import { ChatGoogleGenerativeAI } from "@langchain/google-genai";
import { prisma as db } from "@repo/db/client";
import { storage } from "../storage";
import {
  type ConversationStage,
  setPendingReschedule,
  getPendingReschedule,
  clearPendingReschedule,
} from "./aiHandoffStore";

// ── Date helpers ──────────────────────────────────────────────────────────────

const MONTHS = [
  "January","February","March","April","May","June",
  "July","August","September","October","November","December",
];
const DAYS = ["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"];

function formattedDate(d: Date): string {
  return `${DAYS[d.getDay()]}, ${MONTHS[d.getMonth()]} ${d.getDate()}`;
}

/** Get the day-of-week (0=Sun…6=Sat) of the patient's next scheduled appointment. */
async function getAppointmentDow(patientId: number): Promise<number> {
  const today = new Date(); today.setHours(0, 0, 0, 0);
  const appt = await db.appointment.findFirst({
    where: { patientId, status: "scheduled", date: { gte: today } },
    orderBy: { date: "asc" },
    select: { date: true },
  });
  if (!appt) return -1;
  return new Date(appt.date).getUTCDay();
}

function getTomorrow(): string {
  const t = new Date();
  t.setDate(t.getDate() + 1);
  return formattedDate(t);
}

function getNextWeekDays(): { mon: string; tue: string; wed: string } {
  const today = new Date();
  const dow = today.getDay();
  // Days until next Monday (always at least 1 day away, never 0)
  const daysToMon = (8 - dow) % 7 || 7;
  const mon = new Date(today); mon.setDate(today.getDate() + daysToMon);
  const tue = new Date(mon);   tue.setDate(mon.getDate() + 1);
  const wed = new Date(mon);   wed.setDate(mon.getDate() + 2);
  return { mon: formattedDate(mon), tue: formattedDate(tue), wed: formattedDate(wed) };
}

// ── Date objects for rescheduling ─────────────────────────────────────────────

function getTomorrowDate(): { date: Date; label: string } {
  const d = new Date();
  d.setDate(d.getDate() + 1);
  d.setUTCHours(0, 0, 0, 0);
  return { date: d, label: formattedDate(new Date(d.getTime() + d.getTimezoneOffset() * 60000)) };
}

function getNextWeekDateObjects(): { mon: { date: Date; label: string }; tue: { date: Date; label: string }; wed: { date: Date; label: string } } {
  const today = new Date();
  const dow   = today.getDay();
  const daysToMon = (8 - dow) % 7 || 7;

  const mkDate = (offset: number) => {
    const d = new Date(today);
    d.setDate(today.getDate() + offset);
    d.setUTCHours(0, 0, 0, 0);
    const label = formattedDate(new Date(today.getFullYear(), today.getMonth(), today.getDate() + offset));
    return { date: d, label };
  };
  return { mon: mkDate(daysToMon), tue: mkDate(daysToMon + 1), wed: mkDate(daysToMon + 2) };
}

// ── Time parsing ──────────────────────────────────────────────────────────────

/** Parse patient's time preference into 24-h "HH:MM" string or null. */
async function parseTime(message: string, apiKey: string): Promise<string | null> {
  const t = message.toLowerCase();

  // Keyword shortcuts
  if (/\bmorning\b|mañana|manhã|上午|صباح|maten/i.test(t))   return "09:00";
  if (/\bafternoon\b|tarde|après-midi|下午|مساء|aprèmidi/i.test(t)) return "13:00";

  // Numeric patterns: "10am", "10:30", "2pm", "14:00"
  const ampm  = t.match(/\b(\d{1,2})(?::(\d{2}))?\s*(am|pm)\b/);
  const clock = t.match(/\b([01]?\d|2[0-3]):([0-5]\d)\b/);

  if (ampm) {
    let h = parseInt(ampm[1]!);
    const m = ampm[2] ? parseInt(ampm[2]) : 0;
    if (ampm[3] === "pm" && h < 12) h += 12;
    if (ampm[3] === "am" && h === 12) h = 0;
    return `${String(h).padStart(2, "0")}:${String(m).padStart(2, "0")}`;
  }
  if (clock) return clock[0]!;

