) -> PlandoOptions:
        try:
            return base | cls[part]
        except Exception as e:
            raise KeyError(f"{part} is not a recognized name for a plando module. "
                           f"Known options: {', '.join(str(flag.name) for flag in cls)}") from e

    def __str__(self) -> str:
        if self.value:
            return ", ".join(str(flag.name) for flag in PlandoOptions if self.value & flag.value)
        return "None"


seeddigits = 20


def get_seed(seed: Optional[int] = None) -> int:
    if seed is None:
        random.seed(None)
        return random.randint(0, pow(10, seeddigits) - 1)
    return seed