'use client';
import { useState, useEffect } from 'react';
import Link from 'next/link';
import { settingsApi, type AboutInfo, type StoreSettings } from '@/lib/api-client';

type FormData = StoreSettings;

const TABS = [
  { id: 'general', label: 'General', icon: '⚙️' },
  { id: 'social', label: 'Redes sociales', icon: '🌐' },
  { id: 'footer', label: 'Footer', icon: '📄' },
  { id: 'ai', label: 'IA para SEO', icon: '✨' },
  { id: 'smtp', label: 'SMTP / Email', icon: '✉️' },
  { id: 'couriers', label: 'Transportistas', icon: '🚚' },
  { id: 'about', label: 'About', icon: 'ℹ️' },
] as const;
type TabId = (typeof TABS)[number]['id'];

export default function SettingsPage() {
  const [data, setData] = useState<FormData | null>(null);
  const [form, setForm] = useState<FormData | null>(null);
  const [loading, setLoading] = useState(true);
  const [saving, setSaving] = useState(false);
  const [msg, setMsg] = useState('');
  const [err, setErr] = useState('');
  const [tab, setTab] = useState<TabId>('general');
  const [couriersText, setCouriersText] = useState('');
  const [about, setAbout] = useState<AboutInfo | null>(null);
  const [aboutLoading, setAboutLoading] = useState(false);

  const loadAbout = async () => {
    setAboutLoading(true);
    try {
      setAbout(await settingsApi.about());
    } catch {
      setErr('Error al cargar información del sistema');
    } finally {
      setAboutLoading(false);
    }
  };

  useEffect(() => {
    Promise.all([
      settingsApi.get().then(d => {
        setData(d); setForm(d);
        setCouriersText((d.couriers ?? []).join('\n'));
      }),
      loadAbout(),
    ]).catch(() => setErr('Error al cargar ajustes')).finally(() => setLoading(false));
  }, []);

  const handleCouriersChange = (text: string) => {
    setCouriersText(text);
    const list = text.split('\n').map(c => c.trim()).filter(Boolean).slice(0, 30);
    setForm(f => f ? { ...f, couriers: list } : f);
  };

  const formatDuration = (seconds: number) => {
    const days = Math.floor(seconds / 86400);
    const hours = Math.floor((seconds % 86400) / 3600);
    const minutes = Math.floor((seconds % 3600) / 60);
    if (days > 0) return `${days}d ${hours}h ${minutes}m`;
    if (hours > 0) return `${hours}h ${minutes}m`;
    return `${minutes}m`;
  };

  const infoRow = (label: string, value: string | number) => (
    <div className="rounded-xl border border-gray-100 bg-gray-50 px-4 py-3">
      <p className="text-xs font-medium uppercase tracking-wide text-gray-400">{label}</p>
      <p className="mt-1 break-words text-sm font-semibold text-gray-800">{value}</p>
    </div>
  );

  const handleSave = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!form) return;
    setSaving(true); setErr(''); setMsg('');
    try {
      const { aiApiKey, smtpPass, ...settingsWithoutSecrets } = form;
      const updated = await settingsApi.update({
        ...settingsWithoutSecrets,
        ...(aiApiKey ? { aiApiKey } : {}),
        ...(smtpPass ? { smtpPass } : {}),
      });
      setData(updated); setForm(updated);
      setMsg('Cambios guardados correctamente');
      setTimeout(() => setMsg(''), 4000);
    } catch (er) {
      setErr(er instanceof Error ? er.message : 'Error al guardar');
    } finally {
      setSaving(false);
    }
  };

