from __future__ import annotations

from datetime import UTC, date, datetime
from typing import Literal

from fastapi import APIRouter, Depends
from sqlalchemy import select
from sqlalchemy.orm import Session

from app.api.deps import get_current_user, get_db
from app.core.config import get_settings
from app.models.booking import Booking
from app.models.customer import Customer
from app.models.data_quality import DataQualityIssue
from app.models.outbox import OutboxEvent
from app.models.vehicle import Vehicle
from app.schemas import (
    AttentionItem,
    AutomationRunOut,
    CurrentUser,
    DashboardOut,
    TodayItem,
)
from app.services.operations import compute_metrics

router = APIRouter(prefix="/api/v1/dashboard", tags=["dashboard"])
settings = get_settings()

_SEVERITY_ORDER = {"high": 0, "medium": 1, "low": 2}


def _today() -> date:
    # Seeded dates are shifted to the real reset moment by `seed_loader.py`'s anchor
    # shift, so "today" must be real wall-clock time, not the frozen `demo_today` setting.
    return datetime.now(UTC).date()


@router.get("", response_model=DashboardOut)
def get_dashboard(
    db: Session = Depends(get_db),
    _user: CurrentUser = Depends(get_current_user),
) -> DashboardOut:
    metrics = compute_metrics(db)

    vehicles_by_id = {v.id: v for v in db.scalars(select(Vehicle)).all()}
    customers_by_id = {c.id: c for c in db.scalars(select(Customer)).all()}

    issues = db.scalars(
        select(DataQualityIssue)
        .where(DataQualityIssue.status == "open")
        .order_by(DataQualityIssue.detected_at.asc())
    ).all()
    attention_items = []
    for issue in issues:
        entity: Vehicle | Customer | None
        link_type: Literal["vehicle", "customer"]
        if issue.entity_type == "vehicle":
            entity = vehicles_by_id.get(issue.entity_id)
            link_type = "vehicle"
        else:
            entity = customers_by_id.get(issue.entity_id)
            link_type = "customer"
        link_ref = entity.public_ref if entity else ""
        title = f"{issue.rule_type.replace('_', ' ').title()} — {link_ref}"
        attention_items.append(
            AttentionItem(
                kind="quality_issue",
                severity=issue.severity,
                title=title,
                detail=issue.evidence_json.get("summary", ""),
                link_type=link_type,
                link_ref=link_ref,
                issue_ref=issue.public_ref,
            )
        )
    attention_items.sort(key=lambda item: _SEVERITY_ORDER.get(item.severity, 3))
    attention_items = attention_items[:8]

    today = _today()
    bookings = db.scalars(select(Booking)).all()
    today_items: list[TodayItem] = []
    for b in bookings:
        vehicle = vehicles_by_id.get(b.vehicle_id)
        vehicle_ref = vehicle.public_ref if vehicle else ""
        if b.starts_at.date() == today and b.status in ("reserved", "active"):
            today_items.append(
                TodayItem(
                    kind="departure", booking_ref=b.public_ref, vehicle_ref=vehicle_ref,
                    scheduled_at=b.starts_at,
                )
            )
        if b.ends_at.date() == today and b.status in ("active", "returned"):
            today_items.append(
                TodayItem(
                    kind="return", booking_ref=b.public_ref, vehicle_ref=vehicle_ref,
                    scheduled_at=b.ends_at,
                )
            )
    today_items.sort(key=lambda item: item.scheduled_at)

    recent = db.scalars(
        select(OutboxEvent).order_by(OutboxEvent.occurred_at.desc()).limit(5)
    ).all()
    recent_automation = [
        AutomationRunOut(
            event_id=str(r.event_id),
            event_type=r.event_type,
            aggregate_ref=r.payload_json.get("aggregate_ref", ""),
            status=r.delivery_status,
            attempts=r.attempts,
            last_error=r.last_error,
            occurred_at=r.occurred_at,
        )
        for r in recent
    ]

    return DashboardOut(
        metrics=metrics,
        attention_items=attention_items,
        today=today_items,
        recent_automation=recent_automation,
    )