"""АРМ администратора: учётные записи, состояние стенда, аудит, копии.

ТЗ выделяет администратора отдельной ролью с собственным разделом: управление
учётными записями, состояние компонентов, резервное копирование не реже раза
в сутки, журналы и мониторинг нагрузки.

Границы роли из ТЗ соблюдаются здесь же: администратор **не** правит оценки
и не вмешивается в занятия — этих точек в модуле нет вовсе, а не «есть,
но с проверкой».
"""

import csv
import io
import logging
import re
from datetime import datetime, timedelta, timezone
from urllib.parse import quote, quote_plus
from uuid import UUID
from xml.etree import ElementTree as ET

from fastapi import APIRouter, Depends, HTTPException, Request, Response
from fastapi.encoders import jsonable_encoder
from fastapi.responses import JSONResponse, StreamingResponse
from pydantic import BaseModel, Field
from sqlalchemy import func, select
from sqlalchemy.engine import make_url
from sqlalchemy.exc import IntegrityError
from sqlalchemy.ext.asyncio import AsyncSession
from starlette.concurrency import run_in_threadpool

from app.admin import backup as backup_service
from app.api.auth import (
    add_audit_entry, audit, audit_required, hash_password, invalidate_login, require,
)
from app.config import get_settings
from app.db.base import get_session
from app.db.models import AuditLog, Session as SessionRow, Trainee, User
from app.domain import ekp
from app.domain.roles import ROLE_LABELS, SCREENS, Role
from app.domain.timers import NORMATIVES
from app.dialog.llm import is_loopback_url
from app.monitoring import recent_events, sample_metrics
from app.session.hub import hub

log = logging.getLogger(__name__)
router = APIRouter(prefix="/api/admin", tags=["admin"])


def _configuration_xml() -> bytes:
    """Безопасный переносимый снимок конфигурации без паролей и ключей."""
    settings = get_settings()
    root = ET.Element("lctConfiguration", {"version": "1"})
    ET.SubElement(root, "platform", {
        "offline": str(settings.offline).lower(),
        "voiceEnabled": str(settings.voice_enabled).lower(),
        "secureCookies": str(settings.secure_cookies).lower(),
    })
    models = ET.SubElement(root, "localModels")
    ET.SubElement(models, "dialogue", {"name": settings.llm_model_caller})
    ET.SubElement(models, "russianControl", {
        "name": settings.llm_model_control,
        "grammarEnabled": str(settings.grammar_llm_enabled).lower(),
    })
    ET.SubElement(models, "speechToText", {
        "name": settings.stt_model,
        "enabled": str(settings.voice_enabled).lower(),
    })
    workstations = ET.SubElement(root, "workstations")
    for role, screens in SCREENS.items():
        workstation = ET.SubElement(workstations, "workstation", {
            "role": role.value, "label": ROLE_LABELS[role],
        })
        for path in screens:
            ET.SubElement(workstation, "screen", {"path": path})
    timers = ET.SubElement(root, "timerLimits")
    for code, normative in NORMATIVES.items():
        ET.SubElement(timers, "timer", {
            "code": code.value,
            "milliseconds": str(settings.limit_ms(code)),
            "defaultMilliseconds": str(normative.limit_ms),
        })
    reference = ekp.reference()
    ET.SubElement(root, "ekp", {
        "version": reference.version,
        "incidents": str(len(reference.incidents)),
    })
    ET.indent(root, space="  ")
    return ET.tostring(root, encoding="utf-8", xml_declaration=True)


@router.get("/config.xml")
async def configuration_xml(request: Request) -> Response:
    require(request, Role.ADMIN)
    return Response(
        content=_configuration_xml(),
        media_type="application/xml",
        headers={"Content-Disposition": 'attachment; filename="lct-workstations.xml"'},
    )


class UserOut(BaseModel):
    id: UUID
    login: str
    full_name: str
    role: Role
    auth_provider: str
    service: str | None
    blocked: bool
    created_at: datetime


class UserCreate(BaseModel):
    login: str = Field(min_length=3, max_length=80)
    full_name: str = Field(min_length=1, max_length=120)
    password: str = Field(min_length=8, max_length=1024, description="Пароль должен быть от 8 до 1024 символов")
    role: Role
    service: str | None = None


class UserPatch(BaseModel):
    """Что администратор меняет у существующей записи. Пароль — сбросом,
    а не чтением: старый он не видит и увидеть не может."""

