import { useEffect, useState } from 'react';
import { useNavigate } from 'react-router-dom';
import { useTranslation } from 'react-i18next';
import {
  CheckCircle2, ArrowRight, ArrowLeft,
  Building2, UserCircle, Smartphone, SkipForward,
  Loader2, Eye, EyeOff
} from 'lucide-react';
import { useAuth } from '../lib/auth';
import { api } from '../lib/api';
import { initMetaSDK, launchEmbeddedSignup } from '../lib/meta-signup';
import { useToast } from '../hooks/useToast';
import { logError, logWarn } from '../lib/logger';

// ─── Modes ───────────────────────────────────────────────────────────────────

const MODE_KEYS = [
  { value: 'EDTECH',           labelKey: 'onboarding.mode_edtech_label',            descKey: 'onboarding.mode_edtech_desc' },
  { value: 'CRM_MARKETING',    labelKey: 'onboarding.mode_crm_label',               descKey: 'onboarding.mode_crm_desc' },
  { value: 'AI_AGENT',         labelKey: 'onboarding.mode_ai_label',                descKey: 'onboarding.mode_ai_desc' },
  { value: 'CUSTOMER_SERVICE', labelKey: 'onboarding.mode_customer_service_label',  descKey: 'onboarding.mode_customer_service_desc' },
];

// ─── Slug helpers ─────────────────────────────────────────────────────────────

function toSlug(name: string): string {
  return name
    .toLowerCase()
    .normalize('NFD').replace(/[̀-ͯ]/g, '')
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/^-+|-+$/g, '')
    .slice(0, 40);
}

// ─── Steps ───────────────────────────────────────────────────────────────────

const STEP_KEYS = [
  { id: 'org',       titleKey: 'onboarding.step_org',       icon: Building2 },
  { id: 'admin',     titleKey: 'onboarding.step_admin',     icon: UserCircle },
  { id: 'whatsapp',  titleKey: 'onboarding.step_whatsapp',  icon: Smartphone },
];

// ─── Wizard ──────────────────────────────────────────────────────────────────

export default function OnboardingWizard() {
  const { t } = useTranslation();
  const [step, setStep]     = useState(0);
  const [loading, setLoading] = useState(false);
  const [showPass, setShowPass] = useState(false);
  const { token } = useAuth();
  const navigate  = useNavigate();
  const toast     = useToast();

  const [org, setOrg] = useState({
    name: '',
    slug: '',
    slugTouched: false,
    mode: 'EDTECH',
  });

  const [admin, setAdmin] = useState({
    adminName: '',
    adminEmail: '',
    password: '',
  });

  const [wa, setWa] = useState({
    wabaId: '',
    metaBusinessId: '',
    accessToken: '',
    skip: false,
  });

  const [tokenValidState, setTokenValidState] = useState<'idle' | 'checking' | 'valid' | 'invalid'>('idle');

  const validateToken = async (tok: string) => {
    if (!tok.trim() || !token) return;
    setTokenValidState('checking');
    try {
      const res = await api.post('/v1/organizations/whatsapp-validate-token', { token: tok }, token);
      setTokenValidState(res.valid ? 'valid' : 'invalid');
    } catch {
      setTokenValidState('idle');
    }
  };

  // Auto-generate slug from name unless user edited it manually
  useEffect(() => {
    if (!org.slugTouched) {
      setOrg(s => ({ ...s, slug: toSlug(s.name) }));
    }
  }, [org.name, org.slugTouched]);

  useEffect(() => { initMetaSDK(); }, []);

  // ── Navigation ──────────────────────────────────────────────────────────────

  const canNext = () => {
    if (step === 0) return org.name.trim().length >= 2 && org.slug.length >= 3;
    if (step === 1) return admin.adminEmail.includes('@') && admin.adminName.trim().length >= 2;
    return true;
  };

  const next = () => setStep(s => Math.min(s + 1, STEP_KEYS.length - 1));
  const back = () => setStep(s => Math.max(s - 1, 0));

