import { useEffect, useState } from 'react';
import { useNavigate } from 'react-router-dom';
import {
  Plus, Trash2, Eye, EyeOff, Copy, Pencil, Save, X, RefreshCw, ShieldAlert, MoreVertical,
  Mail, Globe, Server, Database, Cloud, Shield, Lock, Wifi, CreditCard, Building2, Printer,
  Smartphone, KeyRound, HardDrive, Router, UserCog,
} from 'lucide-react';
import { useUi } from '../../context/ui-context.jsx';
import { useAction } from '../../hooks/useAsync.js';
import { useDebouncedValue } from '../../hooks/useDebouncedValue.js';
import {
  getVaultStatus, createVaultPin, unlockVault, changeVaultPin, forgotVaultPin, setVaultToken,
  listVaultEntries, getVaultEntry, createVaultEntry, updateVaultEntry, deleteVaultEntry,
} from '../../services/vault.js';
import { Button } from '../../components/Button.jsx';
import { Field } from '../../components/Field.jsx';
import { PasswordInput } from '../../components/PasswordInput.jsx';
import { DetailPopup } from '../../components/DetailPopup.jsx';
import { Flyout, FlyoutItem } from '../../components/Flyout.jsx';
import { SearchInput } from '../../components/SearchInput.jsx';
import { BRAND_ICONS } from '../../data/brandIcons.js';

const EMPTY_FORM = { title: '', url: '', username: '', password: '', notes: '', iconKey: '' };
const AUTO_LOCK_MS = 3 * 60 * 1000; // 3 minutos: salir solo del menu si queda abierto sin atencion

// Catalogo fijo de iconos genericos (debe coincidir con backend/src/modules/vault/service.js#ICON_KEYS) --
// a proposito NO se usa ningun servicio externo de favicon (ej. google/s2/favicons): revelaria a
// terceros que urls internas tiene guardadas cada usuario, inaceptable para un repositorio de
// credenciales. El usuario elige uno de esta lista, o uno de marca (BRAND_ICONS), o se deja
// "Auto" (inicial del nombre).
const ICONS = {
  mail: Mail, globe: Globe, server: Server, database: Database, cloud: Cloud, shield: Shield,
  lock: Lock, wifi: Wifi, card: CreditCard, building: Building2, printer: Printer,
  phone: Smartphone, key: KeyRound, disk: HardDrive, router: Router, user: UserCog,
};

function BrandSvg({ icon, size = 22 }) {
  return (
    <svg viewBox="0 0 24 24" width={size} height={size} fill={`#${icon.hex}`}>
      <path d={icon.path} />
    </svg>
  );
}

function EntryIcon({ iconKey, title, size = 22 }) {
  const Icon = ICONS[iconKey];
  const brand = BRAND_ICONS[iconKey];
  return (
    <div className={`vault-card-icon ${brand ? 'brand' : ''}`}>
      {Icon ? <Icon size={size} /> : brand ? <BrandSvg icon={brand} size={size} /> : <span>{(title || '?').trim().charAt(0).toUpperCase()}</span>}
    </div>
  );
}

function randomPassword(length = 20) {
  const chars = 'ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnpqrstuvwxyz23456789!@#$%^&*';
  const bytes = crypto.getRandomValues(new Uint32Array(length));
  return Array.from(bytes, (b) => chars[b % chars.length]).join('');
}

export default function ContrasenasPage() {
  const { t, pushToast, openDialog } = useUi();
  const runAction = useAction();
  const navigate = useNavigate();

  const [locked, setLocked] = useState(true);
  const [checking, setChecking] = useState(true);
  const [hasPinSet, setHasPinSet] = useState(null);
  const [entries, setEntries] = useState(null);
  const [search, setSearch] = useState('');
  const debouncedSearch = useDebouncedValue(search, 300);

  const [pin, setPin] = useState('');
  const [pinConfirm, setPinConfirm] = useState('');
  const [pinError, setPinError] = useState('');
  const [busy, setBusy] = useState(false);

  const [selected, setSelected] = useState(null); // entrada abierta en el popup
  const [editing, setEditing] = useState(false);
  const [form, setForm] = useState(EMPTY_FORM);
  const [revealedPassword, setRevealedPassword] = useState(null);
  const [passwordVisible, setPasswordVisible] = useState(false);
  const [creating, setCreating] = useState(false);

  const [changingPin, setChangingPin] = useState(false);
  const [pinChangeForm, setPinChangeForm] = useState({ current: '', next: '', next2: '' });
  const [pinChangeError, setPinChangeError] = useState('');

  async function loadEntries(query) {
    const data = await listVaultEntries(query);
    setEntries(data);
    setLocked(false);
  }

  async function checkAccess() {
    setChecking(true);
    try {
      await loadEntries();
    } catch {
      setLocked(true);
      try {
        const status = await getVaultStatus();
        setHasPinSet(status.hasPinSet);
      } catch { /* ignora, se reintenta al enviar el pin */ }
    } finally {
      setChecking(false);
    }
  }

