/**
 * POST { month: 'YYYY-MM' } → editorial preview for active tenant.
 */
import { NextRequest, NextResponse } from 'next/server';
import { createClient } from '@/lib/supabase/server';
import { resolveActiveTenant, restGet } from '@/lib/tenant-context';
import { isAgencyRole, userRole } from '@/lib/agency';
import { asPlanObject } from '@/lib/calendar-documents';
import { generateMonthPreview } from '@/lib/calendar-generate';
import type { RrssMonthPlan } from '@/components/RrssMonthView';

export const dynamic = 'force-dynamic';
export const maxDuration = 60;

export async function POST(req: NextRequest) {
  const supabase = await createClient();
  const {
    data: { user },
  } = await supabase.auth.getUser();
  if (!user) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
  }
  if (!isAgencyRole(userRole(user))) {
    return NextResponse.json({ error: 'Solo agencia' }, { status: 403 });
  }
  const ctx = await resolveActiveTenant(user);
  if (!ctx.tenantId || ctx.portfolioWide) {
    return NextResponse.json(
      { error: 'Selecciona un cliente en Contexto.' },
      { status: 400 }
    );
  }

  const body = (await req.json().catch(() => ({}))) as { month?: string };
  const month = String(body.month || '').slice(0, 7);
  if (!/^\d{4}-\d{2}$/.test(month)) {
    return NextResponse.json({ error: 'month YYYY-MM requerido' }, { status: 400 });
  }

  let slug = 'cliente';
  const t = await restGet<{ slug?: string }[]>(
    `/rest/v1/tenants?id=eq.${encodeURIComponent(ctx.tenantId)}&select=slug`
  );
  slug = t.data?.[0]?.slug || ctx.label.toLowerCase().replace(/\s+/g, '-');

  const docs = await restGet<{ content?: unknown }[]>(
    `/rest/v1/documents?tenant_id=eq.${encodeURIComponent(
      ctx.tenantId
    )}&type=eq.calendar&select=content&order=created_at.desc&limit=48`
  );
  const history: RrssMonthPlan[] = [];
  for (const d of docs.data || []) {
    const plan = asPlanObject(d.content) as RrssMonthPlan | null;
    if (plan?.month && plan.month !== month && Array.isArray(plan.pieces)) {
      history.push(plan as unknown as RrssMonthPlan);
    }
  }
  // Prefer same calendar month from prior years first (e.g. 2025-11 before 2026-10)
  const mm = month.slice(5, 7);
  history.sort((a, b) => {
    const aSame = a.month.slice(5, 7) === mm ? 0 : 1;
    const bSame = b.month.slice(5, 7) === mm ? 0 : 1;
    if (aSame !== bSame) return aSame - bSame;
    return String(b.month).localeCompare(String(a.month));
  });

  const result = await generateMonthPreview({
    ym: month,
    slug,
    label: ctx.label,
    history,
  });

  return NextResponse.json({
    ok: true,
    plan: result.plan,
    rationale: result.rationale,
    source: result.source,
    brand: slug,
  });
}