    role: Role | None = None
    service: str | None = None
    blocked: bool | None = None
    password: str | None = Field(default=None, min_length=8, max_length=1024)


def _out(user: User) -> UserOut:
    return UserOut(
        id=user.id,
        login=user.login,
        full_name=user.full_name,
        role=Role(user.role),
        auth_provider=user.auth_provider,
        service=user.service,
        blocked=user.blocked,
        created_at=user.created_at,
    )


@router.get("/users", response_model=list[UserOut])
async def users(request: Request, db: AsyncSession = Depends(get_session)) -> list[UserOut]:
    require(request, Role.ADMIN)
    rows = await db.scalars(select(User).order_by(User.created_at))
    return [_out(user) for user in rows]


@router.post("/users", response_model=UserOut, status_code=201)
async def create_user(
    body: UserCreate, request: Request, db: AsyncSession = Depends(get_session)
) -> UserOut:
    who = require(request, Role.ADMIN)

    user = User(
        login=body.login,
        full_name=body.full_name,
        password_hash=hash_password(body.password),
        role=body.role.value,
        service=body.service,
    )
    # У обучающегося должна быть карточка курсанта: на ней висят профиль,
    # история и проверка «это твой разбор» (lct-23).
    if body.role is Role.TRAINEE:
        trainee = Trainee(name=body.full_name)
        db.add(trainee)
        await db.flush()
        user.trainee_id = trainee.id

    db.add(user)
    add_audit_entry(db, who.login, who.role.value, "user.create", body.login,
                    ROLE_LABELS[body.role])
    try:
        await db.commit()
    except IntegrityError as exc:
        await db.rollback()
        raise HTTPException(status_code=409, detail="login_taken") from exc

    return _out(user)


@router.patch("/users/{user_id}", response_model=UserOut)
async def patch_user(
    user_id: UUID, body: UserPatch, request: Request, db: AsyncSession = Depends(get_session)
) -> UserOut:
    who = require(request, Role.ADMIN)
    user = await db.get(User, user_id)
    if user is None:
        raise HTTPException(status_code=404, detail="user_not_found")

    if user.auth_provider == "ldap" and any(
        value is not None for value in (body.role, body.service, body.password)
    ):
        raise HTTPException(status_code=409, detail="directory_managed_account")

    changed: list[str] = []
    if body.role is not None:
        if user.login == who.login and body.role is not Role.ADMIN:
            raise HTTPException(status_code=409, detail="cannot_demote_yourself")
        if body.role is Role.TRAINEE and user.trainee_id is None:
            trainee = Trainee(name=user.full_name)
            db.add(trainee)
            await db.flush()
            user.trainee_id = trainee.id
        user.role = body.role.value
        changed.append(f"роль {body.role.value}")
    if body.service is not None:
        user.service = body.service
        changed.append(f"служба {body.service}")
    if body.blocked is not None:
        # Блокировка себя оставила бы стенд без администратора до похода в базу.
        if body.blocked and user.login == who.login:
            raise HTTPException(status_code=409, detail="cannot_block_yourself")
        user.blocked = body.blocked
        changed.append("заблокирован" if body.blocked else "разблокирован")
    if body.password is not None:
        user.password_hash = hash_password(body.password)
        changed.append("пароль сброшен")

    if not changed:
        return _out(user)
    user.auth_version += 1
    add_audit_entry(db, who.login, who.role.value, "user.update", user.login,
                    ", ".join(changed))
    await db.commit()
    invalidate_login(user.login, user.auth_version)
    return _out(user)


class AuditOut(BaseModel):
    at: datetime
    actor: str
    role: str
    action: str
    object_id: str | None
    detail: str


def _csv_value(value: object) -> str:
    """Prevent spreadsheet formula execution in user-controlled audit fields."""
    if value is None:
        return ""
    text = str(value)
    probe = text.lstrip(" \t\r\n\ufeff\u200b")
    if probe.startswith(("=", "+", "-", "@")) or text.startswith(("\t", "\r", "\n")):
        return "'" + text
    return text


def _csv_row(values: tuple[object, ...]) -> str:
    output = io.StringIO(newline="")
    csv.writer(output, lineterminator="\r\n").writerow(
        [_csv_value(value) for value in values]
    )
    return output.getvalue()