  // ── Submit ──────────────────────────────────────────────────────────────────

  const handleSubmit = async () => {
    setLoading(true);
    try {
      // 1. Create organisation + admin user
      const result = await api.post('/v1/organizations', {
        name:       org.name.trim(),
        slug:       org.slug,
        mode:       org.mode,
        adminName:  admin.adminName.trim(),
        adminEmail: admin.adminEmail.trim().toLowerCase(),
        ...(admin.password && { password: admin.password }),
      }, token) as { id: string; admin: { tempPassword: string } };

      const newOrgId = result.id;

      // 2. Connect WhatsApp if provided
      if (!wa.skip && wa.wabaId) {
        await api.post(`/v1/organizations/${newOrgId}/whatsapp-setup`, {
          wabaId: wa.wabaId.trim(),
          ...(wa.accessToken && { accessToken: wa.accessToken.trim() }),
        }, token);

        if (wa.metaBusinessId) {
          await api.put(`/v1/organizations/${newOrgId}`, {
            metaBusinessId: wa.metaBusinessId.trim(),
          }, token);
        }
      }

      navigate('/clients');
    } catch (err: any) {
      logError(err);
      toast.error(err.message || t('onboarding.create_error'));
    } finally {
      setLoading(false);
    }
  };

  // ── Embedded Signup ─────────────────────────────────────────────────────────

  const handleEmbeddedSignup = async () => {
    try {
      const result = await launchEmbeddedSignup();
      setWa(s => ({
        ...s,
        wabaId:      result.waba_id,
        accessToken: result.code,
        skip:        false,
      }));
    } catch (err) {
      logWarn('[OnboardingWizard] Facebook login failed', err);
      toast.error(t('onboarding.fb_error'));
    }
  };

  // ── Render ──────────────────────────────────────────────────────────────────

  return (
    <div className="max-w-2xl mx-auto py-12 px-6">
      <div className="bg-white rounded-3xl shadow-xl overflow-hidden border border-gray-100">

        {/* Step bar */}
        <div className="flex border-b border-gray-50">
          {STEP_KEYS.map((s, i) => {
            const Icon = s.icon;
            return (
              <div key={s.id} className={`flex-1 flex items-center justify-center gap-2 py-5 border-b-2 transition-all ${
                i <= step ? 'border-indigo-600 text-indigo-600' : 'border-transparent text-gray-400'
              }`}>
                <div className={`w-7 h-7 rounded-full flex items-center justify-center text-xs font-bold ${
                  i < step ? 'bg-indigo-100 text-indigo-600' : i === step ? 'bg-indigo-600 text-white' : 'bg-gray-100'
                }`}>
                  {i < step ? <CheckCircle2 className="w-4 h-4" /> : <Icon className="w-4 h-4" />}
                </div>
                <span className="hidden md:block font-medium text-sm">{t(s.titleKey)}</span>
              </div>
            );
          })}
        </div>

        {/* Content */}
        <div className="p-10 min-h-[420px]">

          {/* Step 0 — Organisation */}
          {step === 0 && (
            <div className="space-y-6 animate-in fade-in slide-in-from-bottom-4">
              <div>
                <h2 className="text-2xl font-bold text-gray-900">{t('onboarding.org_title')}</h2>
                <p className="text-gray-400 text-sm mt-1">{t('onboarding.org_subtitle')}</p>
              </div>

              <div className="space-y-4">
                {/* Nom */}
                <div>
                  <label className="block text-xs font-bold uppercase text-gray-400 mb-1.5">{t('onboarding.org_name_label')}</label>
                  <input
                    type="text"
                    value={org.name}
                    onChange={e => setOrg(s => ({ ...s, name: e.target.value }))}
                    placeholder="ex: École Polytechnique de Dakar"
                    className="w-full px-4 py-3 rounded-xl border border-gray-200 outline-none focus:ring-2 focus:ring-indigo-500/20 focus:border-indigo-500 transition"
                  />
                </div>

