import secrets
import string
import uuid

from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.auth.users import current_active_user
from app.db import get_async_session
from app.llm.game_setup import run_game_setup_turn
from app.models.character import Character
from app.models.game import Game, GameParticipant
from app.models.message import Message
from app.models.user import User
from app.schemas.game import GameCreate, GameJoin, GameRead
from app.schemas.game_setup import GameSetupChatRequest, GameSetupChatResponse
from app.schemas.message import MessageRead
from app.ws_tickets import issue_ticket

router = APIRouter(prefix="/api/games", tags=["games"])

CODE_ALPHABET = string.ascii_uppercase + string.digits


def _generate_participation_code() -> str:
    return "".join(secrets.choice(CODE_ALPHABET) for _ in range(8))


async def _serialize_games(
    session: AsyncSession, games: list[Game], viewer_id: uuid.UUID
) -> list[GameRead]:
    if not games:
        return []

    game_ids = [g.id for g in games]

    creators = (
        await session.execute(select(User.id, User.name).where(User.id.in_([g.creator_id for g in games])))
    ).all()
    creator_names = {row.id: row.name for row in creators}

    participant_rows = (
        await session.execute(
            select(GameParticipant.game_id, GameParticipant.user_id, GameParticipant.character_id, User.name)
            .join(User, User.id == GameParticipant.user_id)
            .where(GameParticipant.game_id.in_(game_ids))
        )
    ).all()
    participants_by_game: dict[uuid.UUID, list[str]] = {}
    viewer_participation: dict[uuid.UUID, uuid.UUID | None] = {}
    for game_id, participant_user_id, character_id, name in participant_rows:
        participants_by_game.setdefault(game_id, []).append(name)
        if participant_user_id == viewer_id:
            viewer_participation[game_id] = character_id

    result = []
    for game in games:
        names = participants_by_game.get(game.id, [])
        is_participant = game.id in viewer_participation
        result.append(
            GameRead(
                id=game.id,
                name=game.name,
                description=game.description,
                creator_id=game.creator_id,
                creator_name=creator_names.get(game.creator_id, "?"),
                player_count=len(names),
                player_names=names,
                participation_code=game.participation_code if game.creator_id == viewer_id else None,
                created_at=game.created_at,
                is_participant=is_participant,
                my_character_id=viewer_participation.get(game.id),
                status=game.status,
                ended_reason=game.ended_reason,
            )
        )
    return result


@router.get("", response_model=list[GameRead])
async def list_games(
    session: AsyncSession = Depends(get_async_session),
    user: User = Depends(current_active_user),
) -> list[GameRead]:
    games = (
        (await session.execute(select(Game).order_by(Game.created_at.desc()))).scalars().all()
    )
    return await _serialize_games(session, list(games), user.id)


@router.post("", response_model=GameRead)
async def create_game(
    payload: GameCreate,
    session: AsyncSession = Depends(get_async_session),
    user: User = Depends(current_active_user),
) -> GameRead:
    game = Game(
        name=payload.name,
        description=payload.description,
        creator_id=user.id,
        participation_code=_generate_participation_code(),
    )
    session.add(game)
    await session.flush()

    session.add(GameParticipant(game_id=game.id, user_id=user.id))
    await session.commit()
    await session.refresh(game)

    serialized = await _serialize_games(session, [game], user.id)
    return serialized[0]


@router.post("/setup-chat", response_model=GameSetupChatResponse)
async def game_setup_chat(
    payload: GameSetupChatRequest,
    user: User = Depends(current_active_user),
) -> GameSetupChatResponse:
    result = await run_game_setup_turn(payload.messages)
    return GameSetupChatResponse(**result)


