import asyncio
import hashlib
import hmac
import json
import logging
import time
import uuid
from contextlib import asynccontextmanager, suppress
from datetime import UTC, datetime
from ipaddress import ip_address, ip_network
from typing import Annotated, Any

import httpx
import redis.asyncio as redis
import structlog
import uvicorn
from fastapi import (
    Depends,
    FastAPI,
    Header,
    Query,
    Request,
    Response,
    WebSocket,
    WebSocketDisconnect,
)
from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse
from sqlalchemy import and_, desc, func, or_, select, text
from sqlalchemy.ext.asyncio import AsyncSession
from starlette.exceptions import HTTPException as StarletteHTTPException

from app.auth import AuthError, JWKSValidator, Principal
from app.db import (
    Database,
    Dialog,
    Document,
    Message,
    MessageAttachment,
    PopularQuestion,
    TextResource,
    UserIdentity,
    UxSession,
)
from app.integrations import (
    DependencyFailure,
    OpenLinesClient,
    RateLimiter,
    RedisIdempotency,
    S3Client,
    SafetyClient,
)
from app.realtime import RealtimeFanout
from app.schemas import (
    AttachmentCompleteRequest,
    AttachmentInitRequest,
    BootstrapRequest,
    ConsentsRequest,
    MessageRequest,
    OpenLinesInbox,
    OtpSettingsResponse,
    SessionStartRequest,
    decode_cursor,
    encode_cursor,
)
from app.services import (
    AuditContext,
    DomainError,
    SettingsSnapshot,
    apply_inbox,
    audit,
    bootstrap,
    complete_attachment,
    create_dialog,
    dialog_dto,
    get_profile,
    init_attachment,
    load_settings,
    message_dto,
    owned_dialog,
    record_consents,
    resolve_user,
    send_message,
    start_session,
)
from app.settings import get_settings


def configure_logging(level: str) -> None:
    logging.basicConfig(level=level, format="%(message)s")
    structlog.configure(
        processors=[
            structlog.contextvars.merge_contextvars,
            structlog.processors.TimeStamper(fmt="iso", utc=True, key="timestamp"),
            structlog.stdlib.add_log_level,
            structlog.processors.JSONRenderer(),
        ]
    )


async def refresh_settings_cache(app: FastAPI) -> None:
    while True:
        try:
            async with app.state.db.sessions() as db:
                app.state.snapshot = await load_settings(db)
        except Exception:
            log.warning("settings.refresh_failed")
        await asyncio.sleep(30)


@asynccontextmanager
async def lifespan(app: FastAPI):
    settings = get_settings()
    configure_logging(settings.log_level)
    app.state.settings = settings
    app.state.db = Database(settings.database_url)
    app.state.http = httpx.AsyncClient()
    app.state.redis = redis.from_url(settings.redis_url, decode_responses=True)
    app.state.redis_rt = redis.from_url(settings.redis_realtime_url, decode_responses=True)
    app.state.jwks = JWKSValidator(settings, app.state.http)
    app.state.rate_limiter = RateLimiter(app.state.redis)
    app.state.idempotency = RedisIdempotency(app.state.redis)
    app.state.safety = SafetyClient(settings, app.state.http)
    app.state.openlines = OpenLinesClient(settings, app.state.http)
    app.state.s3 = S3Client(settings)
    app.state.realtime = RealtimeFanout(app.state.redis_rt)
    app.state.snapshot = None
    try:
        async with app.state.db.sessions() as db:
            app.state.snapshot = await load_settings(db)
    except Exception:
        structlog.get_logger().warning("settings.warmup_failed")
    settings_task = asyncio.create_task(refresh_settings_cache(app))
    try:
        await app.state.jwks.refresh()
    except Exception:
        structlog.get_logger().warning("jwks.warmup_failed")
    yield
    settings_task.cancel()
    with suppress(asyncio.CancelledError):
        await settings_task
    await app.state.http.aclose()
    await app.state.redis.aclose()
    await app.state.redis_rt.aclose()
    await app.state.db.close()


app = FastAPI(
    title="HAN Chat API",
    version="1.0.0",
    openapi_version="3.1.0",
    docs_url=None,
    redoc_url=None,
    lifespan=lifespan,
)
log = structlog.get_logger()


