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()}`;
}

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();
  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) };
}

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() {
  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) };
}

/** Format "HH:MM" (24-h) → "H:MM am/pm" */
export function timeLabel(hhmm: string): string {
  const [h, m] = hhmm.split(":").map(Number);
  const h12 = (h! % 12) || 12;
  const ampm = (h! >= 12) ? "pm" : "am";
  return `${h12}:${String(m!).padStart(2, "0")} ${ampm}`;
}

// ── Datetime helpers ─────────────────────────────────────────────────────────

/** Returns true if the message contains an explicit time (not just a date). */
function messageHasTime(msg: string): boolean {
  return (
    /\b\d{1,2}(?::\d{2})?\s*(?:am|pm)\b/i.test(msg) ||
    /\b([01]?\d|2[0-3]):[0-5]\d\b/.test(msg)         ||
    /\b(morning|afternoon|evening|mañana|tarde|manhã|上午|下午|صباح|مساء|maten|aprèmidi)\b/i.test(msg)
  );
}

/**
 * Parse only a date (no time) from a message like "5/18" or "next Monday".
 * Returns a UTC-midnight Date and a date-only display label, or null.
 */
export async function parseDateOnlyFromMessage(
  message: string,
  apiKey: string,
): Promise<{ date: Date; dateLabel: string } | null> {
  const now      = new Date();
  const todayStr = now.toLocaleDateString("en-CA");

  // Regex: M/D, M-D, MM/DD patterns
  const slashMatch = message.match(/\b(\d{1,2})[\/\-](\d{1,2})(?:[\/\-](\d{2,4}))?\b/);
  if (slashMatch) {
    const mo = parseInt(slashMatch[1]!);
    const dy = parseInt(slashMatch[2]!);
    let yr   = slashMatch[3]
      ? (slashMatch[3].length === 2 ? 2000 + parseInt(slashMatch[3]) : parseInt(slashMatch[3]))
      : now.getFullYear();
    const candidate = new Date(`${yr}-${String(mo).padStart(2,"0")}-${String(dy).padStart(2,"0")}T00:00:00`);
    if (candidate <= now) yr += 1;
    const dateStr   = `${yr}-${String(mo).padStart(2,"0")}-${String(dy).padStart(2,"0")}`;
    const parsedDate = new Date(dateStr + "T00:00:00.000Z");
    if (!isNaN(parsedDate.getTime())) {
      const local     = new Date(dateStr + "T00:00:00");
      const dateLabel = `${DAYS[local.getDay()]!}, ${MONTHS[local.getMonth()]!} ${local.getDate()}`;
      return { date: parsedDate, dateLabel };
    }
  }

  // Gemini fallback for "next Monday", "Tuesday", etc.
  try {
    const llm = new ChatGoogleGenerativeAI({ model: "gemini-1.5-flash", apiKey });
    const res = await llm.invoke([
      {
        role: "system",
        content:
          `Today is ${todayStr}. Extract only the date from the patient message.
Return ONLY raw JSON: {"date":"YYYY-MM-DD"}
- date must be a future date after ${todayStr}.
- For relative names like "Monday" or "next Tuesday", use the next upcoming calendar date.
- If no valid future date found, return {"date":null}.`,
      },
      { role: "user", content: message },
    ]);
    const jsonMatch = String(res.content).match(/\{[\s\S]*?"date"[\s\S]*?\}/);
    if (!jsonMatch) return null;
    const json = JSON.parse(jsonMatch[0]);
    if (!json.date || json.date === "null") return null;
    const dateStr    = String(json.date).trim();
    const parsedDate = new Date(dateStr + "T00:00:00.000Z");
    if (isNaN(parsedDate.getTime())) return null;
    const local     = new Date(dateStr + "T00:00:00");
    const dateLabel = `${DAYS[local.getDay()]!}, ${MONTHS[local.getMonth()]!} ${local.getDate()}`;
    return { date: parsedDate, dateLabel };
  } catch {
    return null;
  }
}

// ── Datetime parsing ──────────────────────────────────────────────────────────

/**
 * Parse a natural-language date + time preference from a patient SMS.
 * Returns a future Date (UTC midnight), a 24-h startTime string, and a display label.
 */
async function parseDatetimeFromMessage(
  message: string,
  apiKey: string,
): Promise<{ date: Date; startTime: string; displayLabel: string } | null> {
  const now     = new Date();
  const todayStr = now.toLocaleDateString("en-CA"); // YYYY-MM-DD local

  // ── Step 1: regex pre-processing for common formats ───────────────────────
  // Extract time (handles "10am", "10:30am", "2 pm", "14:00", "morning", "afternoon")
  let preTime: string | null = null;
  const ampmMatch = message.match(/\b(\d{1,2})(?::(\d{2}))?\s*(am|pm)\b/i);
  if (ampmMatch) {
    let h = parseInt(ampmMatch[1]!);
    const m = ampmMatch[2] ? parseInt(ampmMatch[2]) : 0;
    const period = ampmMatch[3]!.toLowerCase();
    if (period === "pm" && h < 12) h += 12;
    if (period === "am" && h === 12) h = 0;
    preTime = `${String(h).padStart(2,"0")}:${String(m).padStart(2,"0")}`;
  } else if (/\bmorning\b/i.test(message))   preTime = "09:00";
  else if (/\bafternoon\b/i.test(message))   preTime = "13:00";