  const field = (key: Exclude<keyof FormData, 'aiApiKeyConfigured' | 'smtpPassConfigured' | 'smtpSecure'>, label: string, opts?: { type?: string; placeholder?: string; rows?: number; hint?: string }) => (
    <div key={key}>
      <label className="block text-sm font-medium text-gray-700 mb-1">{label}</label>
      {opts?.rows ? (
        <textarea value={form?.[key] ?? ''} onChange={e => setForm(f => f ? { ...f, [key]: e.target.value } : f)}
          rows={opts.rows} placeholder={opts.placeholder}
          className="w-full px-4 py-2.5 border border-gray-300 rounded-xl text-sm focus:ring-2 focus:ring-[#2D6A4F] outline-none resize-none" />
      ) : (
        <input type={opts?.type ?? 'text'} value={form?.[key] ?? ''}
          onChange={e => setForm(f => f ? { ...f, [key]: e.target.value } : f)}
          placeholder={opts?.placeholder} maxLength={key === 'contactAddress' ? 400 : 200}
          className="w-full px-4 py-2.5 border border-gray-300 rounded-xl text-sm focus:ring-2 focus:ring-[#2D6A4F] outline-none" />
      )}
      {opts?.hint && <p className="text-xs text-gray-400 mt-1">{opts.hint}</p>}
    </div>
  );

  return (
    <div className="space-y-6">
      <div>
        <h1 className="text-2xl font-bold text-gray-900">Ajustes de tienda</h1>
        <p className="text-sm text-gray-500 mt-0.5">Configuración general de la tienda visible para los clientes.</p>
      </div>

      {msg && <div className="bg-green-50 text-green-700 text-sm px-4 py-3 rounded-xl border border-green-200">{msg}</div>}
      {err && <div className="bg-red-50 text-red-700 text-sm px-4 py-3 rounded-xl border border-red-200">{err}</div>}

      {loading ? (
        <div className="bg-white rounded-2xl border border-gray-200 p-12 flex items-center justify-center text-gray-400 text-sm">Cargando...</div>
      ) : (
        <div className="flex gap-6">
          {/* Sidebar tabs */}
          <nav className="w-48 shrink-0 space-y-1">
            {TABS.map(t => (
              <button
                key={t.id}
                onClick={() => setTab(t.id)}
                className={`w-full text-left px-4 py-2.5 rounded-xl text-sm font-medium transition-colors ${
                  tab === t.id
                    ? 'bg-[#2D6A4F] text-white'
                    : 'text-gray-600 hover:bg-gray-100'
                }`}
              >
                <span className="mr-2">{t.icon}</span>
                {t.label}
              </button>
            ))}
            <div className="my-3 border-t border-gray-200" />
            <p className="px-4 text-xs font-semibold uppercase tracking-wide text-gray-400">Sistema</p>
            <Link href="/settings/tax-rates" className="flex w-full items-center gap-2 px-4 py-2.5 rounded-xl text-sm font-medium text-gray-600 hover:bg-gray-100 transition-colors">
              <span>💰</span> IVA
            </Link>
            <Link href="/settings/audit" className="flex w-full items-center gap-2 px-4 py-2.5 rounded-xl text-sm font-medium text-gray-600 hover:bg-gray-100 transition-colors">
              <span>📋</span> Auditoría
            </Link>
            <Link href="/settings/logs" className="flex w-full items-center gap-2 px-4 py-2.5 rounded-xl text-sm font-medium text-gray-600 hover:bg-gray-100 transition-colors">
              <span>🖥️</span> Logs
            </Link>
          </nav>

          {/* Form area */}
          <form onSubmit={handleSave} className="flex-1 bg-white rounded-2xl border border-gray-200 overflow-hidden">
            {tab === 'general' && (
              <>
                <div className="px-6 py-4 bg-gray-50 border-b border-gray-200">
                  <h2 className="text-base font-semibold text-gray-800">Información general</h2>
                  <p className="text-xs text-gray-400 mt-0.5">Nombre y eslogan de la tienda.</p>
                </div>
                <div className="p-6 space-y-5">
                  {field('storeName', 'Nombre de la tienda', { placeholder: 'Mercado de Vida' })}
                  {field('storeTagline', 'Eslogan', { placeholder: 'Productos naturales y ecológicos' })}
                </div>

