import jsPDF from "jspdf";
import QRCode from "qrcode";

interface LabelData {
  partNumber: string;
  quantity: number;
}

/** Load an image from a URL and return its base64 data URL */
async function loadImageAsBase64(url: string): Promise<string> {
  return new Promise((resolve, reject) => {
    const img = new Image();
    img.crossOrigin = "anonymous";
    img.onload = () => {
      const canvas = document.createElement("canvas");
      canvas.width = img.naturalWidth;
      canvas.height = img.naturalHeight;
      const ctx = canvas.getContext("2d");
      if (!ctx) return reject(new Error("Canvas not supported"));
      ctx.drawImage(img, 0, 0);
      resolve(canvas.toDataURL("image/png"));
    };
    img.onerror = () => reject(new Error("Failed to load image"));
    img.src = url;
  });
}

/**
 * Generate a 49mm x 12mm label PDF with:
 * - Company icon (left, square)
 * - Code, Quantity, Count date (center)
 * - QR code (right) containing "PartNumber,Quantity"
 */
export async function generateLabelPdf(data: LabelData): Promise<jsPDF> {
  const labelW = 49; // mm
  const labelH = 12; // mm
  const contentLeft = 1; // small padding
  const contentRight = labelW - 1;

  const doc = new jsPDF({
    orientation: "landscape",
    unit: "mm",
    format: [labelW, labelH],
  });

  const now = new Date();
  const countDate = `${String(now.getDate()).padStart(2, "0")}/${String(now.getMonth() + 1).padStart(2, "0")}/${now.getFullYear()}`;

  // --- Icon (left side, square, filling most of the label height) ---
  const iconSize = 9;
  const iconX = contentLeft;
  const iconY = (labelH - iconSize) / 2;
  try {
    const iconBase64 = await loadImageAsBase64("/images/linse-icon.png");
    doc.addImage(iconBase64, "PNG", iconX, iconY, iconSize, iconSize);
  } catch {
    // If icon fails, skip
  }

  // --- Text (center, maximised for 12mm height) ---
  const textX = iconX + iconSize + 1.5;

  // Code
  doc.setFontSize(7);
  doc.setFont("helvetica", "bold");
  doc.setTextColor(0, 0, 0);
  doc.text(`Code: ${data.partNumber}`, textX, 3.8);

  // Quantity
  doc.text(`Quantity:  ${data.quantity}`, textX, 7.2);

  // Count date
  doc.setFontSize(5.5);
  doc.setFont("helvetica", "normal");
  doc.text(`Count date: ${countDate}`, textX, 10.4);

  // --- QR Code (right side, filling most of the label height) ---
  const qrContent = `${data.partNumber},${data.quantity}`;
  try {
    const qrDataUrl = await QRCode.toDataURL(qrContent, {
      width: 200,
      margin: 0,
      errorCorrectionLevel: "M",
      color: { dark: "#000000", light: "#ffffff" },
    });

    const qrSize = 10;
    const qrX = contentRight - qrSize;
    const qrY = (labelH - qrSize) / 2;
    doc.addImage(qrDataUrl, "PNG", qrX, qrY, qrSize, qrSize);
  } catch {
    doc.setFontSize(4);
    doc.text("QR Error", contentRight - 10, labelH / 2);
  }

  return doc;
}