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

  // Mientras esta desbloqueado, cada cambio de busqueda (con debounce) vuelve a pedir el listado
  // ya filtrado -- nombre/usuario/enlace se comparan tal cual, las notas se descifran solo en el
  // servidor para comparar (nunca viaja el contenido al cliente, ver vault/service.js#listEntries).
  useEffect(() => {
    if (locked || checking) return;
    loadEntries(debouncedSearch).catch(() => {});
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [debouncedSearch]);

  // Por seguridad: salir de este menu (a otro, o cerrando la pestaña) siempre bloquea de nuevo --
  // el token de desbloqueo se borra al desmontar, asi que la proxima vez que se entra aca pide el
  // PIN de nuevo, sin importar cuanto haya durado la sesion del sistema.
  useEffect(() => () => setVaultToken(null), []);

  // Si queda abierto sin atencion, sale solo al Panel a los 3 minutos de haberse desbloqueado.
  useEffect(() => {
    if (locked) return;
    const timer = setTimeout(() => {
      pushToast({ tone: 'warning', message: t('vault_auto_lock_notice') });
      navigate('/');
    }, AUTO_LOCK_MS);
    return () => clearTimeout(timer);
  }, [locked]);

  async function submitPin() {
    setPinError('');
    if (!/^\d{4}$/.test(pin)) { setPinError(t('vault_pin_invalid')); return; }
    setBusy(true);
    try {
      if (!hasPinSet) {
        if (pin !== pinConfirm) { setPinError(t('vault_pin_mismatch')); setBusy(false); return; }
        await createVaultPin(pin);
      }
      await unlockVault(pin);
      setPin(''); setPinConfirm('');
      await loadEntries();
    } catch (err) {
      setPinError(err.message);
    } finally {
      setBusy(false);
    }
  }

  async function handleForgotPin() {
    await runAction(async () => {
      await forgotVaultPin();
      pushToast({ tone: 'success', message: t('vault_forgot_pin_sent') });
    });
  }

  async function submitChangePin() {
    setPinChangeError('');
    if (!/^\d{4}$/.test(pinChangeForm.next)) { setPinChangeError(t('vault_pin_invalid')); return; }
    if (pinChangeForm.next !== pinChangeForm.next2) { setPinChangeError(t('vault_pin_mismatch')); return; }
    try {
      await changeVaultPin(pinChangeForm.current, pinChangeForm.next);
      setChangingPin(false);
      setPinChangeForm({ current: '', next: '', next2: '' });
      pushToast({ tone: 'success', message: t('common_saved') });
    } catch (err) {
      setPinChangeError(err.message);
    }
  }

  function openEntry(entry) {
    setSelected(entry);
    setForm({ title: entry.title, url: entry.url || '', username: entry.username || '', password: '', notes: '', iconKey: entry.icon_key || '' });
    setRevealedPassword(null);
    setPasswordVisible(false);
    setEditing(false);
    setCreating(false);
  }

  function openCreate() {
    setSelected(null);
    setForm(EMPTY_FORM);
    setRevealedPassword(null);
    setPasswordVisible(false);
    setEditing(true);
    setCreating(true);
  }

  function closePopup() {
    setSelected(null);
    setCreating(false);
    setEditing(false);
  }

  async function reveal() {
    await runAction(async () => {
      const full = await getVaultEntry(selected.id);
      setRevealedPassword(full.password);
      setForm((f) => ({ ...f, notes: full.notes || '' }));
      setPasswordVisible(true);
    });
  }

  function startEdit() {
    setForm((f) => ({ ...f, password: revealedPassword || '' }));
    setEditing(true);
  }

  function cancelEdit() {
    if (creating) { closePopup(); return; }
    setEditing(false);
    openEntry(selected);
  }

  async function save() {
    if (!form.title.trim()) return;
    await runAction(async () => {
      if (creating) {
        await createVaultEntry(form);
        pushToast({ tone: 'success', message: t('common_saved') });
      } else {
        await updateVaultEntry(selected.id, form);
        pushToast({ tone: 'success', message: t('common_saved') });
      }
      closePopup();
      await loadEntries();
    });
  }

  function confirmDelete(entry) {
    openDialog({
      tone: 'warning',
      title: t('common_confirm_delete_title'),
      message: t('common_confirm_delete_msg'),
      actions: [
        { label: t('common_cancel'), variant: 'standard' },
        {
          label: t('common_delete'), variant: 'danger',
          onClick: () => runAction(async () => {
            await deleteVaultEntry(entry.id);
            await loadEntries();
            pushToast({ tone: 'success', message: t('common_saved') });
          }),
        },
      ],
    });
  }