def client_ip(request: Request) -> str | None:
    """Trust forwarded client addresses only from configured reverse proxies."""
    peer = request.client.host if request.client else ""
    try:
        peer_address = ip_address(peer)
        trusted = any(
            peer_address in ip_network(value.strip(), strict=False)
            for value in request.app.state.settings.trusted_proxy_cidrs.split(",")
            if value.strip()
        )
    except ValueError:
        trusted = False
    forwarded = request.headers.get("X-Forwarded-For", "") if trusted else ""
    candidate = forwarded.split(",", 1)[0].strip() if forwarded else peer
    try:
        return str(ip_address(candidate))
    except ValueError:
        return None


def request_trace_id(request: Request) -> str:
    parts = request.headers.get("traceparent", "").lower().split("-")
    if (
        len(parts) == 4
        and len(parts[0]) == 2
        and len(parts[1]) == 32
        and len(parts[2]) == 16
        and len(parts[3]) == 2
    ):
        try:
            int("".join(parts), 16)
            if parts[1] != "0" * 32 and parts[2] != "0" * 16:
                return parts[1]
        except ValueError:
            pass
    return uuid.uuid4().hex


def user_agent_hash(request: Request) -> str | None:
    value = " ".join(request.headers.get("User-Agent", "").split())
    return hashlib.sha256(value[:1024].encode()).hexdigest() if value else None


def audit_context(request: Request, ux_session_id: uuid.UUID | None = None) -> AuditContext:
    return AuditContext(
        request_id=request.state.request_id,
        trace_id=request.state.trace_id,
        ux_session_id=ux_session_id,
        user_agent_hash=request.state.user_agent_hash,
        client_ip=client_ip(request),
    )


@app.middleware("http")
async def request_context(request: Request, call_next: Any) -> Response:
    request_id = request.headers.get("X-Request-ID", "")
    try:
        request_id = str(uuid.UUID(request_id)) if request_id else str(uuid.uuid4())
    except ValueError:
        request_id = str(uuid.uuid4())
    request.state.request_id = request_id
    request.state.trace_id = request_trace_id(request)
    request.state.user_agent_hash = user_agent_hash(request)
    request.state.started_at = time.monotonic()
    structlog.contextvars.clear_contextvars()
    structlog.contextvars.bind_contextvars(
        request_id=request_id,
        trace_id=request.state.trace_id,
        ux_session_id=request.headers.get("X-Ux-Session-Id"),
        method=request.method,
        route=request.url.path,
        **{"service.name": "api-backend"},
    )
    origin = request.headers.get("Origin")
    cached_settings = request.app.state.snapshot
    allowed_origins = (
        cached_settings.strings("security.cors.allowed_origins") if cached_settings else []
    )
    if request.method == "OPTIONS" and origin in allowed_origins:
        response = Response(status_code=204)
    else:
        response = await call_next(request)
    if origin in allowed_origins:
        response.headers["Access-Control-Allow-Origin"] = origin
        response.headers["Access-Control-Allow-Headers"] = (
            "Authorization,Content-Type,Idempotency-Key,X-Request-ID,X-Ux-Session-Id"
        )
        response.headers["Access-Control-Allow-Methods"] = "GET,POST,OPTIONS"
        response.headers["Vary"] = "Origin"
    response.headers["X-Request-ID"] = request_id
    response.headers["X-Content-Type-Options"] = "nosniff"
    response.headers["Cache-Control"] = response.headers.get("Cache-Control", "no-store")
    log.info(
        "request.complete",
        status_code=response.status_code,
        duration_ms=round((time.monotonic() - request.state.started_at) * 1000, 2),
    )
    return response


def error_response(request: Request, code: str, message: str, status: int, details: Any = None):
    return JSONResponse(
        status_code=status,
        content={
            "error": {
                "code": code,
                "message": message,
                "request_id": getattr(request.state, "request_id", str(uuid.uuid4())),
                "details": details or {},
            }
        },
    )


@app.exception_handler(DomainError)
async def domain_error(request: Request, exc: DomainError):
    response = error_response(request, exc.code, exc.message, exc.status, exc.details)
    if "retry_after" in exc.details:
        response.headers["Retry-After"] = str(exc.details["retry_after"])
    return response