                {/* Slug */}
                <div>
                  <label className="block text-xs font-bold uppercase text-gray-400 mb-1.5">{t('onboarding.slug_label')}</label>
                  <div className="flex items-center gap-0 border border-gray-200 rounded-xl overflow-hidden focus-within:ring-2 focus-within:ring-indigo-500/20 focus-within:border-indigo-500">
                    <span className="px-3 py-3 bg-gray-50 text-gray-400 text-sm font-mono border-r border-gray-200 whitespace-nowrap">xamle.studio/</span>
                    <input
                      type="text"
                      value={org.slug}
                      onChange={e => setOrg(s => ({ ...s, slug: toSlug(e.target.value), slugTouched: true }))}
                      placeholder="ecole-poly-dakar"
                      className="flex-1 px-3 py-3 outline-none text-sm font-mono bg-white"
                    />
                  </div>
                  <p className="text-[11px] text-gray-400 mt-1">{t('onboarding.slug_hint')}</p>
                </div>

                {/* Mode */}
                <div>
                  <label className="block text-xs font-bold uppercase text-gray-400 mb-2">{t('onboarding.mode_label')}</label>
                  <div className="grid grid-cols-2 gap-2">
                    {MODE_KEYS.map(m => (
                      <button
                        key={m.value}
                        type="button"
                        onClick={() => setOrg(s => ({ ...s, mode: m.value }))}
                        className={`text-left p-3.5 rounded-xl border-2 transition-all ${
                          org.mode === m.value
                            ? 'border-indigo-500 bg-indigo-50/60'
                            : 'border-gray-100 hover:border-gray-200 bg-white'
                        }`}
                      >
                        <p className="font-semibold text-sm text-gray-800">{t(m.labelKey)}</p>
                        <p className="text-[11px] text-gray-400 mt-0.5 leading-snug">{t(m.descKey)}</p>
                      </button>
                    ))}
                  </div>
                </div>
              </div>
            </div>
          )}

          {/* Step 1 — Admin */}
          {step === 1 && (
            <div className="space-y-6 animate-in fade-in slide-in-from-bottom-4">
              <div>
                <h2 className="text-2xl font-bold text-gray-900">{t('onboarding.admin_title')}</h2>
                <p className="text-gray-400 text-sm mt-1">{t('onboarding.admin_subtitle')}</p>
              </div>

              <div className="space-y-4">
                <div>
                  <label className="block text-xs font-bold uppercase text-gray-400 mb-1.5">{t('onboarding.admin_name_label')}</label>
                  <input
                    type="text"
                    value={admin.adminName}
                    onChange={e => setAdmin(s => ({ ...s, adminName: e.target.value }))}
                    placeholder="Prénom Nom"
                    className="w-full px-4 py-3 rounded-xl border border-gray-200 outline-none focus:ring-2 focus:ring-indigo-500/20 focus:border-indigo-500 transition"
                  />
                </div>

                <div>
                  <label className="block text-xs font-bold uppercase text-gray-400 mb-1.5">{t('onboarding.admin_email_label')}</label>
                  <input
                    type="email"
                    value={admin.adminEmail}
                    onChange={e => setAdmin(s => ({ ...s, adminEmail: e.target.value }))}
                    placeholder="admin@ecole.sn"
                    className="w-full px-4 py-3 rounded-xl border border-gray-200 outline-none focus:ring-2 focus:ring-indigo-500/20 focus:border-indigo-500 transition"
                  />
                </div>