@router.get("/audit", response_model=list[AuditOut])
async def audit_log(
    request: Request,
    action: str | None = None,
    actor: str | None = None,
    limit: int = 200,
    offset: int = 0,
    db: AsyncSession = Depends(get_session),
) -> list[AuditOut]:
    """Журнал действий. Администратор его читает, но не правит: точки удаления
    или изменения записи здесь нет — ТЗ требует хранения, а не управления."""
    require(request, Role.ADMIN)
    query = (
        select(AuditLog)
        .order_by(AuditLog.at.desc(), AuditLog.id.desc())
        .limit(max(1, min(limit, 1001)))
        .offset(max(0, min(offset, 10_000_000)))
    )
    if action:
        query = query.where(AuditLog.action == action)
    if actor:
        query = query.where(AuditLog.actor == actor)
    rows = await db.scalars(query)
    return [
        AuditOut(
            at=row.at, actor=row.actor, role=row.role,
            action=row.action, object_id=row.object_id, detail=row.detail,
        )
        for row in rows
    ]


@router.get("/audit.csv")
async def audit_csv(
    request: Request,
    action: str | None = None,
    actor: str | None = None,
    db: AsyncSession = Depends(get_session),
) -> StreamingResponse:
    """Stream the complete filtered security log for offline review/archive."""
    require(request, Role.ADMIN)
    query = select(AuditLog).order_by(AuditLog.at.asc(), AuditLog.id.asc())
    if action:
        query = query.where(AuditLog.action == action)
    if actor:
        query = query.where(AuditLog.actor == actor)

    async def rows():
        yield "\ufeff" + _csv_row(("Когда UTC", "Пользователь", "Роль", "Действие", "Объект", "Подробности"))
        result = await db.stream_scalars(query)
        async for row in result:
            yield _csv_row((
                row.at.isoformat(), row.actor, row.role, row.action,
                row.object_id, row.detail,
            ))

    return StreamingResponse(
        rows(),
        media_type="text/csv; charset=utf-8",
        headers={"Content-Disposition": 'attachment; filename="lct-audit.csv"'},
    )


class ServiceState(BaseModel):
    name: str
    ok: bool
    detail: str


class RuntimeMetrics(BaseModel):
    at: datetime
    uptime_seconds: float
    cpu_percent: float
    load_1m_percent: float | None
    cpu_cores: int
    rss_bytes: int | None
    memory_total_bytes: int | None
    memory_available_bytes: int | None
    disk_total_bytes: int
    disk_free_bytes: int
    threads: int
    active_sessions: int
    restored_sessions: int
    completed_sessions_24h: int


class DiagnosticEvent(BaseModel):
    at: datetime
    level: str
    source: str
    message: str


class FailureEvent(BaseModel):
    at: datetime
    actor: str
    action: str
    object_id: str | None
    detail: str


class DiagnosticReport(BaseModel):
    generated_at: datetime
    metrics: RuntimeMetrics
    recent_system_events: list[DiagnosticEvent]
    failed_actions_24h: list[FailureEvent]


async def _runtime_metrics(db: AsyncSession) -> RuntimeMetrics:
    from app.main import app

    raw = sample_metrics()
    since = datetime.now(timezone.utc) - timedelta(hours=24)
    completed = await db.scalar(
        select(func.count()).select_from(SessionRow).where(SessionRow.ended_at >= since)
    )
    return RuntimeMetrics(
        **raw,
        active_sessions=sum(not item.ended for item in hub._sessions.values()),  # noqa: SLF001
        restored_sessions=getattr(app.state, "sessions_restored", 0),
        completed_sessions_24h=completed or 0,
    )


async def _diagnostic_report(db: AsyncSession) -> DiagnosticReport:
    since = datetime.now(timezone.utc) - timedelta(hours=24)
    rows = await db.scalars(
        select(AuditLog)
        .where(AuditLog.at >= since, AuditLog.action.like("%.failed"))
        .order_by(AuditLog.at.desc())
        .limit(200)
    )
    return DiagnosticReport(
        generated_at=datetime.now(timezone.utc),
        metrics=await _runtime_metrics(db),
        recent_system_events=[DiagnosticEvent(**item) for item in recent_events(limit=100)],
        failed_actions_24h=[
            FailureEvent(
                at=row.at, actor=row.actor, action=row.action,
                object_id=row.object_id, detail=row.detail,
            )
            for row in rows
        ],
    )


