import asyncio
import json
import time
import uuid

import aiohttp

from ...utils.logging import debug_log, log
from ...utils.network import build_worker_url, get_client_session, probe_worker
try:
    from ...utils.trace_logger import trace_debug, trace_info
except ImportError:
    def trace_debug(*_args, **_kwargs):
        return None

    def trace_info(*_args, **_kwargs):
        return None

try:
    from ..schemas import parse_positive_int
except ImportError:
    def parse_positive_int(value, default):
        try:
            parsed = int(value)
            return parsed if parsed > 0 else default
        except (TypeError, ValueError):
            return default

_least_busy_rr_index = 0


async def worker_is_active(worker):
    """Ping worker's /prompt endpoint to confirm it's reachable."""
    url = build_worker_url(worker)
    return await probe_worker(url, timeout=3.0) is not None


async def worker_ws_is_active(worker):
    """Ping worker's websocket endpoint to confirm it's reachable."""
    session = await get_client_session()
    url = build_worker_url(worker, "/distributed/worker_ws")
    try:
        ws = await session.ws_connect(url, heartbeat=20, timeout=3)
        await ws.close()
        return True
    except asyncio.TimeoutError:
        debug_log(f"[Distributed] Worker WS probe timed out: {url}")
        return False
    except aiohttp.ClientConnectorError:
        debug_log(f"[Distributed] Worker WS unreachable: {url}")
        return False
    except Exception as e:
        debug_log(f"[Distributed] Worker WS probe unexpected error: {e}")
        return False


async def _probe_worker_active(worker, use_websocket, semaphore):
    async with semaphore:
        is_active = await (worker_ws_is_active(worker) if use_websocket else worker_is_active(worker))
        return worker, is_active


async def _dispatch_via_websocket(worker_url, payload, client_id, timeout=60.0):
    """Open a fresh worker websocket, dispatch one prompt, wait for ack, then close."""
    request_id = uuid.uuid4().hex
    ws_payload = {
        "type": "dispatch_prompt",
        "request_id": request_id,
        "prompt": payload.get("prompt"),
        "workflow": payload.get("workflow"),
        "client_id": client_id,
    }
    ws_url = worker_url.replace("http://", "ws://").replace("https://", "wss://")
    ws_url = f"{ws_url}/distributed/worker_ws"
    session = await get_client_session()

    async with session.ws_connect(ws_url, heartbeat=20, timeout=timeout) as ws:
        await ws.send_json(ws_payload)
        async for msg in ws:
            if msg.type == aiohttp.WSMsgType.TEXT:
                data = json.loads(msg.data or "{}")
                if data.get("type") == "dispatch_ack" and data.get("request_id") == request_id:
                    if data.get("ok"):
                        return
                    error_text = data.get("error") or "Worker rejected websocket dispatch."
                    validation_error = data.get("validation_error")
                    node_errors = data.get("node_errors")
                    if validation_error:
                        error_text = f"{error_text} | validation_error={validation_error}"
                    if node_errors:
                        error_text = f"{error_text} | node_errors={node_errors}"
                    raise RuntimeError(error_text)
            elif msg.type in (aiohttp.WSMsgType.ERROR, aiohttp.WSMsgType.CLOSED):
                raise RuntimeError(f"Worker websocket closed unexpectedly: {msg.type}")

    raise RuntimeError("Worker websocket closed before dispatch_ack was received.")


async def dispatch_worker_prompt(
    worker,
    prompt_obj,
    workflow_meta,
    client_id=None,
    use_websocket=False,
    trace_execution_id=None,
):
    """Send the prepared prompt to a worker ComfyUI instance."""
    worker_url = build_worker_url(worker)
    url = build_worker_url(worker, "/prompt")
    payload = {"prompt": prompt_obj}
    extra_data = {}
    if workflow_meta:
        extra_data.setdefault("extra_pnginfo", {})["workflow"] = workflow_meta
    if extra_data:
        payload["extra_data"] = extra_data

    if use_websocket:
        try:
            await _dispatch_via_websocket(
                worker_url,
                {
                    "prompt": prompt_obj,
                    "workflow": workflow_meta,
                },
                client_id,
            )
            return
        except Exception as exc:
            worker_id = worker.get("id")
            if trace_execution_id:
                trace_info(trace_execution_id, f"Websocket dispatch failed for worker {worker_id}: {exc}")
            else:
                log(f"[Distributed] Websocket dispatch failed for worker {worker_id}: {exc}")
            raise

    session = await get_client_session()
    async with session.post(
        url,
        json=payload,
        timeout=aiohttp.ClientTimeout(total=60),
    ) as resp:
        resp.raise_for_status()


