import { promises as fs } from 'fs'
import path from 'path'
import { getCurrentSeasonSlug, readSpielplanData } from './spielplan-data.js'
import { getServerDataPath } from './paths.js'
import { sendLiveTickerFinishedPush, sendLiveTickerScoreChangedPush, sendLiveTickerStartedPush } from './push-notifications.js'
import { error as loggerError } from './logger.js'

const TICKER_WINDOW_BEFORE_MS = 30 * 60 * 1000
const TICKER_WINDOW_AFTER_MS = 6 * 60 * 60 * 1000
const FINISHED_VISIBLE_MS = 60 * 60 * 1000
const LIVE_START_STATE_FILE = getServerDataPath('live-ticker-notifications.json')
const LIVE_TICKER_STATE_FILE = getServerDataPath('live-ticker-observed-state.json')
const LIVE_START_STATE_RETENTION_MS = 2 * 24 * 60 * 60 * 1000
const cache = new Map()
let liveStartNotifications = null
let observedLiveTickerStates = null
let refreshInFlight = null

function matchTime(row) {
  const timestamp = Number(row.Timestamp)
  return Number.isFinite(timestamp) ? timestamp * 1000 : NaN
}

function score(data) {
  const home = data.is_completed ? data.matches_home : data.match?.reduce((sum, item) => sum + (Number(item.matches_home) || 0), 0)
  const away = data.is_completed ? data.matches_guest : data.match?.reduce((sum, item) => sum + (Number(item.matches_guest) || 0), 0)
  return `${home ?? 0}:${away ?? 0}`
}

function completedTime(data, fallback) {
  const timestamp = Date.parse(data.end_date || data.entry_date || '')
  return Number.isFinite(timestamp) ? timestamp : fallback
}

async function readLiveStartNotifications() {
  if (liveStartNotifications) return liveStartNotifications
  try {
    const parsed = JSON.parse(await fs.readFile(LIVE_START_STATE_FILE, 'utf8'))
    liveStartNotifications = parsed && typeof parsed === 'object' ? parsed : {}
  } catch (error) {
    if (error?.code !== 'ENOENT') loggerError('[live-ticker] Push-Status konnte nicht gelesen werden', { error })
    liveStartNotifications = {}
  }
  return liveStartNotifications
}

async function saveLiveStartNotifications(nowMs) {
  const state = await readLiveStartNotifications()
  for (const [meetingId, notifiedAt] of Object.entries(state)) {
    if (nowMs - Date.parse(notifiedAt) > LIVE_START_STATE_RETENTION_MS) delete state[meetingId]
  }
  await fs.mkdir(path.dirname(LIVE_START_STATE_FILE), { recursive: true })
  await fs.writeFile(LIVE_START_STATE_FILE, `${JSON.stringify(state, null, 2)}\n`, 'utf8')
}

async function notifyLiveStart(entry, nowMs) {
  const state = await readLiveStartNotifications()
  if (state[entry.meetingId]) return
  state[entry.meetingId] = new Date(nowMs).toISOString()
  try {
    await saveLiveStartNotifications(nowMs)
    await sendLiveTickerStartedPush(entry)
  } catch (error) {
    loggerError('[live-ticker] Start-Push konnte nicht gesendet werden', { meetingId: entry.meetingId, error })
  }
}

async function readObservedLiveTickerStates() {
  if (observedLiveTickerStates) return observedLiveTickerStates
  try {
    const parsed = JSON.parse(await fs.readFile(LIVE_TICKER_STATE_FILE, 'utf8'))
    observedLiveTickerStates = parsed && typeof parsed === 'object' ? parsed : {}
  } catch (error) {
    if (error?.code !== 'ENOENT') loggerError('[live-ticker] Beobachtete Stände konnten nicht gelesen werden', { error })
    observedLiveTickerStates = {}
  }
  return observedLiveTickerStates
}

async function saveObservedLiveTickerStates(nowMs) {
  const states = await readObservedLiveTickerStates()
  for (const [meetingId, state] of Object.entries(states)) {
    if (nowMs - Date.parse(state?.updatedAt || '') > LIVE_START_STATE_RETENTION_MS) delete states[meetingId]
  }
  await fs.mkdir(path.dirname(LIVE_TICKER_STATE_FILE), { recursive: true })
  await fs.writeFile(LIVE_TICKER_STATE_FILE, `${JSON.stringify(states, null, 2)}\n`, 'utf8')
}

