from __future__ import annotations

from datetime import datetime, timedelta
from types import SimpleNamespace

from fastapi import APIRouter, Depends, Request
from fastapi.responses import HTMLResponse
from fastapi.templating import Jinja2Templates

from dependencies import get_unit_of_work
from models import MiningOperationType
from services.unit_of_work import UnitOfWork

router = APIRouter(tags=["Dashboard"])
templates = Jinja2Templates(directory="templates")


def _load_metrics(_: UnitOfWork) -> dict[str, object]:
    today = datetime.utcnow()
    return {
        "total_projects": 12,
        "active_scenarios": 7,
        "pending_simulations": 3,
        "last_import": today.strftime("%Y-%m-%d"),
    }


def _load_recent_projects(_: UnitOfWork) -> list[SimpleNamespace]:
    now = datetime.utcnow()
    return [
        SimpleNamespace(
            id=1,
            name="Copper Ridge Expansion",
            operation_type=MiningOperationType.OPEN_PIT,
            updated_at=now - timedelta(days=2),
        ),
        SimpleNamespace(
            id=2,
            name="Lithium Basin North",
            operation_type=MiningOperationType.UNDERGROUND,
            updated_at=now - timedelta(days=5),
        ),
        SimpleNamespace(
            id=3,
            name="Nickel Underground Phase II",
            operation_type=MiningOperationType.IN_SITU_LEACH,
            updated_at=now - timedelta(days=9),
        ),
    ]


def _load_simulation_updates(_: UnitOfWork) -> list[SimpleNamespace]:
    now = datetime.utcnow()
    return [
        SimpleNamespace(
            title="Monte Carlo Batch #21 completed",
            description="1,000 runs processed for Lithium Basin North.",
            timestamp=now - timedelta(hours=4),
        ),
        SimpleNamespace(
            title="Scenario validation queued",
            description="Copper Ridge Expansion pending validation on new cost inputs.",
            timestamp=now - timedelta(days=1, hours=3),
        ),
    ]


def _load_scenario_alerts(_: UnitOfWork) -> list[SimpleNamespace]:
    return [
        SimpleNamespace(
            title="Variance exceeds threshold",
            message="Nickel Underground Phase II deviates 18% from baseline forecast.",
            link="/projects/3/view",
        ),
        SimpleNamespace(
            title="Simulation backlog",
            message="Lithium Basin North has 2 pending simulation batches.",
            link="/projects/2/view",
        ),
    ]


@router.get("/", response_class=HTMLResponse, include_in_schema=False, name="dashboard.home")
def dashboard_home(
    request: Request,
    uow: UnitOfWork = Depends(get_unit_of_work),
) -> HTMLResponse:
    context = {
        "request": request,
        "metrics": _load_metrics(uow),
        "recent_projects": _load_recent_projects(uow),
        "simulation_updates": _load_simulation_updates(uow),
        "scenario_alerts": _load_scenario_alerts(uow),
    }
    return templates.TemplateResponse("dashboard.html", context)