import { promises as fs } from 'fs'
import path from 'path'
import { readUsers, isHiddenUser } from './auth.js'
import { readMembers } from './members.js'
import { readTermine } from './termine.js'
import { readNews } from './news.js'
import { getServerDataPath } from './paths.js'
import { getDefaultSpielplanSeason, readSpielplanData } from './spielplan-data.js'
import { notificationSettingsForUser } from './notification-settings.js'
import { sendPushToUsers } from './push-notifications.js'
import { info as loggerInfo, error as loggerError } from './logger.js'

const TIME_ZONE = 'Europe/Berlin'
const STATE_FILE = getServerDataPath('notification-scheduler-state.json')
const DATE_FORMATTER = new Intl.DateTimeFormat('en-CA', {
  timeZone: TIME_ZONE,
  year: 'numeric',
  month: '2-digit',
  day: '2-digit'
})
const TIME_FORMATTER = new Intl.DateTimeFormat('en-GB', {
  timeZone: TIME_ZONE,
  hour: '2-digit',
  minute: '2-digit',
  hour12: false
})
const DATE_TIME_FORMATTER = new Intl.DateTimeFormat('de-DE', {
  timeZone: TIME_ZONE,
  weekday: 'short',
  day: '2-digit',
  month: '2-digit',
  year: 'numeric',
  hour: '2-digit',
  minute: '2-digit',
  hour12: false
})

function berlinDateKey(date = new Date()) {
  return DATE_FORMATTER.format(date)
}

function berlinTimeKey(date = new Date()) {
  return TIME_FORMATTER.format(date)
}

function addDays(date, days) {
  const next = new Date(date)
  next.setUTCDate(next.getUTCDate() + days)
  return next
}

function normalizeText(value) {
  return String(value || '')
    .normalize('NFKD')
    .replace(/[\u0300-\u036f]/g, '')
    .replace(/[’'`]/g, '')
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, ' ')
    .trim()
}

function slugify(value) {
  return normalizeText(value).replace(/\s+/g, '-')
}

function userDisplayName(user) {
  return String(user?.name || `${user?.firstName || ''} ${user?.lastName || ''}`.trim() || '').trim()
}

function hasTimedSettings(user) {
  const settings = notificationSettingsForUser(user)
  return settings.newNews || settings.eventsToday || settings.eventsTomorrow || settings.ownTeamMatches ||
    settings.allTeamMatches || settings.selectedTeamSlugs.length > 0 || settings.birthdays
}

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

async function writeState(state) {
  await fs.mkdir(path.dirname(STATE_FILE), { recursive: true })
  await fs.writeFile(STATE_FILE, `${JSON.stringify(state, null, 2)}\n`, 'utf8')
}

function pruneState(state, todayKey) {
  const entries = Object.entries(state).filter(([key]) => key.startsWith(todayKey))
  return Object.fromEntries(entries)
}

function runKey(dateKey, time, category) {
  return `${dateKey}:${time}:${category}`
}

function parseTerminDate(termin) {
  const rawDate = String(termin?.datum || '').trim()
  if (!rawDate) return null
  const time = String(termin?.uhrzeit || '00:00').trim() || '00:00'
  if (/^\d{4}-\d{2}-\d{2}$/.test(rawDate)) return new Date(`${rawDate}T${time.padStart(5, '0')}:00+02:00`)
  const german = rawDate.match(/^(\d{1,2})\.(\d{1,2})\.(\d{4})$/)
  if (german) {
    const [, day, month, year] = german
    return new Date(`${year}-${month.padStart(2, '0')}-${day.padStart(2, '0')}T${time.padStart(5, '0')}:00+02:00`)
  }
  const parsed = new Date(rawDate)
  return Number.isNaN(parsed.getTime()) ? null : parsed
}

function eventsOn(termine, dateKey) {
  return termine
    .map(termin => ({ termin, date: parseTerminDate(termin) }))
    .filter(entry => entry.date && berlinDateKey(entry.date) === dateKey)
    .map(entry => ({ title: entry.termin.titel, source: 'termin', item: entry.termin }))
}

function expiringNewsOn(news, dateKey) {
  return news
    .filter(item => !item?.isHidden && item?.expiresAt)
    .map(item => ({ item, date: new Date(item.expiresAt) }))
    .filter(entry => !Number.isNaN(entry.date.getTime()) && berlinDateKey(entry.date) === dateKey)
    .map(entry => ({ title: entry.item.title, source: 'news', item: entry.item }))
}

function formatNewsExpirySummary(news, fallback) {
  if (news.length === 1) return String(news[0].title || fallback).slice(0, 140)
  return `${news.length} News laufen heute ab: ${news.slice(0, 3).map(item => item.title).filter(Boolean).join(', ')}`.slice(0, 140)
}

