import { defineStore } from 'pinia'
import { ref, computed } from 'vue'
import axios from 'axios'
import api from '@/api'
import { sampleStation, SAMPLE_REASONS } from '@/data/sample'
import { isGrafanaEmbed, grafanaWindow } from '@/embed'
import type { StationPayload, Reason, RejectRequest, RejectResult, WindowCode } from '@/types/station'

// Same convention as PressV: loadCache() → hydrate() → refresh() → startPolling().
//
// Connection loss on this LIVE terminal: never fabricate carts. A failed fetch keeps
// the last known REAL payload (stale > fake — an operator must never book against a
// demo cart) and flips `disconnected`, so the UI shows a reconnect spinner and polling
// retries faster. Bundled sample data renders ONLY under `npm run dev` (no gateway) —
// gated behind `import.meta.env.DEV`, so `vite build` strips it from production.

const CACHE_KEY = 'temper_rejects_payload'

export const useTemperRejectsStore = defineStore('temperRejects', () => {
  const payload = ref<StationPayload | null>(null)
  const reasons = ref<Reason[]>([])
  const window = ref<WindowCode>('7T')
  // Grafana embed: when hosted in a Grafana iframe (?embed=grafana), the native window
  // picker is hidden and the listed-carts window is driven by Grafana's own time range
  // (from/to epoch ms) instead of the preset. Read once from the URL — a Grafana time
  // change reloads the iframe, which re-runs this store setup.
  const embedded = ref(isGrafanaEmbed())
  const grafanaWin = embedded.value ? grafanaWindow() : null
  const checkedPresses = ref<string[]>([]) // press filter (default = all)
  const loading = ref(false)
  const error = ref<string | null>(null)
  const usingSample = ref(false)
  const disconnected = ref(false)
  const lastUpdated = ref<number | null>(null)

  let timer: ReturnType<typeof setTimeout> | null = null
  let pollMs = 20000
  const RETRY_MS = 5000 // faster cadence while disconnected, to recover quickly
  let filterInitialized = false

  const hasData = computed(() => payload.value !== null)
  const allPresses = computed(() => payload.value?.presses ?? [])

  // entries per press (over ALL entries) — for the sidebar hit-count badges.
  const pressCounts = computed<Record<string, number>>(() => {
    const m: Record<string, number> = {}
    for (const p of allPresses.value) m[p] = 0
    for (const e of payload.value?.entries ?? []) m[e.press] = (m[e.press] ?? 0) + 1
    return m
  })

  const filteredEntries = computed(() => {
    const checked = new Set(checkedPresses.value)
    return (payload.value?.entries ?? []).filter((e) => checked.has(e.press))
  })

  function saveCache() {
    try {
      sessionStorage.setItem(CACHE_KEY, JSON.stringify({ payload: payload.value, window: window.value, checkedPresses: checkedPresses.value }))
    } catch {
      /* best-effort */
    }
  }
  function loadCache() {
    try {
      const raw = sessionStorage.getItem(CACHE_KEY)
      if (!raw) return
      const blob = JSON.parse(raw) as { payload: StationPayload | null; window: WindowCode; checkedPresses: string[] }
      payload.value = blob.payload ?? null
      if (blob.window) window.value = blob.window
      if (blob.checkedPresses?.length) {
        checkedPresses.value = blob.checkedPresses
        filterInitialized = true
      }
    } catch {
      /* corrupt cache — ignore */
    }
  }

  async function hydrate() {
    if (!hasData.value) loading.value = true
    await Promise.all([refresh(), fetchReasons()])
  }