@router.get("/diagnostics", response_model=DiagnosticReport)
async def diagnostics(
    request: Request, db: AsyncSession = Depends(get_session)
) -> DiagnosticReport:
    """Live load plus a bounded, redacted incident report for the admin."""
    require(request, Role.ADMIN)
    return await _diagnostic_report(db)


@router.get("/diagnostics.json")
async def download_diagnostics(
    request: Request, db: AsyncSession = Depends(get_session)
) -> JSONResponse:
    require(request, Role.ADMIN)
    report = await _diagnostic_report(db)
    return JSONResponse(
        jsonable_encoder(report),
        headers={"Content-Disposition": 'attachment; filename="lct-diagnostics.json"'},
    )


@router.get("/status", response_model=list[ServiceState])
async def status(request: Request, db: AsyncSession = Depends(get_session)) -> list[ServiceState]:
    """Состояние компонентов стенда — то, что администратор смотрит до занятия,
    а не после жалобы преподавателя."""
    require(request, Role.ADMIN)
    from app.main import app
    from app.voice.models import get_voice_models

    settings = get_settings()
    states: list[ServiceState] = []

    try:
        sessions_total = await db.scalar(select(func.count()).select_from(SessionRow))
        states.append(ServiceState(name="База данных", ok=True, detail=f"занятий в журнале: {sessions_total}"))
    except Exception as exc:  # noqa: BLE001
        states.append(ServiceState(name="База данных", ok=False, detail=str(exc)[:200]))

    models_ready = getattr(app.state, "models_ready", False) or get_voice_models() is not None
    states.append(
        ServiceState(
            name="Модели речи",
            ok=bool(models_ready),
            detail="распознавание и синтез готовы" if models_ready else "не загружены: занятие пойдёт без голоса",
        )
    )
    metrics = sample_metrics()
    disk_free = metrics["disk_free_bytes"]
    disk_total = max(metrics["disk_total_bytes"], 1)
    disk_ok = disk_free >= 1024 ** 3 and disk_free / disk_total >= 0.05
    load = metrics["load_1m_percent"]
    states.append(ServiceState(
        name="Нагрузка backend",
        ok=disk_ok and (load is None or load < 100),
        detail=(
            f"CPU процесса {metrics['cpu_percent']:.1f}%; "
            + (f"нагрузка хоста {load:.1f}%; " if load is not None else "")
            + f"RAM процесса {(metrics['rss_bytes'] or 0) / 1024 ** 2:.0f} МБ; "
            + f"свободно на диске {disk_free / 1024 ** 3:.1f} ГБ"
        ),
    ))
    states.append(
        ServiceState(
            name="Эмбеддинги",
            ok=bool(getattr(app.state, "embeddings_ready", False)),
            detail="слот-автомат работает" if getattr(app.state, "embeddings_ready", False)
            else "нет модели: подсказки идут по порядку чек-листа",
        )
    )
    llm_configured = (
        is_loopback_url(
            settings.llm_base_url,
            allow_docker_host=settings.allow_docker_host_models,
        )
        if settings.offline or settings.llm_provider == "local"
        else bool(settings.llm_api_key and settings.llm_base_url)
    )
    states.append(
        ServiceState(
            name="Провайдер LLM",
            ok=llm_configured,
            detail=(f"локальный адрес разрешён: {settings.llm_base_url}"
                    if llm_configured else "не настроен: звонящий читает офлайн-таблицу"),
        )
    )