                <div className="px-6 py-4 bg-gray-50 border-t border-b border-gray-200">
                  <h2 className="text-base font-semibold text-gray-800">Contacto</h2>
                  <p className="text-xs text-gray-400 mt-0.5">Datos visibles en la página de contacto.</p>
                </div>
                <div className="p-6 space-y-5">
                  {field('contactEmail', 'Email de contacto', { type: 'email', placeholder: 'info@mercadodevida.es' })}
                  {field('contactPhone', 'Teléfono', { placeholder: '+34 600 000 000' })}
                  {field('contactAddress', 'Dirección', { placeholder: 'Calle ejemplo, ciudad', rows: 3 })}
                </div>
              </>
            )}

            {tab === 'social' && (
              <>
                <div className="px-6 py-4 bg-gray-50 border-b border-gray-200">
                  <h2 className="text-base font-semibold text-gray-800">Redes sociales</h2>
                  <p className="text-xs text-gray-400 mt-0.5">Enlaces a perfiles sociales mostrados en el footer.</p>
                </div>
                <div className="p-6 space-y-5">
                  {field('facebookUrl', 'Facebook', { placeholder: 'https://facebook.com/...' })}
                  {field('instagramUrl', 'Instagram', { placeholder: 'https://instagram.com/...' })}
                  {field('twitterUrl', 'X (Twitter)', { placeholder: 'https://x.com/...' })}
                  {field('pinterestUrl', 'Pinterest', { placeholder: 'https://pinterest.com/...' })}
                </div>
              </>
            )}

            {tab === 'ai' && (
              <>
                <div className="px-6 py-4 bg-gray-50 border-b border-gray-200">
                  <h2 className="text-base font-semibold text-gray-800">Modelo de IA para SEO</h2>
                  <p className="text-xs text-gray-400 mt-0.5">Se usa solo para completar campos SEO que estén vacíos.</p>
                </div>
                <div className="p-6 space-y-5">
                  {field('aiProvider', 'Proveedor', { placeholder: 'OpenAI compatible' })}
                  {field('aiBaseUrl', 'URL base de la API', { type: 'url', placeholder: 'https://api.openai.com/v1' })}
                  {field('aiModel', 'Modelo', { placeholder: 'gpt-4o-mini' })}
                  {field('aiApiKey', 'API key', { type: 'password', placeholder: form?.aiApiKeyConfigured ? 'API key configurada (escribe para reemplazar)' : 'sk-...' })}
                  {field('aiSeoTitlePrompt', 'Prompt para Título SEO', { rows: 4, hint: 'Usa {{name}}, {{description}} y {{brand}} como variables.' })}
                  {field('aiSeoDescriptionPrompt', 'Prompt para Descripción SEO (Google)', { rows: 5, hint: 'Usa {{name}}, {{description}} y {{brand}} como variables.' })}
                  {field('aiProductDescriptionPrompt', 'Prompt para Descripción del producto', { rows: 5, hint: 'Se usa solo cuando la descripción normal está vacía. Debe pedir HTML (párrafos y listas) para que se renderice bonito en la tienda. Variables: {{name}}, {{description}} y {{brand}}.' })}
                  <div className="pt-2 border-t border-gray-100">
                    <h3 className="text-sm font-semibold text-gray-800 mb-1">Categorías</h3>
                    <p className="text-xs text-gray-400 mb-4">Se usan cuando la descripción o los campos SEO de una categoría están vacíos. Variables: {'{{name}}'} y {'{{description}}'}.</p>
                  </div>
                  {field('aiCategoryDescriptionPrompt', 'Prompt para Descripción de categoría', { rows: 4, hint: 'Variables: {{name}} y {{description}}.' })}
                  {field('aiCategorySeoTitlePrompt', 'Prompt para Título SEO de categoría', { rows: 4, hint: 'Variables: {{name}} y {{description}}.' })}
                  {field('aiCategorySeoDescriptionPrompt', 'Prompt para Descripción SEO de categoría', { rows: 5, hint: 'Variables: {{name}} y {{description}}.' })}
                </div>
              </>
            )}