  // LLM fallback
  try {
    const llm = new ChatGoogleGenerativeAI({ model: "gemini-1.5-flash", apiKey });
    const res = await llm.invoke([
      { role: "system", content: 'Extract the time from the message. Return ONLY a 24-hour time in "HH:MM" format (e.g., "10:00", "14:30"). If no time is mentioned, return "null".' },
      { role: "user",   content: message },
    ]);
    const raw = String(res.content).trim();
    if (/^([01]?\d|2[0-3]):[0-5]\d$/.test(raw)) return raw;
  } catch { /* fall through */ }

  return null;
}

// ── Appointment update ────────────────────────────────────────────────────────

async function moveAppointment(
  patientId: number,
  newDate: Date,
  newStartTime: string,   // "HH:MM"
): Promise<string> {
  const today = new Date(); today.setHours(0, 0, 0, 0);
  const appt = await db.appointment.findFirst({
    where: { patientId, status: "scheduled", date: { gte: today } },
    orderBy: { date: "asc" },
  });
  if (!appt) return "no_appointment";

  // Preserve original duration
  const [sh, sm] = appt.startTime.split(":").map(Number);
  const [eh, em] = appt.endTime.split(":").map(Number);
  const durationMin = (eh! * 60 + em!) - (sh! * 60 + sm!);
  const [nh, nm] = newStartTime.split(":").map(Number);
  const endTotalMin = nh! * 60 + nm! + durationMin;
  const newEndTime = `${String(Math.floor(endTotalMin / 60)).padStart(2, "0")}:${String(endTotalMin % 60).padStart(2, "0")}`;

  await storage.updateAppointment(appt.id, {
    date:      newDate,
    startTime: newStartTime,
    endTime:   newEndTime,
    status:    "scheduled",
  } as any);

  return "ok";
}

// ── Intent classifiers ────────────────────────────────────────────────────────

function yes(t: string) {
  return /\b(yes|yeah|yep|sure|ok|okay|please|absolutely|definitely|sí|si|sim|好的|نعم|wi|oke)\b/i.test(t);
}
function no(t: string) {
  return /\b(no|nope|not|don't|won't|can't|لا|pa ka|não)\b/i.test(t);
}
function wantsAsap(t: string) {
  return /\b(asap|soon|soonest|next day|tomorrow|quick|fastest|earliest|lo antes|mañana|amanhã|明天|明日|غدًا|demen)\b/i.test(t);
}
function wantsNextWeek(t: string) {
  return /\b(next week|semana|prochain|prochaine|下周|下週|الأسبوع القادم|semèn pwochèn)\b/i.test(t);
}
function prefersMonday(t: string)    { return /monday|lunes|segunda|周一|月曜|الاثنين|lendi/i.test(t); }
function prefersTuesday(t: string)   { return /tuesday|martes|terça|周二|火曜|الثلاثاء|madi/i.test(t); }
function prefersWednesday(t: string) { return /wednesday|miércoles|quarta|周三|水曜|الأربعاء|mèkredi/i.test(t); }

// ── LLM helper ────────────────────────────────────────────────────────────────

async function llmReply(system: string, user: string, fallback: string, apiKey: string): Promise<string> {
  try {
    const llm = new ChatGoogleGenerativeAI({ model: "gemini-1.5-flash", apiKey });
    const res = await llm.invoke([
      { role: "system", content: system },
      { role: "user",   content: user },
    ]);
    return String(res.content).trim() || fallback;
  } catch {
    return fallback;
  }
}

// ── Transfer fallback ─────────────────────────────────────────────────────────

const TRANSFER: Record<string, string> = {
  English:          "Our office staff will contact you shortly to help with rescheduling.",
  Spanish:          "El personal de nuestra oficina le contactará pronto para ayudarle a reprogramar.",
  Portuguese:       "Nossa equipe entrará em contato em breve para ajudá-lo a reagendar.",
  Mandarin:         "我们的工作人员将很快与您联系以帮助重新安排预约。",
  Cantonese:        "我們的工作人員將很快聯絡您以協助重新安排預約。",
  Arabic:           "سيتصل بك موظفو مكتبنا قريباً لمساعدتك في إعادة الجدولة.",
  "Haitian Creole": "Anplwaye biwo nou yo pral kontakte ou byento pou ede ou repwograme.",
};

// ── Main step function ────────────────────────────────────────────────────────

export async function runRescheduleStep(
  message:   string,
  stage:     ConversationStage,
  language:  string,
  patientId: number,
  apiKey:    string,
  userId:    number = 0,
): Promise<{ reply: string; nextStage: ConversationStage }> {

  const lang = language || "English";
  const t    = message.toLowerCase();
  const tx   = TRANSFER[lang] ?? TRANSFER["English"]!;

