import { useCallback, useEffect, useRef, useState } from 'react'

import { useSiteSelection } from '../context/SiteSelectionContext'
import { getJson } from '../api/postgrest'
import type { SiteStatusRow } from '../types/ems'

const POLL_MS = 30_000

export function useSiteStatus() {
  const { selectedSiteId, ready: selectionReady, error: selectionError } = useSiteSelection()
  const [row, setRow] = useState<SiteStatusRow | null>(null)
  const [statusReady, setStatusReady] = useState(false)
  const [fetchError, setFetchError] = useState<string | null>(null)
  const selectedSiteIdRef = useRef(selectedSiteId)
  selectedSiteIdRef.current = selectedSiteId

  const load = useCallback(async () => {
    if (!selectionReady) {
      return
    }
    if (selectedSiteId == null) {
      setRow(null)
      setFetchError(null)
      setStatusReady(true)
      return
    }
    const sid = selectedSiteId
    try {
      const rows = await getJson<SiteStatusRow[]>('/vw_site_status', {
        site_id: `eq.${sid}`,
      })
      if (selectedSiteIdRef.current !== sid) return
      setRow(Array.isArray(rows) && rows.length > 0 ? rows[0]! : null)
      setFetchError(null)
    } catch {
      if (selectedSiteIdRef.current !== sid) return
      setRow(null)
      setFetchError('Stav lokality se nepodařilo načíst')
    } finally {
      if (selectedSiteIdRef.current === sid) {
        setStatusReady(true)
      }
    }
  }, [selectionReady, selectedSiteId])

  useEffect(() => {
    if (!selectionReady) return
    setStatusReady(false)
  }, [selectionReady, selectedSiteId])

  useEffect(() => {
    void load()
    const id = window.setInterval(() => void load(), POLL_MS)
    return () => window.clearInterval(id)
  }, [load])

  const ready = selectionReady && statusReady
  const error = selectionError ?? fetchError

  const hasTelemetry =
    row != null &&
    (row.pv_power_w != null ||
      row.battery_power_w != null ||
      row.grid_power_w != null ||
      row.battery_soc_percent != null)

  return {
    site: row,
    ready,
    error,
    /** Máme řádek lokality a alespoň jednu telemetrickou hodnotu (jinak skeleton). */
    hasLiveData: row != null && hasTelemetry,
    reload: load,
  }
}