from fastapi import APIRouter, HTTPException
from sqlalchemy import select
from sqlalchemy.orm import selectinload

from app.api.deps import DbSession, CurrentUser, require_participant, require_organizer, get_participant
from app.models import Marathon, MarathonStatus, Game, GameStatus, Challenge, User
from app.models.challenge import ChallengeStatus
from app.schemas import (
    ChallengeCreate,
    ChallengeUpdate,
    ChallengeResponse,
    MessageResponse,
    GameShort,
    ChallengePreview,
    ChallengesPreviewResponse,
    ChallengesSaveRequest,
    ChallengesGenerateRequest,
)
from app.schemas.challenge import ChallengePropose, ProposedByUser
from app.services.gpt import gpt_service
from app.services.telegram_notifier import telegram_notifier

router = APIRouter(tags=["challenges"])


async def get_challenge_or_404(db, challenge_id: int) -> Challenge:
    result = await db.execute(
        select(Challenge)
        .options(selectinload(Challenge.game), selectinload(Challenge.proposed_by))
        .where(Challenge.id == challenge_id)
    )
    challenge = result.scalar_one_or_none()
    if not challenge:
        raise HTTPException(status_code=404, detail="Challenge not found")
    return challenge


def build_challenge_response(challenge: Challenge, game: Game) -> ChallengeResponse:
    """Helper to build ChallengeResponse with proposed_by"""
    proposed_by = None
    if challenge.proposed_by:
        proposed_by = ProposedByUser(
            id=challenge.proposed_by.id,
            nickname=challenge.proposed_by.nickname
        )

    return ChallengeResponse(
        id=challenge.id,
        title=challenge.title,
        description=challenge.description,
        type=challenge.type,
        difficulty=challenge.difficulty,
        points=challenge.points,
        estimated_time=challenge.estimated_time,
        proof_type=challenge.proof_type,
        proof_hint=challenge.proof_hint,
        game=GameShort(id=game.id, title=game.title, cover_url=None),
        is_generated=challenge.is_generated,
        created_at=challenge.created_at,
        status=challenge.status,
        proposed_by=proposed_by,
    )


@router.get("/games/{game_id}/challenges", response_model=list[ChallengeResponse])
async def list_challenges(game_id: int, current_user: CurrentUser, db: DbSession):
    """List challenges for a game. Participants can view approved and pending challenges."""
    # Get game and check access
    result = await db.execute(
        select(Game).where(Game.id == game_id)
    )
    game = result.scalar_one_or_none()
    if not game:
        raise HTTPException(status_code=404, detail="Game not found")

    participant = await get_participant(db, current_user.id, game.marathon_id)

    # Check access
    if not current_user.is_admin:
        if not participant:
            raise HTTPException(status_code=403, detail="You are not a participant of this marathon")
        # Regular participants can only see challenges for approved games or their own games
        if not participant.is_organizer:
            if game.status != GameStatus.APPROVED.value and game.proposed_by_id != current_user.id:
                raise HTTPException(status_code=403, detail="Game not accessible")

    # Get challenges with proposed_by
    query = select(Challenge).options(selectinload(Challenge.proposed_by)).where(Challenge.game_id == game_id)

    # Regular participants see approved and pending challenges (but not rejected)
    if not current_user.is_admin and participant and not participant.is_organizer:
        query = query.where(Challenge.status.in_([ChallengeStatus.APPROVED.value, ChallengeStatus.PENDING.value]))

    result = await db.execute(query.order_by(Challenge.status.desc(), Challenge.difficulty, Challenge.created_at))
    challenges = result.scalars().all()

    return [build_challenge_response(c, game) for c in challenges]


@router.get("/marathons/{marathon_id}/challenges", response_model=list[ChallengeResponse])
async def list_marathon_challenges(marathon_id: int, current_user: CurrentUser, db: DbSession):
    """List all challenges for a marathon (from all approved games). Participants only."""
    # Check marathon exists
    result = await db.execute(select(Marathon).where(Marathon.id == marathon_id))
    marathon = result.scalar_one_or_none()
    if not marathon:
        raise HTTPException(status_code=404, detail="Marathon not found")

