from __future__ import annotations

import asyncio
import hashlib
import logging
import os
import secrets
from contextlib import asynccontextmanager
from datetime import datetime, timezone
from typing import Any, Optional

import httpx
from fastapi import Depends, FastAPI, HTTPException, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse
from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer

from backend import config, db, push, telegram
from backend.middleware import rate_limit_auth_register, rate_limit_register, rate_limit_signal, verify_admin_token, verify_webhook_secret
from backend.models import (
    AdminBlockRequest,
    AdminCreateUserRequest,
    AdminSetPasswordRequest,
    AuthRegisterRequest,
    AuthRegisterResponse,
    RegisterRequest,
    RegisterResponse,
    SignalRequest,
    SignalResponse,
)

_api_key_bearer = HTTPBearer(auto_error=False)

logging.basicConfig(level=logging.INFO)
logging.getLogger("httpx").setLevel(logging.WARNING)
logger = logging.getLogger(__name__)


def _hash_api_key(key: str) -> str:
    """SHA-256 хэш для API-ключа (без соли — для быстрого сравнения)."""
    return hashlib.sha256(key.encode()).hexdigest()


def _hash_password(password: str) -> str:
    """Hash a password using PBKDF2-HMAC-SHA256 (stdlib, no external deps).

    Stored format: ``<salt_hex>:<dk_hex>``
    """
    salt = os.urandom(16)
    dk = hashlib.pbkdf2_hmac("sha256", password.encode("utf-8"), salt, 260_000)
    return f"{salt.hex()}:{dk.hex()}"

# aggregator = telegram.SignalAggregator(interval=10)  # v2.0 feature — отключено в v1 (ADR-004)

_KEEPALIVE_INTERVAL = 600  # 10 минут


async def _keep_alive_loop(app_url: str) -> None:
    """Периодически пингует /health чтобы предотвратить cold start на бесплатных хостингах."""
    health_url = f"{app_url.rstrip('/')}/health"
    async with httpx.AsyncClient(timeout=10.0) as client:
        while True:
            await asyncio.sleep(_KEEPALIVE_INTERVAL)
            try:
                resp = await client.get(health_url)
                logger.info("Keep-alive ping %s → %d", health_url, resp.status_code)
            except Exception as exc:
                logger.warning("Keep-alive ping failed: %s", exc)


@asynccontextmanager
async def lifespan(app: FastAPI):
    # Startup
    await db.init_db()
    logger.info("Database initialized")

    if not await telegram.validate_bot_token():
        logger.error(
            "CRITICAL: BOT_TOKEN is invalid — Telegram delivery is broken. Update .env and restart."
        )

    if config.WEBHOOK_ENABLED:
        await telegram.set_webhook(url=config.WEBHOOK_URL, secret=config.WEBHOOK_SECRET)
        logger.info("Webhook registered")

    # v2.0 feature — агрегатор отключён в v1 (ADR-004)
    # task = asyncio.create_task(aggregator.run())
    # logger.info("Aggregator started")

    keepalive_task: asyncio.Task | None = None
    if config.APP_URL:
        keepalive_task = asyncio.create_task(_keep_alive_loop(config.APP_URL))
        logger.info("Keep-alive task started (target: %s/health)", config.APP_URL)
    else:
        logger.info("APP_URL not set — keep-alive disabled")

    yield

    # Shutdown
    if keepalive_task is not None:
        keepalive_task.cancel()
        try:
            await keepalive_task
        except asyncio.CancelledError:
            pass
        logger.info("Keep-alive task stopped")

    # aggregator.stop()
    # await aggregator.flush()
    # task.cancel()
    # try:
    #     await task
    # except asyncio.CancelledError:
    #     pass
    # logger.info("Aggregator stopped, final flush done")


app = FastAPI(lifespan=lifespan)

app.add_middleware(
    CORSMiddleware,
    allow_origins=[config.FRONTEND_ORIGIN],
    allow_methods=["POST"],
    allow_headers=["Content-Type", "Authorization"],
)


@app.get("/health")
@app.get("/api/health")
async def health() -> dict[str, Any]:
    return {"status": "ok"}


@app.post("/api/register", response_model=RegisterResponse)
async def register(body: RegisterRequest, _: None = Depends(rate_limit_register)) -> RegisterResponse:
    api_key = secrets.token_hex(32)
    result = await db.register_user(uuid=body.uuid, name=body.name, api_key_hash=_hash_api_key(api_key))
    return RegisterResponse(user_id=result["user_id"], uuid=result["uuid"], api_key=api_key)


@app.post("/api/signal", response_model=SignalResponse)
async def signal(
    body: SignalRequest,
    credentials: Optional[HTTPAuthorizationCredentials] = Depends(_api_key_bearer),
    _: None = Depends(rate_limit_signal),
) -> SignalResponse:
    if credentials is None:
        raise HTTPException(status_code=401, detail="Unauthorized")
    key_hash = _hash_api_key(credentials.credentials)
    stored_hash = await db.get_api_key_hash_by_uuid(body.user_id)
    if stored_hash is None or not secrets.compare_digest(key_hash, stored_hash):
        raise HTTPException(status_code=401, detail="Unauthorized")

    if await db.is_user_blocked(body.user_id):
        raise HTTPException(status_code=403, detail="User is blocked")

    geo = body.geo
    lat = geo.lat if geo else None
    lon = geo.lon if geo else None
    accuracy = geo.accuracy if geo else None

    signal_id = await db.save_signal(
        user_uuid=body.user_id,
        timestamp=body.timestamp,
        lat=lat,
        lon=lon,
        accuracy=accuracy,
    )

    user_name = await db.get_user_name(body.user_id)
    ts = datetime.fromtimestamp(body.timestamp / 1000, tz=timezone.utc)
    name = user_name or body.user_id[:8]
    geo_info = (
        f"📍 {lat}, {lon} (±{accuracy}м)"
        if geo
        else "Без геолокации"
    )
    text = (
        f"🚨 Сигнал от {name}\n"
        f"⏰ {ts.strftime('%H:%M:%S')} UTC\n"
        f"{geo_info}"
    )
    asyncio.create_task(telegram.send_message(text))

    return SignalResponse(status="ok", signal_id=signal_id)


