from datetime import datetime, timedelta, timezone

from fastapi import APIRouter, Depends, Query
from pydantic import BaseModel
from sqlalchemy import func, select
from sqlalchemy.orm import Session, joinedload

from app.auth.jwt_auth import get_current_user
from app.config import get_settings
from app.database import get_db
from app.models import Event, Host, Problem
from app.schemas.list_models import EventSummary
from app.services.event_summary import event_to_summary
from app.services.host_health import DAILY_REPORT_TYPES, HEARTBEAT_TYPE, count_stale_hosts

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


def fetch_recent_events(db: Session, *, limit: int = 8) -> list[EventSummary]:
    """Последние события по времени приёма ingest (received_at)."""
    rows = db.scalars(
        select(Event)
        .join(Host)
        .options(joinedload(Event.host))
        .order_by(Event.received_at.desc())
        .limit(limit)
    ).all()
    return [event_to_summary(e) for e in rows]


class TopHostItem(BaseModel):
    host_id: int
    hostname: str
    display_name: str | None = None
    count: int


class TopTypeItem(BaseModel):
    type: str
    count: int


class DashboardSummary(BaseModel):
    events_last_24h: int
    hosts_total: int
    hosts_stale: int
    heartbeats_24h: int
    daily_reports_24h: int
    problems_open: int
    problems_opened_24h: int
    problems_resolved_24h: int
    severity_24h: dict[str, int]
    top_hosts: list[TopHostItem]
    top_event_types: list[TopTypeItem]
    recent_events: list[EventSummary]


@router.get("/summary", response_model=DashboardSummary)
def dashboard_summary(
    db: Session = Depends(get_db),
    _user: str = Depends(get_current_user),
) -> DashboardSummary:
    since = datetime.now(timezone.utc) - timedelta(hours=24)

    events_24h = db.scalar(
        select(func.count()).select_from(Event).where(Event.received_at >= since)
    ) or 0
    hosts_total = db.scalar(select(func.count()).select_from(Host)) or 0
    settings = get_settings()
    hosts_stale = count_stale_hosts(db, settings.sac_heartbeat_stale_minutes)
    heartbeats_24h = db.scalar(
        select(func.count())
        .select_from(Event)
        .where(Event.received_at >= since, Event.type == HEARTBEAT_TYPE)
    ) or 0
    daily_reports_24h = db.scalar(
        select(func.count())
        .select_from(Event)
        .where(Event.received_at >= since, Event.type.in_(DAILY_REPORT_TYPES))
    ) or 0
    problems_open = (
        db.scalar(select(func.count()).select_from(Problem).where(Problem.status == "open")) or 0
    )
    problems_opened_24h = (
        db.scalar(select(func.count()).select_from(Problem).where(Problem.created_at >= since)) or 0
    )
    problems_resolved_24h = (
        db.scalar(
            select(func.count()).select_from(Problem).where(
                Problem.status == "resolved",
                Problem.updated_at >= since,
            )
        )
        or 0
    )

    top_host_rows = db.execute(
        select(Host.id, Host.hostname, Host.display_name, func.count())
        .select_from(Event)
        .join(Host, Event.host_id == Host.id)
        .where(Event.received_at >= since)
        .group_by(Host.id, Host.hostname, Host.display_name)
        .order_by(func.count().desc())
        .limit(10)
    ).all()
    top_hosts = [
        TopHostItem(host_id=row[0], hostname=row[1], display_name=row[2], count=row[3]) for row in top_host_rows
    ]

    top_type_rows = db.execute(
        select(Event.type, func.count())
        .where(Event.received_at >= since)
        .group_by(Event.type)
        .order_by(func.count().desc())
        .limit(10)
    ).all()
    top_event_types = [TopTypeItem(type=row[0], count=row[1]) for row in top_type_rows]

    severity_rows = db.execute(
        select(Event.severity, func.count())
        .where(Event.received_at >= since)
        .group_by(Event.severity)
    ).all()
    severity_24h = {row[0]: row[1] for row in severity_rows}

    recent_events = fetch_recent_events(db, limit=8)

    return DashboardSummary(
        events_last_24h=events_24h,
        hosts_total=hosts_total,
        hosts_stale=hosts_stale,
        heartbeats_24h=heartbeats_24h,
        daily_reports_24h=daily_reports_24h,
        problems_open=problems_open,
        problems_opened_24h=problems_opened_24h,
        problems_resolved_24h=problems_resolved_24h,
        severity_24h=severity_24h,
        top_hosts=top_hosts,
        top_event_types=top_event_types,
        recent_events=recent_events,
    )


@router.get("/recent-events", response_model=list[EventSummary])
def dashboard_recent_events(
    limit: int = Query(8, ge=1, le=50),
    db: Session = Depends(get_db),
    _user: str = Depends(get_current_user),
) -> list[EventSummary]:
    return fetch_recent_events(db, limit=limit)