import json
import secrets

from fastapi import APIRouter, Depends, Header, HTTPException, status
from pydantic import BaseModel
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.audit.log import write_audit_log
from app.auth.security import hash_password
from app.config import settings
from app.db.models import AuditLog, PendingTransaction, Round, User
from app.db.session import get_session
from app.rounds.config import get_round_config
from app.wallet.hd import derive_user_wif

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


async def require_admin(x_admin_token: str = Header(default="")) -> None:
    if not settings.admin_token or x_admin_token != settings.admin_token:
        raise HTTPException(status.HTTP_403_FORBIDDEN, "invalid admin token")


_CONFIG_FIELDS = (
    "fee_address",
    "bet_amount_sats",
    "round_duration_seconds",
    "round_cooldown_seconds",
    "min_amount_sats",
    "fee_rate_sat_vb",
    "rbf_timeout_seconds",
    "draw_animation_seconds",
    "paused",
)


class RoundConfigResponse(BaseModel):
    fee_address: str
    bet_amount_sats: int
    round_duration_seconds: int
    round_cooldown_seconds: int
    min_amount_sats: int
    fee_rate_sat_vb: int
    rbf_timeout_seconds: int
    draw_animation_seconds: int
    paused: bool


class RoundConfigUpdate(BaseModel):
    fee_address: str | None = None
    bet_amount_sats: int | None = None
    round_duration_seconds: int | None = None
    round_cooldown_seconds: int | None = None
    min_amount_sats: int | None = None
    fee_rate_sat_vb: int | None = None
    rbf_timeout_seconds: int | None = None
    draw_animation_seconds: int | None = None
    paused: bool | None = None


def _config_response(config) -> RoundConfigResponse:
    return RoundConfigResponse(**{field: getattr(config, field) for field in _CONFIG_FIELDS})


@router.get("/config", response_model=RoundConfigResponse, dependencies=[Depends(require_admin)])
async def read_config(session: AsyncSession = Depends(get_session)) -> RoundConfigResponse:
    config = await get_round_config(session)
    await session.commit()
    return _config_response(config)


@router.put("/config", response_model=RoundConfigResponse, dependencies=[Depends(require_admin)])
async def update_config(
    body: RoundConfigUpdate, session: AsyncSession = Depends(get_session)
) -> RoundConfigResponse:
    config = await get_round_config(session)
    for field in _CONFIG_FIELDS:
        value = getattr(body, field)
        if value is not None:
            setattr(config, field, value)
    await session.commit()
    return _config_response(config)


@router.post("/pause", response_model=RoundConfigResponse, dependencies=[Depends(require_admin)])
async def pause_lottery(session: AsyncSession = Depends(get_session)) -> RoundConfigResponse:
    """Maintenance switch: the round in progress (if any) still closes, draws,
    and pays out its winner normally — only opening the *next* round is
    suppressed until /admin/resume is called (rounds/service.py)."""
    config = await get_round_config(session)
    config.paused = True
    await write_audit_log(session, "lottery_paused", {})
    await session.commit()
    return _config_response(config)


@router.post("/resume", response_model=RoundConfigResponse, dependencies=[Depends(require_admin)])
async def resume_lottery(session: AsyncSession = Depends(get_session)) -> RoundConfigResponse:
    config = await get_round_config(session)
    config.paused = False
    await write_audit_log(session, "lottery_resumed", {})
    await session.commit()
    return _config_response(config)


class AdminUserResponse(BaseModel):
    id: int
    username: str
    address: str
    balance_sats: int
    created_at: str


@router.get("/users", response_model=list[AdminUserResponse], dependencies=[Depends(require_admin)])
async def list_users(session: AsyncSession = Depends(get_session)) -> list[AdminUserResponse]:
    users = (await session.scalars(select(User).order_by(User.id))).all()
    return [
        AdminUserResponse(
            id=u.id,
            username=u.username,
            address=u.address,
            balance_sats=u.cached_balance_sats,
            created_at=u.created_at.isoformat(),
        )
        for u in users
    ]


class AdminPrivkeyResponse(BaseModel):
    address: str
    wif: str


@router.get(
    "/users/{user_id}/privkey", response_model=AdminPrivkeyResponse, dependencies=[Depends(require_admin)]
)
async def user_privkey(user_id: int, session: AsyncSession = Depends(get_session)) -> AdminPrivkeyResponse:
    """Exports a user's raw private key for manual intervention (e.g. sweeping
    funds back if something's stuck). Every access is audit-logged since this is
    the most sensitive data the platform holds."""
    user = await session.get(User, user_id)
    if user is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "user not found")

    wif = derive_user_wif(user.derivation_index)
    await write_audit_log(session, "admin_privkey_accessed", {"user_id": user_id}, user_id=user_id)
    await session.commit()
    return AdminPrivkeyResponse(address=user.address, wif=wif)


class AdminPasswordResetResponse(BaseModel):
    username: str
    new_password: str