  // Extract date for M/D, M-D, MM/DD, MM-DD, M/D/YYYY patterns
  let preDate: string | null = null;
  const slashMatch = message.match(/\b(\d{1,2})[\/\-](\d{1,2})(?:[\/\-](\d{2,4}))?\b/);
  if (slashMatch) {
    const mo = parseInt(slashMatch[1]!);
    const dy = parseInt(slashMatch[2]!);
    let yr   = slashMatch[3]
      ? (slashMatch[3].length === 2 ? 2000 + parseInt(slashMatch[3]) : parseInt(slashMatch[3]))
      : now.getFullYear();
    // If the resulting date is in the past, assume next year
    const candidate = new Date(`${yr}-${String(mo).padStart(2,"0")}-${String(dy).padStart(2,"0")}T00:00:00`);
    if (candidate <= now) yr += 1;
    preDate = `${yr}-${String(mo).padStart(2,"0")}-${String(dy).padStart(2,"0")}`;
  }

  // If regex resolved both date and time, return immediately — no AI call needed
  if (preDate && preTime) {
    const parsedDate = new Date(preDate + "T00:00:00.000Z");
    if (!isNaN(parsedDate.getTime())) {
      const localDate   = new Date(preDate + "T00:00:00");
      const displayLabel = `${DAYS[localDate.getDay()]!}, ${MONTHS[localDate.getMonth()]!} ${localDate.getDate()} at ${timeLabel(preTime)}`;
      return { date: parsedDate, startTime: preTime, displayLabel };
    }
  }

  // ── Step 2: fall back to Google AI for natural language ───────────────────
  try {
    const llm = new ChatGoogleGenerativeAI({ model: "gemini-1.5-flash", apiKey });
    const res = await llm.invoke([
      {
        role: "system",
        content:
          `Today is ${todayStr}. Extract the preferred appointment date and time from the patient's message.
Return ONLY a raw JSON object — no markdown, no code block, no explanation:
{"date":"YYYY-MM-DD","time":"HH:MM"}
Rules:
- date must be a future date after ${todayStr}, in YYYY-MM-DD format.
- time must be 24-hour HH:MM format. "morning" → "09:00", "afternoon" → "13:00".
- For relative names like "Monday" or "next Tuesday", use the next upcoming calendar date.
- If no time is mentioned, use "09:00".
- If no valid future date can be found, return {"date":null,"time":null}.`,
      },
      { role: "user", content: message },
    ]);

    // Robustly extract the JSON object from any wrapping text Gemini might add
    const raw = String(res.content);
    const jsonMatch = raw.match(/\{[\s\S]*?"date"[\s\S]*?\}/);
    if (!jsonMatch) return null;
    const json = JSON.parse(jsonMatch[0]);
    if (!json.date || json.date === "null") return null;

    // Normalise date to YYYY-MM-DD
    const dateStr   = String(json.date).trim();
    const parsedDate = new Date(dateStr + "T00:00:00.000Z");
    if (isNaN(parsedDate.getTime())) return null;

    // Normalise time: accept "HH:MM", "H:MM", or "HH:MM AM/PM"
    let startTime = preTime ?? "09:00"; // use regex-extracted time if available
    if (!preTime && typeof json.time === "string") {
      const rawTime = json.time.trim();
      const t24 = rawTime.match(/^(\d{1,2}):(\d{2})(?:\s*(am|pm))?$/i);
      if (t24) {
        let h = parseInt(t24[1]!);
        const m = parseInt(t24[2]!);
        const per = t24[3]?.toLowerCase();
        if (per === "pm" && h < 12) h += 12;
        if (per === "am" && h === 12) h = 0;
        startTime = `${String(h).padStart(2,"0")}:${String(m).padStart(2,"0")}`;
      }
    }

    const localDate    = new Date(dateStr + "T00:00:00");
    const displayLabel = `${DAYS[localDate.getDay()]!}, ${MONTHS[localDate.getMonth()]!} ${localDate.getDate()} at ${timeLabel(startTime)}`;
    return { date: parsedDate, startTime, displayLabel };
  } catch {
    return null;
  }
}

// ── Availability checks ───────────────────────────────────────────────────────

/**
 * Returns true if the given date+time is within the office's configured hours.
 * Falls back to true (unrestricted) if no hours are configured.
 */
export async function isWithinOfficeHours(
  date: Date,
  time: string,
  userId: number,
): Promise<boolean> {
  try {
    const record = await storage.getOfficeHours(userId);
    if (!record?.data) return true;

    const data = record.data as any;
    const dayNames = ["sunday","monday","tuesday","wednesday","thursday","friday","saturday"] as const;
    const dayName  = dayNames[date.getUTCDay()]!;

    // Override dates: all slots are open
    const ymd = date.toISOString().split("T")[0]!;
    if ((data.overrideDates as string[] | undefined)?.includes(ymd)) return true;

    // Check both doctors' and hygienists' hours — if within either, it's valid
    for (const group of [data.doctors, data.hygienists]) {
      const slot = group?.[dayName];
      if (!slot?.enabled) continue;
      if (
        (time >= slot.amStart && time < slot.amEnd) ||
        (time >= slot.pmStart && time < slot.pmEnd)
      ) return true;
    }
    return false;
  } catch {
    return true;
  }
}

/**
 * Returns whether the office is open at all on a given date (day-level check).
 * Also returns the display day name (e.g. "Sunday") for use in error messages.
 */
export async function isOfficeDayOpen(
  date: Date,
  userId: number,
): Promise<{ open: boolean; displayDay: string }> {
  const displayDays = ["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"];
  const displayDay  = displayDays[date.getUTCDay()]!;
  try {
    const record = await storage.getOfficeHours(userId);
    if (!record?.data) return { open: true, displayDay };

    const data = record.data as any;
    const dayKeys = ["sunday","monday","tuesday","wednesday","thursday","friday","saturday"] as const;
    const dayKey  = dayKeys[date.getUTCDay()]!;

    // Override date — office is fully open
    const ymd = date.toISOString().split("T")[0]!;
    if ((data.overrideDates as string[] | undefined)?.includes(ymd)) return { open: true, displayDay };