                <div>
                  <label className="block text-xs font-bold uppercase text-gray-400 mb-1.5">
                    {t('onboarding.admin_pass_label')} <span className="text-gray-300 font-normal normal-case">({t('onboarding.admin_pass_optional')})</span>
                  </label>
                  <div className="relative">
                    <input
                      type={showPass ? 'text' : 'password'}
                      value={admin.password}
                      onChange={e => setAdmin(s => ({ ...s, password: e.target.value }))}
                      placeholder={t('onboarding.admin_pass_placeholder')}
                      className="w-full px-4 py-3 pr-10 rounded-xl border border-gray-200 outline-none focus:ring-2 focus:ring-indigo-500/20 focus:border-indigo-500 transition"
                    />
                    <button
                      type="button"
                      onClick={() => setShowPass(v => !v)}
                      className="absolute right-3 top-1/2 -translate-y-1/2 text-gray-400 hover:text-gray-600"
                    >
                      {showPass ? <EyeOff className="w-4 h-4" /> : <Eye className="w-4 h-4" />}
                    </button>
                  </div>
                  <p className="text-[11px] text-gray-400 mt-1">{t('onboarding.admin_pass_hint')}</p>
                </div>
              </div>
            </div>
          )}

          {/* Step 2 — WhatsApp */}
          {step === 2 && (
            <div className="space-y-5 animate-in fade-in slide-in-from-bottom-4">
              <div>
                <h2 className="text-2xl font-bold text-gray-900">{t('onboarding.wa_title')}</h2>
                <p className="text-gray-400 text-sm mt-1">{t('onboarding.wa_subtitle')}</p>
              </div>

              {/* Contextual help block */}
              {!wa.wabaId && (
                <details className="bg-blue-50 border border-blue-100 rounded-2xl group">
                  <summary className="p-4 cursor-pointer list-none flex items-center gap-2 text-blue-700 text-sm font-medium select-none">
                    <span>❓</span> {t('onboarding.whatsapp_help_title')}
                    <span className="ml-auto text-blue-400 group-open:rotate-180 transition-transform">▾</span>
                  </summary>
                  <div className="px-4 pb-4 text-xs text-blue-800 space-y-2 leading-relaxed">
                    <div className="flex gap-2">
                      <span className="font-bold shrink-0">WABA ID</span>
                      <span><a href="https://business.facebook.com/wa/manage/home" target="_blank" rel="noreferrer" className="underline font-medium">WhatsApp Manager</a> → {t('onboarding.help_waba_id')}</span>
                    </div>
                    <div className="flex gap-2">
                      <span className="font-bold shrink-0">Business ID</span>
                      <span><a href="https://business.facebook.com/settings/info" target="_blank" rel="noreferrer" className="underline font-medium">Meta Business</a> — {t('onboarding.help_business_id')}</span>
                    </div>
                    <div className="flex gap-2">
                      <span className="font-bold shrink-0">Token</span>
                      <span>{t('onboarding.help_token')}</span>
                    </div>
                    <div className="mt-3 p-2 bg-blue-100 rounded-xl text-blue-700">
                      💡 {t('onboarding.help_new_to_meta')}
                    </div>
                  </div>
                </details>
              )}

              {wa.wabaId ? (
                /* Already captured via Embedded Signup */
                <div className="p-4 bg-emerald-50 border border-emerald-200 rounded-2xl flex items-center gap-3">
                  <CheckCircle2 className="w-5 h-5 text-emerald-500 shrink-0" />
                  <div>
                    <p className="font-semibold text-emerald-700 text-sm">{t('onboarding.fb_account_connected')}</p>
                    <p className="text-[11px] text-emerald-600 font-mono mt-0.5">WABA : {wa.wabaId}</p>
                  </div>
                  <button onClick={() => setWa(s => ({ ...s, wabaId: '', accessToken: '' }))} className="ml-auto text-xs text-emerald-500 hover:underline">{t('common.edit')}</button>
                </div>
              ) : (
                <div className="space-y-3">
                  {/* Option A — Direct */}
                  <div className="border border-indigo-100 bg-indigo-50/40 rounded-2xl p-5">
                    <p className="text-xs font-bold uppercase tracking-wider text-indigo-500 mb-3">{t('onboarding.already_configured')}</p>
                    <div className="space-y-4">