@app.exception_handler(AuthError)
async def auth_error(request: Request, exc: AuthError):
    return error_response(request, exc.code, "Authentication failed", 401)


@app.exception_handler(RequestValidationError)
async def validation_error(request: Request, exc: RequestValidationError):
    details = [
        {"field": ".".join(str(part) for part in item["loc"][1:]), "type": item["type"]}
        for item in exc.errors()
    ]
    return error_response(request, "validation_error", "Request validation failed", 400, details)


@app.exception_handler(StarletteHTTPException)
async def http_error(request: Request, exc: StarletteHTTPException):
    code = "not_found" if exc.status_code == 404 else "forbidden"
    return error_response(request, code, "Resource was not found", exc.status_code)


@app.exception_handler(Exception)
async def unhandled_error(request: Request, exc: Exception):
    log.exception("request.failed", error_code="internal_error")
    return error_response(request, "internal_error", "Internal server error", 500)


async def session(request: Request):
    async for value in request.app.state.db.session():
        yield value


Session = Annotated[AsyncSession, Depends(session)]


async def principal(
    request: Request, authorization: Annotated[str | None, Header()] = None
) -> Principal:
    if not authorization or not authorization.startswith("Bearer "):
        raise AuthError()
    return await request.app.state.jwks.validate(authorization.removeprefix("Bearer ").strip())


PrincipalDep = Annotated[Principal, Depends(principal)]


async def current_user(db: Session, auth: PrincipalDep) -> UserIdentity:
    return await resolve_user(db, auth)


UserDep = Annotated[UserIdentity, Depends(current_user)]


async def required_user_audit_context(
    request: Request,
    db: Session,
    user: UserDep,
    x_ux_session_id: Annotated[str, Header(alias="X-Ux-Session-Id")],
) -> AuditContext:
    session_id = ux_id(x_ux_session_id)
    if session_id is None:
        raise DomainError("validation_error", 400, "X-Ux-Session-Id is required")
    exists = await db.scalar(
        select(UxSession.id).where(UxSession.id == session_id, UxSession.user_id == user.id)
    )
    if exists is None:
        raise DomainError("validation_error", 400, "X-Ux-Session-Id is invalid")
    return audit_context(request, session_id)


UserAuditContextDep = Annotated[AuditContext, Depends(required_user_audit_context)]


async def snapshot(db: Session) -> SettingsSnapshot:
    return await load_settings(db)


SnapshotDep = Annotated[SettingsSnapshot, Depends(snapshot)]


def ux_id(value: str | None) -> uuid.UUID | None:
    try:
        return uuid.UUID(value) if value else None
    except ValueError:
        raise DomainError("validation_error", 400, "X-Ux-Session-Id must be UUID") from None


async def service_auth(request: Request, expected: str) -> None:
    authorization = request.headers.get("Authorization", "")
    supplied = authorization.removeprefix("Bearer ").strip()
    if not supplied or not hmac.compare_digest(supplied, expected):
        raise AuthError()


async def required_idempotency(key: str | None) -> str:
    if not key or len(key) > 128:
        raise DomainError("validation_error", 400, "Valid Idempotency-Key is required")
    return key


async def enforce_limit(
    request: Request,
    identity_type: str,
    identity: str,
    route: str,
    limit_value: tuple[int, int],
    *,
    fail_closed: bool,
) -> None:
    limit, window = limit_value
    key = request.app.state.rate_limiter.key(identity_type, identity, route, window)
    try:
        retry_after = await request.app.state.rate_limiter.consume(key, limit, window)
    except DependencyFailure:
        if fail_closed:
            raise DomainError(
                "dependency_unavailable", 503, "Rate limit service is unavailable"
            ) from None
        return
    if retry_after:
        raise DomainError(
            "rate_limit_exceeded",
            429,
            "Rate limit exceeded",
            {"retry_after": retry_after},
        )


@app.get("/health/live", tags=["health"])
async def live() -> dict[str, str]:
    return {"status": "live"}


