"""Telnet server for the MUD."""

import asyncio
import logging
import pathlib
import time
import tomllib
from typing import cast

import telnetlib3
from telnetlib3.server_shell import readline2

import mudlib.commands
import mudlib.commands.fly
import mudlib.commands.look
import mudlib.commands.movement
import mudlib.commands.quit
from mudlib.combat.commands import register_combat_commands
from mudlib.combat.engine import process_combat
from mudlib.content import load_commands
from mudlib.effects import clear_expired
from mudlib.player import Player, players
from mudlib.world.terrain import World

log = logging.getLogger(__name__)

PORT = 6789
TICK_RATE = 10  # ticks per second
TICK_INTERVAL = 1.0 / TICK_RATE

# Module-level world instance, generated once at startup
_world: World | None = None


def load_world_config(world_name: str = "earth") -> dict:
    """Load world configuration from TOML file."""
    worlds_dir = pathlib.Path(__file__).resolve().parents[2] / "worlds"
    config_path = worlds_dir / world_name / "config.toml"
    with open(config_path, "rb") as f:
        return tomllib.load(f)


async def game_loop() -> None:
    """Run periodic game tasks at TICK_RATE ticks per second."""
    log.info("game loop started (%d ticks/sec)", TICK_RATE)
    while True:
        t0 = asyncio.get_event_loop().time()
        clear_expired()
        process_combat()
        elapsed = asyncio.get_event_loop().time() - t0
        sleep_time = TICK_INTERVAL - elapsed
        if sleep_time > 0:
            await asyncio.sleep(sleep_time)


def find_passable_start(world: World, start_x: int, start_y: int) -> tuple[int, int]:
    """Find a passable tile starting from (start_x, start_y) and searching outward.

    Args:
        world: The world to search in
        start_x: Starting X coordinate
        start_y: Starting Y coordinate

    Returns:
        Tuple of (x, y) for the first passable tile found
    """
    # Try the starting position first
    if world.is_passable(start_x, start_y):
        return start_x, start_y

    # Spiral outward from the starting position (wrapping)
    for radius in range(1, 100):
        for dx in range(-radius, radius + 1):
            for dy in range(-radius, radius + 1):
                # Only check the perimeter of the current radius
                if abs(dx) != radius and abs(dy) != radius:
                    continue

                x, y = world.wrap(start_x + dx, start_y + dy)

                if world.is_passable(x, y):
                    return x, y

    # Fallback to starting position if nothing found
    return start_x, start_y


async def shell(
    reader: telnetlib3.TelnetReader | telnetlib3.TelnetReaderUnicode,
    writer: telnetlib3.TelnetWriter | telnetlib3.TelnetWriterUnicode,
) -> None:
    """Shell callback that handles player connection and command loop."""
    _reader = cast(telnetlib3.TelnetReaderUnicode, reader)
    _writer = cast(telnetlib3.TelnetWriterUnicode, writer)

    assert _world is not None, "World must be initialized before accepting connections"

    log.debug("new connection from %s", _writer.get_extra_info("peername"))

    _writer.write("Welcome to the MUD!\r\n")
    _writer.write("What is your name? ")
    await _writer.drain()

    name_input = await readline2(_reader, _writer)
    if name_input is None or not name_input.strip():
        _writer.close()
        return

    player_name = name_input.strip()

    # Find a passable starting position (start at world center)
    center_x = _world.width // 2
    center_y = _world.height // 2
    start_x, start_y = find_passable_start(_world, center_x, center_y)

    # Create player
    player = Player(
        name=player_name,
        x=start_x,
        y=start_y,
        writer=_writer,
        reader=_reader,
    )

    # Register player
    players[player_name] = player
    log.info("%s connected at (%d, %d)", player_name, start_x, start_y)

    _writer.write(f"\r\nWelcome, {player_name}!\r\n")
    _writer.write("Type 'help' for commands or 'quit' to disconnect.\r\n\r\n")
    await _writer.drain()

    # Show initial map
    await mudlib.commands.look.cmd_look(player, "")

    # Command loop
    while not _writer.is_closing():
        _writer.write("mud> ")
        await _writer.drain()

        inp = await readline2(_reader, _writer)
        if inp is None:
            break

        command = inp.strip()
        if not command:
            continue

        # Dispatch command
        await mudlib.commands.dispatch(player, command)

        # Check if writer was closed by quit command
        if _writer.is_closing():
            break

    # Clean up: remove from registry if still present
    if player_name in players:
        del players[player_name]
        log.info("%s disconnected", player_name)

    _writer.close()


async def run_server() -> None:
    """Start the MUD telnet server."""
    global _world

    # Generate world once at startup (cached to build/ after first run)
    cache_dir = pathlib.Path(__file__).resolve().parents[2] / "build"
    config = load_world_config()
    world_cfg = config["world"]
    log.info(
        "loading world (seed=%d, %dx%d)...",
        world_cfg["seed"],
        world_cfg["width"],
        world_cfg["height"],
    )
    t0 = time.monotonic()
    _world = World(
        seed=world_cfg["seed"],
        width=world_cfg["width"],
        height=world_cfg["height"],
        cache_dir=cache_dir,
    )
    elapsed = time.monotonic() - t0
    if _world.cached:
        log.info("world loaded from cache in %.2fs", elapsed)
    else:
        log.info("world generated in %.2fs (cached for next run)", elapsed)

    # Inject world into command modules
    mudlib.commands.fly.world = _world
    mudlib.commands.look.world = _world
    mudlib.commands.movement.world = _world

    # Load content-defined commands from TOML files
    content_dir = pathlib.Path(__file__).resolve().parents[2] / "content" / "commands"
    if content_dir.exists():
        log.info("loading content from %s", content_dir)
        content_commands = load_commands(content_dir)
        for cmd_def in content_commands:
            mudlib.commands.register(cmd_def)
            log.debug("registered content command: %s", cmd_def.name)

    # Load combat moves and register as commands
    combat_dir = pathlib.Path(__file__).resolve().parents[2] / "content" / "combat"
    if combat_dir.exists():
        log.info("loading combat moves from %s", combat_dir)
        register_combat_commands(combat_dir)
        log.info("registered combat commands")

    # connect_maxwait: how long to wait for telnet option negotiation (CHARSET
    # etc) before starting the shell. default is 4.0s which is painful.
    # MUD clients like tintin++ reject CHARSET immediately via MTTS, but
    # telnetlib3 still waits for the full timeout. 0.5s is plenty.
    server = await telnetlib3.create_server(
        host="127.0.0.1", port=PORT, shell=shell, connect_maxwait=0.5
    )
    log.info("listening on 127.0.0.1:%d", PORT)

    loop_task = asyncio.create_task(game_loop())

    try:
        while True:
            await asyncio.sleep(3600)
    except KeyboardInterrupt:
        log.info("shutting down...")
        loop_task.cancel()
        server.close()
        await server.wait_closed()