'use client';
import { useState, useEffect } from 'react';
import { Loader2, Save, Eye, EyeOff, RefreshCw, Check, AlertCircle, BarChart3, Coins } from 'lucide-react';
import AdminBilling from './admin/AdminBilling';

const TABS_SYS = [
  { id: 'settings', label: 'Настройки API' },
  { id: 'billing',  label: 'Биллинг' },
];

const CATEGORIES = [
  { slug: 'ai_providers', title: 'AI провайдеры',
    hint: 'Ключи, URL и модели для текстовой и картиночной генерации. Меняются на лету — рестарт engine не нужен.' },
  { slug: 'payments', title: 'ЮKassa',
    hint: 'Shop ID и Secret Key из личного кабинета ЮKassa. Webhook URL для настройки: https://engine.postcast.ru/api/billing/webhook' },
  { slug: 'photo_search', title: 'Поиск фото',
    hint: 'Yandex Search API: provider, ключ, folder, лимиты.' },
];

export default function SystemSettings() {
  const [sysTab, setSysTab] = useState('settings');
  const [byCategory, setByCategory] = useState({});
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState('');

  async function load() {
    setLoading(true);
    setError('');
    try {
      const result = {};
      for (const cat of CATEGORIES) {
        const res = await fetch(`/api/admin/settings?category=${cat.slug}`);
        if (!res.ok) throw new Error((await res.json()).error || `HTTP ${res.status}`);
        result[cat.slug] = await res.json();
      }
      setByCategory(result);
    } catch (err) {
      setError(err.message);
    } finally {
      setLoading(false);
    }
  }

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

  if (loading) {
    return (
      <div className="card p-12 text-center">
        <Loader2 className="w-6 h-6 animate-spin mx-auto text-accent" />
      </div>
    );
  }

  if (error) {
    return (
      <div className="card p-5 border-red-500/40">
        <div className="flex items-center gap-2 text-red-400">
          <AlertCircle className="w-4 h-4" />
          {error}
        </div>
        <button onClick={load} className="btn-ghost mt-3 text-sm">
          <RefreshCw className="w-4 h-4" /> Повторить
        </button>
      </div>
    );
  }

  return (
    <div className="space-y-6">
      {/* Вкладки системной страницы */}
      <div className="flex gap-1 border-b border-border pb-0">
        {TABS_SYS.map(t => (
          <button key={t.id} onClick={() => setSysTab(t.id)}
            className={`px-4 py-2 text-sm font-medium border-b-2 transition-colors -mb-px ${
              sysTab === t.id ? 'border-accent text-accent' : 'border-transparent text-gray-400 hover:text-gray-200'
            }`}>
            {t.label}
          </button>
        ))}
      </div>

      {sysTab === 'billing' && <AdminBilling />}

      {sysTab === 'settings' && (<>
      <UsageSummary />
      {CATEGORIES.map(cat => (
        <CategoryBlock
          key={cat.slug}
          category={cat}
          rows={byCategory[cat.slug] || []}
          onSaved={() => load()}
        />
      ))}
      </>)}
    </div>
  );
}

const RANGE_LABELS = [
  { key: 'today', label: 'Сегодня' },
  { key: 'week',  label: 'Неделя' },
  { key: 'month', label: 'Месяц' },
  { key: 'all',   label: 'Всё' },
];

function UsageSummary() {
  const [range, setRange] = useState('today');
  const [groupBy, setGroupBy] = useState('service');
  const [data, setData] = useState(null);
  const [loading, setLoading] = useState(true);
  const [err, setErr] = useState('');

  async function load() {
    setLoading(true);
    setErr('');
    try {
      const res = await fetch(`/api/admin/usage/summary?range=${range}&group_by=${groupBy}`);
      if (!res.ok) throw new Error((await res.json()).error || `HTTP ${res.status}`);
      setData(await res.json());
    } catch (e) {
      setErr(e.message);
    } finally {
      setLoading(false);
    }
  }

  useEffect(() => { load(); /* eslint-disable-next-line react-hooks/exhaustive-deps */ }, [range, groupBy]);

  const fmtRub  = v => (Number(v) || 0).toLocaleString('ru-RU', { minimumFractionDigits: 2, maximumFractionDigits: 2 }) + ' ₽';
  const fmtInt  = v => (Number(v) || 0).toLocaleString('ru-RU');