  // ── asked_reschedule_confirm: patient answered "Would you like to reschedule?" ──
  if (stage === "asked_reschedule_confirm") {
    if (no(t)) {
      const fallbacks: Record<string, string> = {
        English:          "No problem! Feel free to reach out whenever you're ready. Have a great day!",
        Spanish:          "¡Sin problema! No dude en contactarnos cuando esté listo. ¡Que tenga un buen día!",
        Portuguese:       "Sem problema! Entre em contato quando estiver pronto. Tenha um ótimo dia!",
        Mandarin:         "没关系！随时联系我们。祝您有美好的一天！",
        Cantonese:        "沒問題！隨時聯繫我們。祝您有美好的一天！",
        Arabic:           "لا بأس! لا تتردد في التواصل معنا متى كنت مستعداً. أتمنى لك يوماً رائعاً!",
        "Haitian Creole": "Pa gen pwoblèm! Kontakte nou nenpòt ki lè ou prèt. Pase yon bèl jounen!",
      };
      const fallback = fallbacks[lang] ?? fallbacks["English"]!;
      const reply = await llmReply(
        `You are a friendly dental office assistant. The patient does not want to reschedule. Write a warm, brief closing message in ${lang}. 1 sentence, no formatting.`,
        `Patient said: "${message}"`, fallback, apiKey
      );
      return { reply, nextStage: "done" };
    }

    if (yes(t)) {
      // Check if original appointment was Mon–Thu (days 1–4)
      const dow = await getAppointmentDow(patientId);
      const isMonToThu = dow >= 1 && dow <= 4;

      if (isMonToThu) {
        // Offer ASAP or next week
        const fallbacks: Record<string, string> = {
          English:          "Would you like to reschedule as soon as possible, or would you prefer next week?",
          Spanish:          "¿Le gustaría reprogramar lo antes posible, o prefiere la semana que viene?",
          Portuguese:       "Gostaria de reagendar o mais rápido possível, ou prefere a semana que vem?",
          Mandarin:         "您想尽快重新安排预约，还是下周更方便？",
          Cantonese:        "您想盡快重新安排預約，還是下週更方便？",
          Arabic:           "هل تفضل إعادة الجدولة في أقرب وقت ممكن، أم تفضل الأسبوع القادم؟",
          "Haitian Creole": "Èske ou ta renmen repwograme pi vit posib, oswa ou prefere semèn pwochèn?",
        };
        const fallback = fallbacks[lang] ?? fallbacks["English"]!;
        const reply = await llmReply(
          `You are a friendly dental office assistant. The patient wants to reschedule. Their original appointment was on a weekday. Ask in ${lang} whether they prefer to reschedule as soon as possible or next week. 1 sentence, no formatting.`,
          `Patient said: "${message}"`, fallback, apiKey
        );
        return { reply, nextStage: "asked_reschedule_preference" };
      } else {
        // Original appointment was Fri/Sat/Sun — go straight to next week
        const { mon, tue, wed } = getNextWeekDays();
        const fallbacks: Record<string, string> = {
          English:          `I can schedule you for next week. Would ${mon}, ${tue}, or ${wed} work for you?`,
          Spanish:          `Puedo programarle para la semana que viene. ¿Le vendría bien el ${mon}, ${tue} o el ${wed}?`,
          Portuguese:       `Posso agendá-lo para a semana que vem. ${mon}, ${tue} ou ${wed} seria bom para você?`,
          Mandarin:         `我可以安排您在下周预约。${mon}、${tue} 或 ${wed} 方便吗？`,
          Cantonese:        `我可以安排您在下週預約。${mon}、${tue} 或 ${wed} 方便嗎？`,
          Arabic:           `يمكنني جدولتك للأسبوع القادم. هل ${mon} أو ${tue} أو ${wed} مناسب لك؟`,
          "Haitian Creole": `Mwen ka pwograme ou pou semèn pwochèn. ${mon}, ${tue}, oswa ${wed} ka travay pou ou?`,
        };
        const fallback = fallbacks[lang] ?? fallbacks["English"]!;
        const reply = await llmReply(
          `You are a friendly dental office assistant. Offer the patient next week's Monday (${mon}), Tuesday (${tue}), or Wednesday (${wed}) in ${lang}. 1-2 sentences, no formatting.`,
          `Patient wants to reschedule.`, fallback, apiKey
        );
        return { reply, nextStage: "asked_reschedule_next_week" };
      }
    }