@app.get("/health/ready", tags=["health"])
async def ready(request: Request, db: Session):
    components: dict[str, str] = {}
    try:
        await db.execute(text("SELECT 1"))
        revision = await db.scalar(text("SELECT version_num FROM han_app.alembic_version LIMIT 1"))
        if revision != "0005_otp_settings":
            raise RuntimeError("unexpected database revision")
        await load_settings(db)
        components["postgres"] = "ok"
        components["settings"] = "ok"
    except Exception:
        components["postgres"] = "failed"
        components["settings"] = "failed"
    for name, client in (
        ("redis", request.app.state.redis),
        ("redis_realtime", request.app.state.redis_rt),
    ):
        try:
            await client.ping()
            components[name] = "ok"
        except Exception:
            components[name] = "failed"
    components["jwks"] = "ok" if request.app.state.jwks._keys else "failed"
    try:
        safety_response = await request.app.state.http.get(
            f"{str(request.app.state.settings.message_safety_url).rstrip('/')}/health/ready",
            timeout=2,
        )
        components["safety"] = "ok" if safety_response.is_success else "failed"
    except httpx.HTTPError:
        components["safety"] = "failed"
    components["openlines"] = "ok" if await request.app.state.openlines.ready() else "degraded"
    components["s3"] = "ok" if await request.app.state.s3.ready() else "degraded"
    critical = {"postgres", "settings", "redis", "jwks", "safety"}
    failed = any(components.get(name) == "failed" for name in critical)
    status = (
        "not_ready" if failed else ("degraded" if "degraded" in components.values() else "ready")
    )
    return JSONResponse(
        {"status": status, "components": components}, status_code=503 if failed else 200
    )


@app.get("/api/v1/public/app-config", tags=["public"])
async def app_config(request: Request, response: Response, settings: SnapshotDep):
    await enforce_limit(
        request,
        "ip",
        client_ip(request) or "unknown",
        "public",
        settings.limit("rate_limit.public_endpoints.per_ip"),
        fail_closed=False,
    )
    response.headers["Cache-Control"] = (
        f"public, max-age={settings.integer('security.public_cache.max_age_seconds')}"
    )
    response.headers["ETag"] = f'"{settings.version}"'
    values = settings.values
    return {
        "auth": {
            "phone_enabled": settings.boolean("auth.phone.enabled"),
            "password_enabled": settings.boolean("auth.password.enabled"),
        },
        "operator": {"call_phone": values["operator.call.phone"]},
        "consents": {
            name: {
                "required": settings.boolean(f"consent.{name}.required"),
                "document_url": values.get(f"consent.{name}.document_url"),
                "version": values[f"consent.{name}.version"],
            }
            for name in ("personal_data", "user_agreement", "marketing")
        },
        "attachments": {
            "allowed_extensions": settings.strings("chat.attachments.allowed_extensions"),
            "allowed_mime_types": settings.strings("chat.attachments.allowed_mime_types"),
            "max_size_mb": settings.integer("chat.attachments.max_size_mb"),
        },
        "ux": {"idle_timeout_minutes": settings.integer("ux.session.idle_timeout_minutes")},
    }


@app.get("/api/v1/public/content", tags=["public"])
async def content(
    request: Request,
    db: Session,
    settings: SnapshotDep,
    response: Response,
    locale: str = "ru",
):
    await enforce_limit(
        request,
        "ip",
        client_ip(request) or "unknown",
        "public",
        settings.limit("rate_limit.public_endpoints.per_ip"),
        fail_closed=False,
    )
    locale = "ru"
    texts = (
        await db.execute(
            select(TextResource)
            .where(TextResource.locale == locale, TextResource.record_status == "A")
            .order_by(TextResource.sort_order)
        )
    ).scalars()
    questions = (
        await db.execute(
            select(PopularQuestion)
            .where(PopularQuestion.locale == locale, PopularQuestion.record_status == "A")
            .order_by(PopularQuestion.sort_order)
        )
    ).scalars()
    response.headers["ETag"] = f'"{settings.version}"'
    return {
        "locale": locale,
        "texts": {item.mnemonic: item.text_value for item in texts},
        "popular_questions": [
            {"id": item.id, "mnemonic": item.mnemonic, "text": item.question_text}
            for item in questions
        ],
        "version": settings.version,
    }


@app.post("/api/v1/auth/bootstrap", tags=["auth"])
async def auth_bootstrap(
    body: BootstrapRequest, request: Request, db: Session, auth: PrincipalDep, settings: SnapshotDep
):
    return await bootstrap(db, auth, body, settings, audit_context(request))