    // Open if at least one group (doctors or hygienists) has the day enabled
    const doctorDay = data.doctors?.[dayKey];
    const hygDay    = data.hygienists?.[dayKey];
    if (doctorDay?.enabled || hygDay?.enabled) return { open: true, displayDay };

    return { open: false, displayDay };
  } catch {
    return { open: true, displayDay };
  }
}

/**
 * Returns the office hours for a given day as a human-readable string,
 * e.g. "9:00 am – 12:00 pm and 1:00 pm – 5:00 pm".
 * Returns null if no hours are configured or the day is closed.
 */
export async function getOfficeHoursDisplay(date: Date, userId: number): Promise<string | null> {
  try {
    const record = await storage.getOfficeHours(userId);
    if (!record?.data) return null;

    const data    = record.data as any;
    const dayKeys = ["sunday","monday","tuesday","wednesday","thursday","friday","saturday"] as const;
    const dayKey  = dayKeys[date.getUTCDay()]!;

    for (const group of [data.doctors, data.hygienists]) {
      const slot = group?.[dayKey];
      if (!slot?.enabled) continue;
      return `${timeLabel(slot.amStart)} – ${timeLabel(slot.amEnd)} and ${timeLabel(slot.pmStart)} – ${timeLabel(slot.pmEnd)}`;
    }
    return null;
  } catch {
    return null;
  }
}

/**
 * Returns true if no existing appointment for the patient's staff conflicts with
 * the new date+startTime.
 */
async function isSlotAvailable(
  patientId: number,
  newDate: Date,
  newStartTime: string,
): Promise<boolean> {
  try {
    const today = new Date(); today.setHours(0, 0, 0, 0);
    const current = await db.appointment.findFirst({
      where: { patientId, status: "scheduled", date: { gte: today } },
      orderBy: { date: "asc" },
      select: { staffId: true, startTime: true, endTime: true },
    });
    if (!current) return true;

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

    // Check for overlapping appointments for the same staff member on that day
    const conflicts = await db.appointment.findMany({
      where: {
        staffId:   current.staffId,
        date:      newDate,
        status:    { not: "cancelled" },
        patientId: { not: patientId }, // exclude the patient's own appointment
      },
      select: { startTime: true, endTime: true },
    });

    for (const c of conflicts) {
      if (newStartTime < c.endTime && newEndTime > c.startTime) return false;
    }
    return true;
  } catch {
    return true;
  }
}

// ── Time parsing (legacy) ─────────────────────────────────────────────────────

export async function parseTime(message: string, apiKey: string): Promise<string | null> {
  const t = message.toLowerCase();
  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";
  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]!;
  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. 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,
): Promise<"ok" | "no_appointment"> {
  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";

  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 endTotal    = nh! * 60 + nm! + durationMin;
  const newEndTime  = `${String(Math.floor(endTotal / 60)).padStart(2,"0")}:${String(endTotal % 60).padStart(2,"0")}`;

  await storage.updateAppointment(appt.id, {
    date:      newDate,
    startTime: newStartTime,
    endTime:   newEndTime,
    status:    "scheduled",
    movedByAi: true,
  } 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_datetime ─────────────────────────────────────────────
  // Patient provides date/time preference.
  // If only a date is given, ask for the time. If both are given, ask to confirm.
  if (stage === "asked_reschedule_datetime") {
    const hasTime = messageHasTime(message);

    if (!hasTime) {
      // Try to parse date only
      const parsedDate = await parseDateOnlyFromMessage(message, apiKey);
      if (!parsedDate) {
        const fallbacks: Record<string, string> = {
          English:          "I didn't catch that. What day would you prefer? For example: 'Monday', 'next Tuesday', or '5/18'.",
          Spanish:          "No entendí. ¿Qué día prefiere? Por ejemplo: 'lunes', 'próximo martes' o '18/5'.",
          Portuguese:       "Não entendi. Que dia você prefere? Por exemplo: 'Segunda', 'próxima terça' ou '18/5'.",
          Mandarin:         "我没听清。您希望哪天？例如：'星期一'、'下周二'或'5月18日'。",
          Cantonese:        "我沒聽清。您希望哪天？例如：'星期一'、'下週二'或'5月18日'。",
          Arabic:           "لم أفهم. ما اليوم الذي تفضله؟ مثلاً: 'الاثنين' أو '18/5'.",
          "Haitian Creole": "Mwen pa konprann. Ki jou ou prefere? Pa egzanp: 'Lendi', 'Madi pwochèn', oswa '5/18'.",
        };
        return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
      }

      // Date found — check that the office is actually open that day
      const { date, dateLabel } = parsedDate;
      const dayCheck = await isOfficeDayOpen(date, userId);
      if (!dayCheck.open) {
        const fallbacks: Record<string, string> = {
          English:          `Our office is closed on ${dateLabel} (${dayCheck.displayDay}). Can you please choose another day?`,
          Spanish:          `Nuestra oficina está cerrada el ${dateLabel} (${dayCheck.displayDay}). ¿Puede elegir otro día?`,
          Portuguese:       `Nosso consultório está fechado em ${dateLabel} (${dayCheck.displayDay}). Pode escolher outro dia?`,
          Mandarin:         `我们诊所在 ${dateLabel}（${dayCheck.displayDay}）不开放。请您选择另一天好吗？`,
          Cantonese:        `我們診所在 ${dateLabel}（${dayCheck.displayDay}）不開放。請您選擇另一天好嗎？`,
          Arabic:           `مكتبنا مغلق في ${dateLabel} (${dayCheck.displayDay}). هل يمكنك اختيار يوم آخر؟`,
          "Haitian Creole": `Biwo nou fèmen nan ${dateLabel} (${dayCheck.displayDay}). Tanpri chwazi yon lòt jou?`,
        };
        return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
      }