    return { reply: tx, nextStage: "done" };
  }

  // ── asked_reschedule_preference: patient chose ASAP or next week ──────────
  if (stage === "asked_reschedule_preference") {
    if (wantsAsap(t) || yes(t)) {
      const tomorrow = getTomorrow();
      const fallbacks: Record<string, string> = {
        English:          `Can you come in tomorrow, ${tomorrow}?`,
        Spanish:          `¿Podría venir mañana, ${tomorrow}?`,
        Portuguese:       `Você pode vir amanhã, ${tomorrow}?`,
        Mandarin:         `您明天（${tomorrow}）能来吗？`,
        Cantonese:        `您明天（${tomorrow}）能來嗎？`,
        Arabic:           `هل يمكنك الحضور غداً، ${tomorrow}؟`,
        "Haitian Creole": `Èske ou ka vini demen, ${tomorrow}?`,
      };
      const fallback = fallbacks[lang] ?? fallbacks["English"]!;
      const reply = await llmReply(
        `You are a friendly dental office assistant. Ask the patient in ${lang} if they can come in tomorrow, ${tomorrow}. 1 sentence, no formatting.`,
        `Patient wants to reschedule ASAP.`, fallback, apiKey
      );
      return { reply, nextStage: "asked_reschedule_asap" };
    }

    if (wantsNextWeek(t)) {
      const { mon, tue, wed } = getNextWeekDays();
      const fallbacks: Record<string, string> = {
        English:          `I can schedule you for next week. Would ${mon}, ${tue}, or ${wed} work for you?`,
        Spanish:          `Puedo programarle para la semana que viene. ¿Le vendría bien el ${mon}, ${tue} o el ${wed}?`,
        Portuguese:       `Posso agendá-lo para a semana que vem. ${mon}, ${tue} ou ${wed} seria bom para você?`,
        Mandarin:         `我可以安排您在下周预约。${mon}、${tue} 或 ${wed} 方便吗？`,
        Cantonese:        `我可以安排您在下週預約。${mon}、${tue} 或 ${wed} 方便嗎？`,
        Arabic:           `يمكنني جدولتك للأسبوع القادم. هل ${mon} أو ${tue} أو ${wed} مناسب لك؟`,
        "Haitian Creole": `Mwen ka pwograme ou pou semèn pwochèn. ${mon}, ${tue}, oswa ${wed} ka travay pou ou?`,
      };
      const fallback = fallbacks[lang] ?? fallbacks["English"]!;
      const reply = await llmReply(
        `You are a friendly dental office assistant. Offer next week's Monday (${mon}), Tuesday (${tue}), or Wednesday (${wed}) in ${lang}. 1-2 sentences, no formatting.`,
        `Patient prefers next week.`, fallback, apiKey
      );
      return { reply, nextStage: "asked_reschedule_next_week" };
    }

    return { reply: tx, nextStage: "done" };
  }

  // ── asked_reschedule_asap: patient answered "Can you come tomorrow?" ───────
  if (stage === "asked_reschedule_asap") {
    if (yes(t)) {
      const { date, label } = getTomorrowDate();
      setPendingReschedule(userId, patientId, { newDate: date, dayLabel: label });

      const fallbacks: Record<string, string> = {
        English:          `${label} it is! Would you prefer morning (9am–12pm) or afternoon (1pm–5pm)?`,
        Spanish:          `¡${label} perfecto! ¿Prefiere la mañana (9am–12pm) o la tarde (1pm–5pm)?`,
        Portuguese:       `${label} ótimo! Você prefere manhã (9h–12h) ou tarde (13h–17h)?`,
        Mandarin:         `${label}，太好了！您想预约上午（9点–12点）还是下午（1点–5点）？`,
        Cantonese:        `${label}，太好了！您想預約上午（9點–12點）還是下午（1點–5點）？`,
        Arabic:           `${label} ممتاز! هل تفضل الصباح (9ص–12م) أم بعد الظهر (1م–5م)؟`,
        "Haitian Creole": `${label} pafè! Èske ou prefere maten (9am–12pm) oswa apremidi (1pm–5pm)?`,
      };
      const fallback = fallbacks[lang] ?? fallbacks["English"]!;
      const reply = await llmReply(
        `You are a friendly dental office assistant. The patient confirmed ${label}. Ask in ${lang} whether they prefer morning (9am-12pm) or afternoon (1pm-5pm). 1 sentence, no formatting.`,
        `Patient confirmed tomorrow.`, fallback, apiKey
      );
      return { reply, nextStage: "asked_reschedule_time" };
    }