            {tab === 'smtp' && (
              <>
                <div className="px-6 py-4 bg-gray-50 border-b border-gray-200">
                  <h2 className="text-base font-semibold text-gray-800">Correo SMTP</h2>
                  <p className="text-xs text-gray-400 mt-0.5">Se usa para enviar enlaces de recuperación de contraseña.</p>
                </div>
                <div className="p-6 space-y-5">
                  {field('smtpHost', 'Servidor SMTP', { placeholder: 'ssl0.ovh.net' })}
                  {field('smtpPort', 'Puerto', { type: 'number', placeholder: '465' })}
                  <label className="flex items-center gap-2 text-sm text-gray-700">
                    <input type="checkbox" checked={form?.smtpSecure ?? true} onChange={e => setForm(f => f ? { ...f, smtpSecure: e.target.checked } : f)} />
                    Conexión segura SSL/TLS
                  </label>
                  {field('smtpUser', 'Usuario / cuenta de correo', { type: 'email', placeholder: 'info@mercadodevida.es' })}
                  {field('smtpPass', 'Contraseña SMTP', { type: 'password', placeholder: form?.smtpPassConfigured ? 'Contraseña configurada (escribe para reemplazar)' : 'Contraseña del buzón' })}
                  {field('smtpFrom', 'Remitente', { type: 'email', placeholder: 'info@mercadodevida.es' })}
                  <div className="border-t border-gray-200 pt-4 mt-2">
                    <h3 className="mb-3 text-sm font-semibold text-gray-800">Reportes automáticos</h3>
                    {field('smtpReportEmail', 'Email destino de reportes', { type: 'email', placeholder: 'direccion@ejemplo.com' })}
                    <p className="text-xs text-gray-400 -mt-2">Recibirás el reporte de cierre de caja por email al cerrar cada sesión.</p>
                  </div>
                </div>
              </>
            )}

            {tab === 'couriers' && (
              <>
                <div className="px-6 py-4 bg-gray-50 border-b border-gray-200">
                  <h2 className="text-base font-semibold text-gray-800">Transportistas</h2>
                  <p className="text-xs text-gray-400 mt-0.5">Lista editable de transportistas. Se usa al marcar un pedido como enviado y aparece en el email al cliente. Uno por línea.</p>
                </div>
                <div className="p-6 space-y-5">
                  <textarea
                    value={couriersText}
                    onChange={e => handleCouriersChange(e.target.value)}
                    rows={8}
                    placeholder={'Correos\nSEUR\nMRW'}
                    className="w-full px-4 py-2.5 border border-gray-300 rounded-xl text-sm focus:ring-2 focus:ring-[#2D6A4F] outline-none resize-none font-mono"
                  />
                  <p className="text-xs text-gray-400">Máximo 30 transportistas, cada nombre de hasta 60 caracteres.</p>
                </div>
              </>
            )}

            {tab === 'about' && (
              <>
                <div className="px-6 py-4 bg-gray-50 border-b border-gray-200 flex items-center justify-between gap-4">
                  <div>
                    <h2 className="text-base font-semibold text-gray-800">About / Sistema</h2>
                    <p className="text-xs text-gray-400 mt-0.5">Versiones de servicios e información segura del servidor.</p>
                  </div>
                  <button
                    type="button"
                    onClick={() => void loadAbout()}
                    disabled={aboutLoading}
                    className="rounded-xl border border-gray-300 px-3 py-2 text-xs font-semibold text-gray-700 hover:bg-white disabled:opacity-50"
                  >
                    {aboutLoading ? 'Actualizando…' : 'Actualizar'}
                  </button>
                </div>
                <div className="p-6 space-y-6">
                  {about ? (
                    <>
                      <div className="rounded-2xl border border-[#2D6A4F]/20 bg-[#2D6A4F]/5 p-5">
                        <p className="text-xs font-medium uppercase tracking-wide text-[#2D6A4F]">Versión producto</p>
                        <p className="mt-1 text-3xl font-bold text-[#1B4332]">v{about.productVersion}</p>
                        <p className="mt-2 text-xs text-gray-500">Generado: {new Date(about.generatedAt).toLocaleString('es-ES')}</p>
                      </div>

