from __future__ import annotations

import json

from world_simulator.api.persistence import (
    BackgroundSnapshotWriter,
    SnapshotStore,
    build_snapshot,
    restore_snapshot,
    world_from_dict,
)
from world_simulator.api.players import PlayerManager
from world_simulator.config import (
    GameConfig,
    NpcConfig,
    ServerConfig,
    SimulationConfig,
    WorldConfig,
)
from world_simulator.simulation.connectors.base import NpcDirective, TickPlan
from world_simulator.simulation.spawning import create_world
from world_simulator.simulation.tick import apply_tick_plan


def test_world_survives_dict_round_trip() -> None:
    world = create_world(_config(npc_count=8))
    # Advance a few ticks so optional/nested state (goals, memory, events) is populated.
    for tick in range(1, 4):
        apply_tick_plan(
            world,
            tick,
            TickPlan(
                source="test",
                directives=[
                    NpcDirective(npc_id=world.npcs[0].id, action="speak",
                                 target_npc_id=world.npcs[1].id, message=f"hi {tick}")
                ],
            ),
        )

    restored = world_from_dict(world.to_dict())

    assert restored.to_dict() == world.to_dict()


def test_world_survives_json_round_trip() -> None:
    world = create_world(_config(npc_count=5))
    encoded = json.loads(world.to_json())

    restored = world_from_dict(encoded)

    assert restored.to_dict() == world.to_dict()


def test_player_manager_round_trip() -> None:
    players = PlayerManager()
    character = players.create(name="Pilot", icon="*", country_id="qwen", created_tick=3)
    character.pending_action = {"action": "move", "target": {"x": 1.0, "y": 0.0, "z": 2.0}}
    character.spawned = True

    restored = PlayerManager()
    restored.restore(players.snapshot())

    again = restored.get(character.token)
    assert again.name == "Pilot"
    assert again.country_id == "qwen"
    assert again.npc_id == character.npc_id
    assert again.spawned is True
    assert again.pending_action == character.pending_action
    # Counter is preserved so new ids do not collide with restored ones.
    new_character = restored.create(name="Second", icon="", created_tick=5)
    assert new_character.npc_id != character.npc_id


def test_snapshot_store_loads_newest_valid_slot(tmp_path) -> None:
    store = SnapshotStore(tmp_path)
    world = create_world(_config(npc_count=3))

    store.save(build_snapshot(world, PlayerManager().snapshot()))
    world.tick = 7
    store.save(build_snapshot(world, PlayerManager().snapshot()))

    loaded = store.load()
    assert loaded is not None
    assert loaded["tick"] == 7
    restored_world, _ = restore_snapshot(loaded)
    assert restored_world.tick == 7


def test_snapshot_store_falls_back_when_newest_slot_is_corrupt(tmp_path) -> None:
    store = SnapshotStore(tmp_path)
    world = create_world(_config(npc_count=3))

    store.save(build_snapshot(world, PlayerManager().snapshot()))  # slot 0, tick 0
    world.tick = 5
    store.save(build_snapshot(world, PlayerManager().snapshot()))  # slot 1, tick 5

    # Corrupt the newest slot (slot 1) as if a write had been torn.
    (tmp_path / "world_state.1.json").write_text("{ broken", encoding="utf-8")

    fresh = SnapshotStore(tmp_path)
    loaded = fresh.load()
    assert loaded is not None
    assert loaded["tick"] == 0  # falls back to the older, intact slot


def test_snapshot_store_clear_deletes_slots(tmp_path) -> None:
    store = SnapshotStore(tmp_path)
    world = create_world(_config(npc_count=3))
    store.save(build_snapshot(world, PlayerManager().snapshot()))
    world.tick = 4
    store.save(build_snapshot(world, PlayerManager().snapshot()))

    store.clear()

    assert not list(tmp_path.glob("world_state.*.json"))
    assert store.load() is None
    # Clearing again (nothing on disk) is a no-op, not an error.
    store.clear()
    # The next save starts the ping-pong from slot 0 again.
    store.save(build_snapshot(world, PlayerManager().snapshot()))
    assert (tmp_path / "world_state.0.json").exists()


def test_background_writer_persists_latest(tmp_path) -> None:
    store = SnapshotStore(tmp_path)
    writer = BackgroundSnapshotWriter(store)
    world = create_world(_config(npc_count=2))

    for tick in range(1, 6):
        world.tick = tick
        writer.submit(build_snapshot(world, PlayerManager().snapshot()))
    writer.close()

    loaded = SnapshotStore(tmp_path).load()
    assert loaded is not None
    assert loaded["tick"] == 5


def _config(*, npc_count: int) -> GameConfig:
    return GameConfig(
        world=WorldConfig(width=80, depth=80, terrain="plain_green", seed=42),
        npcs=NpcConfig(count=npc_count),
        simulation=SimulationConfig(tick_ms=500),
        server=ServerConfig(host="127.0.0.1", port=8000),
    )