  function copyToClipboard(value) {
    navigator.clipboard?.writeText(value);
    pushToast({ tone: 'success', message: t('vault_copied') });
  }

  if (checking) return <div className="text-muted">{t('common_loading')}</div>;

  if (locked) {
    return (
      <div style={{ maxWidth: 360, margin: '60px auto' }} className="panel-card">
        <div style={{ display: 'flex', alignItems: 'center', gap: 8, marginBottom: 12 }}>
          <ShieldAlert size={20} />
          <h3 style={{ margin: 0 }}>{hasPinSet ? t('vault_enter_pin_title') : t('vault_create_pin_title')}</h3>
        </div>
        {!hasPinSet && <p className="text-muted" style={{ fontSize: '.8rem' }}>{t('vault_create_pin_hint')}</p>}
        <Field label={t('vault_pin_label')}>
          <input
            className="input" type="password" inputMode="numeric" maxLength={4} autoFocus
            value={pin} onChange={(e) => setPin(e.target.value.replace(/\D/g, ''))}
            onKeyDown={(e) => { if (e.key === 'Enter') submitPin(); }}
          />
        </Field>
        {!hasPinSet && (
          <Field label={t('vault_pin_confirm_label')}>
            <input
              className="input" type="password" inputMode="numeric" maxLength={4}
              value={pinConfirm} onChange={(e) => setPinConfirm(e.target.value.replace(/\D/g, ''))}
              onKeyDown={(e) => { if (e.key === 'Enter') submitPin(); }}
            />
          </Field>
        )}
        {pinError && <div className="login-error">{pinError}</div>}
        <Button variant="accent" onClick={submitPin} disabled={busy} style={{ width: '100%', marginTop: 8 }}>
          {hasPinSet ? t('vault_unlock') : t('vault_create_pin_submit')}
        </Button>
        {hasPinSet && (
          <button type="button" className="link-button" style={{ marginTop: 10 }} onClick={handleForgotPin}>
            {t('vault_forgot_pin')}
          </button>
        )}
      </div>
    );
  }

  return (
    <div>
      <div className="toolbar">
        <h2 className="page-title mt-0" style={{ marginBottom: 0 }}>{t('nav_passwords')}</h2>
        <SearchInput value={search} onChange={setSearch} />
        <div style={{ flex: 1 }} />
        <Button variant="standard" icon={RefreshCw} onClick={() => setChangingPin(true)}>{t('vault_change_pin')}</Button>
        <Button variant="accent" icon={Plus} onClick={openCreate}>{t('vault_new_entry')}</Button>
      </div>

      {entries.length === 0 && (
        <div className="text-muted">{search.trim() ? t('common_search_no_results') : t('common_empty')}</div>
      )}

      <div className="vault-grid">
        {entries.map((entry) => (
          <div key={entry.id} className="vault-card" onClick={() => openEntry(entry)}>
            <div className="vault-card-menu" onClick={(e) => e.stopPropagation()}>
              <Flyout trigger={({ onClick }) => (
                <button className="icon-btn row-menu-btn" onClick={onClick}><MoreVertical size={16} /></button>
              )}>
                <FlyoutItem icon={Trash2} danger onClick={() => confirmDelete(entry)}>{t('common_delete')}</FlyoutItem>
              </Flyout>
            </div>
            <EntryIcon iconKey={entry.icon_key} title={entry.title} />
            <div className="vault-card-title">{entry.title}</div>
            {entry.url && <div className="vault-card-url">{entry.url}</div>}
          </div>
        ))}
      </div>

      <DetailPopup
        open={creating || !!selected}
        title={creating ? t('vault_new_entry') : (selected?.title || '')}
        onClose={closePopup}
        width={480}
        height={640}
      >
        {editing && (
          <Field label={t('vault_field_icon')}>
            <div className="vault-icon-picker">
              <button
                type="button"
                className={`vault-icon-option ${!form.iconKey ? 'selected' : ''}`}
                title={t('vault_icon_auto')}
                onClick={() => setForm((f) => ({ ...f, iconKey: '' }))}
              >
                {(form.title || '?').trim().charAt(0).toUpperCase() || 'A'}
              </button>
              {Object.entries(ICONS).map(([key, Icon]) => (
                <button
                  type="button"
                  key={key}
                  className={`vault-icon-option ${form.iconKey === key ? 'selected' : ''}`}
                  onClick={() => setForm((f) => ({ ...f, iconKey: key }))}
                >
                  <Icon size={18} />
                </button>
              ))}
            </div>
            <div className="vault-icon-picker vault-icon-picker-brands">
              {Object.entries(BRAND_ICONS).map(([key, icon]) => (
                <button
                  type="button"
                  key={key}
                  className={`vault-icon-option brand ${form.iconKey === key ? 'selected' : ''}`}
                  title={icon.title}
                  onClick={() => setForm((f) => ({ ...f, iconKey: key }))}
                >
                  <BrandSvg icon={icon} size={16} />
                </button>
              ))}
            </div>
          </Field>
        )}