                      {/* Step 1 — WABA ID */}
                      <div className="flex gap-3">
                        <span className="mt-0.5 w-5 h-5 rounded-full bg-indigo-100 text-indigo-600 text-[10px] font-bold flex items-center justify-center shrink-0">1</span>
                        <div className="flex-1">
                          <label className="block text-xs font-bold text-slate-500 mb-1">WABA ID <span className="text-red-400">*</span></label>
                          <input
                            type="text"
                            placeholder="ex: 938685848818318"
                            value={wa.wabaId}
                            onChange={e => setWa(s => ({ ...s, wabaId: e.target.value }))}
                            className="w-full border border-slate-200 rounded-xl px-3 py-2.5 text-sm font-mono outline-none focus:ring-2 focus:ring-indigo-500/20 focus:border-indigo-400"
                          />
                          <p className="text-[10px] text-slate-400 mt-1">
                            <a href="https://business.facebook.com/wa/manage/home" target="_blank" rel="noreferrer" className="text-indigo-500 underline">WhatsApp Manager</a> → colonne "Compte WhatsApp Business"
                          </p>
                        </div>
                      </div>

                      {/* Step 2 — Business ID */}
                      <div className="flex gap-3">
                        <span className="mt-0.5 w-5 h-5 rounded-full bg-indigo-100 text-indigo-600 text-[10px] font-bold flex items-center justify-center shrink-0">2</span>
                        <div className="flex-1">
                          <label className="block text-xs font-bold text-slate-500 mb-1">Business ID Meta <span className="text-slate-300">(recommandé)</span></label>
                          <input
                            type="text"
                            placeholder="ex: 25855038707486178"
                            value={wa.metaBusinessId}
                            onChange={e => setWa(s => ({ ...s, metaBusinessId: e.target.value }))}
                            className="w-full border border-slate-200 rounded-xl px-3 py-2.5 text-sm font-mono outline-none focus:ring-2 focus:ring-indigo-500/20 focus:border-indigo-400"
                          />
                          <p className="text-[10px] text-slate-400 mt-1">
                            <a href="https://business.facebook.com/settings/info" target="_blank" rel="noreferrer" className="text-indigo-500 underline">Paramètres Meta → Informations de l'entreprise</a>
                          </p>
                        </div>
                      </div>

                      {/* Step 3 — Token */}
                      <div className="flex gap-3">
                        <span className="mt-0.5 w-5 h-5 rounded-full bg-indigo-100 text-indigo-600 text-[10px] font-bold flex items-center justify-center shrink-0">3</span>
                        <div className="flex-1">
                          <label className="block text-xs font-bold text-slate-500 mb-1">
                            Token système <span className="text-slate-300">(optionnel)</span>
                          </label>
                          <div className="relative">
                            <input
                              type="password"
                              placeholder="EAAxxxxxxx... — vide = token plateforme"
                              value={wa.accessToken}
                              onChange={e => { setWa(s => ({ ...s, accessToken: e.target.value })); setTokenValidState('idle'); }}
                              onBlur={e => validateToken(e.target.value)}
                              className={`w-full border rounded-xl px-3 py-2.5 text-sm font-mono outline-none focus:ring-2 pr-8 ${
                                tokenValidState === 'valid'   ? 'border-emerald-400 focus:ring-emerald-300' :
                                tokenValidState === 'invalid' ? 'border-red-400 focus:ring-red-300' :
                                'border-slate-200 focus:ring-indigo-500/20 focus:border-indigo-400'
                              }`}
                            />
                            {tokenValidState === 'checking' && (
                              <span className="absolute right-3 top-1/2 -translate-y-1/2 text-[10px] text-slate-400 animate-pulse">…</span>
                            )}
                            {tokenValidState === 'valid' && (
                              <span className="absolute right-3 top-1/2 -translate-y-1/2 text-emerald-500 text-sm">✓</span>
                            )}
                            {tokenValidState === 'invalid' && (
                              <span className="absolute right-3 top-1/2 -translate-y-1/2 text-red-500 text-sm">✗</span>
                            )}
                          </div>
                          {tokenValidState === 'valid' && (
                            <p className="text-[10px] text-emerald-600 mt-1">✅ {t('onboarding.token_valid_msg')}</p>
                          )}
                          {tokenValidState === 'invalid' && (
                            <p className="text-[10px] text-red-500 mt-1">❌ {t('onboarding.token_invalid_msg')}</p>
                          )}
                          {tokenValidState === 'idle' && (
                            <p className="text-[10px] text-slate-400 mt-1">{t('onboarding.token_idle_hint')}</p>
                          )}
                        </div>
                      </div>
                    </div>
                  </div>

