import { randomBytes } from 'crypto';
import { NextRequest, NextResponse } from 'next/server';
import { db } from '@/lib/db';
import { getWwwOrigin } from '@/lib/hosts';
import { getSessionUserId } from '@/lib/session';
import { buildMilestonePostForQr, milestoneThreshold, socialLocale } from '@/lib/social-milestones';
import { ensureSocialMilestoneCard } from '@/lib/social-milestones-server';

export const dynamic = 'force-dynamic';

// Returns at most one item. A missing response is treated as no consent, never as approval.
export async function GET(request: NextRequest) {
  const userId = getSessionUserId();
  if (!userId) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });

  const user = await db.user.findUnique({
    where: { id: userId }, select: { socialPromptOptOut: true, xHandle: true, primaryUseCase: true },
  });
  if (!user || user.socialPromptOptOut) return NextResponse.json({ milestone: null });

  const milestone = await db.socialMilestone.findFirst({
    where: {
      userId,
      OR: [
        { status: { in: ['detected', 'shown'] } },
        { status: 'approved', brandStatus: { in: ['approved', 'processing', 'failed'] } },
      ],
    },
    orderBy: { detectedAt: 'asc' },
    include: { qr: { select: { id: true, title: true, createdAt: true } } },
  });
  if (!milestone) return NextResponse.json({ milestone: null });

  if (milestone.status === 'detected') {
    await db.socialMilestone.update({ where: { id: milestone.id }, data: { status: 'shown', shownAt: new Date() } });
  }
  const threshold = milestoneThreshold(milestone.kind);
  if (!threshold) return NextResponse.json({ milestone: null });
  const locale = socialLocale(request.nextUrl.searchParams.get('locale'));
  const shareToken = milestone.shareToken || randomBytes(9).toString('base64url');
  if (!milestone.shareToken) {
    await db.socialMilestone.update({ where: { id: milestone.id }, data: { shareToken } });
  }
  const shareUrl = `${getWwwOrigin()}/s/m/${shareToken}`;
  const card = await ensureSocialMilestoneCard({
    milestoneId: milestone.id,
    cardData: milestone.cardData,
    kind: milestone.kind,
    detectedAt: milestone.detectedAt,
    language: locale,
    qr: milestone.qr,
    primaryUseCase: user.primaryUseCase,
    refresh: ['detected', 'shown'].includes(milestone.status),
    snapshotAt: new Date(),
  });

  return NextResponse.json({
    milestone: {
      id: milestone.id, qrTitle: milestone.qr.title, threshold,
      defaultXHandle: user.xHandle,
      brandStatus: milestone.brandStatus,
      brandPostUrl: milestone.brandPostUrl,
      brandPostError: milestone.brandPostError,
      language: locale,
      shareUrl,
      preview: buildMilestonePostForQr(
        user.primaryUseCase,
        card.totalUniqueScans || threshold,
        null,
        locale,
        milestone.qr.title,
      ),
      card,
    },
  });
}