@app.post("/api/v1/consents", status_code=201, tags=["auth"])
async def consents(
    body: ConsentsRequest,
    request: Request,
    db: Session,
    user: UserDep,
    settings: SnapshotDep,
    context: UserAuditContextDep,
):
    return await record_consents(db, user, body, settings, context)


@app.post("/api/v1/analytics/session-start", status_code=201, tags=["analytics"])
async def analytics_session(
    body: SessionStartRequest, request: Request, db: Session, user: UserDep
):
    return await start_session(db, user, body, audit_context(request))


@app.get("/api/v1/me", tags=["profile"])
async def me(db: Session, user: UserDep):
    return await get_profile(db, user)


@app.get("/api/v1/me/documents", tags=["profile"])
async def documents(db: Session, user: UserDep, limit: int = Query(50, ge=1, le=100)):
    items = (
        (
            await db.execute(
                select(Document)
                .where(Document.user_id == user.id, Document.record_status == "A")
                .order_by(desc(Document.sent_at), desc(Document.id))
                .limit(limit + 1)
            )
        )
        .scalars()
        .all()
    )
    return {"items": [document_dto(item) for item in items[:limit]], "next_cursor": None}


def document_dto(item: Document) -> dict[str, Any]:
    return {
        "document_id": item.id,
        "name": item.name,
        "mime_type": item.mime_type,
        "size_bytes": item.size_bytes,
        "checksum": f"sha256:{item.checksum_sha256}",
        "sent_at": item.sent_at,
    }


async def owned_document(db: AsyncSession, user_id: uuid.UUID, document_id: uuid.UUID):
    item = (
        await db.execute(
            select(Document).where(
                Document.id == document_id,
                Document.user_id == user_id,
                Document.record_status == "A",
            )
        )
    ).scalar_one_or_none()
    if not item:
        raise DomainError("not_found", 404, "Resource was not found")
    return item


@app.get("/api/v1/documents/{document_id}", tags=["profile"])
async def document(document_id: uuid.UUID, db: Session, user: UserDep):
    return document_dto(await owned_document(db, user.id, document_id))


@app.get("/api/v1/documents/{document_id}/download-url", tags=["profile"])
async def document_download(
    document_id: uuid.UUID,
    request: Request,
    db: Session,
    user: UserDep,
    settings: SnapshotDep,
    context: UserAuditContextDep,
):
    await enforce_limit(
        request,
        "user",
        str(user.id),
        "download_url",
        settings.limit("rate_limit.download_url.per_user"),
        fail_closed=True,
    )
    item = await owned_document(db, user.id, document_id)
    db.add(
        audit(
            "document.download_url_issued",
            context,
            user.id,
            "document",
            item.id,
            metadata={"expires_in_seconds": 300},
        )
    )
    await db.commit()
    url = await request.app.state.s3.presign_get(item.storage_bucket, item.object_key)
    return {"download_url": url, "expires_at": datetime.now(UTC)}


@app.post("/api/v1/dialogs", tags=["dialogs"])
async def dialogs_create(
    request: Request,
    db: Session,
    user: UserDep,
    context: UserAuditContextDep,
    idempotency_key: Annotated[str | None, Header()] = None,
):
    key = await required_idempotency(idempotency_key)
    scope = "dialogs.create"
    fingerprint = hashlib.sha256(f"POST:/api/v1/dialogs:{user.id}".encode()).hexdigest()
    try:
        cached = await request.app.state.idempotency.get(scope, user.id, key)
    except Exception:
        cached = None
    if cached:
        if cached["fingerprint"] != fingerprint:
            raise DomainError("idempotency_key_reused", 409, "Idempotency key was reused")
        return JSONResponse(cached["body"], status_code=cached["status"])
    body, status = await create_dialog(db, user, context, key)
    try:
        await request.app.state.idempotency.put(
            scope,
            user.id,
            key,
            {
                "fingerprint": fingerprint,
                "status": status,
                "body": json.loads(json.dumps(body, default=str)),
            },
        )
    except Exception:
        log.warning("idempotency.cache_write_failed")
    return JSONResponse(json.loads(json.dumps(body, default=str)), status_code=status)


