import { useCallback, useEffect, useMemo, useState } from 'react';
import { Link } from 'react-router-dom';
import { fetchTmUsers } from '../api';
import DashboardLoading from './DashboardLoading';
import exportCsv from './exportCsv';

const SURVEY_ORIGIN = 'https://tgics.cttr.in';
const EMPTY_TOTALS = { tms: 0, contacts_created: 0, doctors_with_surveys: 0, total_surveys: 0 };

function mrWhatsappLink(row) {
  const userId = String(row.user_id || '').trim();
  if (!userId) {
    return { href: '', label: 'Link unavailable' };
  }
  let digits = String(row.phone || '').replace(/\D+/g, '');
  if (digits.length === 10) {
    digits = `91${digits}`;
  }
  if (!digits) {
    return { href: '', label: 'No WhatsApp number' };
  }
  const name = String(row.name || '').trim();
  const link = `${SURVEY_ORIGIN}/${userId}`;
  const text = `Dear${name ? ` ${name}` : ''},\n\nPlease share this TGICS link with your enrolled doctors. They should open it and enter their WhatsApp mobile number to continue:\n${link}`;
  return {
    href: `https://api.whatsapp.com/send?phone=${digits}&text=${encodeURIComponent(text)}`,
    label: '',
  };
}

export default function TmUsersSection({ onUnauthorized }) {
  const [items, setItems] = useState([]);
  const [totals, setTotals] = useState(EMPTY_TOTALS);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState('');
  const [query, setQuery] = useState('');

  const load = useCallback(async (refresh = false) => {
    setLoading(true);
    setError('');
    try {
      const res = await fetchTmUsers(refresh);
      setItems(Array.isArray(res.data?.items) ? res.data.items : []);
      setTotals({ ...EMPTY_TOTALS, ...(res.data?.totals || {}) });
    } catch (err) {
      if (err.status === 401) {
        onUnauthorized?.();
        return;
      }
      setError(err.message || 'Unable to load Territory Managers.');
    } finally {
      setLoading(false);
    }
  }, [onUnauthorized]);

  useEffect(() => {
    load(false);
  }, [load]);

  const filtered = useMemo(() => {
    const q = query.trim().toLowerCase();
    if (!q) return items;
    return items.filter((row) =>
      [row.name, row.employee_code, row.position_name, row.position_code]
        .some((v) => String(v || '').toLowerCase().includes(q))
    );
  }, [items, query]);

  const handleExport = () => {
    exportCsv(
      'tgics_mr_dashboard',
      ['MR ID', 'Name', 'Employee code', 'Position name', 'Doctors Enrolled', 'Active Doctors', 'Total surveys'],
      filtered.map((row) => [
        row.user_id,
        row.name,
        row.employee_code,
        row.position_name,
        row.contacts_created,
        row.doctors_with_surveys,
        row.total_surveys,
      ])
    );
  };

  return (
    <>
      <div className="dash-stats">
        <div className="dash-stat primary">
          <small>Total MR Count</small>
          <strong>{loading ? '…' : totals.tms}</strong>
        </div>
        <div className="dash-stat info emphasized">
          <small>Total Doctors Enrolled</small>
          <strong>{loading ? '…' : totals.contacts_created}</strong>
        </div>
        <div className="dash-stat warning emphasized">
          <small>Active Doctors</small>
          <strong>{loading ? '…' : totals.doctors_with_surveys}</strong>
        </div>
        <div className="dash-stat success">
          <small>Total Surveys</small>
          <strong>{loading ? '…' : totals.total_surveys}</strong>
        </div>
      </div>

      <main className="dash-card">
        <div className="dash-toolbar">
          <p className="dash-muted">
          {loading
            ? ''
            : query.trim()
                ? `${filtered.length} of ${items.length} MRs`
                : `${items.length} MRs`}
          </p>
          <div className="dash-toolbar-actions">
            <input
              type="search"
              className="dash-input"
              placeholder="Search name, employee code or position"
              value={query}
              onChange={(e) => setQuery(e.target.value)}
            />
            <button type="button" className="dash-btn info" onClick={() => load(true)} disabled={loading}>
              Refresh Data
            </button>
            <button
              type="button"
              className="dash-btn dark"
              onClick={handleExport}
              disabled={loading || filtered.length === 0}
            >
              Export
            </button>
          </div>
        </div>

        {error ? <p className="error">{error}</p> : null}

        {loading ? <DashboardLoading /> : null}

        {!loading && !error && filtered.length === 0 ? (
          <p className="dash-muted dash-center">No MRs found.</p>
        ) : null}

        {filtered.length > 0 ? (
          <div className="table-wrap">
            <table className="dash-table">
              <thead>
                <tr>
                  <th>No</th>
                  <th className="text-left">Name</th>
                  <th>Employee code</th>
                  <th>Position name</th>
                  <th className="dash-col-emphasis">Doctors Enrolled</th>
                  <th className="dash-col-emphasis">Active Doctors</th>
                  <th>Total surveys</th>
                  <th>Doctors</th>
                  <th>WhatsApp</th>
                </tr>
              </thead>
              <tbody>
                {filtered.map((row, index) => {
                  const whatsapp = mrWhatsappLink(row);
                  return (
                  <tr key={row.user_id}>
                    <td>{index + 1}</td>
                    <td className="text-left">{row.name || '-'}</td>
                    <td>{row.employee_code || '-'}</td>
                    <td>{row.position_name || '-'}</td>
                    <td className="dash-num dash-col-emphasis">{row.contacts_created}</td>
                    <td className="dash-num dash-col-emphasis">{row.doctors_with_surveys}</td>
                    <td className="dash-num">{row.total_surveys}</td>
                    <td>
                      {row.contacts_created > 0 ? (
                        <Link
                          className="dash-btn info dash-btn-link"
                          target="_blank"
                          rel="noopener noreferrer"
                          to={`/dashboard/doctors?${new URLSearchParams({
                            mr: row.user_id,
                            mr_name: row.name,
                            mr_code: row.employee_code,
                          })}`}
                        >
                          View Doctors
                        </Link>
                      ) : (
                        <span className="dash-muted">-</span>
                      )}
                    </td>
                    <td>
                      {whatsapp.href ? (
                        <a
                          className="dash-btn whatsapp dash-btn-link"
                          href={whatsapp.href}
                          target="_blank"
                          rel="noopener noreferrer"
                        >
                          Send WhatsApp
                        </a>
                      ) : (
                        <span className="dash-muted">{whatsapp.label}</span>
                      )}
                    </td>
                  </tr>
                  );
                })}
              </tbody>
            </table>
          </div>
        ) : null}
      </main>
    </>
  );
}