src/lib/invoiceUtils.ts

import html2canvas from 'html2canvas';
import jsPDF from 'jspdf';

/**
 * Export invoice element as high-quality image
 */
export async function exportInvoiceAsImage(
  element: HTMLElement, 
  options?: { scale?: number; format?: 'png' | 'jpeg'; quality?: number }
): Promise<string> {
  const { scale = 3, format = 'png', quality = 0.95 } = options || {};
  
  const canvas = await html2canvas(element, {
    scale, // Higher quality for better readability
    useCORS: true,
    backgroundColor: '#ffffff',
    logging: false,
    windowWidth: element.scrollWidth,
    windowHeight: element.scrollHeight,
  });
  
  const imageFormat = format === 'jpeg' ? 'image/jpeg' : 'image/png';
  return canvas.toDataURL(imageFormat, quality);
}

/**
 * Downloads the invoice as an image file
 * @param base64Image - Base64 encoded image string
 * @param filename - Name of the file to download
 */
export function downloadInvoiceImage(base64Image: string, filename: string = 'invoice.png') {
  const link = document.createElement('a');
  link.href = base64Image;
  link.download = filename;
  document.body.appendChild(link);
  link.click();
  document.body.removeChild(link);
}

/**
 * Shares invoice via WhatsApp Web
 * @param phoneNumber - Customer's phone number (with country code, e.g., 919876543210)
 * @param billNumber - Invoice/Bill number
 * @param amount - Total amount
 * @param base64Image - Base64 encoded image (optional, for future file sharing)
 */
export function shareInvoiceViaWhatsApp(
  phoneNumber: string,
  billNumber: string,
  amount: number,
  language: 'en' | 'mr' = 'mr'
) {
  // Clean phone number (remove spaces, hyphens, etc.)
  const cleanedNumber = phoneNumber.replace(/[^\d+]/g, '');
  
  // Ensure country code is present
  const formattedNumber = cleanedNumber.startsWith('+') || cleanedNumber.startsWith('91')
    ? cleanedNumber
    : `91${cleanedNumber}`;

  // Create message text based on language
  const message = language === 'mr'
    ? `नमस्कार,\n\nतुमचे बिल नंबर *${billNumber}* तयार झाले आहे.\n\nएकूण रक्कम: ₹${amount.toLocaleString('en-IN')}\n\nकृपया रक्कम वेळेवर भरावी.\n\nधन्यवाद!`
    : `Hello,\n\nYour bill number *${billNumber}* is ready.\n\nTotal Amount: ₹${amount.toLocaleString('en-IN')}\n\nPlease pay on time.\n\nThank you!`;

  // WhatsApp Web/API URL
  const whatsappUrl = `https://wa.me/${formattedNumber}?text=${encodeURIComponent(message)}`;
  
  // Open WhatsApp
  window.open(whatsappUrl, '_blank');
}

/**
 * Shares invoice image via WhatsApp using the device's native share (mobile)
 * @param base64Image - Base64 encoded image
 * @param billNumber - Invoice number
 * @param partyName - Customer name
 */
export async function shareInvoiceImageNative(
  base64Image: string,
  billNumber: string,
  partyName: string
) {
  try {
    // Convert base64 to blob
    const response = await fetch(base64Image);
    const blob = await response.blob();
    
    // Create a file from blob
    const file = new File([blob], `Invoice_${billNumber}.png`, { type: 'image/png' });

    // Check if Web Share API is supported
    if (navigator.share && navigator.canShare({ files: [file] })) {
      await navigator.share({
        title: `Invoice ${billNumber}`,
        text: `Invoice for ${partyName}`,
        files: [file],
      });
      return true;
    } else {
      // Fallback: Download the image
      downloadInvoiceImage(base64Image, `Invoice_${billNumber}_${partyName}.png`);
      return false;
    }
  } catch (error) {
    console.error('Error sharing invoice:', error);
    // Fallback: Download the image
    downloadInvoiceImage(base64Image, `Invoice_${billNumber}_${partyName}.png`);
    return false;
  }
}