    # Check user is participant or admin
    participant = await get_participant(db, current_user.id, marathon_id)
    if not current_user.is_admin and not participant:
        raise HTTPException(status_code=403, detail="You are not a participant of this marathon")

    # Get all approved challenges from approved games in this marathon
    result = await db.execute(
        select(Challenge)
        .join(Game, Challenge.game_id == Game.id)
        .options(selectinload(Challenge.game), selectinload(Challenge.proposed_by))
        .where(
            Game.marathon_id == marathon_id,
            Game.status == GameStatus.APPROVED.value,
            Challenge.status == ChallengeStatus.APPROVED.value,
        )
        .order_by(Game.title, Challenge.difficulty, Challenge.created_at)
    )
    challenges = result.scalars().all()

    return [build_challenge_response(c, c.game) for c in challenges]


@router.post("/games/{game_id}/challenges", response_model=ChallengeResponse)
async def create_challenge(
    game_id: int,
    data: ChallengeCreate,
    current_user: CurrentUser,
    db: DbSession,
):
    """Create a challenge for a game. Organizers only."""
    # Get game and check access
    result = await db.execute(
        select(Game).where(Game.id == game_id)
    )
    game = result.scalar_one_or_none()
    if not game:
        raise HTTPException(status_code=404, detail="Game not found")

    # Check marathon is in preparing state
    result = await db.execute(select(Marathon).where(Marathon.id == game.marathon_id))
    marathon = result.scalar_one()
    if marathon.status != MarathonStatus.PREPARING.value:
        raise HTTPException(status_code=400, detail="Cannot add challenges to active or finished marathon")

    # Only organizers can add challenges
    await require_organizer(db, current_user, game.marathon_id)

    # Can only add challenges to approved games
    if game.status != GameStatus.APPROVED.value:
        raise HTTPException(status_code=400, detail="Can only add challenges to approved games")

    challenge = Challenge(
        game_id=game_id,
        title=data.title,
        description=data.description,
        type=data.type.value,
        difficulty=data.difficulty.value,
        points=data.points,
        estimated_time=data.estimated_time,
        proof_type=data.proof_type.value,
        proof_hint=data.proof_hint,
        is_generated=False,
        status=ChallengeStatus.APPROVED.value,  # Organizer-created challenges are auto-approved
    )
    db.add(challenge)
    await db.commit()
    await db.refresh(challenge)

    return build_challenge_response(challenge, game)


@router.post("/marathons/{marathon_id}/preview-challenges", response_model=ChallengesPreviewResponse)
async def preview_challenges(
    marathon_id: int,
    current_user: CurrentUser,
    db: DbSession,
    data: ChallengesGenerateRequest | None = None,
):
    """Generate challenges preview for approved games in marathon using GPT (without saving). Organizers only."""
    # Check marathon
    result = await db.execute(select(Marathon).where(Marathon.id == marathon_id))
    marathon = result.scalar_one_or_none()
    if not marathon:
        raise HTTPException(status_code=404, detail="Marathon not found")

    if marathon.status != MarathonStatus.PREPARING.value:
        raise HTTPException(status_code=400, detail="Cannot generate challenges for active or finished marathon")

    # Only organizers can generate challenges
    await require_organizer(db, current_user, marathon_id)

    # Get only APPROVED games
    query = select(Game).where(
        Game.marathon_id == marathon_id,
        Game.status == GameStatus.APPROVED.value,
    )

    # Filter by specific game IDs if provided
    if data and data.game_ids:
        query = query.where(Game.id.in_(data.game_ids))

    result = await db.execute(query)
    games = result.scalars().all()

    if not games:
        raise HTTPException(status_code=400, detail="No approved games found")

    # Build games list for generation (skip games that already have challenges, unless specific IDs requested)
    games_to_generate = []
    game_map = {}
    for game in games:
        # If specific games requested, generate even if they have challenges
        if data and data.game_ids:
            games_to_generate.append({
                "id": game.id,
                "title": game.title,
                "genre": game.genre
            })
            game_map[game.id] = game.title
        else:
            # Otherwise only generate for games without challenges
            existing = await db.scalar(
                select(Challenge.id).where(Challenge.game_id == game.id).limit(1)
            )
            if not existing:
                games_to_generate.append({
                    "id": game.id,
                    "title": game.title,
                    "genre": game.genre
                })
                game_map[game.id] = game.title

    if not games_to_generate:
        return ChallengesPreviewResponse(challenges=[])

