import { NextResponse } from "next/server";
import { z } from "zod";

import { getAppSettings, toApprovalThresholdNumber } from "@/lib/app-settings";
import { snapshotAppSettings } from "@/lib/audit-snapshots";
import { createAuditLog } from "@/lib/audit-log";
import { canManageUsers } from "@/lib/domain";
import prisma from "@/lib/prisma";
import { getCurrentViewer } from "@/lib/session";

const settingsSchema = z.object({
  approvalThreshold: z.coerce.number().min(0).max(100000)
});

export async function PATCH(request: Request) {
  const viewer = await getCurrentViewer();

  if (!viewer) {
    return NextResponse.json({ error: "Nicht angemeldet." }, { status: 401 });
  }

  if (!canManageUsers(viewer.role)) {
    return NextResponse.json({ error: "Nur Vorstand allgemein, AG Orga oder AG Finanzen duerfen Einstellungen aendern." }, { status: 403 });
  }

  const body = await request.json().catch(() => null);
  const parsed = settingsSchema.safeParse(body);

  if (!parsed.success) {
    return NextResponse.json({ error: "Bitte eine gueltige Freigabe-Schwelle eingeben." }, { status: 400 });
  }

  const existingSettings = await getAppSettings();
  const previousSnapshot = snapshotAppSettings(existingSettings);

  const appSettings = await prisma.appSettings.update({
    where: {
      id: existingSettings.id
    },
    data: {
      approvalThreshold: parsed.data.approvalThreshold
    }
  });

  await createAuditLog(prisma, {
    actorId: viewer.id,
    action: "settings.update",
    entityType: "settings",
    entityId: appSettings.id,
    entityLabel: "Freigabe-Schwelle",
    summary: `Freigabe-Schwelle wurde auf ${toApprovalThresholdNumber(appSettings.approvalThreshold).toFixed(2)} EUR gesetzt.`,
    metadata: {
      approvalThreshold: toApprovalThresholdNumber(appSettings.approvalThreshold),
      rollback: {
        kind: "settings.update",
        previous: previousSnapshot
      }
    }
  });

  return NextResponse.json({
    ok: true,
    approvalThreshold: toApprovalThresholdNumber(appSettings.approvalThreshold)
  });
}