@app.get("/api/v1/dialogs", tags=["dialogs"])
async def dialogs_list(
    request: Request,
    db: Session,
    user: UserDep,
    limit: int = Query(50, ge=1, le=100),
    cursor: str | None = None,
):
    query = select(Dialog).where(Dialog.user_id == user.id, Dialog.record_status == "A")
    if cursor:
        decoded = decode_cursor(
            cursor, request.app.state.settings.cursor_hmac_secret.get_secret_value().encode()
        )
        updated, item_id = datetime.fromisoformat(decoded["updated_at"]), uuid.UUID(decoded["id"])
        query = query.where(
            or_(
                Dialog.updated_at < updated, and_(Dialog.updated_at == updated, Dialog.id < item_id)
            )
        )
    items = (
        (
            await db.execute(
                query.order_by(desc(Dialog.updated_at), desc(Dialog.id)).limit(limit + 1)
            )
        )
        .scalars()
        .all()
    )
    next_cursor = None
    if len(items) > limit:
        last = items[limit - 1]
        next_cursor = encode_cursor(
            {"updated_at": last.updated_at.isoformat(), "id": str(last.id)},
            request.app.state.settings.cursor_hmac_secret.get_secret_value().encode(),
        )
    return {"items": [dialog_dto(item) for item in items[:limit]], "next_cursor": next_cursor}


@app.get("/api/v1/dialogs/{dialog_id}", tags=["dialogs"])
async def dialog_get(dialog_id: uuid.UUID, db: Session, user: UserDep):
    return dialog_dto(await owned_dialog(db, user.id, dialog_id))


@app.get("/api/v1/dialogs/{dialog_id}/messages", tags=["dialogs"])
async def messages_list(
    request: Request,
    dialog_id: uuid.UUID,
    db: Session,
    user: UserDep,
    limit: int = Query(50, ge=1, le=100),
    after: str | None = None,
):
    await owned_dialog(db, user.id, dialog_id)
    query = select(Message).where(Message.dialog_id == dialog_id, Message.record_status == "A")
    if after:
        decoded = decode_cursor(
            after, request.app.state.settings.cursor_hmac_secret.get_secret_value().encode()
        )
        created, item_id = datetime.fromisoformat(decoded["created_at"]), uuid.UUID(decoded["id"])
        query = query.where(
            or_(
                Message.created_at > created,
                and_(Message.created_at == created, Message.id > item_id),
            )
        )
    items = (
        (await db.execute(query.order_by(Message.created_at, Message.id).limit(limit + 1)))
        .scalars()
        .all()
    )
    page = items[:limit]
    attachment_rows = (
        (
            await db.execute(
                select(MessageAttachment).where(
                    MessageAttachment.message_id.in_([item.id for item in page]),
                    MessageAttachment.record_status == "A",
                )
            )
        )
        .scalars()
        .all()
        if page
        else []
    )
    attachments = {item.message_id: item for item in attachment_rows}
    next_cursor = None
    if len(items) > limit:
        last = page[-1]
        next_cursor = encode_cursor(
            {"created_at": last.created_at.isoformat(), "id": str(last.id)},
            request.app.state.settings.cursor_hmac_secret.get_secret_value().encode(),
        )
    return {
        "items": [
            message_dto(item, [attachments[item.id]] if item.id in attachments else [])
            for item in page
        ],
        "next_cursor": next_cursor,
    }


@app.post("/api/v1/dialogs/{dialog_id}/messages", status_code=201, tags=["dialogs"])
async def message_create(
    dialog_id: uuid.UUID,
    body: MessageRequest,
    request: Request,
    db: Session,
    user: UserDep,
    business: SnapshotDep,
    context: UserAuditContextDep,
    idempotency_key: Annotated[str | None, Header()] = None,
):
    key = await required_idempotency(idempotency_key)
    scope = f"dialogs.{dialog_id}.messages.create"
    fingerprint = hashlib.sha256(
        json.dumps(body.model_dump(mode="json"), sort_keys=True, separators=(",", ":")).encode()
    ).hexdigest()
    try:
        cached = await request.app.state.idempotency.get(scope, user.id, key)
    except Exception:
        cached = None
    if cached:
        if cached["fingerprint"] != fingerprint:
            raise DomainError("idempotency_key_reused", 409, "Idempotency key was reused")
        return cached["body"]
    await enforce_limit(
        request,
        "user",
        str(user.id),
        "message_send",
        business.limit("rate_limit.message_send.per_user"),
        fail_closed=True,
    )
    await enforce_limit(
        request,
        "dialog",
        str(dialog_id),
        "message_send",
        business.limit("rate_limit.message_send.per_dialog"),
        fail_closed=True,
    )
    result = await send_message(
        db,
        user,
        dialog_id,
        body,
        key,
        context,
        request.app.state.settings,
        request.app.state.safety,
        request.app.state.openlines,
        request.app.state.s3,
        request.app.state.realtime,
    )
    try:
        await request.app.state.idempotency.put(
            scope,
            user.id,
            key,
            {
                "fingerprint": fingerprint,
                "status": 201,
                "body": json.loads(json.dumps(result, default=str)),
            },
        )
    except Exception:
        log.warning("idempotency.cache_write_failed")
    return result