    # Generate challenges for all games in one API call
    preview_challenges = []
    try:
        challenges_by_game = await gpt_service.generate_challenges(games_to_generate)

        for game_id, challenges_data in challenges_by_game.items():
            game_title = game_map.get(game_id, "Unknown")
            for ch_data in challenges_data:
                preview_challenges.append(ChallengePreview(
                    game_id=game_id,
                    game_title=game_title,
                    title=ch_data.title,
                    description=ch_data.description,
                    type=ch_data.type,
                    difficulty=ch_data.difficulty,
                    points=ch_data.points,
                    estimated_time=ch_data.estimated_time,
                    proof_type=ch_data.proof_type,
                    proof_hint=ch_data.proof_hint,
                ))

    except Exception as e:
        print(f"Error generating challenges: {e}")

    return ChallengesPreviewResponse(challenges=preview_challenges)


@router.post("/marathons/{marathon_id}/save-challenges", response_model=MessageResponse)
async def save_challenges(
    marathon_id: int,
    data: ChallengesSaveRequest,
    current_user: CurrentUser,
    db: DbSession,
):
    """Save previewed challenges to database. Organizers only."""
    # Check marathon
    result = await db.execute(select(Marathon).where(Marathon.id == marathon_id))
    marathon = result.scalar_one_or_none()
    if not marathon:
        raise HTTPException(status_code=404, detail="Marathon not found")

    if marathon.status != MarathonStatus.PREPARING.value:
        raise HTTPException(status_code=400, detail="Cannot add challenges to active or finished marathon")

    # Only organizers can save challenges
    await require_organizer(db, current_user, marathon_id)

    # Verify all games belong to this marathon AND are approved
    result = await db.execute(
        select(Game.id).where(
            Game.marathon_id == marathon_id,
            Game.status == GameStatus.APPROVED.value,
        )
    )
    valid_game_ids = set(row[0] for row in result.fetchall())

    saved_count = 0
    for ch_data in data.challenges:
        if ch_data.game_id not in valid_game_ids:
            continue  # Skip challenges for invalid/unapproved games

        # Validate type
        ch_type = ch_data.type
        if ch_type not in ["completion", "no_death", "speedrun", "collection", "achievement", "challenge_run"]:
            ch_type = "completion"

        # Validate difficulty
        difficulty = ch_data.difficulty
        if difficulty not in ["easy", "medium", "hard"]:
            difficulty = "medium"

        # Validate proof_type
        proof_type = ch_data.proof_type
        if proof_type not in ["screenshot", "video", "steam"]:
            proof_type = "screenshot"

        challenge = Challenge(
            game_id=ch_data.game_id,
            title=ch_data.title[:100],
            description=ch_data.description,
            type=ch_type,
            difficulty=difficulty,
            points=max(1, min(500, ch_data.points)),
            estimated_time=ch_data.estimated_time,
            proof_type=proof_type,
            proof_hint=ch_data.proof_hint,
            is_generated=True,
        )
        db.add(challenge)
        saved_count += 1

    await db.commit()

    return MessageResponse(message=f"Сохранено {saved_count} заданий")


@router.patch("/challenges/{challenge_id}", response_model=ChallengeResponse)
async def update_challenge(
    challenge_id: int,
    data: ChallengeUpdate,
    current_user: CurrentUser,
    db: DbSession,
):
    """Update a challenge. Organizers only."""
    challenge = await get_challenge_or_404(db, challenge_id)

    # Check marathon is in preparing state
    result = await db.execute(select(Marathon).where(Marathon.id == challenge.game.marathon_id))
    marathon = result.scalar_one()
    if marathon.status != MarathonStatus.PREPARING.value:
        raise HTTPException(status_code=400, detail="Cannot update challenges in active or finished marathon")