function formatEventSummary(events, fallback) {
  if (events.length === 1) return String(events[0].title || fallback).slice(0, 140)
  return `${events.length} Einträge: ${events.slice(0, 3).map(event => event.title).filter(Boolean).join(', ')}`.slice(0, 140)
}

function matchDate(row) {
  const timestamp = Number(row?.Timestamp)
  if (Number.isFinite(timestamp) && timestamp > 0) return new Date(timestamp * 1000)
  const raw = String(row?.Termin || '').trim()
  const match = raw.match(/^(\d{1,2})\.(\d{1,2})\.(\d{4})(?:\s+(\d{1,2}:\d{2}))?/)
  if (!match) return null
  const [, day, month, year, time = '00:00'] = match
  const parsed = new Date(`${year}-${month.padStart(2, '0')}-${day.padStart(2, '0')}T${time}:00+02:00`)
  return Number.isNaN(parsed.getTime()) ? null : parsed
}

function matchTeams(row) {
  return [row?.HeimMannschaft, row?.GastMannschaft].map(value => String(value || '').trim()).filter(Boolean)
}

function matchesOn(rows, dateKey) {
  return rows
    .map(row => ({ row, date: matchDate(row) }))
    .filter(entry => entry.date && berlinDateKey(entry.date) === dateKey)
}

function matchSummary(matches, fallback) {
  if (!matches.length) return fallback
  if (matches.length === 1) {
    const teams = matchTeams(matches[0].row).join(' - ')
    const when = DATE_TIME_FORMATTER.format(matches[0].date)
    return `${when}: ${teams}`.slice(0, 140)
  }
  return `${matches.length} Punktspiele am ${dateKeyToGerman(berlinDateKey(matches[0]?.date || new Date()))}`
}

function dateKeyToGerman(dateKey) {
  const [year, month, day] = String(dateKey).split('-')
  return `${day}.${month}.${year}`
}

function teamSlugsForMatch(match) {
  return matchTeams(match.row).map(slugify)
}

async function readTeamMembers(season) {
  const fileNames = season ? [`mannschaften_${season}.csv`, 'mannschaften.csv'] : ['mannschaften.csv']
  for (const fileName of fileNames) {
    try {
      const raw = await fs.readFile(getServerDataPath('public-data', fileName), 'utf8')
      const lines = raw.split(/\r?\n/).filter(line => line.trim())
      const rows = []
      for (const line of lines.slice(1)) {
        const values = parseCsvLine(line)
        rows.push({ team: values[0] || '', captain: values[6] || '', players: values[7] || '' })
      }
      return rows
    } catch (error) {
      if (error?.code !== 'ENOENT') loggerError('[notification-scheduler] Mannschaften konnten nicht gelesen werden:', { fileName, error })
    }
  }
  return []
}

function parseCsvLine(line) {
  const values = []
  let current = ''
  let inQuotes = false
  for (let index = 0; index < line.length; index += 1) {
    const char = line[index]
    const next = line[index + 1]
    if (char === '"' && inQuotes && next === '"') {
      current += '"'
      index += 1
    } else if (char === '"') {
      inQuotes = !inQuotes
    } else if (char === ',' && !inQuotes) {
      values.push(current.trim())
      current = ''
    } else {
      current += char
    }
  }
  values.push(current.trim())
  return values
}

function personNameMatches(candidate, userName) {
  const normalizedCandidate = normalizeText(candidate)
  const normalizedUserName = normalizeText(userName)
  if (!normalizedCandidate || !normalizedUserName) return false
  if (normalizedCandidate === normalizedUserName) return true

  const candidateParts = new Set(normalizedCandidate.split(' ').filter(Boolean))
  const userParts = normalizedUserName.split(' ').filter(Boolean)
  return userParts.length >= 2 && userParts.every(part => candidateParts.has(part))
}

function ownTeamSlugsForUser(user, teamRows) {
  const name = userDisplayName(user)
  if (!normalizeText(name)) return []
  return teamRows
    .filter(row => personNameMatches(row.captain, name) ||
      String(row.players || '').replace(/\r?\n/g, ';').split(/[;,]+/).some(player => personNameMatches(player, name)))
    .map(row => slugify(row.team))
    .filter(Boolean)
}

function selectedMatchesForUser(_user, settings, matches) {
  const selected = new Set((settings.selectedTeamSlugs || []).map(slugify))
  if (selected.size === 0) return []
  return matches.filter(match => teamSlugsForMatch(match).some(slug => selected.has(slug)))
}

function ownMatchesForUser(user, settings, matches, teamRows) {
  if (settings.ownTeamMatches === false) return []
  const ownSlugs = new Set(ownTeamSlugsForUser(user, teamRows))
  if (ownSlugs.size === 0) return []
  return matches.filter(match => teamSlugsForMatch(match).some(slug => ownSlugs.has(slug)))
}

