import { NextResponse } from "next/server";
import { withTransaction } from "@/lib/db";
import { authErrorResponse, requireRole } from "@/lib/auth/session";
import { isSameOrigin } from "@/lib/origin";
import { parseCsvWithHeader, splitCodes } from "@/lib/csv";

interface ImportRow {
  rowNum: number;
  name: string;
  name_en: string | null;
  name_pl: string | null;
  price: number;
  allergens: string[];
  additives: string[];
}

export async function POST(request: Request) {
  if (!isSameOrigin(request)) {
    return NextResponse.json({ error: "Nicht erlaubt." }, { status: 403 });
  }
  try {
    await requireRole(["staff", "admin"]);
    const form = await request.formData();
    const file = form.get("file");
    if (!(file instanceof File)) {
      return NextResponse.json({ error: "invalid_input" }, { status: 400 });
    }

    const { header, rows: cells } = parseCsvWithHeader(await file.text());
    const nameIdx = header.indexOf("name");
    const priceIdx = header.indexOf("price");
    if (nameIdx === -1 || priceIdx === -1) {
      return NextResponse.json({ error: "missing_columns" }, { status: 400 });
    }
    const nameEnIdx = header.indexOf("name_en");
    const namePlIdx = header.indexOf("name_pl");
    const allergensIdx = header.indexOf("allergens");
    const additivesIdx = header.indexOf("additives");

    const rows: ImportRow[] = [];
    const skipped: { row: number; reason: string }[] = [];
    cells.forEach((c, i) => {
      const rowNum = i + 2; // 1-indexiert + Kopfzeile
      const name = (c[nameIdx] ?? "").trim();
      if (!name) {
        skipped.push({ row: rowNum, reason: "Name fehlt" });
        return;
      }
      const priceRaw = (c[priceIdx] ?? "").trim().replace(",", ".");
      const price = Number.parseFloat(priceRaw);
      if (Number.isNaN(price) || price < 0) {
        skipped.push({ row: rowNum, reason: `Ungültiger Preis „${c[priceIdx] ?? ""}“` });
        return;
      }
      rows.push({
        rowNum,
        name,
        name_en: nameEnIdx >= 0 ? c[nameEnIdx]?.trim() || null : null,
        name_pl: namePlIdx >= 0 ? c[namePlIdx]?.trim() || null : null,
        price,
        allergens: allergensIdx >= 0 ? splitCodes(c[allergensIdx]) : [],
        additives: additivesIdx >= 0 ? splitCodes(c[additivesIdx]) : [],
      });
    });

    let created = 0;
    let updated = 0;
    if (rows.length > 0) {
      await withTransaction(async (client) => {
        for (const row of rows) {
          // Gerichtsnamen sind nicht eindeutig (keine DB-Constraint) – bei
          // mehreren Treffern lieber überspringen als versehentlich alle
          // gleichnamigen Gerichte mit denselben Werten zu überschreiben.
          const existing = await client.query<{ id: string }>(
            "select id from dishes where name = $1",
            [row.name]
          );
          if (existing.rows.length > 1) {
            skipped.push({
              row: row.rowNum,
              reason: `„${row.name}“ ist mehrdeutig (mehrere Gerichte mit diesem Namen) – übersprungen`,
            });
            continue;
          }
          if (existing.rows.length === 1) {
            await client.query(
              `update dishes set name_en = $1, name_pl = $2, price = $3, allergens = $4, additives = $5
               where id = $6`,
              [row.name_en, row.name_pl, row.price, row.allergens, row.additives, existing.rows[0].id]
            );
            updated++;
          } else {
            await client.query(
              `insert into dishes (name, name_en, name_pl, price, allergens, additives)
               values ($1, $2, $3, $4, $5, $6)`,
              [row.name, row.name_en, row.name_pl, row.price, row.allergens, row.additives]
            );
            created++;
          }
        }
      });
    }

    return NextResponse.json({ created, updated, skipped });
  } catch (err) {
    const res = authErrorResponse(err);
    if (res) return res;
    throw err;
  }
}