    if (no(t)) {
      // Can't make tomorrow — offer next week instead
      const { mon, tue, wed } = getNextWeekDays();
      const fallbacks: Record<string, string> = {
        English:          `No problem! What about next week? Would ${mon}, ${tue}, or ${wed} work for you?`,
        Spanish:          `¡Sin problema! ¿Qué le parece la semana que viene? ¿Le vendría bien el ${mon}, ${tue} o el ${wed}?`,
        Portuguese:       `Sem problema! E na semana que vem? ${mon}, ${tue} ou ${wed} seria bom?`,
        Mandarin:         `没关系！下周怎么样？${mon}、${tue} 或 ${wed} 方便吗？`,
        Cantonese:        `沒問題！下週怎麼樣？${mon}、${tue} 或 ${wed} 方便嗎？`,
        Arabic:           `لا بأس! ماذا عن الأسبوع القادم؟ هل ${mon} أو ${tue} أو ${wed} يناسبك؟`,
        "Haitian Creole": `Pa gen pwoblèm! Ki sa ki dire semèn pwochèn? ${mon}, ${tue}, oswa ${wed} ka travay?`,
      };
      const fallback = fallbacks[lang] ?? fallbacks["English"]!;
      const reply = await llmReply(
        `You are a friendly dental office assistant. The patient cannot come tomorrow. Offer next week: ${mon}, ${tue}, or ${wed} in ${lang}. 1-2 sentences, no formatting.`,
        `Patient can't come tomorrow.`, fallback, apiKey
      );
      return { reply, nextStage: "asked_reschedule_next_week" };
    }

    return { reply: tx, nextStage: "done" };
  }

  // ── asked_reschedule_next_week: patient choosing Mon/Tue/Wed ─────────────
  if (stage === "asked_reschedule_next_week") {
    const nwd = getNextWeekDateObjects();
    let chosen: { date: Date; label: string } | null = null;
    if (prefersMonday(t))    chosen = nwd.mon;
    if (prefersTuesday(t))   chosen = nwd.tue;
    if (prefersWednesday(t)) chosen = nwd.wed;

    if (chosen) {
      setPendingReschedule(userId, patientId, { newDate: chosen.date, dayLabel: chosen.label });

      const day = chosen.label;
      const fallbacks: Record<string, string> = {
        English:          `${day} works! Would you prefer morning (9am–12pm) or afternoon (1pm–5pm)?`,
        Spanish:          `¡${day} perfecto! ¿Prefiere la mañana (9am–12pm) o la tarde (1pm–5pm)?`,
        Portuguese:       `${day} ótimo! Você prefere manhã (9h–12h) ou tarde (13h–17h)?`,
        Mandarin:         `${day}，好的！您想预约上午（9点–12点）还是下午（1点–5点）？`,
        Cantonese:        `${day}，好的！您想預約上午（9點–12點）還是下午（1點–5點）？`,
        Arabic:           `${day} رائع! هل تفضل الصباح (9ص–12م) أم بعد الظهر (1م–5م)؟`,
        "Haitian Creole": `${day} pafè! Èske ou prefere maten (9am–12pm) oswa apremidi (1pm–5pm)?`,
      };
      const fallback = fallbacks[lang] ?? fallbacks["English"]!;
      const reply = await llmReply(
        `You are a friendly dental office assistant. The patient chose ${day}. Ask in ${lang} whether they prefer morning (9am-12pm) or afternoon (1pm-5pm). 1 sentence, no formatting.`,
        `Patient chose ${day}.`, fallback, apiKey
      );
      return { reply, nextStage: "asked_reschedule_time" };
    }

    // Day not clearly detected — ask again with the specific options
    const { mon, tue, wed } = getNextWeekDays();
    const fallbacks: Record<string, string> = {
      English:          `Which day works best — ${mon}, ${tue}, or ${wed}?`,
      Spanish:          `¿Qué día le viene mejor — el ${mon}, ${tue} o el ${wed}?`,
      Portuguese:       `Qual dia é melhor — ${mon}, ${tue} ou ${wed}?`,
      Mandarin:         `哪天最方便——${mon}、${tue} 还是 ${wed}？`,
      Cantonese:        `哪天最方便——${mon}、${tue} 還是 ${wed}？`,
      Arabic:           `أي يوم هو الأفضل لك — ${mon} أو ${tue} أو ${wed}؟`,
      "Haitian Creole": `Ki jou ki pi bon — ${mon}, ${tue}, oswa ${wed}?`,
    };
    const fallback = fallbacks[lang] ?? fallbacks["English"]!;
    return { reply: fallback, nextStage: "asked_reschedule_next_week" };
  }