/**
 * Formats phone number for WhatsApp
 * @param phone - Phone number in any format
 * @returns Formatted phone number with country code
 */
export function formatPhoneForWhatsApp(phone: string): string {
  const cleaned = phone.replace(/[^\d+]/g, '');
  
  if (cleaned.startsWith('+91')) {
    return cleaned;
  } else if (cleaned.startsWith('91') && cleaned.length === 12) {
    return `+${cleaned}`;
  } else if (cleaned.length === 10) {
    return `+91${cleaned}`;
  }
  
  return cleaned;
}

/**
 * Validates Indian phone number
 * @param phone - Phone number to validate
 * @returns true if valid
 */
export function isValidIndianPhoneNumber(phone: string): boolean {
  const cleaned = phone.replace(/[^\d]/g, '');
  
  // Check if it's a 10-digit number starting with 6-9
  if (cleaned.length === 10 && /^[6-9]\d{9}$/.test(cleaned)) {
    return true;
  }
  
  // Check if it's a 12-digit number starting with 91
  if (cleaned.length === 12 && cleaned.startsWith('91') && /^91[6-9]\d{9}$/.test(cleaned)) {
    return true;
  }
  
  return false;
}

/**
 * Export invoice as PDF
 */
export async function exportInvoiceAsPDF(
  element: HTMLElement,
  filename: string = 'invoice.pdf',
  options?: { orientation?: 'portrait' | 'landscape'; format?: 'a4' | 'letter' }
): Promise<void> {
  const { orientation = 'portrait', format = 'a4' } = options || {};
  
  // Generate high-quality image first
  const imageData = await exportInvoiceAsImage(element, { scale: 3, format: 'jpeg', quality: 0.95 });
  
  // Create PDF
  const pdf = new jsPDF({
    orientation,
    unit: 'mm',
    format,
  });
  
  // Calculate dimensions to fit page
  const imgProps = pdf.getImageProperties(imageData);
  const pdfWidth = pdf.internal.pageSize.getWidth();
  const pdfHeight = (imgProps.height * pdfWidth) / imgProps.width;
  
  // Add image to PDF
  pdf.addImage(imageData, 'JPEG', 0, 0, pdfWidth, pdfHeight);
  
  // Save PDF
  pdf.save(filename);
}

/**
 * Generate invoice text for WhatsApp or SMS
 */
export function generateInvoiceText(
  billNumber: string,
  partyName: string,
  items: Array<{ name: string; quantity: number; rate: number; amount: number }>,
  charges: { bardhana?: number; hamali?: number; adhath?: number; cess?: number; gaadiBharni?: number },
  total: number,
  language: 'en' | 'mr' = 'mr'
): string {
  if (language === 'mr') {
    let text = `🧾 *बिल नंबर:* ${billNumber}\n`;
    text += `👤 *पार्टी:* ${partyName}\n`;
    text += `📅 *तारीख:* ${new Date().toLocaleDateString('mr-IN')}\n\n`;
    text += `*📦 माल तपशील:*\n`;
    text += `${'─'.repeat(35)}\n`;
    
    items.forEach((item, i) => {
      text += `${i + 1}. ${item.name}\n`;
      text += `   ${item.quantity} पोत्या × ₹${item.rate} = ₹${item.amount.toLocaleString('en-IN')}\n`;
    });
    
    text += `${'─'.repeat(35)}\n`;
    