async function notifyLiveTickerChanges(entry, nowMs) {
  const states = await readObservedLiveTickerStates()
  const previous = states[entry.meetingId]
  const startedNow = entry.hasLiveData && !previous?.hasLiveData
  const finishedNow = entry.completed && previous && !previous.completed
  const scoreChanged = entry.hasLiveData && !entry.completed && previous?.hasLiveData && previous.score !== entry.score

  states[entry.meetingId] = {
    hasLiveData: entry.hasLiveData,
    completed: entry.completed,
    score: entry.score,
    updatedAt: new Date(nowMs).toISOString()
  }
  try {
    await saveObservedLiveTickerStates(nowMs)
    if (startedNow) await notifyLiveStart(entry, nowMs)
    if (scoreChanged) await sendLiveTickerScoreChangedPush(entry)
    if (finishedNow) await sendLiveTickerFinishedPush(entry)
  } catch (error) {
    loggerError('[live-ticker] Live-Push konnte nicht gesendet werden', { meetingId: entry.meetingId, error })
  }
}

async function refreshLiveTickerOnce(now = new Date()) {
  const season = getCurrentSeasonSlug(now)
  const { data } = await readSpielplanData({ season })
  const nowMs = now.getTime()
  const candidates = data.filter((row) => {
    const startsAt = matchTime(row)
    return Number.isFinite(startsAt) && startsAt - TICKER_WINDOW_BEFORE_MS <= nowMs && nowMs <= startsAt + TICKER_WINDOW_AFTER_MS
  })

  await Promise.all(candidates.map(async (row) => {
    const meetingId = String(row.MeetingId || row.BegegnungNr || '').trim()
    if (!/^\d{6,}$/.test(meetingId)) return
    try {
      const response = await fetch(`https://www.mytischtennis.de/api/meeting/${meetingId}/live`, {
        headers: { accept: 'application/json', 'accept-language': 'de-DE,de;q=0.9' },
        signal: AbortSignal.timeout(10_000)
      })
      if (!response.ok) throw new Error(`HTTP ${response.status}`)
      const payload = await response.json()
      const report = payload?.data
      if (!report) throw new Error('Keine Spieldaten erhalten')
      const completedAt = report.is_completed ? completedTime(report, nowMs) : null
      const previous = cache.get(meetingId)
      const entry = {
        meetingId,
        homeTeam: report.team_home || row.HeimMannschaft,
        awayTeam: report.team_guest || row.GastMannschaft,
        score: score(report),
        startsAt: matchTime(row),
        hasLiveData: report.has_nu_live_push_data === true,
        completed: report.is_completed === true,
        completedAt: completedAt || previous?.completedAt || null,
        updatedAt: new Date(nowMs).toISOString()
      }
      cache.set(meetingId, entry)
      await notifyLiveTickerChanges(entry, nowMs)
    } catch (error) {
      const previous = cache.get(meetingId)
      if (previous) cache.set(meetingId, { ...previous, updatedAt: previous.updatedAt, error: 'Live-Daten derzeit nicht erreichbar' })
    }
  }))

  for (const [meetingId, entry] of cache) {
    if (entry.completed && entry.completedAt && nowMs - entry.completedAt > FINISHED_VISIBLE_MS) cache.delete(meetingId)
  }
  return getLiveTicker(now)
}

export function refreshLiveTicker(now = new Date()) {
  if (refreshInFlight) return refreshInFlight
  refreshInFlight = refreshLiveTickerOnce(now).finally(() => { refreshInFlight = null })
  return refreshInFlight
}

export function getLiveTicker(now = new Date()) {
  const nowMs = now.getTime()
  const matches = [...cache.values()]
    .filter((entry) => !entry.completed || !entry.completedAt || nowMs - entry.completedAt <= FINISHED_VISIBLE_MS)
    .sort((a, b) => Number(b.hasLiveData && !b.completed) - Number(a.hasLiveData && !a.completed) || a.startsAt - b.startsAt)
  return { matches, updatedAt: new Date(nowMs).toISOString() }
}