function notificationSeasonForSettings(settings, fallbackSeason) {
  return String(settings?.selectedTeamSeason || fallbackSeason || '').trim()
}

async function loadMatchContextForSeasons(seasons, dateKey, tomorrowKey) {
  const entries = await Promise.all(seasons.map(async season => {
    const [spielplan, teamRows] = await Promise.all([readSpielplanData({ season }), readTeamMembers(season)])
    const todayMatches = matchesOn(spielplan.data || [], dateKey)
    const tomorrowMatches = matchesOn(spielplan.data || [], tomorrowKey)
    return [season, { spielplan, teamRows, todayMatches, tomorrowMatches, allMatches: [...todayMatches, ...tomorrowMatches] }]
  }))
  return Object.fromEntries(entries)
}

function parseBirthday(value) {
  const raw = String(value || '').trim()
  if (!raw) return null
  const iso = raw.match(/^(\d{4})-(\d{1,2})-(\d{1,2})$/)
  if (iso) return { month: Number(iso[2]), day: Number(iso[3]) }
  const german = raw.match(/^(\d{1,2})\.(\d{1,2})(?:\.(\d{2,4}))?$/)
  if (german) return { month: Number(german[2]), day: Number(german[1]) }
  return null
}

function hasBirthdayNotificationConsent(person) {
  return person?.visibility?.showBirthday === true || person?.showBirthday === true
}

function formatBirthdaySummary(names) {
  const visibleNames = names.map(name => String(name || '').trim()).filter(Boolean)
  if (visibleNames.length === 1) return `${visibleNames[0]} hat heute Geburtstag.`
  return `Geburtstage heute: ${visibleNames.slice(0, 5).join(', ')}${visibleNames.length > 5 ? ` und ${visibleNames.length - 5} weitere` : ''}.`
}

async function birthdaysOn(dateKey) {
  const [, month, day] = dateKey.split('-').map(Number)
  const [manualMembers, users] = await Promise.all([readMembers(), readUsers()])
  const people = []
  for (const member of manualMembers) {
    if (member?.active === false) continue
    if (!hasBirthdayNotificationConsent(member)) continue
    const birthday = parseBirthday(member.geburtsdatum || member.birthday)
    if (birthday?.month === month && birthday?.day === day) {
      people.push(String(member.name || `${member.firstName || ''} ${member.lastName || ''}`.trim()).trim())
    }
  }
  for (const user of users) {
    if (isHiddenUser(user) || user?.active === false) continue
    if (!hasBirthdayNotificationConsent(user)) continue
    const birthday = parseBirthday(user.geburtsdatum || user.birthday)
    if (birthday?.month === month && birthday?.day === day) {
      people.push(userDisplayName(user))
    }
  }
  return [...new Set(people.filter(Boolean))].sort((a, b) => a.localeCompare(b, 'de'))
}

async function sendIfDue(state, dateKey, time, category, enabled, send) {
  const key = runKey(dateKey, time, category)
  if (!enabled || state[key]) return null
  const result = await send()
  state[key] = { at: new Date().toISOString(), result }
  return result
}

export async function runNotificationSchedulerTick(now = new Date()) {
  const dateKey = berlinDateKey(now)
  const time = berlinTimeKey(now)
  const users = (await readUsers()).filter(user => !isHiddenUser(user) && hasTimedSettings(user))
  const dueUsers = users.filter(user => notificationSettingsForUser(user).notificationTime === time)
  if (!dueUsers.length) return { dueUsers: 0, time, dateKey }

  let state = pruneState(await readState(), dateKey)
  const tomorrowKey = berlinDateKey(addDays(now, 1))
  const [termine, news, defaultSeason] = await Promise.all([readTermine(), readNews(), getDefaultSpielplanSeason()])
  const todayTermine = eventsOn(termine, dateKey)
  const tomorrowTermine = eventsOn(termine, tomorrowKey)
  const expiringNewsToday = expiringNewsOn(news, dateKey)
  const todayEvents = todayTermine
  const tomorrowEvents = tomorrowTermine
  const seasonsForMatches = [...new Set(dueUsers
    .map(user => notificationSeasonForSettings(notificationSettingsForUser(user), defaultSeason))
    .filter(Boolean))]
  const matchContexts = await loadMatchContextForSeasons(seasonsForMatches, dateKey, tomorrowKey)
  const todaysBirthdays = await birthdaysOn(dateKey)
  const results = {}