                      <section>
                        <h3 className="mb-3 text-sm font-semibold text-gray-800">Servicios</h3>
                        <div className="grid gap-3 md:grid-cols-2 xl:grid-cols-3">
                          {about.services.map(service => (
                            <div key={service.id} className="rounded-xl border border-gray-200 p-4">
                              <p className="text-sm font-semibold text-gray-900">{service.name}</p>
                              <p className="mt-1 font-mono text-xs text-gray-500">{service.id}</p>
                              <p className="mt-3 inline-flex rounded-full bg-gray-100 px-2.5 py-1 font-mono text-xs font-semibold text-gray-700">v{service.version}</p>
                            </div>
                          ))}
                        </div>
                      </section>

                      <section>
                        <h3 className="mb-3 text-sm font-semibold text-gray-800">Servidor</h3>
                        <div className="grid gap-3 md:grid-cols-2 xl:grid-cols-3">
                          {infoRow('Host', about.server.hostname)}
                          {infoRow('Sistema', `${about.server.platform} ${about.server.arch}`)}
                          {infoRow('Kernel / Release', about.server.release)}
                          {infoRow('Node.js', about.server.nodeVersion)}
                          {infoRow('PID backend', about.server.pid)}
                          {infoRow('Zona horaria', about.server.timezone)}
                          {infoRow('Uptime host', formatDuration(about.server.uptimeSeconds))}
                          {infoRow('Uptime proceso', formatDuration(about.server.processUptimeSeconds))}
                          {infoRow('Arranque proceso', new Date(about.server.processStartedAt).toLocaleString('es-ES'))}
                          {infoRow('CPU cores', about.server.cpuCount)}
                          {infoRow('RAM total', `${about.server.totalMemoryMb} MB`)}
                          {infoRow('RAM libre', `${about.server.freeMemoryMb} MB`)}
                        </div>
                      </section>

                      <section>
                        <h3 className="mb-3 text-sm font-semibold text-gray-800">Proceso y base de datos</h3>
                        <div className="grid gap-3 md:grid-cols-2 xl:grid-cols-3">
                          {infoRow('RSS proceso', `${about.server.processMemoryMb.rss} MB`)}
                          {infoRow('Heap usado', `${about.server.processMemoryMb.heapUsed} MB`)}
                          {infoRow('Heap total', `${about.server.processMemoryMb.heapTotal} MB`)}
                          {infoRow('PostgreSQL', about.database.postgresVersion)}
                        </div>
                      </section>
                    </>
                  ) : (
                    <div className="rounded-xl border border-gray-200 p-8 text-center text-sm text-gray-500">
                      {aboutLoading ? 'Cargando información del sistema…' : 'No se pudo cargar la información del sistema.'}
                    </div>
                  )}
                </div>
              </>
            )}

            {tab === 'footer' && (
              <>
                <div className="px-6 py-4 bg-gray-50 border-b border-gray-200">
                  <h2 className="text-base font-semibold text-gray-800">Footer</h2>
                  <p className="text-xs text-gray-400 mt-0.5">Texto del pie de página del sitio.</p>
                </div>
                <div className="p-6 space-y-5">
                  {field('footerText', 'Texto del pie de página', {
                    placeholder: '© {{year}} Mercado de Vida. Todos los derechos reservados.',
                    rows: 3,
                    hint: 'Usa {{year}} para insertar el año actual automáticamente.',
                  })}
                </div>
              </>
            )}

            {tab !== 'about' && (
              <div className="px-6 py-5 bg-gray-50 border-t border-gray-200 flex justify-end">
                <button type="submit" disabled={saving || !form}
                  className="px-6 py-2.5 bg-[#2D6A4F] hover:bg-[#1B4332] disabled:opacity-50 text-white text-sm font-semibold rounded-xl transition-colors">
                  {saving ? 'Guardando...' : 'Guardar cambios'}
                </button>
              </div>
            )}
          </form>
        </div>
      )}
    </div>
  );
}