// index.js
const easyinvoice = require("easyinvoice");
const fs = require("fs");
const path = require("path");
const yargs = require("yargs/yargs");
const { hideBin } = require("yargs/helpers");

// Late import for ESM compatibility with inquirer
let inquirer;
Promise.resolve().then(() => {
  inquirer = require("inquirer");
});

const FOLDERS = {
  DATA: "data",
  INVOICE: "invoice",
};

const FILES = {
  SENDERS: path.join(FOLDERS.DATA, "sender.json"),
  CLIENTS: path.join(FOLDERS.DATA, "client.json"),
  PRODUCTS: path.join(FOLDERS.DATA, "products.json"),
  INVOICES: path.join(FOLDERS.DATA, "invoices.json"),
};

// --- UTILITY FUNCTIONS ---
function loadJson(filePath) {
  try {
    if (!fs.existsSync(filePath)) {
      console.error(`Error: File not found at ${filePath}. Please create it.`);
      process.exit(1);
    }
    return JSON.parse(fs.readFileSync(filePath, "utf8"));
  } catch (err) {
    console.error(`Error loading or parsing ${filePath}:`, err.message);
    process.exit(1);
  }
}

function getNextInvoiceNumber(year, invoicesData) {
  const yearInvoices = invoicesData.invoices.filter((inv) =>
    inv.number.startsWith(`${year}-`)
  );
  let lastNum = 0;
  if (yearInvoices.length > 0) {
    lastNum = Math.max(
      ...yearInvoices.map((inv) => parseInt(inv.number.split("-")[1], 10))
    );
  }
  return `${year}-${String(lastNum + 1).padStart(4, "0")}`;
}

async function createInvoice(invoiceData, invoiceFilePath) {
  try {
    const result = await easyinvoice.createInvoice(invoiceData);
    const invoiceFolder = path.dirname(invoiceFilePath);
    if (!fs.existsSync(invoiceFolder)) {
      fs.mkdirSync(invoiceFolder, { recursive: true });
    }
    fs.writeFileSync(invoiceFilePath, result.pdf, "base64");
    console.log(`✅ Invoice generated: ${invoiceFilePath}`);
    return true;
  } catch (err) {
    console.error("Error creating invoice PDF:", err.message);
    return false;
  }
}

function saveInvoiceRecord(invoiceData, invoiceProducts) {
  const invoicesData = loadJson(FILES.INVOICES);

  const subtotal = invoiceProducts.reduce(
    (sum, p) => sum + p.price * p.quantity,
    0
  );
  const taxTotal = invoiceProducts.reduce((sum, p) => {
    const taxRate = p["tax-rate"] || 0;
    return sum + (p.price * p.quantity * taxRate) / 100;
  }, 0);

  invoicesData.invoices.push({
    number: invoiceData.information.number,
    date: invoiceData.information.date,
    sender: invoiceData.sender.company,
    client: invoiceData.client.company,
    products: invoiceProducts.map((p) => ({
      description: p.description,
      price: p.price,
      quantity: p.quantity,
      taxRate: p["tax-rate"],
    })),
    subtotal: parseFloat(subtotal.toFixed(2)),
    taxTotal: parseFloat(taxTotal.toFixed(2)),
    total: parseFloat((subtotal + taxTotal).toFixed(2)),
  });
  try {
    fs.writeFileSync(FILES.INVOICES, JSON.stringify(invoicesData, null, 2));
    console.log("✅ Invoice record saved to invoices.json.");
  } catch (err) {
    console.error("Error writing to invoices.json:", err.message);
  }
}

async function main() {
  const argv = yargs(hideBin(process.argv))
    .parserConfiguration({ "update-notifier-off": true })
    .option("interactive", {
      type: "boolean",
      describe: "Run in interactive mode",
    })
    .option("sender", {
      type: "string",
      describe: "Sender key from sender.json",
    })
    .option("client", {
      type: "string",
      describe: "Client key from client.json",
    })
    .option("products", {
      type: "array",
      describe: "Product keys from products.json",
    })
    .option("test", {
      type: "boolean",
      describe: "Run in test mode (uses first available options, dev only)",
    })
    .help().argv;

  let senderKey, clientKey, productKeys;

  const senders = loadJson(FILES.SENDERS);
  const clients = loadJson(FILES.CLIENTS);
  const productsData = loadJson(FILES.PRODUCTS);

