import { NextResponse } from "next/server";
import { PrismaClient } from "@prisma/client";
import fs from "fs/promises";
import path from "path";
import { parse } from "csv-parse/sync";

// Path to users.csv - adjust as needed
const csvFilePath = path.resolve(process.cwd(), "public/users.csv");
const prisma = new PrismaClient();

type CsvRow = {
  Name: string;
  Email: string;
  PasswordHash: string;
  Role?: string;
};

function normalizeRole(role: string | undefined): string {
  // Only allow ADMIN, SCIENTIST, GUEST; default GUEST
  if (!role || !role.trim()) return "GUEST";
  const r = role.trim().toUpperCase();
  return ["ADMIN", "SCIENTIST", "GUEST"].includes(r) ? r : "GUEST";
}

export async function POST() {
  try {
    // 1. Read the CSV file
    const fileContent = await fs.readFile(csvFilePath, "utf8");

    // 2. Parse the CSV
    const records: CsvRow[] = parse(fileContent, {
      columns: true,
      skip_empty_lines: true,
    });

    // 3. Transform each CSV row to User model format
    const users = records.map(row => ({
      name: row.Name,
      email: row.Email,
      passwordHash: row.PasswordHash,
      role: normalizeRole(row.Role),
    }));

    // 4. Bulk create users in database
    await prisma.user.createMany({
      data: users,
      skipDuplicates: true, // because email is unique
    });

    return NextResponse.json({ success: true, count: users.length });
  } catch (error: any) {
    console.error(error);
    return NextResponse.json({ success: false, error: error.message }, { status: 500 });
  } finally {
    await prisma.$disconnect();
  }
}