      // Day is open — save date and ask for time
      setPendingReschedule(userId, patientId, { newDate: date, dayLabel: dateLabel });

      const fallbacks: Record<string, string> = {
        English:          `What time do you prefer on ${dateLabel}?`,
        Spanish:          `¿A qué hora prefiere el ${dateLabel}?`,
        Portuguese:       `Que horário você prefere em ${dateLabel}?`,
        Mandarin:         `您希望在 ${dateLabel} 几点？`,
        Cantonese:        `您希望在 ${dateLabel} 幾點？`,
        Arabic:           `ما الوقت الذي تفضله في ${dateLabel}؟`,
        "Haitian Creole": `Ki lè ou prefere nan ${dateLabel}?`,
      };
      const askTimeReply = await llmReply(
        `You are a friendly dental office assistant. The patient wants to reschedule to ${dateLabel} but hasn't given a time. Ask them in ${lang} what time they prefer on that day. 1 sentence, no formatting.`,
        `Patient wants ${dateLabel} but gave no time.`,
        fallbacks[lang] ?? fallbacks["English"]!,
        apiKey,
      );
      return { reply: askTimeReply, nextStage: "asked_reschedule_time_for_date" };
    }

    // Both date and time present — parse the full datetime
    const parsed = await parseDatetimeFromMessage(message, apiKey);
    if (!parsed) {
      const fallbacks: Record<string, string> = {
        English:          "I didn't catch that. What day and time would you prefer? For example: 'Monday at 10am' or '5/18 at 2pm'.",
        Spanish:          "No entendí. ¿Qué día y hora prefiere? Por ejemplo: 'lunes a las 10am' o '18/5 a las 2pm'.",
        Portuguese:       "Não entendi. Que dia e horário você prefere? Por exemplo: 'Segunda às 10h' ou '18/5 às 14h'.",
        Mandarin:         "我没听清。您希望哪天几点？例如：'星期一上午10点'或'5月18日下午2点'。",
        Cantonese:        "我沒聽清。您希望哪天幾點？例如：'星期一上午10點'或'5月18日下午2點'。",
        Arabic:           "لم أفهم. ما اليوم والوقت الذي تفضله؟ مثلاً: 'الاثنين الساعة 10 صباحاً'.",
        "Haitian Creole": "Mwen pa konprann. Ki jou ak ki lè ou prefere? Pa egzanp: 'Lendi 10am' oswa '5/18 2pm'.",
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
    }

    const { date, startTime, displayLabel } = parsed;

    // Check the office is open on that day before confirming
    const dayCheck2 = await isOfficeDayOpen(date, userId);
    if (!dayCheck2.open) {
      // Extract a date-only label for the message (strip the "at HH:MM" part)
      const datePart = displayLabel.split(" at ")[0] ?? displayLabel;
      const fallbacks: Record<string, string> = {
        English:          `Our office is closed on ${datePart} (${dayCheck2.displayDay}). Can you please choose another day?`,
        Spanish:          `Nuestra oficina está cerrada el ${datePart} (${dayCheck2.displayDay}). ¿Puede elegir otro día?`,
        Portuguese:       `Nosso consultório está fechado em ${datePart} (${dayCheck2.displayDay}). Pode escolher outro dia?`,
        Mandarin:         `我们诊所在 ${datePart}（${dayCheck2.displayDay}）不开放。请您选择另一天好吗？`,
        Cantonese:        `我們診所在 ${datePart}（${dayCheck2.displayDay}）不開放。請您選擇另一天好嗎？`,
        Arabic:           `مكتبنا مغلق في ${datePart} (${dayCheck2.displayDay}). هل يمكنك اختيار يوم آخر؟`,
        "Haitian Creole": `Biwo nou fèmen nan ${datePart} (${dayCheck2.displayDay}). Tanpri chwazi yon lòt jou?`,
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
    }

    setPendingReschedule(userId, patientId, { newDate: date, dayLabel: displayLabel, startTime });

    const fallbacks: Record<string, string> = {
      English:          `Just to confirm — do you prefer ${displayLabel}?`,
      Spanish:          `Solo para confirmar — ¿prefiere el ${displayLabel}?`,
      Portuguese:       `Só para confirmar — você prefere ${displayLabel}?`,
      Mandarin:         `确认一下——您希望的时间是 ${displayLabel} 吗？`,
      Cantonese:        `確認一下——您希望的時間是 ${displayLabel} 嗎？`,
      Arabic:           `فقط للتأكيد — هل تفضل ${displayLabel}؟`,
      "Haitian Creole": `Jis pou konfime — èske ou prefere ${displayLabel}?`,
    };
    const confirmReply = await llmReply(
      `You are a friendly dental office AI assistant. The patient mentioned a date/time preference that you interpreted as "${displayLabel}". Ask them in ${lang} to confirm: "Do you mean ${displayLabel}?" 1 sentence, natural and friendly. No formatting.`,
      `Patient said: "${message}"`,
      fallbacks[lang] ?? fallbacks["English"]!,
      apiKey,
    );
    return { reply: confirmReply, nextStage: "asked_reschedule_confirm_datetime" };
  }