                  {/* Separator */}
                  <div className="flex items-center gap-3 text-slate-300">
                    <div className="flex-1 h-px bg-slate-100" />
                    <span className="text-xs font-medium">ou</span>
                    <div className="flex-1 h-px bg-slate-100" />
                  </div>

                  {/* Option B — Embedded Signup */}
                  <div className="border border-slate-100 rounded-2xl p-5">
                    <p className="text-xs font-bold uppercase tracking-wider text-slate-400 mb-2">{t('onboarding.new_account_via_fb')}</p>
                    <p className="text-xs text-slate-500 mb-3">{t('onboarding.new_account_desc')}</p>
                    <button
                      onClick={handleEmbeddedSignup}
                      className="w-full bg-[#1877F2] hover:bg-[#166fe5] text-white py-3 rounded-xl font-bold text-sm transition flex items-center justify-center gap-2"
                    >
                      <svg className="w-5 h-5" fill="currentColor" viewBox="0 0 24 24"><path d="M24 12.073c0-6.627-5.373-12-12-12s-12 5.373-12 12c0 5.99 4.388 10.954 10.125 11.854v-8.385H7.078v-3.47h3.047V9.43c0-3.007 1.792-4.669 4.533-4.669 1.312 0 2.686.235 2.686.235v2.953H15.83c-1.491 0-1.956.925-1.956 1.874v2.25h3.328l-.532 3.47h-2.796v8.385C19.612 23.027 24 18.062 24 12.073z"/></svg>
                      Se connecter avec Facebook
                    </button>
                  </div>
                </div>
              )}

              {/* Skip */}
              <button
                onClick={() => setWa(s => ({ ...s, skip: true, wabaId: '', accessToken: '', metaBusinessId: '' }))}
                className="flex items-center gap-1.5 text-xs text-slate-400 hover:text-slate-600 transition mx-auto"
              >
                <SkipForward className="w-3.5 h-3.5" />
                {t('onboarding.skip_whatsapp')}
              </button>
            </div>
          )}
        </div>

        {/* Footer */}
        <div className="bg-gray-50 px-10 py-5 flex justify-between items-center border-t border-gray-100">
          <button
            onClick={back}
            disabled={step === 0}
            className="flex items-center gap-2 text-sm font-bold text-gray-400 hover:text-gray-600 disabled:opacity-0 transition"
          >
            <ArrowLeft className="w-4 h-4" /> {t('common.back')}
          </button>

          <button
            onClick={step === STEP_KEYS.length - 1 ? handleSubmit : next}
            disabled={loading || !canNext()}
            className="bg-indigo-600 hover:bg-indigo-700 text-white px-8 py-3 rounded-xl font-bold flex items-center gap-3 shadow-lg shadow-indigo-500/30 transition disabled:opacity-40"
          >
            {loading
              ? <><Loader2 className="w-4 h-4 animate-spin" /> {t('onboarding.creating')}</>
              : step === STEP_KEYS.length - 1
                ? <><CheckCircle2 className="w-4 h-4" /> {t('onboarding.create_org')}</>
                : <>{t('common.next')} <ArrowRight className="w-4 h-4" /></>
            }
          </button>
        </div>
      </div>
    </div>
  );
}