"use client";

// Settings panel for the desktop shell's encrypted local search index.
//
// Deliberately small: the index's PRIMARY trigger is the live push connection
// (see lib/mail-index-client.ts's indexOnStateChange, wired into
// stores/email-store.ts's handleStateChange), so this panel is a status readout
// plus a manual catch-up button - not the mechanism.
//
// Renders nothing at all outside the Electron shell, where the routes 404.

import { useCallback, useEffect, useState } from 'react';
import { Button } from '@/components/ui/button';
import { SettingsSection, SettingItem } from './settings-section';
import { isElectronShell } from '@/lib/electron-bridge';
import { useAccountStore } from '@/stores/account-store';
import { catchUpIndex, fetchIndexStats, type IndexStats } from '@/lib/mail-index-client';

const TYPE_LABELS: Record<string, string> = {
  mail: 'Mail',
  calendar: 'Calendar',
  contact: 'Contacts',
  file: 'Files',
};

export function LocalIndexSettings() {
  const slot = useAccountStore((s) => s.accounts.find((a) => a.id === s.activeAccountId)?.cookieSlot);
  const [stats, setStats] = useState<IndexStats[] | null>(null);
  const [busy, setBusy] = useState(false);
  const [message, setMessage] = useState<string | null>(null);
  // `null` until the first probe resolves, so we don't flash a panel that then
  // vanishes on a non-desktop build.
  const [available, setAvailable] = useState<boolean | null>(null);

  const refreshStats = useCallback(async () => {
    const next = await fetchIndexStats(slot);
    setStats(next);
    setAvailable(next !== null);
  }, [slot]);

  useEffect(() => {
    if (!isElectronShell()) {
      setAvailable(false);
      return;
    }
    void refreshStats();
  }, [refreshStats]);

  const handleRebuild = async () => {
    setBusy(true);
    setMessage(null);
    try {
      const result = await catchUpIndex(slot);
      if (result.unavailable) {
        setAvailable(false);
        setMessage(result.error ?? 'The encrypted index is unavailable on this system.');
        return;
      }
      if (!result.ok) {
        setMessage(result.error ?? 'Indexing failed.');
        return;
      }
      const written = Object.entries(result.written ?? {})
        .map(([type, n]) => `${TYPE_LABELS[type] ?? type}: ${n}`)
        .join(', ');
      const failed = (result.errors ?? []).map((e) => `${e.contentType} (${e.message})`).join('; ');
      setMessage(
        [
          written ? `Indexed ${written}.` : 'Nothing to index.',
          result.skipped?.length ? `Not supported: ${result.skipped.join(', ')}.` : '',
          failed ? `Problems: ${failed}` : '',
        ]
          .filter(Boolean)
          .join(' '),
      );
      await refreshStats();
    } finally {
      setBusy(false);
    }
  };

  if (available === false || available === null) return null;

  const total = (stats ?? []).reduce((sum, s) => sum + s.count, 0);

  return (
    <SettingsSection
      title="Local search index"
      description={
        'An encrypted index of your recent mail, calendar events, contacts and file names, ' +
        'stored on this device only. It updates automatically as items arrive, and powers ' +
        'local search and AI answers about your own data. Files are indexed by name and ' +
        'location, not by their contents.'
      }
    >
      <SettingItem
        label="Indexed items"
        description={
          total > 0
            ? (stats ?? [])
                .map((s) => `${TYPE_LABELS[s.contentType] ?? s.contentType}: ${s.count}`)
                .join(' · ')
            : 'Nothing indexed yet.'
        }
      >
        <span className="text-sm text-muted-foreground tabular-nums">{total}</span>
      </SettingItem>

      <SettingItem
        label="Update now"
        description={
          message ??
          'Catches up on anything that changed while the app was closed. Normally not needed - ' +
            'the index updates itself when mail, events, contacts or files change.'
        }
      >
        <Button variant="outline" size="sm" onClick={handleRebuild} disabled={busy}>
          {busy ? 'Indexing…' : 'Update index'}
        </Button>
      </SettingItem>
    </SettingsSection>
  );
}