  // ── asked_reschedule_time_for_date ────────────────────────────────────────
  // Patient was asked "What time do you prefer on [date]?" and now replies with a time.
  if (stage === "asked_reschedule_time_for_date") {
    const pending = getPendingReschedule(userId, patientId);
    if (!pending) {
      const fallbacks: Record<string, string> = {
        English:          "Sorry, I lost track. What day and time would you prefer?",
        Spanish:          "Lo siento, perdí el hilo. ¿Qué día y hora prefiere?",
        Portuguese:       "Desculpe, perdi o fio. Que dia e horário você prefere?",
        Mandarin:         "抱歉，我失去了之前的信息。您希望哪天几点？",
        Cantonese:        "抱歉，我失去了之前的資訊。您希望哪天幾點？",
        Arabic:           "عذراً، فقدت المعلومات السابقة. ما اليوم والوقت الذي تفضله؟",
        "Haitian Creole": "Regrèt, mwen pèdi trak. Ki jou ak ki lè ou prefere?",
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
    }

    // Parse the time from the patient's reply
    const startTime = await parseTime(message, apiKey);
    if (!startTime) {
      const fallbacks: Record<string, string> = {
        English:          `I didn't catch the time. What time would you prefer on ${pending.dayLabel}? For example: '10am', '2pm', or '1:30pm'.`,
        Spanish:          `No entendí la hora. ¿Qué hora prefiere el ${pending.dayLabel}? Por ejemplo: '10am', '2pm' o '1:30pm'.`,
        Portuguese:       `Não entendi o horário. Que hora você prefere em ${pending.dayLabel}? Por exemplo: '10h', '14h' ou '13:30'.`,
        Mandarin:         `我没听清时间。您在 ${pending.dayLabel} 几点？例如：上午10点、下午2点或下午1:30。`,
        Cantonese:        `我沒聽清時間。您在 ${pending.dayLabel} 幾點？例如：上午10點、下午2點或下午1:30。`,
        Arabic:           `لم أفهم الوقت. ما الوقت الذي تفضله في ${pending.dayLabel}؟ مثلاً: 10 صباحاً أو 2 مساءً.`,
        "Haitian Creole": `Mwen pa konprann lè a. Ki lè ou prefere nan ${pending.dayLabel}? Pa egzanp: 10am, 2pm, oswa 1:30pm.`,
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_time_for_date" };
    }

    // Check that the requested time is within the office's working hours
    const withinHours = await isWithinOfficeHours(pending.newDate, startTime, userId);
    if (!withinHours) {
      const hoursDisplay = await getOfficeHoursDisplay(pending.newDate, userId);
      const timeLbl = timeLabel(startTime);
      const fallbacks: Record<string, string> = {
        English: hoursDisplay
          ? `Our office is not available at ${timeLbl} on ${pending.dayLabel}. Our hours are ${hoursDisplay}. What other time do you prefer?`
          : `Our office is not available at ${timeLbl} on ${pending.dayLabel}. What other time do you prefer?`,
        Spanish: hoursDisplay
          ? `Nuestra oficina no está disponible a las ${timeLbl} el ${pending.dayLabel}. Nuestro horario es ${hoursDisplay}. ¿Qué otro horario prefiere?`
          : `Nuestra oficina no está disponible a las ${timeLbl} el ${pending.dayLabel}. ¿Qué otro horario prefiere?`,
        Portuguese: hoursDisplay
          ? `Nosso consultório não está disponível às ${timeLbl} em ${pending.dayLabel}. Nosso horário é ${hoursDisplay}. Que outro horário você prefere?`
          : `Nosso consultório não está disponível às ${timeLbl} em ${pending.dayLabel}. Que outro horário você prefere?`,
        Mandarin: hoursDisplay
          ? `我们诊所在 ${pending.dayLabel} ${timeLbl} 不开放。我们的工作时间是 ${hoursDisplay}。您希望改什么时间？`
          : `我们诊所在 ${pending.dayLabel} ${timeLbl} 不开放。您希望改什么时间？`,
        Cantonese: hoursDisplay
          ? `我們診所在 ${pending.dayLabel} ${timeLbl} 不開放。我們的工作時間是 ${hoursDisplay}。您希望改什麼時間？`
          : `我們診所在 ${pending.dayLabel} ${timeLbl} 不開放。您希望改什麼時間？`,
        Arabic: hoursDisplay
          ? `مكتبنا غير متاح في ${timeLbl} يوم ${pending.dayLabel}. ساعات العمل: ${hoursDisplay}. ما وقت آخر تفضله؟`
          : `مكتبنا غير متاح في ${timeLbl} يوم ${pending.dayLabel}. ما وقت آخر تفضله؟`,
        "Haitian Creole": hoursDisplay
          ? `Biwo nou pa disponib a ${timeLbl} nan ${pending.dayLabel}. Orè nou se ${hoursDisplay}. Ki lòt lè ou prefere?`
          : `Biwo nou pa disponib a ${timeLbl} nan ${pending.dayLabel}. Ki lòt lè ou prefere?`,
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_time_for_date" };
    }

    // Time is valid — build the full display label and ask for confirmation
    const fullLabel = `${pending.dayLabel} at ${timeLabel(startTime)}`;
    setPendingReschedule(userId, patientId, { newDate: pending.newDate, dayLabel: fullLabel, startTime });

    const fallbacks: Record<string, string> = {
      English:          `Just to confirm — do you prefer ${fullLabel}?`,
      Spanish:          `Solo para confirmar — ¿prefiere el ${fullLabel}?`,
      Portuguese:       `Só para confirmar — você prefere ${fullLabel}?`,
      Mandarin:         `确认一下——您希望的时间是 ${fullLabel} 吗？`,
      Cantonese:        `確認一下——您希望的時間是 ${fullLabel} 嗎？`,
      Arabic:           `فقط للتأكيد — هل تفضل ${fullLabel}؟`,
      "Haitian Creole": `Jis pou konfime — èske ou prefere ${fullLabel}?`,
    };
    const confirmReply = await llmReply(
      `You are a friendly dental office AI assistant. The patient wants ${fullLabel}. Ask them in ${lang} to confirm: "Do you mean ${fullLabel}?" 1 sentence, natural and friendly. No formatting.`,
      `Patient said: "${message}"`,
      fallbacks[lang] ?? fallbacks["English"]!,
      apiKey,
    );
    return { reply: confirmReply, nextStage: "asked_reschedule_confirm_datetime" };
  }