    # Only organizers can update challenges
    await require_organizer(db, current_user, challenge.game.marathon_id)

    if data.title is not None:
        challenge.title = data.title
    if data.description is not None:
        challenge.description = data.description
    if data.type is not None:
        challenge.type = data.type.value
    if data.difficulty is not None:
        challenge.difficulty = data.difficulty.value
    if data.points is not None:
        challenge.points = data.points
    if data.estimated_time is not None:
        challenge.estimated_time = data.estimated_time
    if data.proof_type is not None:
        challenge.proof_type = data.proof_type.value
    if data.proof_hint is not None:
        challenge.proof_hint = data.proof_hint

    await db.commit()
    await db.refresh(challenge)

    return build_challenge_response(challenge, challenge.game)


@router.delete("/challenges/{challenge_id}", response_model=MessageResponse)
async def delete_challenge(challenge_id: int, current_user: CurrentUser, db: DbSession):
    """Delete a challenge. Organizers can delete any, participants can delete their own pending."""
    challenge = await get_challenge_or_404(db, challenge_id)

    # Check marathon is in preparing state
    result = await db.execute(select(Marathon).where(Marathon.id == challenge.game.marathon_id))
    marathon = result.scalar_one()
    if marathon.status != MarathonStatus.PREPARING.value:
        raise HTTPException(status_code=400, detail="Cannot delete challenges from active or finished marathon")

    participant = await get_participant(db, current_user.id, challenge.game.marathon_id)

    # Check permissions
    if current_user.is_admin or (participant and participant.is_organizer):
        # Organizers can delete any challenge
        pass
    elif challenge.proposed_by_id == current_user.id and challenge.status == ChallengeStatus.PENDING.value:
        # Participants can delete their own pending challenges
        pass
    else:
        raise HTTPException(status_code=403, detail="You can only delete your own pending challenges")

    await db.delete(challenge)
    await db.commit()

    return MessageResponse(message="Challenge deleted")


# ============ Proposed challenges endpoints ============

@router.post("/games/{game_id}/propose-challenge", response_model=ChallengeResponse)
async def propose_challenge(
    game_id: int,
    data: ChallengePropose,
    current_user: CurrentUser,
    db: DbSession,
):
    """Propose a challenge for a game. Participants only, during PREPARING phase."""
    # Get game
    result = await db.execute(select(Game).where(Game.id == game_id))
    game = result.scalar_one_or_none()
    if not game:
        raise HTTPException(status_code=404, detail="Game not found")

    # Check marathon is in preparing state
    result = await db.execute(select(Marathon).where(Marathon.id == game.marathon_id))
    marathon = result.scalar_one()
    if marathon.status != MarathonStatus.PREPARING.value:
        raise HTTPException(status_code=400, detail="Cannot propose challenges to active or finished marathon")

    # Check user is participant
    participant = await get_participant(db, current_user.id, game.marathon_id)
    if not participant and not current_user.is_admin:
        raise HTTPException(status_code=403, detail="You are not a participant of this marathon")

    # Can only propose challenges to approved games
    if game.status != GameStatus.APPROVED.value:
        raise HTTPException(status_code=400, detail="Can only propose challenges to approved games")

    challenge = Challenge(
        game_id=game_id,
        title=data.title,
        description=data.description,
        type=data.type.value,
        difficulty=data.difficulty.value,
        points=data.points,
        estimated_time=data.estimated_time,
        proof_type=data.proof_type.value,
        proof_hint=data.proof_hint,
        is_generated=False,
        proposed_by_id=current_user.id,
        status=ChallengeStatus.PENDING.value,
    )
    db.add(challenge)
    await db.commit()
    await db.refresh(challenge)

    # Load proposed_by relationship
    challenge.proposed_by = current_user

    return build_challenge_response(challenge, game)


@router.get("/marathons/{marathon_id}/proposed-challenges", response_model=list[ChallengeResponse])
async def list_proposed_challenges(marathon_id: int, current_user: CurrentUser, db: DbSession):
    """List all pending proposed challenges for a marathon. Organizers only."""
    # Check marathon exists
    result = await db.execute(select(Marathon).where(Marathon.id == marathon_id))
    marathon = result.scalar_one_or_none()
    if not marathon:
        raise HTTPException(status_code=404, detail="Marathon not found")