@app.post("/api/v1/dialogs/{dialog_id}/attachments/init", status_code=201, tags=["attachments"])
async def attachment_init(
    dialog_id: uuid.UUID,
    body: AttachmentInitRequest,
    request: Request,
    db: Session,
    user: UserDep,
    settings: SnapshotDep,
    context: UserAuditContextDep,
):
    await enforce_limit(
        request,
        "user",
        str(user.id),
        "attachment_init",
        settings.limit("rate_limit.message_send.per_user"),
        fail_closed=True,
    )
    return await init_attachment(db, user, dialog_id, body, settings, request.app.state.s3, context)


@app.post(
    "/api/v1/dialogs/{dialog_id}/attachments/{attachment_id}/complete",
    tags=["attachments"],
)
async def attachment_complete(
    dialog_id: uuid.UUID,
    attachment_id: uuid.UUID,
    body: AttachmentCompleteRequest,
    request: Request,
    db: Session,
    user: UserDep,
    context: UserAuditContextDep,
):
    return await complete_attachment(
        db, user, dialog_id, attachment_id, body, request.app.state.s3, context
    )


@app.get(
    "/api/v1/dialogs/{dialog_id}/attachments/{attachment_id}/download-url",
    tags=["attachments"],
)
async def attachment_download(
    dialog_id: uuid.UUID,
    attachment_id: uuid.UUID,
    request: Request,
    db: Session,
    user: UserDep,
    settings: SnapshotDep,
    context: UserAuditContextDep,
):
    await enforce_limit(
        request,
        "user",
        str(user.id),
        "download_url",
        settings.limit("rate_limit.download_url.per_user"),
        fail_closed=True,
    )
    item = (
        await db.execute(
            select(MessageAttachment).where(
                MessageAttachment.id == attachment_id,
                MessageAttachment.dialog_id == dialog_id,
                MessageAttachment.owner_user_id == user.id,
                MessageAttachment.record_status == "A",
                MessageAttachment.scan_status == "clean",
            )
        )
    ).scalar_one_or_none()
    if not item:
        raise DomainError("not_found", 404, "Resource was not found")
    db.add(
        audit(
            "attachment.download_url_issued",
            context,
            user.id,
            "attachment",
            item.id,
            metadata={"expires_in_seconds": 300},
        )
    )
    await db.commit()
    return {
        "download_url": await request.app.state.s3.presign_get(
            item.storage_bucket, item.object_key
        ),
        "expires_at": datetime.now(UTC),
    }


@app.post("/internal/openlines/v1/inbox", tags=["internal"])
async def inbox(event: OpenLinesInbox, request: Request, db: Session, settings: SnapshotDep):
    await service_auth(
        request, request.app.state.settings.bitrix_api_inbox_token.get_secret_value()
    )
    body, status = await apply_inbox(
        db,
        event,
        audit_context(request),
        settings,
        request.app.state.s3,
        request.app.state.http,
        request.app.state.settings,
        request.app.state.realtime,
    )
    return JSONResponse(body, status_code=status)