@app.post("/api/auth/register", response_model=AuthRegisterResponse, status_code=201)
async def auth_register(
    body: AuthRegisterRequest,
    _: None = Depends(rate_limit_auth_register),
) -> AuthRegisterResponse:
    password_hash = _hash_password(body.password)
    push_sub_json = (
        body.push_subscription.model_dump_json() if body.push_subscription else None
    )
    try:
        reg_id = await db.create_registration(
            email=str(body.email),
            login=body.login,
            password_hash=password_hash,
            push_subscription=push_sub_json,
        )
    except Exception as exc:
        # aiosqlite.IntegrityError on email/login UNIQUE conflict
        if "UNIQUE" in str(exc) or "unique" in str(exc).lower():
            raise HTTPException(status_code=409, detail="Email или логин уже существует")
        raise
    reg = await db.get_registration(reg_id)
    asyncio.create_task(
        telegram.send_registration_notification(
            reg_id=reg_id,
            login=body.login,
            email=str(body.email),
            created_at=reg["created_at"] if reg else "",
        )
    )
    return AuthRegisterResponse(status="pending", message="Заявка отправлена на рассмотрение")


async def _handle_callback_query(cb: dict) -> None:
    """Process approve/reject callback from admin Telegram inline buttons."""
    data = cb.get("data", "")
    callback_query_id = cb.get("id", "")
    message = cb.get("message", {})
    chat_id = message.get("chat", {}).get("id")
    message_id = message.get("message_id")

    if ":" not in data:
        return
    action, reg_id_str = data.split(":", 1)
    try:
        reg_id = int(reg_id_str)
    except ValueError:
        return

    reg = await db.get_registration(reg_id)
    if reg is None:
        await telegram.answer_callback_query(callback_query_id)
        return

    if action == "approve":
        updated = await db.update_registration_status(reg_id, "approved")
        if not updated:
            # Already processed (not pending) — ack the callback and stop
            await telegram.answer_callback_query(callback_query_id)
            return
        if chat_id and message_id:
            await telegram.edit_message_text(
                chat_id, message_id, f"✅ Пользователь {reg['login']} одобрен"
            )
        if reg["push_subscription"]:
            asyncio.create_task(
                push.send_push(
                    reg["push_subscription"],
                    "Baton",
                    "Ваша регистрация одобрена!",
                )
            )
    elif action == "reject":
        updated = await db.update_registration_status(reg_id, "rejected")
        if not updated:
            await telegram.answer_callback_query(callback_query_id)
            return
        if chat_id and message_id:
            await telegram.edit_message_text(
                chat_id, message_id, f"❌ Пользователь {reg['login']} отклонён"
            )

    await telegram.answer_callback_query(callback_query_id)


@app.get("/admin/users", dependencies=[Depends(verify_admin_token)])
async def admin_list_users() -> list[dict]:
    return await db.admin_list_users()


@app.post("/admin/users", status_code=201, dependencies=[Depends(verify_admin_token)])
async def admin_create_user(body: AdminCreateUserRequest) -> dict:
    password_hash = _hash_password(body.password) if body.password else None
    result = await db.admin_create_user(body.uuid, body.name, password_hash)
    if result is None:
        raise HTTPException(status_code=409, detail="User with this UUID already exists")
    return result


@app.put("/admin/users/{user_id}/password", dependencies=[Depends(verify_admin_token)])
async def admin_set_password(user_id: int, body: AdminSetPasswordRequest) -> dict:
    changed = await db.admin_set_password(user_id, _hash_password(body.password))
    if not changed:
        raise HTTPException(status_code=404, detail="User not found")
    return {"ok": True}


@app.put("/admin/users/{user_id}/block", dependencies=[Depends(verify_admin_token)])
async def admin_block_user(user_id: int, body: AdminBlockRequest) -> dict:
    changed = await db.admin_set_blocked(user_id, body.is_blocked)
    if not changed:
        raise HTTPException(status_code=404, detail="User not found")
    user = await db.admin_get_user_by_id(user_id)
    return user  # type: ignore[return-value]


@app.delete("/admin/users/{user_id}", status_code=204, dependencies=[Depends(verify_admin_token)])
async def admin_delete_user(user_id: int) -> None:
    deleted = await db.admin_delete_user(user_id)
    if not deleted:
        raise HTTPException(status_code=404, detail="User not found")


@app.post("/api/webhook/telegram")
async def webhook_telegram(
    request: Request,
    _: None = Depends(verify_webhook_secret),
) -> dict[str, Any]:
    update = await request.json()

    # Handle inline button callback queries (approve/reject registration)
    callback_query = update.get("callback_query")
    if callback_query:
        await _handle_callback_query(callback_query)
        return {"ok": True}

    message = update.get("message", {})
    text = message.get("text", "")

    if text.startswith("/start"):
        tg_user = message.get("from", {})
        tg_user_id = str(tg_user.get("id", ""))
        first_name = tg_user.get("first_name", "")
        last_name = tg_user.get("last_name", "")
        name = (first_name + " " + last_name).strip() or tg_user_id
        if tg_user_id:
            await db.register_user(uuid=tg_user_id, name=name)
            logger.info("Telegram /start: registered user %s", tg_user_id)

    return {"ok": True}