    # Only organizers can see all proposed challenges
    await require_organizer(db, current_user, marathon_id)

    # Get all pending challenges from approved games
    result = await db.execute(
        select(Challenge)
        .join(Game, Challenge.game_id == Game.id)
        .options(selectinload(Challenge.game), selectinload(Challenge.proposed_by))
        .where(
            Game.marathon_id == marathon_id,
            Game.status == GameStatus.APPROVED.value,
            Challenge.status == ChallengeStatus.PENDING.value,
        )
        .order_by(Challenge.created_at.desc())
    )
    challenges = result.scalars().all()

    return [build_challenge_response(c, c.game) for c in challenges]


@router.get("/marathons/{marathon_id}/my-proposed-challenges", response_model=list[ChallengeResponse])
async def list_my_proposed_challenges(marathon_id: int, current_user: CurrentUser, db: DbSession):
    """List current user's proposed challenges for a marathon."""
    # Check marathon exists
    result = await db.execute(select(Marathon).where(Marathon.id == marathon_id))
    marathon = result.scalar_one_or_none()
    if not marathon:
        raise HTTPException(status_code=404, detail="Marathon not found")

    # Check user is participant
    participant = await get_participant(db, current_user.id, marathon_id)
    if not participant and not current_user.is_admin:
        raise HTTPException(status_code=403, detail="You are not a participant of this marathon")

    # Get user's proposed challenges
    result = await db.execute(
        select(Challenge)
        .join(Game, Challenge.game_id == Game.id)
        .options(selectinload(Challenge.game), selectinload(Challenge.proposed_by))
        .where(
            Game.marathon_id == marathon_id,
            Challenge.proposed_by_id == current_user.id,
        )
        .order_by(Challenge.created_at.desc())
    )
    challenges = result.scalars().all()

    return [build_challenge_response(c, c.game) for c in challenges]


@router.patch("/challenges/{challenge_id}/approve", response_model=ChallengeResponse)
async def approve_challenge(challenge_id: int, current_user: CurrentUser, db: DbSession):
    """Approve a proposed challenge. Organizers only."""
    challenge = await get_challenge_or_404(db, challenge_id)

    # Check marathon is in preparing state
    result = await db.execute(select(Marathon).where(Marathon.id == challenge.game.marathon_id))
    marathon = result.scalar_one()
    if marathon.status != MarathonStatus.PREPARING.value:
        raise HTTPException(status_code=400, detail="Cannot approve challenges in active or finished marathon")

    # Only organizers can approve
    await require_organizer(db, current_user, challenge.game.marathon_id)

    if challenge.status != ChallengeStatus.PENDING.value:
        raise HTTPException(status_code=400, detail="Challenge is not pending")

    challenge.status = ChallengeStatus.APPROVED.value
    await db.commit()
    await db.refresh(challenge)

    # Send Telegram notification to proposer
    if challenge.proposed_by_id:
        await telegram_notifier.notify_challenge_approved(
            db,
            challenge.proposed_by_id,
            marathon.title,
            challenge.game.title,
            challenge.title
        )

    return build_challenge_response(challenge, challenge.game)


@router.patch("/challenges/{challenge_id}/reject", response_model=ChallengeResponse)
async def reject_challenge(challenge_id: int, current_user: CurrentUser, db: DbSession):
    """Reject a proposed challenge. Organizers only."""
    challenge = await get_challenge_or_404(db, challenge_id)

    # Check marathon is in preparing state
    result = await db.execute(select(Marathon).where(Marathon.id == challenge.game.marathon_id))
    marathon = result.scalar_one()
    if marathon.status != MarathonStatus.PREPARING.value:
        raise HTTPException(status_code=400, detail="Cannot reject challenges in active or finished marathon")

    # Only organizers can reject
    await require_organizer(db, current_user, challenge.game.marathon_id)

    if challenge.status != ChallengeStatus.PENDING.value:
        raise HTTPException(status_code=400, detail="Challenge is not pending")

    # Save info for notification before changing status
    proposer_id = challenge.proposed_by_id
    game_title = challenge.game.title
    challenge_title = challenge.title

    challenge.status = ChallengeStatus.REJECTED.value
    await db.commit()
    await db.refresh(challenge)

    # Send Telegram notification to proposer
    if proposer_id:
        await telegram_notifier.notify_challenge_rejected(
            db,
            proposer_id,
            marathon.title,
            game_title,
            challenge_title
        )

    return build_challenge_response(challenge, challenge.game)
