import { NextRequest, NextResponse } from "next/server";
import { z } from "zod";
import { prisma } from "@/lib/db";
import { phaseInclude } from "@/lib/queries";

const createPhaseSchema = z.object({
  name: z.string().min(1).max(120),
  durationYears: z.number().int().min(1).max(80),
  inflationRate: z.number().min(-20).max(50).nullable().optional(),
  incomeMode: z.enum(["PER_PERSON", "HOUSEHOLD"]).default("HOUSEHOLD"),
});

// Fuegt eine neue Lebensabschnittsphase am Ende der Phasenkette eines Plans an
// (TDD Kapitel 3: Phasen werden chronologisch aneinandergereiht).
export async function POST(
  request: NextRequest,
  { params }: { params: Promise<{ planId: string }> }
) {
  const { planId } = await params;
  const body = await request.json();
  const parsed = createPhaseSchema.safeParse(body);
  if (!parsed.success) {
    return NextResponse.json({ error: parsed.error.flatten() }, { status: 400 });
  }

  const plan = await prisma.plan.findUnique({ where: { id: planId } });
  if (!plan) {
    return NextResponse.json({ error: "Plan nicht gefunden." }, { status: 404 });
  }

  const lastPhase = await prisma.phase.findFirst({
    where: { planId },
    orderBy: { sequenceNumber: "desc" },
    include: { incomeEntries: true, expenseEntries: true },
  });
  const nextSequence = (lastPhase?.sequenceNumber ?? 0) + 1;

  // Einkommen und Ausgaben werden 1:1 aus der letzten Phase uebernommen (manuell
  // anpassbar), damit man sie nicht bei jeder neuen Phase erneut eintippen muss.
  const phase = await prisma.phase.create({
    data: {
      planId,
      sequenceNumber: nextSequence,
      name: parsed.data.name,
      durationYears: parsed.data.durationYears,
      inflationRate: parsed.data.inflationRate ?? null,
      incomeMode: lastPhase?.incomeMode ?? parsed.data.incomeMode,
      incomeEntries: lastPhase
        ? {
            create: lastPhase.incomeEntries.map((e) => ({
              personId: e.personId,
              label: e.label,
              amount: e.amount,
            })),
          }
        : undefined,
      expenseEntries: lastPhase
        ? {
            create: lastPhase.expenseEntries.map((e) => ({ label: e.label, amount: e.amount })),
          }
        : undefined,
    },
    include: phaseInclude,
  });

  return NextResponse.json({ phase }, { status: 201 });
}