import { Router } from "express";
import { db } from "../db.ts";
import type { AuthedRequest } from "../lib/auth.ts";
import { err } from "../lib/auth.ts";
import { bizDayBoundsSqlite } from "../lib/time.ts";

export const notificationsRouter = Router();

/** Build a human message for an appointment reminder/confirmation. */
function buildMessage(biz: any, appt: any, kind: string): string {
  const when = new Date(appt.start_at).toLocaleString("es-MX", {
    weekday: "long",
    day: "numeric",
    month: "long",
    hour: "2-digit",
    minute: "2-digit",
    timeZone: biz.timezone || "America/Mexico_City",
  });
  const svc = appt.service_name || "tu servicio";
  const emp = appt.employee_name ? ` con ${appt.employee_name}` : "";
  if (kind === "confirmation")
    return `¡Hola ${appt.client_name}! Tu cita en ${biz.name} está confirmada: ${svc}${emp}, ${when}.`;
  if (kind === "cancellation")
    return `Hola ${appt.client_name}, tu cita en ${biz.name} (${svc}) fue cancelada. Para reagendar responde a este mensaje.`;
  if (kind === "review")
    return `¡Gracias por tu visita a ${biz.name}, ${appt.client_name}! ¿Nos calificas? Tu opinión nos ayuda a mejorar.`;
  return `Recordatorio ${biz.name}: tienes ${svc}${emp} el ${when}. ¡Te esperamos!`;
}

/** (Re)generate pending notifications for the upcoming appointments of a business. */
export function scheduleReminders(businessId: number) {
  const biz = db.prepare(`SELECT * FROM businesses WHERE id = ?`).get(businessId) as any;
  if (!biz) return;
  // upcoming scheduled appointments in next 7 days (UTC instants — the window is
  // instant-relative, so we bind clean UTC values instead of SQLite's date('now')).
  const nowUtc = new Date().toISOString().slice(0, 19) + "Z";
  const plus7Utc = new Date(Date.now() + 7 * 86400000).toISOString().slice(0, 19) + "Z";
  const appts = db
    .prepare(
      `SELECT a.id, a.start_at, a.status, a.client_id, c.name client_name, c.phone, c.email,
              s.name service_name, e.name employee_name
       FROM appointments a
       JOIN clients c ON c.id = a.client_id
       JOIN services s ON s.id = a.service_id
       LEFT JOIN employees e ON e.id = a.employee_id
       WHERE a.business_id = ? AND a.status = 'scheduled'
          AND a.start_at >= ? AND a.start_at <= ?
       ORDER BY a.start_at ASC`
    )
    .all(businessId, nowUtc, plus7Utc) as any[];
  // delete pending reminders that no longer have a matching upcoming scheduled appt
  db.prepare(
    `DELETE FROM notifications WHERE business_id = ? AND status = 'pending' AND kind IN ('reminder','confirmation')`
  ).run(businessId);
  for (const a of appts) {
    const start = new Date(a.start_at);
    const channel = a.phone ? "whatsapp" : a.email ? "email" : "whatsapp";
    // confirmation (immediate)
    const confSend = new Date().toISOString().replace(/\.\d{3}Z$/, "Z");
    db.prepare(
      `INSERT INTO notifications (business_id, appointment_id, client_id, channel, kind, send_at, status, message)
       VALUES (?, ?, ?, ?, 'confirmation', ?, 'pending', ?)`
    ).run(businessId, a.id, a.client_id, channel, confSend, buildMessage(biz, a, "confirmation"));
    // reminder 24h before
    const reminderAt = new Date(start.getTime() - 24 * 3600000);
    if (reminderAt.getTime() > Date.now()) {
      db.prepare(
        `INSERT INTO notifications (business_id, appointment_id, client_id, channel, kind, send_at, status, message)
         VALUES (?, ?, ?, ?, 'reminder', ?, 'pending', ?)`
      ).run(
        businessId,
        a.id,
        a.client_id,
        channel,
        reminderAt.toISOString().replace(/\.\d{3}Z$/, "Z"),
        buildMessage(biz, a, "reminder")
      );
    }
  }
}

