"""
tui_events.py — Thread-safe event bus between the bot backend and the TUI.

The bot backend runs in a dedicated thread with its own asyncio event loop
(completely isolated from Textual's loop).  Events are posted via a standard
queue.Queue (thread-safe), and the TUI consumer polls it from Textual's loop
using asyncio.get_event_loop().run_in_executor() bridging.

post() is safe to call from any thread or any asyncio loop.

Web frontend: call subscribe() to get a private queue that receives every
event post() delivers.  Call unsubscribe() on disconnect.
"""

import asyncio
import queue
import threading
from dataclasses import dataclass, field
from typing import Any

# Thread-safe queue — works across the bot thread and Textual's thread.
_queue: queue.Queue | None = None
_queue_lock = threading.Lock()

# Set to True when the TUI is running so tdl pipes output instead of
# writing directly to the terminal.
tui_active: bool = False

# ─── Web subscriber broadcast ─────────────────────────────────────────────────

_subscribers: list[queue.Queue] = []
_subscribers_lock = threading.Lock()


def subscribe() -> queue.Queue:
    """Return a new Queue that receives every future post(). Thread-safe."""
    q: queue.Queue = queue.Queue()
    with _subscribers_lock:
        _subscribers.append(q)
    return q


def unsubscribe(q: queue.Queue) -> None:
    """Remove a subscriber queue. Safe to call even if already removed."""
    with _subscribers_lock:
        try:
            _subscribers.remove(q)
        except ValueError:
            pass


# ─── Bot-loop channel-change signal (for web routes) ─────────────────────────
# The TUI sets this via set_bot_context() after the bot asyncio loop starts.
# Web config routes call signal_channel_changed() to wake _watch_channels().

_bot_loop:  asyncio.AbstractEventLoop | None = None
_bot_ch_ev: asyncio.Event | None = None


def set_bot_context(loop: asyncio.AbstractEventLoop, event: asyncio.Event) -> None:
    """Called by _bot_main() once the bot loop and channel event exist."""
    global _bot_loop, _bot_ch_ev
    _bot_loop  = loop
    _bot_ch_ev = event


def signal_channel_changed() -> None:
    """Wake the bot's _watch_channels() coroutine from any thread."""
    if _bot_loop is not None and _bot_ch_ev is not None:
        _bot_loop.call_soon_threadsafe(_bot_ch_ev.set)


def init_bus() -> queue.Queue:
    """Call once from MonitorApp.on_mount() to create the queue."""
    global _queue, tui_active
    _queue = queue.Queue()
    tui_active = True
    return _queue


def get_bus() -> queue.Queue | None:
    return _queue


def post(event: Any) -> None:
    """Fire-and-forget from any thread. Broadcasts to TUI queue + all subscribers."""
    if _queue is not None:
        try:
            _queue.put_nowait(event)
        except queue.Full:
            pass
    with _subscribers_lock:
        subs = list(_subscribers)
    for q in subs:
        try:
            q.put_nowait(event)
        except queue.Full:
            pass


# ─── Event types ──────────────────────────────────────────────────────────────

@dataclass
class EvDownloadQueued:
    """A file has been accepted and is waiting for tdl."""
    batch_id:  str
    filename:  str
    size_mb:   float
    source:    str
    password:  str | None


@dataclass
class EvDownloadStarted:
    """tdl has begun transferring this file."""
    batch_id:  str
    filename:  str


@dataclass
class EvDownloadDone:
    """File fully downloaded (tdl or Telethon fallback)."""
    batch_id:  str
    filename:  str
    via:       str   # "tdl" | "telethon"


@dataclass
class EvDownloadFailed:
    """All download attempts failed."""
    batch_id:  str
    filename:  str
    reason:    str


@dataclass
class EvTdlOutput:
    """A line of output from tdl's stdout/stderr (TUI mode only)."""
    line: str


@dataclass
class EvHit:
    """A scored credential hit to display in the hits panel."""
    severity:  str
    raw:       str
    source:    str
    filename:  str
    reasons:   list[str] = field(default_factory=list)


@dataclass
class EvChannelAdded:
    """A channel was added to the live watch list."""
    channel: str | int


@dataclass
class EvChannelRemoved:
    """A channel was removed from the live watch list."""
    channel: str | int


@dataclass
class EvStatus:
    """Generic one-line status message (startup, errors, etc.)."""
    text: str
    level: str = "info"   # "info" | "warning" | "error"