  // ── asked_reschedule_time: patient picked morning / afternoon / specific time ──
  if (stage === "asked_reschedule_time") {
    const pending = getPendingReschedule(userId, patientId);

    if (!pending) {
      // Edge case: lost state — fall back gracefully
      return { reply: tx, nextStage: "done" };
    }

    const startTime = await parseTime(message, apiKey);

    if (!startTime) {
      // Couldn't parse time — ask again
      const fallbacks: Record<string, string> = {
        English:          "I didn't catch the time. Would you prefer morning (9am–12pm) or afternoon (1pm–5pm)?",
        Spanish:          "No entendí la hora. ¿Prefiere la mañana (9am–12pm) o la tarde (1pm–5pm)?",
        Portuguese:       "Não entendi o horário. Você prefere manhã (9h–12h) ou tarde (13h–17h)?",
        Mandarin:         "我没听清时间。您想预约上午（9点–12点）还是下午（1点–5点）？",
        Cantonese:        "我沒聽清時間。您想預約上午（9點–12點）還是下午（1點–5點）？",
        Arabic:           "لم أفهم الوقت. هل تفضل الصباح (9ص–12م) أم بعد الظهر (1م–5م)؟",
        "Haitian Creole": "Mwen pa konprann lè a. Èske ou prefere maten (9am–12pm) oswa apremidi (1pm–5pm)?",
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_time" };
    }

    // Update the appointment in the database
    const updateResult = await moveAppointment(patientId, pending.newDate, startTime);
    clearPendingReschedule(userId, patientId);

    const [h, m] = startTime.split(":").map(Number);
    const h12    = h! % 12 || 12;
    const ampm   = h! >= 12 ? "pm" : "am";
    const timeLabel = `${h12}:${String(m!).padStart(2, "0")} ${ampm}`;
    const apptLabel = `${pending.dayLabel} at ${timeLabel}`;

    if (updateResult === "no_appointment") {
      const fallbacks: Record<string, string> = {
        English:          `I couldn't find your appointment to update. Our staff will contact you to confirm ${apptLabel}.`,
        Spanish:          `No encontré su cita para actualizar. El personal le contactará para confirmar el ${apptLabel}.`,
        Portuguese:       `Não encontrei sua consulta para atualizar. Nossa equipe entrará em contato para confirmar ${apptLabel}.`,
        Mandarin:         `我找不到您的预约进行更新。我们的工作人员将联系您确认${apptLabel}。`,
        Cantonese:        `我找不到您的預約進行更新。我們的工作人員將聯絡您確認${apptLabel}。`,
        Arabic:           `لم أجد موعدك لتحديثه. سيتصل بك موظفونا لتأكيد ${apptLabel}.`,
        "Haitian Creole": `Mwen pa jwenn randevou ou pou mete ajou. Anplwaye nou yo pral kontakte ou pou konfime ${apptLabel}.`,
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "done" };
    }

    // Success
    const fallbacks: Record<string, string> = {
      English:          `Your appointment has been moved to ${apptLabel}. See you then!`,
      Spanish:          `Su cita ha sido cambiada al ${apptLabel}. ¡Hasta entonces!`,
      Portuguese:       `Sua consulta foi remarcada para ${apptLabel}. Até lá!`,
      Mandarin:         `您的预约已更改为${apptLabel}。到时见！`,
      Cantonese:        `您的預約已更改為${apptLabel}。到時見！`,
      Arabic:           `تم تغيير موعدك إلى ${apptLabel}. نراك قريباً!`,
      "Haitian Creole": `Randevou ou a deplase ale nan ${apptLabel}. N'ap wè ou lè sa a!`,
    };
    const fallback = fallbacks[lang] ?? fallbacks["English"]!;
    const reply = await llmReply(
      `You are a friendly dental office assistant. The patient's appointment has been successfully rescheduled to ${apptLabel}. Confirm in ${lang} with enthusiasm. 1 sentence, no formatting.`,
      `Appointment moved to ${apptLabel}.`, fallback, apiKey
    );
    return { reply, nextStage: "done" };
  }

  return { reply: tx, nextStage: "done" };
}