notificationsRouter.get("/", (req: AuthedRequest, res) => {
  const bid = req.user!.business_id as number;
  const status = req.query.status as string | undefined;
  let rows: any[];
  if (status && status !== "all") {
    rows = db
      .prepare(
        `SELECT n.*, c.name client_name, c.phone, c.email, s.name service_name
         FROM notifications n
         LEFT JOIN clients c ON c.id = n.client_id
         LEFT JOIN appointments a ON a.id = n.appointment_id
         LEFT JOIN services s ON s.id = a.service_id
         WHERE n.business_id = ? AND n.status = ?
         ORDER BY n.send_at DESC LIMIT 200`
      )
      .all(bid, status);
  } else {
    rows = db
      .prepare(
        `SELECT n.*, c.name client_name, c.phone, c.email, s.name service_name
         FROM notifications n
         LEFT JOIN clients c ON c.id = n.client_id
         LEFT JOIN appointments a ON a.id = n.appointment_id
         LEFT JOIN services s ON s.id = a.service_id
         WHERE n.business_id = ?
         ORDER BY n.send_at DESC LIMIT 200`
      )
      .all(bid);
  }
  res.json({ notifications: rows });
});

notificationsRouter.post("/regenerate", (req: AuthedRequest, res) => {
  scheduleReminders(req.user!.business_id as number);
  res.json({ ok: true });
});

/** "Send" a notification — in this demo it simulates sending (marks as sent). */
notificationsRouter.post("/:id/send", (req: AuthedRequest, res) => {
  const bid = req.user!.business_id as number;
  const id = Number(req.params.id);
  const n = db.prepare(`SELECT * FROM notifications WHERE id = ? AND business_id = ?`).get(id, bid) as any;
  if (!n) return err(res, 404, "Notificación no encontrada");
  db.prepare(`UPDATE notifications SET status='sent' WHERE id = ?`).run(id);
  res.json({ ok: true, simulated: true });
});

notificationsRouter.post("/:id/cancel", (req: AuthedRequest, res) => {
  const bid = req.user!.business_id as number;
  const id = Number(req.params.id);
  const n = db.prepare(`SELECT id FROM notifications WHERE id = ? AND business_id = ?`).get(id, bid);
  if (!n) return err(res, 404, "Notificación no encontrada");
  db.prepare(`UPDATE notifications SET status='canceled' WHERE id = ?`).run(id);
  res.json({ ok: true });
});

notificationsRouter.get("/stats", (req: AuthedRequest, res) => {
  const bid = req.user!.business_id as number;
  const tz =
    (db.prepare(`SELECT timezone t FROM businesses WHERE id = ?`).get(bid) as { t?: string } | undefined)?.t ||
    "America/Mexico_City";
  // tz-correct 30-day window (business-local). created_at is mixed-format, so wrap with datetime().
  const since30 = bizDayBoundsSqlite(tz, -30).start;
  const scalar = (sql: string, ...args: any[]) => (db.prepare(sql).get(bid, ...args) as any)?.v ?? 0;
  res.json({
    pending: scalar(`SELECT COUNT(*) v FROM notifications WHERE business_id = ? AND status='pending'`),
    sent: scalar(`SELECT COUNT(*) v FROM notifications WHERE business_id = ? AND status='sent'`),
    upcoming_reminders: scalar(
      `SELECT COUNT(*) v FROM notifications WHERE business_id = ? AND status='pending' AND kind='reminder' AND send_at >= datetime('now')`
    ),
    no_show_rate: scalar(
      `SELECT COALESCE(ROUND(100.0 * SUM(CASE WHEN status='no_show' THEN 1 ELSE 0 END) / NULLIF(COUNT(*),0),1),0) v
       FROM appointments WHERE business_id = ? AND datetime(created_at) >= ?`,
      since30
    ),
  });
});