import json
import random
from datetime import timedelta

from asgiref.sync import async_to_sync
from channels.layers import get_channel_layer
from django.contrib.auth.decorators import login_required
from django.db import transaction
from django.http import HttpRequest, JsonResponse
from django.utils import timezone
from django.views.decorators.http import require_POST

from .models import GameSession, LieAnswer, Player, Question, RoundConfig, RoundQuestion


MAX_LIE_LENGTH = 255


def _json_body(request: HttpRequest) -> dict:
    if not request.body:
        return {}

    try:
        return json.loads(request.body)
    except json.JSONDecodeError:
        return {}


def _emit_realtime_session_event(session_code: str, event: str, payload: dict) -> None:
    channel_layer = get_channel_layer()
    if not channel_layer:
        return

    try:
        async_to_sync(channel_layer.group_send)(
            f"session_{session_code}",
            {
                "type": "session.event",
                "event": event,
                "payload": payload,
            },
        )
    except Exception:
        # Realtime broadcasting must not fail game flow.
        return


@require_POST
@login_required
def start_lie_question(request: HttpRequest, code: str) -> JsonResponse:
    session_code = code.strip().upper()

    try:
        session = GameSession.objects.get(code=session_code)
    except GameSession.DoesNotExist:
        return JsonResponse({"error": "Session not found"}, status=404)

    if session.host_id != request.user.id:
        return JsonResponse({"error": "Only host can start lie question"}, status=403)

    if session.status != GameSession.Status.LIE:
        return JsonResponse({"error": "Session is not in lie phase"}, status=400)

    with transaction.atomic():
        session = GameSession.objects.select_for_update().get(pk=session.pk)
        if session.status != GameSession.Status.LIE:
            return JsonResponse({"error": "Session is not in lie phase"}, status=400)

        if RoundQuestion.objects.filter(session=session, round_number=session.current_round).exists():
            return JsonResponse({"error": "Lie question already started for round"}, status=409)

        try:
            round_config = RoundConfig.objects.select_related("category").get(
                session=session,
                number=session.current_round,
            )
        except RoundConfig.DoesNotExist:
            return JsonResponse({"error": "Round config not found"}, status=404)

        question_qs = Question.objects.filter(category=round_config.category, is_active=True)
        question_ids = list(question_qs.values_list("id", flat=True))
        if not question_ids:
            return JsonResponse({"error": "No active question for category"}, status=400)

        question = question_qs.get(pk=random.choice(question_ids))

        lie_deadline_at = timezone.now() + timedelta(seconds=round_config.lie_seconds)
        round_question = RoundQuestion.objects.create(
            session=session,
            round_number=session.current_round,
            question=question,
            correct_answer=question.correct_answer,
            lie_deadline_at=lie_deadline_at,
        )

    payload = {
        "round": round_question.round_number,
        "question_id": round_question.id,
        "prompt": round_question.question.prompt,
        "lie_deadline_at": round_question.lie_deadline_at.isoformat(),
        "lie_seconds": round_config.lie_seconds,
    }
    _emit_realtime_session_event(session.code, "lie_question_started", payload)

    return JsonResponse({"question": payload}, status=201)


@require_POST
def submit_lie(request: HttpRequest, code: str) -> JsonResponse:
    session_code = code.strip().upper()
    payload = _json_body(request)

    player_id = payload.get("player_id")
    lie_text = str(payload.get("text", "")).strip()

    if not player_id:
        return JsonResponse({"error": "player_id is required"}, status=400)

    if len(lie_text) < 2 or len(lie_text) > MAX_LIE_LENGTH:
        return JsonResponse({"error": "text must be between 2 and 255 characters"}, status=400)

    try:
        session = GameSession.objects.get(code=session_code)
    except GameSession.DoesNotExist:
        return JsonResponse({"error": "Session not found"}, status=404)

    if session.status != GameSession.Status.LIE:
        return JsonResponse({"error": "Session is not in lie phase"}, status=400)

    try:
        player = Player.objects.get(id=player_id, session=session)
    except Player.DoesNotExist:
        return JsonResponse({"error": "Player not found in session"}, status=404)

    try:
        round_question = RoundQuestion.objects.get(session=session, round_number=session.current_round)
    except RoundQuestion.DoesNotExist:
        return JsonResponse({"error": "No active lie question"}, status=404)

    now = timezone.now()
    if round_question.lie_deadline_at and now > round_question.lie_deadline_at:
        return JsonResponse({"error": "Lie timer expired"}, status=400)

    lie_answer, _ = LieAnswer.objects.update_or_create(
        round_question=round_question,
        player=player,
        defaults={"text": lie_text},
    )

    submitted_count = LieAnswer.objects.filter(round_question=round_question).count()
    players_count = session.players.count()

    event_payload = {
        "round": session.current_round,
        "question_id": round_question.id,
        "player_id": player.id,
        "submitted_count": submitted_count,
        "players_count": players_count,
        "lie_deadline_at": round_question.lie_deadline_at.isoformat() if round_question.lie_deadline_at else None,
    }
    _emit_realtime_session_event(session.code, "lie_submitted", event_payload)

    return JsonResponse(
        {
            "lie": {
                "id": lie_answer.id,
                "player_id": player.id,
                "question_id": round_question.id,
            },
            "progress": {
                "submitted_count": submitted_count,
                "players_count": players_count,
            },
        },
        status=201,
    )