@router.get("/{game_id}", response_model=GameRead)
async def get_game(
    game_id: uuid.UUID,
    session: AsyncSession = Depends(get_async_session),
    user: User = Depends(current_active_user),
) -> GameRead:
    game = await session.get(Game, game_id)
    if game is None:
        raise HTTPException(status_code=404, detail="Game not found")
    serialized = await _serialize_games(session, [game], user.id)
    return serialized[0]


async def _serialize_messages(session: AsyncSession, messages: list[Message]) -> list[MessageRead]:
    if not messages:
        return []

    user_ids = {m.user_id for m in messages if m.user_id is not None}
    character_ids = {m.character_id for m in messages if m.character_id is not None}

    names: dict[uuid.UUID, str] = {}
    if user_ids:
        rows = (await session.execute(select(User.id, User.name).where(User.id.in_(user_ids)))).all()
        names.update({row.id: row.name for row in rows})

    char_names: dict[uuid.UUID, str] = {}
    if character_ids:
        rows = (
            await session.execute(select(Character.id, Character.name).where(Character.id.in_(character_ids)))
        ).all()
        char_names.update({row.id: row.name for row in rows})

    return [
        MessageRead(
            id=m.id,
            sender_type=m.sender_type,
            user_id=m.user_id,
            player_name=names.get(m.user_id) if m.user_id else None,
            character_id=m.character_id,
            character_name=char_names.get(m.character_id) if m.character_id else None,
            content=m.content,
            created_at=m.created_at,
        )
        for m in messages
    ]


async def _require_participant(session: AsyncSession, game_id: uuid.UUID, user_id: uuid.UUID) -> GameParticipant:
    participant = (
        await session.execute(
            select(GameParticipant).where(
                GameParticipant.game_id == game_id, GameParticipant.user_id == user_id
            )
        )
    ).scalar_one_or_none()
    if participant is None:
        raise HTTPException(status_code=403, detail="You have not joined this game")
    return participant


@router.get("/{game_id}/messages", response_model=list[MessageRead])
async def get_recent_messages(
    game_id: uuid.UUID,
    limit: int = 5,
    session: AsyncSession = Depends(get_async_session),
    user: User = Depends(current_active_user),
) -> list[MessageRead]:
    await _require_participant(session, game_id, user.id)
    rows = (
        await session.execute(
            select(Message)
            .where(Message.game_id == game_id)
            .order_by(Message.created_at.desc(), Message.id.desc())
            .limit(limit)
        )
    ).scalars().all()
    ordered = list(reversed(rows))
    return await _serialize_messages(session, ordered)


@router.get("/{game_id}/messages/full", response_model=list[MessageRead])
async def get_full_messages(
    game_id: uuid.UUID,
    before_id: int | None = None,
    limit: int = 100,
    session: AsyncSession = Depends(get_async_session),
    user: User = Depends(current_active_user),
) -> list[MessageRead]:
    await _require_participant(session, game_id, user.id)
    query = select(Message).where(Message.game_id == game_id)
    if before_id is not None:
        query = query.where(Message.id < before_id)
    query = query.order_by(Message.id.desc()).limit(limit)

    rows = (await session.execute(query)).scalars().all()
    ordered = list(reversed(rows))
    return await _serialize_messages(session, ordered)


@router.post("/{game_id}/join", response_model=GameRead)
async def join_game(
    game_id: uuid.UUID,
    payload: GameJoin,
    session: AsyncSession = Depends(get_async_session),
    user: User = Depends(current_active_user),
) -> GameRead:
    game = await session.get(Game, game_id)
    if game is None:
        raise HTTPException(status_code=404, detail="Game not found")
    if not secrets.compare_digest(payload.participation_code, game.participation_code):
        raise HTTPException(status_code=403, detail="Invalid participation code")

    existing = (
        await session.execute(
            select(GameParticipant).where(
                GameParticipant.game_id == game_id, GameParticipant.user_id == user.id
            )
        )
    ).scalar_one_or_none()

    if existing is None:
        session.add(
            GameParticipant(game_id=game_id, user_id=user.id, character_id=payload.character_id)
        )
    elif payload.character_id is not None:
        existing.character_id = payload.character_id

    await session.commit()

    serialized = await _serialize_games(session, [game], user.id)
    return serialized[0]


@router.post("/{game_id}/ws-ticket")
async def create_ws_ticket(
    game_id: uuid.UUID,
    session: AsyncSession = Depends(get_async_session),
    user: User = Depends(current_active_user),
) -> dict[str, str]:
    await _require_participant(session, game_id, user.id)
    return {"ticket": issue_ticket(game_id, user.id)}