  async function refresh() {
    error.value = null
    try {
      // Grafana embed → exact from→to window; standalone → the preset window.
      const params = grafanaWin ? { from: grafanaWin.from, to: grafanaWin.to } : { window: window.value }
      const res = await api.get<StationPayload>('/overview', { params })
      if (!res.data || !Array.isArray(res.data.entries)) {
        throw new Error('Unexpected /overview response (no backend?)')
      }
      payload.value = res.data
      usingSample.value = res.data.sample === true
      disconnected.value = false
    } catch (e) {
      // Connection lost. Keep the last known REAL data (stale > fabricated): never
      // replace live carts with demo carts on a live terminal, or an operator could
      // book against a fabricated entry. Flag `disconnected` so the UI shows a
      // reconnect spinner (cold start) or a header indicator (stale data) and retries.
      disconnected.value = true
      error.value = e instanceof Error ? e.message : 'Overview API unreachable'
      // Sample data is for `npm run dev` only (no gateway) — `vite build` strips this.
      if (import.meta.env.DEV && (!payload.value || usingSample.value)) {
        payload.value = sampleStation(window.value)
        usingSample.value = true
      }
    } finally {
      // Default the filter to ALL presses on first load (Alle). "Keine" stays a
      // valid explicit state afterwards, so only auto-fill once.
      if (!filterInitialized && payload.value) {
        checkedPresses.value = [...payload.value.presses]
        filterInitialized = true
      }
      loading.value = false
      lastUpdated.value = Date.now()
      saveCache()
    }
  }

  async function fetchReasons() {
    try {
      const res = await api.get<{ reasons: Reason[] }>('/reasons')
      if (Array.isArray(res.data?.reasons) && res.data.reasons.length) {
        reasons.value = res.data.reasons
        return
      }
      throw new Error('no reasons')
    } catch {
      // Keep any reasons already loaded; only seed the bundled sample reasons under
      // `npm run dev` — production must never offer fabricated reason codes.
      if (import.meta.env.DEV && !reasons.value.length) reasons.value = SAMPLE_REASONS
    }
  }

  async function setWindow(code: WindowCode) {
    window.value = code
    await refresh()
  }

  // ── press filter ────────────────────────────────────────────────────────────
  function togglePress(press: string) {
    const i = checkedPresses.value.indexOf(press)
    if (i >= 0) checkedPresses.value.splice(i, 1)
    else checkedPresses.value.push(press)
    saveCache()
  }
  function selectAllPresses() {
    checkedPresses.value = [...allPresses.value]
    saveCache()
  }
  function selectNoPresses() {
    checkedPresses.value = []
    saveCache()
  }

  /** Book one reject. Returns the gateway's own {success} verdict. NEVER fakes success:
   * on this live, login-free terminal an unconfirmed write must not read as booked. */
  async function submitReject(req: RejectRequest): Promise<RejectResult> {
    try {
      const res = await api.post<RejectResult>('/reject', req)
      if (res.data && typeof res.data === 'object' && 'success' in res.data) {
        if (res.data.success) await refresh()
        return res.data
      }
      // Reachable but unexpected shape (e.g. a dev SPA fallback serving index.html) →
      // treat as NOT booked.
      return { success: false, error: 'bad_response' }
    } catch (e) {
      // The gateway returns HTTP 200 + {success:false} for refusals/write failures, so a
      // throw here is a genuine transport failure (backend unreachable / timeout) or a
      // non-2xx carrying a body. Prefer the server's own {success:false}; otherwise report
      // a transport failure. Either way, do NOT report success for an unconfirmed write.
      const data = axios.isAxiosError(e) ? (e.response?.data as RejectResult | undefined) : undefined
      if (data && typeof data === 'object' && 'success' in data) return data
      return { success: false, error: 'unreachable' }
    }
  }

  // Self-scheduling poll: next tick is the normal cadence when connected, a faster
  // retry while disconnected so the terminal recovers as soon as the gateway is back.
  function scheduleNext() {
    timer = setTimeout(async () => {
      await refresh()
      scheduleNext()
    }, disconnected.value ? RETRY_MS : pollMs)
  }
  function startPolling(ms = 20000) {
    if (timer) return
    pollMs = ms
    scheduleNext()
  }
  function stopPolling() {
    if (timer) {
      clearTimeout(timer)
      timer = null
    }
  }

  loadCache()

  return {
    payload,
    reasons,
    window,
    embedded,
    checkedPresses,
    loading,
    error,
    usingSample,
    disconnected,
    lastUpdated,
    hasData,
    allPresses,
    pressCounts,
    filteredEntries,
    hydrate,
    refresh,
    fetchReasons,
    setWindow,
    togglePress,
    selectAllPresses,
    selectNoPresses,
    submitReject,
    startPolling,
    stopPolling,
  }
})