    // Add charges if any
    const totalCharges = (charges.bardhana || 0) + (charges.hamali || 0) + 
                         (charges.adhath || 0) + (charges.cess || 0) + (charges.gaadiBharni || 0);
    
    if (totalCharges > 0) {
      text += `\n*💰 खर्च:*\n`;
      if (charges.bardhana) text += `   बर्धाना: ₹${charges.bardhana.toLocaleString('en-IN')}\n`;
      if (charges.hamali) text += `   हमाली: ₹${charges.hamali.toLocaleString('en-IN')}\n`;
      if (charges.adhath) text += `   अडत: ₹${charges.adhath.toLocaleString('en-IN')}\n`;
      if (charges.cess) text += `   सेस: ₹${charges.cess.toLocaleString('en-IN')}\n`;
      if (charges.gaadiBharni) text += `   गाडी भरणी: ₹${charges.gaadiBharni.toLocaleString('en-IN')}\n`;
      text += `${'─'.repeat(35)}\n`;
    }
    
    text += `\n*💵 एकूण रक्कम: ₹${total.toLocaleString('en-IN')}*\n\n`;
    text += `कृपया रक्कम वेळेवर भरावी.\n\n`;
    text += `धन्यवाद! 🙏`;
    
    return text;
  } else {
    let text = `🧾 *Bill No:* ${billNumber}\n`;
    text += `👤 *Party:* ${partyName}\n`;
    text += `📅 *Date:* ${new Date().toLocaleDateString('en-IN')}\n\n`;
    text += `*📦 Items:*\n`;
    text += `${'─'.repeat(35)}\n`;
    
    items.forEach((item, i) => {
      text += `${i + 1}. ${item.name}\n`;
      text += `   ${item.quantity} bags × ₹${item.rate} = ₹${item.amount.toLocaleString('en-IN')}\n`;
    });
    
    text += `${'─'.repeat(35)}\n`;
    
    const totalCharges = (charges.bardhana || 0) + (charges.hamali || 0) + 
                         (charges.adhath || 0) + (charges.cess || 0) + (charges.gaadiBharni || 0);
    
    if (totalCharges > 0) {
      text += `\n*💰 Charges:*\n`;
      if (charges.bardhana) text += `   Bardhana: ₹${charges.bardhana.toLocaleString('en-IN')}\n`;
      if (charges.hamali) text += `   Hamali: ₹${charges.hamali.toLocaleString('en-IN')}\n`;
      if (charges.adhath) text += `   Commission: ₹${charges.adhath.toLocaleString('en-IN')}\n`;
      if (charges.cess) text += `   Cess: ₹${charges.cess.toLocaleString('en-IN')}\n`;
      if (charges.gaadiBharni) text += `   Loading: ₹${charges.gaadiBharni.toLocaleString('en-IN')}\n`;
      text += `${'─'.repeat(35)}\n`;
    }
    
    text += `\n*💵 Total Amount: ₹${total.toLocaleString('en-IN')}*\n\n`;
    text += `Please pay on time.\n\n`;
    text += `Thank you! 🙏`;
    
    return text;
  }
}

/**
 * Share detailed invoice text via WhatsApp
 */
export function shareDetailedInvoiceText(
  phoneNumber: string,
  invoiceText: string
): void {
  const formattedPhone = formatPhoneForWhatsApp(phoneNumber);
  const encodedText = encodeURIComponent(invoiceText);
  const whatsappUrl = `https://wa.me/${formattedPhone}?text=${encodedText}`;
  
  window.open(whatsappUrl, '_blank');
}

/**
 * Prints the invoice
 * @param element - The invoice element to print
 */
export function printInvoice(element?: HTMLElement) {
  if (element) {
    // Create a new window with just the invoice content
    const printWindow = window.open('', '_blank');
    if (printWindow) {
      printWindow.document.write(`
        <!DOCTYPE html>
        <html>
          <head>
            <title>Print Invoice</title>
            <style>
              body { margin: 0; padding: 20px; font-family: Arial, sans-serif; }
              @media print {
                body { margin: 0; }
                @page { margin: 10mm; }
              }
            </style>
          </head>
          <body>
            ${element.innerHTML}
          </body>
        </html>
      `);
      printWindow.document.close();
      setTimeout(() => {
        printWindow.print();
        printWindow.close();
      }, 250);
    }
  } else {
    // Default browser print
    window.print();
  }
}