// POST /api/offline/reindex - write mail/calendar/contacts/files into the
// encrypted local search index for the calling session's account.
//
// The PRIMARY caller is the renderer's live JMAP push handler: when a
// StateChange arrives it posts the ids that changed, so indexing is reactive to
// each delivery rather than periodic. `{ catchUp: true }` (no ids) is the
// fallback used at app launch to backfill whatever changed while the app was
// closed.
//
// GATED: returns 404 unless VNCMAIL_DESKTOP_STORE_DIR is set, which only
// electron/main.ts does. The same standalone server artifact runs in the
// multi-tenant production Docker image, where this feature must not exist at
// all - 404 rather than 403 so nothing learns the route is there.
import { NextRequest, NextResponse } from 'next/server';
import { logger } from '@/lib/logger';
import { isSqlcipherAvailable } from '@/lib/mail-index/binding';
import { hasKeyChannel, IndexKeyError } from '@/lib/mail-index/key';
import { getStoreDir } from '@/lib/mail-index/paths';
import {
  IndexSessionError, MAX_IDS_PER_CALL, normalizeWindowDays, resolveIndexSession, runIndex,
  type IndexRequest,
} from '@/lib/mail-index/reindex';
import { CONTENT_TYPES, isContentType, type ContentType } from '@/lib/mail-index/store';
import { JmapIndexError } from '@/lib/mail-index/jmap';
import { isFeatureEnabledServer } from '@/lib/admin/feature-gate';

export const runtime = 'nodejs';
export const dynamic = 'force-dynamic';

function parseIdMap(raw: unknown): Partial<Record<ContentType, string[]>> | undefined {
  if (!raw || typeof raw !== 'object' || Array.isArray(raw)) return undefined;
  const out: Partial<Record<ContentType, string[]>> = {};
  for (const [key, value] of Object.entries(raw as Record<string, unknown>)) {
    if (!isContentType(key) || !Array.isArray(value)) continue;
    const ids = value
      .filter((v): v is string => typeof v === 'string' && v.length > 0 && v.length <= 256)
      .slice(0, MAX_IDS_PER_CALL);
    if (ids.length > 0) out[key] = ids;
  }
  return Object.keys(out).length > 0 ? out : undefined;
}

export async function POST(request: NextRequest) {
  if (!isFeatureEnabledServer('aiAssistantEnabled')) {
    return NextResponse.json({ error: 'Feature disabled' }, { status: 403 });
  }

  if (!getStoreDir()) {
    return new NextResponse(null, { status: 404 });
  }
  if (!hasKeyChannel()) {
    return NextResponse.json(
      { error: 'The local index has no key channel in this process.', code: 'no-key-channel' },
      { status: 503 },
    );
  }
  if (!isSqlcipherAvailable()) {
    // The native binding is an optionalDependency, so "not installed" is a
    // normal state on platforms without a prebuild - not an error to log loudly.
    return NextResponse.json(
      { error: 'Encrypted local index is unavailable on this platform.', code: 'no-binding' },
      { status: 503 },
    );
  }

  let body: Record<string, unknown> = {};
  try {
    const text = await request.text();
    if (text.trim()) body = JSON.parse(text) as Record<string, unknown>;
  } catch {
    return NextResponse.json({ error: 'Malformed JSON body' }, { status: 400 });
  }

  const rawTypes = Array.isArray(body.types) ? body.types.filter(isContentType) : [];
  const req: IndexRequest = {
    types: rawTypes.length > 0 ? rawTypes : undefined,
    ids: parseIdMap(body.ids),
    removed: parseIdMap(body.removed),
    // Pruning is a catch-up concern; a single-delivery call shouldn't scan.
    prune: body.catchUp === true,
    // `undefined` (absent) means "use the default"; an explicit null means
    // keep everything. normalizeWindowDays() in runIndex clamps anything
    // unexpected, since this value drives deletion.
    windowDays: body.windowDays === undefined ? undefined : normalizeWindowDays(body.windowDays),
  };

  try {
    const session = await resolveIndexSession(request);
    const result = await runIndex(session, req);
    return NextResponse.json(
      {
        ok: true,
        written: result.written,
        skipped: result.skipped,
        errors: result.errors,
        durationMs: result.durationMs,
        types: CONTENT_TYPES,
      },
      { headers: { 'Cache-Control': 'no-store' } },
    );
  } catch (error) {
    if (error instanceof IndexSessionError) {
      return NextResponse.json({ error: error.message }, { status: error.status });
    }
    if (error instanceof JmapIndexError) {
      return NextResponse.json({ error: error.message }, { status: error.status });
    }
    if (error instanceof IndexKeyError) {
      // no-secure-storage is the Linux-without-a-keyring refusal: a real,
      // expected outcome with a user-facing explanation, not a server fault.
      const status = error.code === 'no-secure-storage' ? 503 : 500;
      return NextResponse.json({ error: error.message, code: error.code }, { status });
    }
    logger.error('mail-index reindex failed', {
      error: error instanceof Error ? error.message : String(error),
    });
    return NextResponse.json({ error: 'Reindex failed' }, { status: 500 });
  }
}