        <Field label={t('vault_field_title')}>
          <input className="input" value={form.title} disabled={!editing} onChange={(e) => setForm((f) => ({ ...f, title: e.target.value }))} />
        </Field>
        <Field label={t('vault_field_url')}>
          <input className="input" value={form.url} disabled={!editing} onChange={(e) => setForm((f) => ({ ...f, url: e.target.value }))} />
        </Field>
        <Field label={t('vault_field_username')}>
          <input className="input" value={form.username} disabled={!editing} onChange={(e) => setForm((f) => ({ ...f, username: e.target.value }))} />
        </Field>

        <Field label={t('vault_field_password')}>
          {editing ? (
            <div style={{ display: 'flex', gap: 6 }}>
              <div style={{ flex: 1 }}>
                <PasswordInput
                  value={form.password}
                  onChange={(e) => setForm((f) => ({ ...f, password: e.target.value }))}
                  placeholder={creating ? '' : t('vault_password_unchanged_hint')}
                />
              </div>
              <Button variant="standard" onClick={() => setForm((f) => ({ ...f, password: randomPassword() }))}>{t('vault_generate')}</Button>
            </div>
          ) : (
            <div style={{ display: 'flex', alignItems: 'center', gap: 6 }}>
              <input className="input" type={passwordVisible ? 'text' : 'password'} value={passwordVisible ? (revealedPassword || '') : '••••••••'} disabled readOnly style={{ flex: 1 }} />
              {!revealedPassword ? (
                <button className="icon-btn" title={t('vault_reveal')} onClick={reveal}><Eye size={16} /></button>
              ) : (
                <>
                  <button className="icon-btn" onClick={() => setPasswordVisible((v) => !v)}>{passwordVisible ? <EyeOff size={16} /> : <Eye size={16} />}</button>
                  <button className="icon-btn" title={t('vault_copy')} onClick={() => copyToClipboard(revealedPassword)}><Copy size={16} /></button>
                </>
              )}
            </div>
          )}
        </Field>

        <Field label={t('vault_field_notes')}>
          <textarea className="textarea" rows={3} disabled={!editing} value={form.notes} onChange={(e) => setForm((f) => ({ ...f, notes: e.target.value }))} />
        </Field>

        <div style={{ display: 'flex', gap: 8, marginTop: 8 }}>
          {editing ? (
            <>
              <Button variant="accent" icon={Save} onClick={save} disabled={!form.title.trim()}>{t('common_save')}</Button>
              <Button variant="standard" icon={X} onClick={cancelEdit}>{t('common_cancel')}</Button>
            </>
          ) : (
            <Button variant="standard" icon={Pencil} onClick={startEdit}>{t('common_edit')}</Button>
          )}
        </div>
      </DetailPopup>

      <DetailPopup open={changingPin} title={t('vault_change_pin')} onClose={() => setChangingPin(false)} width={360} height={360}>
        <Field label={t('vault_pin_current_label')}>
          <input className="input" type="password" inputMode="numeric" maxLength={4} value={pinChangeForm.current} onChange={(e) => setPinChangeForm((f) => ({ ...f, current: e.target.value.replace(/\D/g, '') }))} />
        </Field>
        <Field label={t('vault_pin_label')}>
          <input className="input" type="password" inputMode="numeric" maxLength={4} value={pinChangeForm.next} onChange={(e) => setPinChangeForm((f) => ({ ...f, next: e.target.value.replace(/\D/g, '') }))} />
        </Field>
        <Field label={t('vault_pin_confirm_label')}>
          <input className="input" type="password" inputMode="numeric" maxLength={4} value={pinChangeForm.next2} onChange={(e) => setPinChangeForm((f) => ({ ...f, next2: e.target.value.replace(/\D/g, '') }))} />
        </Field>
        {pinChangeError && <div className="login-error">{pinChangeError}</div>}
        <div style={{ display: 'flex', gap: 8, marginTop: 8 }}>
          <Button variant="accent" onClick={submitChangePin}>{t('common_save')}</Button>
          <Button variant="standard" onClick={() => setChangingPin(false)}>{t('common_cancel')}</Button>
        </div>
      </DetailPopup>
    </div>
  );
}