  return (
    <section className="card p-5">
      <div className="flex items-center justify-between flex-wrap gap-2 mb-4">
        <div className="flex items-center gap-2">
          <BarChart3 className="w-5 h-5 text-accent" />
          <h2 className="font-semibold">Расход AI</h2>
        </div>
        <div className="flex items-center gap-2">
          <div className="flex rounded-md overflow-hidden border border-border">
            {RANGE_LABELS.map(r => (
              <button
                key={r.key}
                onClick={() => setRange(r.key)}
                className={`px-2.5 py-1 text-xs ${range === r.key ? 'bg-accent text-white' : 'bg-surface2/50 hover:bg-surface2 text-gray-300'}`}
              >
                {r.label}
              </button>
            ))}
          </div>
          <select
            value={groupBy}
            onChange={e => setGroupBy(e.target.value)}
            className="input text-xs h-7 py-0"
          >
            <option value="service">по сервисам</option>
            <option value="provider">по провайдерам</option>
            <option value="model">по моделям</option>
          </select>
          <button onClick={load} className="btn-ghost p-1.5" title="Обновить">
            <RefreshCw className={`w-4 h-4 ${loading ? 'animate-spin' : ''}`} />
          </button>
        </div>
      </div>

      {err && (
        <div className="text-xs text-red-400 mb-3">{err}</div>
      )}

      {data && (
        <>
          <div className="grid grid-cols-2 sm:grid-cols-4 gap-3 mb-4">
            <Stat label="Сумма"           value={fmtRub(data.totals.cost_rub)} accent />
            <Stat label="Вызовов"         value={fmtInt(data.totals.calls)}
                  sub={data.totals.failed ? `${data.totals.failed} ошибок` : 'все успешно'} />
            <Stat label="Токенов"         value={fmtInt(data.totals.prompt_tokens + data.totals.completion_tokens)}
                  sub={`${fmtInt(data.totals.prompt_tokens)} вход / ${fmtInt(data.totals.completion_tokens)} выход`} />
            <Stat label="Картинок"        value={fmtInt(data.totals.image_count)}
                  sub={data.totals.avg_duration_ms ? `сред. ${(data.totals.avg_duration_ms/1000).toFixed(1)}с` : ''} />
          </div>

          {data.breakdown.length > 0 && (
            <div className="rounded-lg border border-border overflow-hidden">
              <table className="w-full text-xs">
                <thead className="bg-surface2/50">
                  <tr className="text-left text-gray-500">
                    <th className="px-3 py-2 font-medium">
                      {groupBy === 'service' ? 'Сервис' : groupBy === 'provider' ? 'Провайдер' : 'Модель'}
                    </th>
                    <th className="px-3 py-2 font-medium text-right">Вызовов</th>
                    <th className="px-3 py-2 font-medium text-right">Токены</th>
                    <th className="px-3 py-2 font-medium text-right">Картинки</th>
                    <th className="px-3 py-2 font-medium text-right">Стоимость</th>
                  </tr>
                </thead>
                <tbody>
                  {data.breakdown.map(row => (
                    <tr key={row.key} className="border-t border-border/50">
                      <td className="px-3 py-2 font-mono">{row.key}</td>
                      <td className="px-3 py-2 text-right">{fmtInt(row.calls)}{row.failed ? <span className="text-red-400 ml-1">({row.failed} err)</span> : null}</td>
                      <td className="px-3 py-2 text-right">{fmtInt(row.prompt_tokens + row.completion_tokens)}</td>
                      <td className="px-3 py-2 text-right">{fmtInt(row.image_count)}</td>
                      <td className="px-3 py-2 text-right font-mono">{fmtRub(row.cost_rub)}</td>
                    </tr>
                  ))}
                </tbody>
              </table>
            </div>
          )}

