"""REST API – aktivní EV session a úprava deadline / target SoC."""

from __future__ import annotations

from datetime import date, datetime
from typing import Annotated, Any

import asyncpg
from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel, field_validator

from app.db_json import record_to_dict
from app.deps import get_pg_pool

router = APIRouter(prefix="/sites/{site_id}/ev", tags=["ev"])


class EvSessionPatchBody(BaseModel):
    target_soc_pct: float | None = None
    target_deadline: datetime | None = None

    @field_validator("target_soc_pct")
    @classmethod
    def _soc_range(cls, v: float | None) -> float | None:
        if v is not None and not (10 <= v <= 100):
            raise ValueError("target_soc_pct must be between 10 and 100")
        return v


class EvSessionPatchResponse(BaseModel):
    success: bool = True
    session_id: int


@router.get("/sessions/active")
async def get_active_ev_sessions(
    site_id: int,
    pool: Annotated[asyncpg.Pool, Depends(get_pg_pool)],
) -> list[dict[str, Any]]:
    async with pool.acquire() as conn:
        site_ok = await conn.fetchval("SELECT EXISTS(SELECT 1 FROM ems.site WHERE id = $1)", site_id)
        if not site_ok:
            raise HTTPException(status_code=404, detail="Site not found")
        rows = await conn.fetch(
            """
            SELECT es.id, es.charger_id, es.vehicle_id,
                   es.session_start, es.energy_delivered_wh,
                   es.target_soc_pct, es.target_deadline,
                   av.make, av.model, av.battery_capacity_kwh,
                   av.default_target_soc_pct, av.default_deadline_hour,
                   ac.code AS charger_code,
                   COALESCE(
                       NULLIF(TRIM(CONCAT_WS(' ', ac.manufacturer, ac.model)), ''),
                       ac.code
                   ) AS charger_name
            FROM ems.ev_session es
            LEFT JOIN ems.asset_vehicle av ON av.id = es.vehicle_id
            JOIN ems.asset_ev_charger ac ON ac.id = es.charger_id
            WHERE es.site_id = $1 AND es.session_end IS NULL
            ORDER BY es.session_start DESC
            """,
            site_id,
        )
    return [record_to_dict(r) for r in rows]


@router.patch("/sessions/{session_id}", response_model=EvSessionPatchResponse)
async def patch_ev_session(
    site_id: int,
    session_id: int,
    body: EvSessionPatchBody,
    pool: Annotated[asyncpg.Pool, Depends(get_pg_pool)],
) -> EvSessionPatchResponse:
    async with pool.acquire() as conn:
        site_ok = await conn.fetchval("SELECT EXISTS(SELECT 1 FROM ems.site WHERE id = $1)", site_id)
        if not site_ok:
            raise HTTPException(status_code=404, detail="Site not found")

        row = await conn.fetchrow(
            """
            UPDATE ems.ev_session
            SET target_soc_pct = $1, target_deadline = $2
            WHERE id = $3 AND site_id = $4
            RETURNING id
            """,
            body.target_soc_pct,
            body.target_deadline,
            session_id,
            site_id,
        )
        if row is None:
            raise HTTPException(status_code=404, detail="Session not found")
        return EvSessionPatchResponse(success=True, session_id=int(row["id"]))


class ArrivalHourItem(BaseModel):
    hour: int
    confidence_pct: int
    samples: int


class ChargerTomorrowArrival(BaseModel):
    tomorrow: list[ArrivalHourItem]


class EvArrivalPredictionResponse(BaseModel):
    insufficient_data: bool
    tomorrow_date: str
    chargers: dict[str, ChargerTomorrowArrival]


@router.get("/arrival-prediction", response_model=EvArrivalPredictionResponse)
async def get_ev_arrival_prediction(
    site_id: int,
    pool: Annotated[asyncpg.Pool, Depends(get_pg_pool)],
) -> EvArrivalPredictionResponse:
    """Top hodiny příjezdu z ems.fn_ev_expected_arrival; při <5 session celkem insufficient_data."""
    async with pool.acquire() as conn:
        site_ok = await conn.fetchval("SELECT EXISTS(SELECT 1 FROM ems.site WHERE id = $1)", site_id)
        if not site_ok:
            raise HTTPException(status_code=404, detail="Site not found")

        n_sessions = int(
            await conn.fetchval(
                "SELECT COUNT(*)::int FROM ems.ev_session WHERE site_id = $1",
                site_id,
            )
            or 0
        )
        insufficient = n_sessions < 5

        tomorrow = await conn.fetchval(
            """
            SELECT (
                CURRENT_TIMESTAMP AT TIME ZONE COALESCE(
                    NULLIF(TRIM(timezone), ''),
                    'Europe/Prague'
                )
            )::date + 1
            FROM ems.site
            WHERE id = $1
            """,
            site_id,
        )
        if tomorrow is None:
            raise HTTPException(status_code=500, detail="Site date resolution failed")
        tomorrow_d: date = tomorrow

        chargers_rows = await conn.fetch(
            "SELECT id, code FROM ems.asset_ev_charger WHERE site_id = $1 ORDER BY id",
            site_id,
        )

        chargers: dict[str, ChargerTomorrowArrival] = {}
        for ch in chargers_rows:
            code = str(ch["code"])
            preds = await conn.fetch(
                "SELECT * FROM ems.fn_ev_expected_arrival($1, $2, $3::date)",
                site_id,
                ch["id"],
                tomorrow_d,
            )
            chargers[code] = ChargerTomorrowArrival(
                tomorrow=[
                    ArrivalHourItem(
                        hour=int(r["expected_hour"]),
                        confidence_pct=int(r["confidence_pct"]),
                        samples=int(r["sample_count"]),
                    )
                    for r in preds
                ]
            )

    return EvArrivalPredictionResponse(
        insufficient_data=insufficient,
        tomorrow_date=tomorrow_d.isoformat(),
        chargers=chargers,
    )