  // ── asked_reschedule_confirm_datetime ─────────────────────────────────────
  // Patient confirms (yes) or corrects (no) the parsed date/time.
  if (stage === "asked_reschedule_confirm_datetime") {
    const pending = getPendingReschedule(userId, patientId);

    if (!pending) {
      // State lost — ask again from scratch
      const fallbacks: Record<string, string> = {
        English:          "Sorry, I lost track. What day and time would you prefer?",
        Spanish:          "Lo siento, perdí el hilo. ¿Qué día y hora prefiere?",
        Portuguese:       "Desculpe, perdi o fio. Que dia e horário você prefere?",
        Mandarin:         "抱歉，我失去了之前的信息。您希望哪天几点？",
        Cantonese:        "抱歉，我失去了之前的資訊。您希望哪天幾點？",
        Arabic:           "عذراً، فقدت المعلومات السابقة. ما اليوم والوقت الذي تفضله؟",
        "Haitian Creole": "Regrèt, mwen pèdi trak. Ki jou ak ki lè ou prefere?",
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
    }

    // Patient said NO / wants to change
    if (no(t)) {
      clearPendingReschedule(userId, patientId);
      const fallbacks: Record<string, string> = {
        English:          "No problem! What day and time would you prefer? For example: 'Monday at 10am' or '5/18 at 2pm'.",
        Spanish:          "¡Sin problema! ¿Qué día y hora prefiere? Por ejemplo: 'lunes a las 10am'.",
        Portuguese:       "Sem problema! Que dia e horário você prefere? Por exemplo: 'Segunda às 10h'.",
        Mandarin:         "没关系！您希望哪天几点？例如：'星期一上午10点'。",
        Cantonese:        "沒問題！您希望哪天幾點？例如：'星期一上午10點'。",
        Arabic:           "لا بأس! ما اليوم والوقت الذي تفضله؟ مثلاً: 'الاثنين الساعة 10 صباحاً'.",
        "Haitian Creole": "Pa gen pwoblèm! Ki jou ak ki lè ou prefere? Pa egzanp: 'Lendi 10am'.",
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
    }

    // Patient said YES — proceed with availability check
    const { newDate: date, startTime: pendingTime, dayLabel: displayLabel } = pending;
    const startTime = pendingTime ?? "09:00";
    clearPendingReschedule(userId, patientId);

    // Check office hours — include actual hours in the message so patient knows what's available
    const withinHours = await isWithinOfficeHours(date, startTime, userId);
    if (!withinHours) {
      const hoursDisplay = await getOfficeHoursDisplay(date, userId);
      const timeLbl      = timeLabel(startTime);
      // Extract date portion for the message (strip "at HH:MM" if present)
      const datePart = displayLabel.split(" at ")[0] ?? displayLabel;
      const fallbacks: Record<string, string> = {
        English: hoursDisplay
          ? `Our office is not available at ${timeLbl} on ${datePart}. Our hours are ${hoursDisplay}. What other time do you prefer?`
          : `Our office is not available at ${timeLbl} on ${datePart}. What other time do you prefer?`,
        Spanish: hoursDisplay
          ? `Nuestra oficina no está disponible a las ${timeLbl} el ${datePart}. Nuestro horario es ${hoursDisplay}. ¿Qué otro horario prefiere?`
          : `Nuestra oficina no está disponible a las ${timeLbl} el ${datePart}. ¿Qué otro horario prefiere?`,
        Portuguese: hoursDisplay
          ? `Nosso consultório não está disponível às ${timeLbl} em ${datePart}. Nosso horário é ${hoursDisplay}. Que outro horário você prefere?`
          : `Nosso consultório não está disponível às ${timeLbl} em ${datePart}. Que outro horário você prefere?`,
        Mandarin: hoursDisplay
          ? `我们诊所在 ${datePart} ${timeLbl} 不开放。我们的工作时间是 ${hoursDisplay}。您希望改什么时间？`
          : `我们诊所在 ${datePart} ${timeLbl} 不开放。您希望改什么时间？`,
        Cantonese: hoursDisplay
          ? `我們診所在 ${datePart} ${timeLbl} 不開放。我們的工作時間是 ${hoursDisplay}。您希望改什麼時間？`
          : `我們診所在 ${datePart} ${timeLbl} 不開放。您希望改什麼時間？`,
        Arabic: hoursDisplay
          ? `مكتبنا غير متاح في ${timeLbl} يوم ${datePart}. ساعات العمل: ${hoursDisplay}. ما وقت آخر تفضله؟`
          : `مكتبنا غير متاح في ${timeLbl} يوم ${datePart}. ما وقت آخر تفضله؟`,
        "Haitian Creole": hoursDisplay
          ? `Biwo nou pa disponib a ${timeLbl} nan ${datePart}. Orè nou se ${hoursDisplay}. Ki lòt lè ou prefere?`
          : `Biwo nou pa disponib a ${timeLbl} nan ${datePart}. Ki lòt lè ou prefere?`,
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
    }

    // Check slot availability
    const available = await isSlotAvailable(patientId, date, startTime);
    if (!available) {
      const fallbacks: Record<string, string> = {
        English:          `Sorry, ${displayLabel} is not available. What other time do you prefer?`,
        Spanish:          `Lo sentimos, ${displayLabel} no está disponible. ¿Qué otro horario prefiere?`,
        Portuguese:       `Infelizmente ${displayLabel} não está disponível. Que outro horário você prefere?`,
        Mandarin:         `抱歉，${displayLabel} 该时间段不可用。您有其他偏好的时间吗？`,
        Cantonese:        `抱歉，${displayLabel} 該時間段不可用。您有其他偏好的時間嗎？`,
        Arabic:           `عذراً، ${displayLabel} غير متاح. ما وقت آخر تفضله؟`,
        "Haitian Creole": `Regrèt, ${displayLabel} pa disponib. Ki lòt lè ou prefere?`,
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
    }