          {data.breakdown.length === 0 && (
            <p className="text-sm text-gray-500">За выбранный период вызовов не было.</p>
          )}
        </>
      )}
    </section>
  );
}

function Stat({ label, value, sub, accent }) {
  return (
    <div className={`rounded-lg p-3 ${accent ? 'bg-accent/10 border border-accent/30' : 'bg-surface2/50 border border-border'}`}>
      <div className="text-[10px] uppercase tracking-wide text-gray-500">{label}</div>
      <div className={`text-lg font-semibold mt-0.5 ${accent ? 'text-accent' : ''}`}>{value}</div>
      {sub && <div className="text-[11px] text-gray-500 mt-0.5">{sub}</div>}
    </div>
  );
}

function CategoryBlock({ category, rows, onSaved }) {
  return (
    <section className="card p-5">
      <div className="mb-4">
        <h2 className="font-semibold">{category.title}</h2>
        {category.hint && <p className="text-xs text-gray-500 mt-1">{category.hint}</p>}
      </div>
      {rows.length === 0 ? (
        <p className="text-sm text-gray-500">Нет настроек в этой категории.</p>
      ) : (
        <div className="space-y-3">
          {rows.map(r => (
            <SettingRow key={r.key} row={r} onSaved={onSaved} />
          ))}
        </div>
      )}
    </section>
  );
}

function SettingRow({ row, onSaved }) {
  const [value, setValue] = useState(row.value ?? '');
  const [saving, setSaving] = useState(false);
  const [saved, setSaved] = useState(false);
  const [reveal, setReveal] = useState(false);
  const [err, setErr] = useState('');

  // если row.value меняется снаружи — синхронизируем
  useEffect(() => { setValue(row.value ?? ''); }, [row.value]);

  const isSecret = row.is_secret;
  const dirty = value !== (row.value ?? '');

  async function save() {
    setSaving(true);
    setErr('');
    try {
      const res = await fetch(`/api/admin/settings/${encodeURIComponent(row.key)}`, {
        method: 'PUT',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ value: value === '' ? null : value }),
      });
      if (!res.ok) throw new Error((await res.json()).error || `HTTP ${res.status}`);
      setSaved(true);
      setTimeout(() => setSaved(false), 1500);
      onSaved?.();
    } catch (e) {
      setErr(e.message);
    } finally {
      setSaving(false);
    }
  }

  // Маскировка отображения секретов: показываем хвост ***last4 пока не reveal=true
  const masked = isSecret && value && !reveal
    ? '•'.repeat(Math.max(value.length - 4, 4)) + value.slice(-4)
    : value;

  return (
    <div className="rounded-lg border border-border bg-surface2/50 p-3">
      <div className="flex items-start justify-between flex-wrap gap-2 mb-2">
        <div className="min-w-0">
          <div className="flex items-center gap-2">
            <span className="text-sm font-medium text-gray-800 dark:text-gray-200">
              {SETTING_LABELS[row.key] || row.description || row.key}
            </span>
            {isSecret && (
              <span className="text-[10px] uppercase tracking-wide px-1.5 py-0.5 rounded bg-amber-500/15 text-amber-500">
                secret
              </span>
            )}
          </div>
          <code className="text-[11px] text-gray-400 font-mono mt-0.5">{row.key}</code>
        </div>
      </div>
      <div className="flex items-center gap-2">
        <input
          type={isSecret && !reveal ? 'password' : 'text'}
          className="input text-sm font-mono"
          value={reveal || !isSecret ? value : masked}
          onChange={e => {
            // При маскированном просмотре редактирование запрещаем — пусть сначала откроют
            if (isSecret && !reveal) return;
            setValue(e.target.value);
          }}
          placeholder={isSecret ? '(скрыто)' : '(пусто)'}
          spellCheck={false}
        />
        {isSecret && (
          <button
            type="button"
            onClick={() => setReveal(v => !v)}
            className="btn-ghost p-2"
            title={reveal ? 'Скрыть' : 'Показать'}
          >
            {reveal ? <EyeOff className="w-4 h-4" /> : <Eye className="w-4 h-4" />}
          </button>
        )}
        <button
          onClick={save}
          disabled={saving || !dirty}
          className="btn-primary text-sm"
        >
          {saving ? <Loader2 className="w-4 h-4 animate-spin" />
            : saved ? <Check className="w-4 h-4" />
            : <Save className="w-4 h-4" />}
          {saved ? 'Сохранено' : 'Сохранить'}
        </button>
      </div>
      {err && (
        <div className="text-xs text-red-400 mt-2">{err}</div>
      )}
      <div className="text-[11px] text-gray-500 mt-2">
        Категория: <code>{row.category}</code> · обновлено{' '}
        {row.updated_at ? new Date(row.updated_at).toLocaleString('ru-RU') : '—'}
      </div>
    </div>
  );
}