    reference = ekp.reference()
    states.append(
        ServiceState(
            name="Классификатор ЕКП",
            ok=True,
            detail=f"версия {reference.version}, кодов {len(reference.incidents)}",
        )
    )
    states.append(
        ServiceState(
            name="Живых занятий",
            ok=True,
            detail=(
                f"активно {sum(not item.ended for item in hub._sessions.values())}; "
                f"восстановлено после запуска {getattr(app.state, 'sessions_restored', 0)}"
            ),  # noqa: SLF001 — реестр в памяти процесса
        )
    )
    try:
        copies = backup_service.listing()
    except backup_service.BackupError as exc:
        states.append(ServiceState(
            name="Резервное копирование",
            ok=False,
            detail=f"ошибка чтения копий: {exc}",
        ))
        copies = []
    if copies:
        latest = copies[0]
        age_seconds = max(0.0, (datetime.now(timezone.utc) - latest["at"]).total_seconds())
        allowed_age = max(60, settings.backup_interval_seconds) + max(
            60, settings.backup_retry_seconds
        )
        states.append(ServiceState(
            name="Резервное копирование",
            ok=age_seconds <= allowed_age,
            detail=(f"последняя копия {latest['name']}, "
                    f"{age_seconds / 3600:.1f} ч назад; хранится {len(copies)}"),
        ))
    else:
        states.append(ServiceState(
            name="Резервное копирование",
            ok=False,
            detail="успешных копий ещё нет",
        ))
    # Секрет сессии по умолчанию — не ошибка запуска, но на стенде это дыра,
    # и увидеть её должен администратор, а не проверяющий.
    default_secret = settings.session_secret.startswith("dev-secret")
    states.append(
        ServiceState(
            name="Секрет сессии",
            ok=not default_secret,
            detail="заменён" if not default_secret else "стоит значение по умолчанию — поменяйте SESSION_SECRET",
        )
    )
    return states


class BackupOut(BaseModel):
    name: str
    size_bytes: int
    at: datetime


@router.get("/backups", response_model=list[BackupOut])
async def backups(request: Request) -> list[BackupOut]:
    require(request, Role.ADMIN)
    try:
        copies = await run_in_threadpool(backup_service.listing)
    except backup_service.BackupError as exc:
        detail = _safe_backup_error(exc)
        raise HTTPException(status_code=503, detail=detail) from exc
    return [BackupOut(**item) for item in copies]


def _safe_backup_error(exc: backup_service.BackupError) -> str:
    """Never echo DATABASE_URL/its password from backup diagnostics to HTTP."""
    message = str(exc)
    dsn = get_settings().database_url
    if dsn:
        message = message.replace(dsn, "[DATABASE_URL скрыт]")
        try:
            password = make_url(dsn).password
        except Exception:  # malformed DSN is handled by backup setup separately
            password = None
        if password:
            # Driver errors may echo the DSN either as configured (percent
            # encoded) or after the URL parser decoded credentials. Redact all
            # common representations; checking only the raw password misses
            # secrets containing @, :, spaces, or other escaped characters.
            encoded = {quote(password, safe=""), quote_plus(password, safe="")}
            variants = {
                password,
                *encoded,
                *(re.sub(r"%[0-9A-F]{2}", lambda match: match.group(0).lower(), item)
                  for item in encoded),
            }
            for secret in sorted(variants, key=len, reverse=True):
                if secret:
                    message = message.replace(secret, "[пароль скрыт]")
    return message


@router.post("/backups", response_model=BackupOut, status_code=201)
async def make_backup(request: Request) -> BackupOut:
    """Копия прямо сейчас. Расписание — отдельно, в `scripts/backup.py`:
    кнопка нужна перед занятием, расписание — чтобы о нём не вспоминали."""
    who = require(request, Role.ADMIN)
    # Record intent before the irreversible filesystem operation. If the DB
    # audit store fails after pg_dump finishes, the attempt is still visible.
    await audit_required(who.login, who.role.value, "backup.create.requested")
    try:
        # pg_dump may run for two minutes; never block the event loop for it.
        created = await run_in_threadpool(backup_service.create)
    except backup_service.BackupError as exc:
        detail = _safe_backup_error(exc)
        # The durable requested event above preserves the attempt even if the
        # outcome write also fails. Keep the concrete storage error visible to
        # the operator instead of replacing it with an audit-store error.
        await audit(who.login, who.role.value, "backup.failed", detail=detail)
        raise HTTPException(status_code=503, detail=detail) from exc
    # A completed backup must not be reported as successful when its security
    # audit could not be persisted. The file remains visible in the backup list
    # so an administrator can reconcile it after the audit store recovers.
    await audit_required(who.login, who.role.value, "backup.create", created["name"])
    return BackupOut(**created)