    // Move the appointment
    const result = await moveAppointment(patientId, date, startTime);

    if (result === "no_appointment") {
      const fallbacks: Record<string, string> = {
        English:          `I wasn't able to find your appointment to update. Our dental receptionist will contact you to confirm ${displayLabel}.`,
        Spanish:          `No encontré su cita. El personal le contactará para confirmar el ${displayLabel}.`,
        Portuguese:       `Não encontrei sua consulta. Nossa equipe confirmará ${displayLabel}.`,
        Mandarin:         `我找不到您的预约进行更新。我们的工作人员将联系您确认${displayLabel}。`,
        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${displayLabel}。`,
        Arabic:           `لم أجد موعدك لتحديثه. سيتصل بك موظفونا لتأكيد ${displayLabel}.`,
        "Haitian Creole": `Mwen pa jwenn randevou ou. Anplwaye nou yo pral kontakte ou pou konfime ${displayLabel}.`,
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "done" };
    }

    // Success — confirm to patient
    const fallback = `Your appointment is moved to ${displayLabel}. Our dental receptionist will confirm it with you tomorrow.`;
    const reply = await llmReply(
      `You are a friendly dental office AI assistant. The patient's appointment has been successfully moved to ${displayLabel}. Write a warm confirmation message in ${lang}: tell them the appointment is moved to ${displayLabel}, and that our dental receptionist will confirm it with them tomorrow. 2 sentences max, no formatting.`,
      `Appointment rescheduled to ${displayLabel}.`,
      fallback,
      apiKey,
    );
    return { reply, nextStage: "done" };
  }

  // ── asked_reschedule_confirm: patient answered the reschedule question ────
  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" };
    }

    // Patient confirmed they want to reschedule.
    // First check if they already included a date (and optionally time) in the same message.
    if (yes(t)) {
      const hasTime = messageHasTime(message);

      if (hasTime) {
        // Try to parse full datetime from the message
        const parsed = await parseDatetimeFromMessage(message, apiKey);
        if (parsed) {
          const { date, startTime, displayLabel } = parsed;
          const dayCheck = await isOfficeDayOpen(date, userId);
          if (!dayCheck.open) {
            const datePart = displayLabel.split(" at ")[0] ?? displayLabel;
            const fallbacks: Record<string, string> = {
              English:          `Our office is closed on ${datePart} (${dayCheck.displayDay}). Can you please choose another day?`,
              Spanish:          `Nuestra oficina está cerrada el ${datePart} (${dayCheck.displayDay}). ¿Puede elegir otro día?`,
              Portuguese:       `Nosso consultório está fechado em ${datePart} (${dayCheck.displayDay}). Pode escolher outro dia?`,
              Mandarin:         `我们诊所在 ${datePart}（${dayCheck.displayDay}）不开放。请您选择另一天好吗？`,
              Cantonese:        `我們診所在 ${datePart}（${dayCheck.displayDay}）不開放。請您選擇另一天好嗎？`,
              Arabic:           `مكتبنا مغلق في ${datePart} (${dayCheck.displayDay}). هل يمكنك اختيار يوم آخر؟`,
              "Haitian Creole": `Biwo nou fèmen nan ${datePart} (${dayCheck.displayDay}). Tanpri chwazi yon lòt jou?`,
            };
            return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
          }
          setPendingReschedule(userId, patientId, { newDate: date, dayLabel: displayLabel, startTime });
          const fallbacks: Record<string, string> = {
            English:          `Just to confirm — do you prefer ${displayLabel}?`,
            Spanish:          `Solo para confirmar — ¿prefiere el ${displayLabel}?`,
            Portuguese:       `Só para confirmar — você prefere ${displayLabel}?`,
            Mandarin:         `确认一下——您希望的时间是 ${displayLabel} 吗？`,
            Cantonese:        `確認一下——您希望的時間是 ${displayLabel} 嗎？`,
            Arabic:           `فقط للتأكيد — هل تفضل ${displayLabel}؟`,
            "Haitian Creole": `Jis pou konfime — èske ou prefere ${displayLabel}?`,
          };
          const confirmReply = await llmReply(
            `You are a friendly dental office AI assistant. The patient mentioned a date/time that you interpreted as "${displayLabel}". Ask them in ${lang} to confirm. 1 sentence, natural and friendly. No formatting.`,
            `Patient said: "${message}"`, fallbacks[lang] ?? fallbacks["English"]!, apiKey,
          );
          return { reply: confirmReply, nextStage: "asked_reschedule_confirm_datetime" };
        }
      }

