import { getApiUser } from "@/session.server";
import prisma from "@/lib/prisma.server";

type Transaction = {
  id: string;
  date: string;
  account: "kasse" | "bank";
  type: "einlage" | "entnahme";
  amount: number;
  description: string;
};

function toTransaction(buchung: { id: string; date: Date; account: "KASSE" | "BANK"; type: "EINLAGE" | "ENTNAHME"; amount: { toString(): string } | number | string; description: string | null | undefined; }): Transaction {
  return {
    id: buchung.id,
    date: buchung.date.toISOString().split("T")[0],
    account: buchung.account === "KASSE" ? "kasse" : "bank",
    type: buchung.type === "EINLAGE" ? "einlage" : "entnahme",
    amount: Number(buchung.amount),
    description: buchung.description || "",
  };
}

export async function loader({ request, params }: { request: Request; params: { id: string } }) {
  const user = await getApiUser(request);
  if (!user) return Response.json({ error: "Unauthorized" }, { status: 401 });
  const { id } = params;

  const company = await prisma.company.findFirst({
    where: { id, userId: user.id },
  });

  if (!company) return Response.json({ error: "Company not found" }, { status: 404 });

  const buchungen = await prisma.buchung.findMany({
    where: { companyId: id },
    orderBy: { date: "desc" },
  });

  const transactions = buchungen.map(toTransaction);
  const balance = transactions.reduce((sum: number, t: Transaction) => sum + (t.type === "einlage" ? t.amount : -t.amount), 0 as number);

  return Response.json({ transactions, balance });
}

export async function action({ request, params }: { request: Request; params: { id: string } }) {
  const user = await getApiUser(request);
  if (!user) return Response.json({ error: "Unauthorized" }, { status: 401 });
  const { id } = params;

  const company = await prisma.company.findFirst({
    where: { id, userId: user.id },
  });
  if (!company) return Response.json({ error: "Company not found" }, { status: 404 });

  const url = new URL(request.url);
  const transactionId = url.searchParams.get("transactionId");
  const method = request.method;
  const data = await request.json().catch(() => ({}));

  if (method === "POST") {
    const amount = Number(data.amount);
    if (!data.date || !data.account || !data.type || Number.isNaN(amount) || amount <= 0) {
      return Response.json({ error: "Ungültige Daten" }, { status: 400 });
    }

    await prisma.buchung.create({
      data: {
        companyId: id,
        date: new Date(data.date),
        account: data.account === "bank" ? "BANK" : "KASSE",
        type: data.type === "entnahme" ? "ENTNAHME" : "EINLAGE",
        amount: amount,
        description: data.description || "",
      },
    });
  } else if (method === "PUT") {
    if (!transactionId) return Response.json({ error: "transactionId required" }, { status: 400 });
    const amount = Number(data.amount);
    if (!data.date || !data.account || !data.type || Number.isNaN(amount) || amount <= 0) {
      return Response.json({ error: "Ungültige Daten" }, { status: 400 });
    }

    const exist = await prisma.buchung.findFirst({ where: { id: transactionId, companyId: id } });
    if (!exist) return Response.json({ error: "Transaction not found" }, { status: 404 });

    await prisma.buchung.update({
      where: { id: transactionId },
      data: {
        date: new Date(data.date),
        account: data.account === "bank" ? "BANK" : "KASSE",
        type: data.type === "entnahme" ? "ENTNAHME" : "EINLAGE",
        amount: amount,
        description: data.description || "",
      },
    });
  } else if (method === "DELETE") {
    if (!transactionId) return Response.json({ error: "transactionId required" }, { status: 400 });

    await prisma.buchung.deleteMany({ where: { id: transactionId, companyId: id } });
  } else {
    return Response.json({ error: "Method not allowed" }, { status: 405 });
  }

  const buchungen = await prisma.buchung.findMany({ where: { companyId: id }, orderBy: { date: "desc" } });
  const transactions = buchungen.map(toTransaction);
  const balance = transactions.reduce((sum: number, t: Transaction) => sum + (t.type === "einlage" ? t.amount : -t.amount), 0 as number);

  return Response.json({ transactions, balance });
}