  results.eventsToday = await sendIfDue(state, dateKey, time, 'eventsToday', todayEvents.length > 0, () => sendPushToUsers({
    title: 'Termine heute',
    body: formatEventSummary(todayEvents, 'Heute stehen Termine an.'),
    data: { type: 'events_today', date: dateKey },
    predicate: (user, settings) => settings.notificationTime === time && settings.eventsToday,
    failureLabel: 'FCM Termine-heute-Push'
  }))

  results.expiringNews = await sendIfDue(state, dateKey, time, 'expiringNews', expiringNewsToday.length > 0, () => sendPushToUsers({
    title: 'News laufen heute ab',
    body: formatNewsExpirySummary(expiringNewsToday, 'Heute laufen News ab.'),
    data: { type: 'news_expiring', date: dateKey },
    predicate: (_user, settings) => settings.notificationTime === time && settings.newNews && !settings.eventsToday,
    failureLabel: 'FCM News-Ablauf-Push'
  }))

  results.eventsTomorrow = await sendIfDue(state, dateKey, time, 'eventsTomorrow', tomorrowEvents.length > 0, () => sendPushToUsers({
    title: 'Termine morgen',
    body: formatEventSummary(tomorrowEvents, 'Morgen stehen Termine an.'),
    data: { type: 'events_tomorrow', date: tomorrowKey },
    predicate: (user, settings) => settings.notificationTime === time && settings.eventsTomorrow,
    failureLabel: 'FCM Termine-morgen-Push'
  }))

  const allResults = []
  const selectedResults = []
  const ownResults = []
  for (const [season, context] of Object.entries(matchContexts)) {
    allResults.push(await sendIfDue(state, dateKey, time, 'allTeamMatches:' + season, context.allMatches.length > 0, () => sendPushToUsers({
      title: 'Punktspiele',
      body: matchSummary(context.allMatches, 'Es stehen Punktspiele an.'),
      data: { type: 'team_matches', date: dateKey, season },
      predicate: (user, settings) => settings.notificationTime === time &&
        notificationSeasonForSettings(settings, defaultSeason) === season &&
        settings.allTeamMatches,
      failureLabel: 'FCM Punktspiele-Push'
    })))

    selectedResults.push(await sendIfDue(state, dateKey, time, 'selectedTeamMatches:' + season, context.allMatches.length > 0, () => sendPushToUsers({
      title: 'Punktspiele deiner Auswahl',
      body: 'Für eine abonnierte Mannschaft steht ein Punktspiel an.',
      bodyForUser: (user, settings) => matchSummary(selectedMatchesForUser(user, settings, context.allMatches), 'Für eine abonnierte Mannschaft steht ein Punktspiel an.'),
      data: { type: 'team_matches', date: dateKey, season },
      predicate: (user, settings) => settings.notificationTime === time &&
        notificationSeasonForSettings(settings, defaultSeason) === season &&
        settings.allTeamMatches === false &&
        selectedMatchesForUser(user, settings, context.allMatches).length > 0,
      failureLabel: 'FCM Mannschaftsauswahl-Push'
    })))

    ownResults.push(await sendIfDue(state, dateKey, time, 'ownTeamMatches:' + season, context.allMatches.length > 0, () => sendPushToUsers({
      title: 'Punktspiel deiner Mannschaft',
      body: 'Für deine Mannschaft steht ein Punktspiel an.',
      bodyForUser: (user, settings) => matchSummary(ownMatchesForUser(user, settings, context.allMatches, context.teamRows), 'Für deine Mannschaft steht ein Punktspiel an.'),
      data: { type: 'team_matches', date: dateKey, season },
      predicate: (user, settings) => settings.notificationTime === time &&
        notificationSeasonForSettings(settings, defaultSeason) === season &&
        settings.allTeamMatches === false &&
        selectedMatchesForUser(user, settings, context.allMatches).length === 0 &&
        ownMatchesForUser(user, settings, context.allMatches, context.teamRows).length > 0,
      failureLabel: 'FCM eigene-Mannschaft-Push'
    })))
  }
  results.allTeamMatches = allResults.some(Boolean)
  results.selectedTeamMatches = selectedResults.some(Boolean)
  results.ownTeamMatches = ownResults.some(Boolean)

  results.birthdays = await sendIfDue(state, dateKey, time, 'birthdays', todaysBirthdays.length > 0, () => sendPushToUsers({
    title: 'Geburtstage heute',
    body: formatBirthdaySummary(todaysBirthdays),
    data: { type: 'birthdays', date: dateKey },
    predicate: (_user, settings) => settings.notificationTime === time && settings.birthdays,
    failureLabel: 'FCM Geburtstags-Push'
  }))

  await writeState(state)
  loggerInfo('[notification-scheduler] Lauf abgeschlossen', { dateKey, time, dueUsers: dueUsers.length, results })
  return { dateKey, time, dueUsers: dueUsers.length, results }
}