      // Try to parse a date-only from the message
      const parsedDate = await parseDateOnlyFromMessage(message, apiKey);
      if (parsedDate) {
        const { date, dateLabel } = parsedDate;
        const dayCheck = await isOfficeDayOpen(date, userId);
        if (!dayCheck.open) {
          const fallbacks: Record<string, string> = {
            English:          `Our office is closed on ${dateLabel} (${dayCheck.displayDay}). Can you please choose another day?`,
            Spanish:          `Nuestra oficina está cerrada el ${dateLabel} (${dayCheck.displayDay}). ¿Puede elegir otro día?`,
            Portuguese:       `Nosso consultório está fechado em ${dateLabel} (${dayCheck.displayDay}). Pode escolher outro dia?`,
            Mandarin:         `我们诊所在 ${dateLabel}（${dayCheck.displayDay}）不开放。请您选择另一天好吗？`,
            Cantonese:        `我們診所在 ${dateLabel}（${dayCheck.displayDay}）不開放。請您選擇另一天好嗎？`,
            Arabic:           `مكتبنا مغلق في ${dateLabel} (${dayCheck.displayDay}). هل يمكنك اختيار يوم آخر؟`,
            "Haitian Creole": `Biwo nou fèmen nan ${dateLabel} (${dayCheck.displayDay}). Tanpri chwazi yon lòt jou?`,
          };
          return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "asked_reschedule_datetime" };
        }
        // Day is open — save and ask for time
        setPendingReschedule(userId, patientId, { newDate: date, dayLabel: dateLabel });
        const fallbacks: Record<string, string> = {
          English:          `What time do you prefer on ${dateLabel}?`,
          Spanish:          `¿A qué hora prefiere el ${dateLabel}?`,
          Portuguese:       `Que horário você prefere em ${dateLabel}?`,
          Mandarin:         `您希望在 ${dateLabel} 几点？`,
          Cantonese:        `您希望在 ${dateLabel} 幾點？`,
          Arabic:           `ما الوقت الذي تفضله في ${dateLabel}؟`,
          "Haitian Creole": `Ki lè ou prefere nan ${dateLabel}?`,
        };
        const askTimeReply = await llmReply(
          `You are a friendly dental office assistant. The patient wants ${dateLabel}. Ask them in ${lang} what time they prefer on that day. 1 sentence, no formatting.`,
          `Patient wants ${dateLabel} but gave no time.`, fallbacks[lang] ?? fallbacks["English"]!, apiKey,
        );
        return { reply: askTimeReply, nextStage: "asked_reschedule_time_for_date" };
      }

      // No date found — ask for day and time
      const fallbacks: Record<string, string> = {
        English:          "What day and time would you like? For example: 'Monday at 10am' or 'next Tuesday afternoon'.",
        Spanish:          "¿Qué día y hora prefiere? Por ejemplo: 'lunes a las 10am' o 'martes por la tarde'.",
        Portuguese:       "Que dia e horário você prefere? Por exemplo: 'Segunda às 10h' ou 'terça de tarde'.",
        Mandarin:         "您希望哪天几点？例如：'星期一上午10点'或'下周二下午'。",
        Cantonese:        "您希望哪天幾點？例如：'星期一上午10點'或'下週二下午'。",
        Arabic:           "ما اليوم والوقت الذي تفضله؟ مثلاً: 'الاثنين الساعة 10 صباحاً' أو 'الثلاثاء بعد الظهر'.",
        "Haitian Creole": "Ki jou ak ki lè ou prefere? Pa egzanp: 'Lendi 10am' oswa 'Madi apremidi'.",
      };
      const fallback = fallbacks[lang] ?? fallbacks["English"]!;
      const reply = await llmReply(
        `You are a friendly dental office assistant. The patient wants to reschedule. Ask them in ${lang} what day and time they prefer. Give 1-2 examples like "Monday at 10am" or "next Tuesday afternoon". 1-2 sentences, no formatting.`,
        `Patient wants to reschedule.`, fallback, apiKey,
      );
      return { reply, nextStage: "asked_reschedule_datetime" };
    }

    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 ${wed} seria bom?`,
        Mandarin:         `我可以安排您在下周预约。${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 ${wed} ka travay?`,
      };
      const fallback = fallbacks[lang] ?? fallbacks["English"]!;
      const reply = await llmReply(
        `You are a friendly dental office assistant. Offer next week's Monday (${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)) {
      const { mon, tue, wed } = getNextWeekDays();
      const fallbacks: Record<string, string> = {
        English:          `No problem! What about next week? Would ${mon}, ${tue}, or ${wed} work?`,
        Spanish:          `¡Sin problema! ¿Qué le parece la semana que viene? ¿El ${mon}, ${tue} o el ${wed}?`,
        Portuguese:       `Sem problema! E na semana que vem? ${mon}, ${tue} ou ${wed}?`,
        Mandarin:         `没关系！下周怎么样？${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؟ ${mon} أو ${tue} أو ${wed}؟`,
        "Haitian Creole": `Pa gen pwoblèm! Semèn pwochèn? ${mon}, ${tue}, oswa ${wed}?`,
      };
      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" };
    }

    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 — ${mon} أو ${tue} أو ${wed}؟`,
      "Haitian Creole": `Ki jou ki pi bon — ${mon}, ${tue}, oswa ${wed}?`,
    };
    return { reply: fallbacks[lang] ?? fallbacks["English"]!, 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) return { reply: tx, nextStage: "done" };

    const startTime = await parseTime(message, apiKey);
    if (!startTime) {
      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" };
    }

    const updateResult = await moveAppointment(patientId, pending.newDate, startTime);
    clearPendingReschedule(userId, patientId);

    const apptLabel = `${pending.dayLabel} at ${timeLabel(startTime)}`;

    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. 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. Anplwaye nou yo pral kontakte ou pou konfime ${apptLabel}.`,
      };
      return { reply: fallbacks[lang] ?? fallbacks["English"]!, nextStage: "done" };
    }

    const fallback = `Your appointment has been moved to ${apptLabel}. Our dental receptionist will confirm it with you tomorrow.`;
    const reply = await llmReply(
      `You are a friendly dental office assistant. The patient's appointment has been rescheduled to ${apptLabel}. Confirm in ${lang}: say the appointment is moved to ${apptLabel} and that our dental receptionist will confirm it with them tomorrow. 2 sentences, no formatting.`,
      `Appointment moved to ${apptLabel}.`, fallback, apiKey,
    );
    return { reply, nextStage: "done" };
  }

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