@app.get(
    "/internal/settings/v1/otp",
    tags=["internal"],
    response_model=OtpSettingsResponse,
    responses={304: {"description": "Cached settings are still current"}},
)
async def otp_settings(
    request: Request,
    settings: SnapshotDep,
    if_none_match: Annotated[str | None, Header()] = None,
):
    await service_auth(
        request, request.app.state.settings.keycloak_settings_bridge_token.get_secret_value()
    )
    etag = f'"{settings.version}"'
    headers = {"ETag": etag, "Cache-Control": "private, max-age=60"}
    if if_none_match == etag:
        return Response(status_code=304, headers=headers)
    return JSONResponse({
        "max_send_attempts_per_24h": settings.integer("otp.phone.max_send_attempts_per_24h"),
        "min_seconds_between_attempts": settings.integer("otp.phone.min_seconds_between_attempts"),
        "max_verify_attempts": settings.integer("otp.phone.max_verify_attempts"),
        "code_length": settings.integer("otp.phone.code_length"),
        "ttl_seconds": settings.integer("otp.phone.ttl_seconds"),
        "sms_order_timeout_ms": settings.integer("otp.phone.sms_order_timeout_ms"),
        "version": settings.version,
        "cache_ttl_seconds": 60,
    }, headers=headers)


def websocket_token(websocket: WebSocket) -> tuple[str | None, str | None]:
    offered = websocket.headers.get("sec-websocket-protocol", "")
    for protocol in (part.strip() for part in offered.split(",")):
        if protocol.startswith("han.jwt."):
            import base64

            encoded = protocol.removeprefix("han.jwt.")
            try:
                token = base64.urlsafe_b64decode(encoded + "=" * (-len(encoded) % 4)).decode()
                return token, protocol
            except (ValueError, UnicodeDecodeError):
                return None, None
    return websocket.query_params.get("access_token"), None


@app.websocket("/api/v1/realtime")
async def realtime(websocket: WebSocket):
    token, protocol = websocket_token(websocket)
    if not token:
        await websocket.close(code=4401)
        return
    try:
        auth = await websocket.app.state.jwks.validate(token)
        async with websocket.app.state.db.sessions() as db:
            user = await resolve_user(db, auth)
            await websocket.accept(subprotocol=protocol)
            await websocket.send_json(
                {"type": "connected", "server_time": datetime.now(UTC).isoformat()}
            )
            event_task: asyncio.Task[Any] | None = None
            receive_task: asyncio.Task[Any] | None = None
            heartbeat_task: asyncio.Task[Any] | None = None
            event_stream = None
            while True:
                receive_task = receive_task or asyncio.create_task(websocket.receive_json())
                heartbeat_task = heartbeat_task or asyncio.create_task(asyncio.sleep(20))
                tasks = {receive_task, heartbeat_task}
                if event_task:
                    tasks.add(event_task)
                done, _ = await asyncio.wait(tasks, return_when=asyncio.FIRST_COMPLETED)
                if heartbeat_task in done:
                    await websocket.send_json(
                        {"type": "ping", "server_time": datetime.now(UTC).isoformat()}
                    )
                    heartbeat_task = None
                if event_task and event_task in done:
                    await websocket.send_json(event_task.result())
                    assert event_stream is not None
                    event_task = asyncio.create_task(anext(event_stream))
                if receive_task in done:
                    payload = receive_task.result()
                    receive_task = None
                    if payload.get("type") == "pong":
                        continue
                    if payload.get("type") != "subscribe":
                        await websocket.close(code=4400)
                        return
                    ids = {uuid.UUID(value) for value in payload.get("dialog_ids", [])[:100]}
                    count = await db.scalar(
                        select(func.count(Dialog.id)).where(
                            Dialog.id.in_(ids),
                            Dialog.user_id == user.id,
                            Dialog.record_status == "A",
                        )
                    )
                    if count != len(ids):
                        await websocket.close(code=4404)
                        return
                    if event_task:
                        event_task.cancel()
                    if event_stream:
                        await event_stream.aclose()
                    event_stream = websocket.app.state.realtime.events(ids)
                    event_task = asyncio.create_task(anext(event_stream))
                    await websocket.send_json(
                        {"type": "subscribed", "dialog_ids": [str(value) for value in ids]}
                    )
    except (AuthError, DomainError, ValueError):
        await websocket.close(code=4401)
    except WebSocketDisconnect:
        return


def run() -> None:
    settings = get_settings()
    uvicorn.run(
        "app.main:app",
        host="0.0.0.0",  # noqa: S104 - required container listener
        port=settings.api_port,
        proxy_headers=False,
    )