  // Test mode: use first available options
  if (argv.test) {
    senderKey = Object.keys(senders)[0];
    clientKey = Object.keys(clients)[0];
    productKeys = [Object.keys(productsData)[0]];
    console.log(
      `🧪 Test mode: Using sender="${senderKey}", client="${clientKey}", products=[${productKeys.join(
        ", "
      )}]`
    );
  } else if (
    argv.interactive ||
    !(argv.sender && argv.client && argv.products)
  ) {
    if (!inquirer) {
      await new Promise((resolve) => setTimeout(resolve, 100)); // wait for dynamic import
      if (!inquirer) {
        // check again
        console.error(
          "Failed to load 'inquirer'. Please ensure it is installed correctly."
        );
        process.exit(1);
      }
    }
    const answers = await inquirer.prompt([
      {
        type: "list",
        name: "sender",
        message: "Select a sender:",
        choices: Object.keys(senders),
      },
      {
        type: "list",
        name: "client",
        message: "Select a client:",
        choices: Object.keys(clients),
      },
      {
        type: "checkbox",
        name: "products",
        message: "Select products:",
        choices: Object.keys(productsData),
        validate: (input) =>
          input.length > 0 ? true : "Please select at least one product.",
      },
    ]);
    senderKey = answers.sender;
    clientKey = answers.client;
    productKeys = answers.products;
  } else {
    senderKey = argv.sender;
    clientKey = argv.client;
    productKeys = argv.products;
  }

  // --- Data Validation and Preparation ---
  if (
    !senders[senderKey] ||
    !clients[clientKey] ||
    !productKeys.every((k) => productsData[k])
  ) {
    console.error("Invalid sender, client, or product key provided.");
    process.exit(1);
  }

  const sender = senders[senderKey];
  const client = clients[clientKey];
  const invoiceProducts = productKeys.map((key) => {
    const product = productsData[key];
    return {
      quantity: 1, // Default quantity
      description: product.description,
      "tax-rate": product.taxRate || 0,
      price: product.price,
    };
  });

  const now = new Date();
  const year = now.getFullYear();
  const devInvoiceNumber = `${year}-DEV-PREVIEW`;

  const senderForInvoice = { ...sender };
  if (sender.taxNumber) {
    senderForInvoice.custom1 = `${sender.taxName || "Tax"} Number: ${
      sender.taxNumber
    }`;
  }

  const commonData = {
    sender: senderForInvoice,
    client,
    products: invoiceProducts,
    bottomNotice: sender.paymentInfo
      ? `Thank you for your business!<br /><br /><br />${sender.paymentInfo}`
      : "Thank you for your business!",
    settings: { currency: "CAD" },
    translate: {
      taxNotation: sender.taxName || "VAT",
      number: "Invoice",
    },
  };

  // --- Development / Preview Run ---
  const devData = {
    ...commonData,
    information: {
      number: devInvoiceNumber,
      date: now.toISOString().split("T")[0],
      dueDate: new Date(new Date().setDate(now.getDate() + 14))
        .toISOString()
        .split("T")[0],
    },
    mode: "development",
  };
  const fileNameKey = client.invoiceFileName || clientKey;
  const devFileName = `${fileNameKey}_${devInvoiceNumber}.pdf`;
  const devFilePath = path.join(FOLDERS.INVOICE, senderKey, devFileName);

  console.log("\nGenerating development preview...");
  await createInvoice(devData, devFilePath);

  // Skip production prompt in test mode
  if (argv.test) {
    console.log("\n🧪 Test mode: Skipping production invoice creation.");
    return;
  }

  // --- Production Prompt ---
  if (!inquirer) await new Promise((resolve) => setTimeout(resolve, 100)); // Ensure inquirer is loaded
  const { proceed } = await inquirer.prompt([
    {
      type: "list",
      name: "proceed",
      message: "Preview generated. What would you like to do?",
      choices: [
        { name: "No - Keep only the preview", value: false },
        { name: "Yes - Create production invoice", value: true },
      ],
      default: 0, // Default to "No"
    },
  ]);

  if (proceed) {
    console.log("\nGenerating production invoice...");
    const invoicesData = loadJson(FILES.INVOICES);
    const prodInvoiceNumber = getNextInvoiceNumber(year, invoicesData);

    const prodData = {
      ...commonData,
      information: {
        number: prodInvoiceNumber,
        date: now.toISOString().split("T")[0],
        dueDate: new Date(new Date().setDate(now.getDate() + 14))
          .toISOString()
          .split("T")[0],
      },
      mode: "production",
    };
    const prodFileName = `${fileNameKey}_${prodInvoiceNumber}.pdf`;
    const prodFilePath = path.join(FOLDERS.INVOICE, senderKey, prodFileName);

    if (await createInvoice(prodData, prodFilePath)) {
      saveInvoiceRecord(prodData, invoiceProducts);
    }
  } else {
    console.log("\nProduction invoice creation cancelled.");
  }
}

// Check if running in test environment
if (process.env.NODE_ENV !== "test") {
  main().catch((err) => console.error("An unexpected error occurred:", err));
}

module.exports = { getNextInvoiceNumber, loadJson }; // For testing