@router.post(
    "/users/{user_id}/reset-password",
    response_model=AdminPasswordResetResponse,
    dependencies=[Depends(require_admin)],
)
async def reset_user_password(
    user_id: int, session: AsyncSession = Depends(get_session)
) -> AdminPasswordResetResponse:
    """Admin-only password reset for a user who's locked out: passwords are
    Argon2-hashed (one-way), so an existing password can never be recovered or
    displayed — this generates and sets a brand new one instead, shown once so
    the admin can relay it to the user. There is no user-facing self-service
    reset; only an admin (via /admin, token-gated) can trigger this."""
    user = await session.get(User, user_id)
    if user is None:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "user not found")

    new_password = secrets.token_urlsafe(12)
    user.password_hash = hash_password(new_password)
    await write_audit_log(session, "admin_password_reset", {"user_id": user_id}, user_id=user_id)
    await session.commit()
    return AdminPasswordResetResponse(username=user.username, new_password=new_password)


class AdminRoundResponse(BaseModel):
    id: int
    status: str
    opened_at: str
    closed_at: str | None
    draw_block_height: int | None
    draw_block_hash: str | None
    winner_user_id: int | None
    winner_username: str | None
    pool_amount_sats: int | None
    winner_amount_sats: int | None
    fee_amount_sats: int | None
    payout_txid: str | None


@router.get("/rounds", response_model=list[AdminRoundResponse], dependencies=[Depends(require_admin)])
async def list_rounds(session: AsyncSession = Depends(get_session), limit: int = 50) -> list[AdminRoundResponse]:
    rounds = (await session.scalars(select(Round).order_by(Round.id.desc()).limit(limit))).all()
    winner_ids = {r.winner_user_id for r in rounds if r.winner_user_id is not None}
    winners = {}
    if winner_ids:
        users = (await session.scalars(select(User).where(User.id.in_(winner_ids)))).all()
        winners = {u.id: u.username for u in users}

    return [
        AdminRoundResponse(
            id=r.id,
            status=r.status,
            opened_at=r.opened_at.isoformat(),
            closed_at=r.closed_at.isoformat() if r.closed_at else None,
            draw_block_height=r.draw_block_height,
            draw_block_hash=r.draw_block_hash,
            winner_user_id=r.winner_user_id,
            winner_username=winners.get(r.winner_user_id) if r.winner_user_id is not None else None,
            pool_amount_sats=r.pool_amount_sats,
            winner_amount_sats=r.winner_amount_sats,
            fee_amount_sats=r.fee_amount_sats,
            payout_txid=r.payout_txid,
        )
        for r in rounds
    ]


class AdminAuditLogResponse(BaseModel):
    id: int
    event_type: str
    payload: dict
    user_id: int | None
    round_id: int | None
    created_at: str


@router.get(
    "/audit-log", response_model=list[AdminAuditLogResponse], dependencies=[Depends(require_admin)]
)
async def list_audit_log(
    session: AsyncSession = Depends(get_session), limit: int = 200
) -> list[AdminAuditLogResponse]:
    entries = (await session.scalars(select(AuditLog).order_by(AuditLog.id.desc()).limit(limit))).all()
    return [
        AdminAuditLogResponse(
            id=e.id,
            event_type=e.event_type,
            payload=json.loads(e.payload_json),
            user_id=e.user_id,
            round_id=e.round_id,
            created_at=e.created_at.isoformat(),
        )
        for e in entries
    ]


class AdminPendingTransactionResponse(BaseModel):
    id: int
    kind: str
    status: str
    round_id: int | None
    withdrawal_id: int | None
    user_id: int | None
    current_txid: str
    fee_rate_sat_vb: int
    attempt_count: int
    broadcast_at: str
    replaced_by_txid: str | None


@router.get(
    "/pending-transactions",
    response_model=list[AdminPendingTransactionResponse],
    dependencies=[Depends(require_admin)],
)
async def list_pending_transactions(
    session: AsyncSession = Depends(get_session),
) -> list[AdminPendingTransactionResponse]:
    entries = (
        await session.scalars(select(PendingTransaction).order_by(PendingTransaction.id.desc()))
    ).all()
    return [
        AdminPendingTransactionResponse(
            id=p.id,
            kind=p.kind,
            status=p.status,
            round_id=p.round_id,
            withdrawal_id=p.withdrawal_id,
            user_id=p.user_id,
            current_txid=p.current_txid,
            fee_rate_sat_vb=p.fee_rate_sat_vb,
            attempt_count=p.attempt_count,
            broadcast_at=p.broadcast_at.isoformat(),
            replaced_by_txid=p.replaced_by_txid,
        )
        for p in entries
    ]