async def select_active_workers(
    workers,
    use_websocket,
    delegate_master,
    trace_execution_id=None,
    probe_concurrency=8,
):
    """Probe workers and return (active_workers, updated_delegate_master)."""
    probe_limit = parse_positive_int(probe_concurrency, 8)
    probe_semaphore = asyncio.Semaphore(probe_limit)

    if trace_execution_id and workers:
        trace_debug(
            trace_execution_id,
            f"Probing {len(workers)} workers with probe_concurrency={probe_limit}",
        )

    probe_results = await asyncio.gather(
        *[
            _probe_worker_active(worker, use_websocket, probe_semaphore)
            for worker in workers
        ]
    )

    active_workers = []
    for worker, is_active in probe_results:
        if is_active:
            active_workers.append(worker)
        else:
            if trace_execution_id:
                trace_info(trace_execution_id, f"Worker {worker['name']} ({worker['id']}) is offline, skipping.")
            else:
                log(f"[Distributed] Worker {worker['name']} ({worker['id']}) is offline, skipping.")

    if trace_execution_id and workers:
        trace_debug(
            trace_execution_id,
            f"Worker probe complete: active={len(active_workers)}/{len(workers)}",
        )

    if not active_workers and delegate_master:
        if trace_execution_id:
            trace_debug(trace_execution_id, "All workers offline while delegate-only requested; enabling master participation.")
        else:
            debug_log("All workers offline while delegate-only requested; enabling master participation.")
        delegate_master = False

    return active_workers, delegate_master


def _extract_queue_remaining(payload):
    if not isinstance(payload, dict):
        return 0
    try:
        queue_remaining = int(payload.get("exec_info", {}).get("queue_remaining", 0))
    except (TypeError, ValueError):
        queue_remaining = 0
    return max(queue_remaining, 0)


async def _probe_worker_queue(worker, semaphore, probe_timeout):
    async with semaphore:
        worker_url = build_worker_url(worker)
        payload = await probe_worker(worker_url, timeout=probe_timeout)
        if payload is None:
            return None
        try:
            reserved_slots = int(worker.get("reserved_slots", 0) or 0)
        except (TypeError, ValueError):
            reserved_slots = 0
        return {
            "worker": worker,
            "queue_remaining": _extract_queue_remaining(payload) + max(reserved_slots, 0),
        }


def _select_idle_round_robin(statuses):
    global _least_busy_rr_index
    if not statuses:
        return None
    index = _least_busy_rr_index % len(statuses)
    _least_busy_rr_index += 1
    return statuses[index]


async def _probe_worker_queues(workers, probe_limit, probe_timeout):
    probe_semaphore = asyncio.Semaphore(probe_limit)
    statuses = await asyncio.gather(
        *[
            _probe_worker_queue(worker, probe_semaphore, probe_timeout)
            for worker in workers
        ]
    )
    return [status for status in statuses if status is not None]


def _select_worker_status(statuses, require_idle=False):
    idle_statuses = [status for status in statuses if status["queue_remaining"] == 0]
    if idle_statuses:
        return _select_idle_round_robin(idle_statuses)
    if require_idle:
        return None
    return min(statuses, key=lambda status: status["queue_remaining"])


async def select_least_busy_worker(
    workers,
    trace_execution_id=None,
    probe_concurrency=8,
    probe_timeout=3.0,
    require_idle=False,
    idle_poll_interval=1.0,
    idle_wait_timeout=None,
):
    """Select a worker by queue depth, optionally waiting until one is idle."""
    if not workers:
        return None

    probe_limit = parse_positive_int(probe_concurrency, 8)
    poll_interval = max(float(idle_poll_interval or 0), 0.0)
    deadline = None
    if idle_wait_timeout is not None:
        deadline = time.monotonic() + max(float(idle_wait_timeout), 0.0)

    while True:
        statuses = await _probe_worker_queues(workers, probe_limit, probe_timeout)
        if not statuses:
            if trace_execution_id:
                trace_info(trace_execution_id, "Least-busy selection failed: no worker queue probes succeeded.")
            else:
                log("[Distributed] Least-busy selection failed: no worker queue probes succeeded.")
            return None

        selected = _select_worker_status(statuses, require_idle=require_idle)
        if selected is not None:
            worker = selected["worker"]
            queue_remaining = selected["queue_remaining"]
            if trace_execution_id:
                trace_debug(
                    trace_execution_id,
                    f"Least-busy worker selected: {worker.get('name')} ({worker.get('id')}), queue_remaining={queue_remaining}",
                )
            else:
                debug_log(
                    f"Least-busy worker selected: {worker.get('name')} ({worker.get('id')}), queue_remaining={queue_remaining}"
                )
            return worker

        if deadline is not None and time.monotonic() >= deadline:
            if trace_execution_id:
                trace_info(trace_execution_id, "No idle load-balance worker became available before timeout.")
            else:
                debug_log("No idle load-balance worker became available before timeout.")
            return None

        await asyncio.sleep(poll_interval)