import { useState } from 'react';
import { TransportQRData } from '../../lib/transport/types';

interface QRCodeDisplayProps {
  qrData: TransportQRData;
  size?: number;
  showDetails?: boolean;
}

// Simple QR code matrix generator (basic implementation)
function generateQRMatrix(data: string, size: number = 21): boolean[][] {
  // This is a simplified representation - in production you'd use a library like 'qrcode'
  const matrix: boolean[][] = Array(size)
    .fill(null)
    .map(() => Array(size).fill(false));

  // Add finder patterns (corners)
  const addFinderPattern = (row: number, col: number) => {
    for (let r = 0; r < 7; r++) {
      for (let c = 0; c < 7; c++) {
        if (r === 0 || r === 6 || c === 0 || c === 6 || (r >= 2 && r <= 4 && c >= 2 && c <= 4)) {
          if (row + r < size && col + c < size) {
            matrix[row + r][col + c] = true;
          }
        }
      }
    }
  };

  addFinderPattern(0, 0);
  addFinderPattern(0, size - 7);
  addFinderPattern(size - 7, 0);

  // Add some data-based pattern
  const hash = data.split('').reduce((acc, char) => acc + char.charCodeAt(0), 0);
  for (let i = 8; i < size - 8; i++) {
    for (let j = 8; j < size - 8; j++) {
      matrix[i][j] = ((i * j + hash) % 3) === 0;
    }
  }

  return matrix;
}

export default function QRCodeDisplay({ qrData, size = 200, showDetails = true }: QRCodeDisplayProps) {
  const [copied, setCopied] = useState(false);
  const [downloading, setDownloading] = useState(false);

  const qrString = JSON.stringify(qrData);
  const matrix = generateQRMatrix(qrString);
  const cellSize = size / matrix.length;

  const handleCopyLink = async () => {
    try {
      await navigator.clipboard.writeText(qrData.quickLookupUrl);
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    } catch (err) {
      console.error('Failed to copy:', err);
    }
  };

  const handleDownload = () => {
    setDownloading(true);

    // Create SVG for download
    const svgContent = `
      <svg xmlns="http://www.w3.org/2000/svg" width="${size}" height="${size}" viewBox="0 0 ${size} ${size}">
        <rect width="100%" height="100%" fill="white"/>
        ${matrix
          .map((row, i) =>
            row
              .map((cell, j) =>
                cell
                  ? `<rect x="${j * cellSize}" y="${i * cellSize}" width="${cellSize}" height="${cellSize}" fill="black"/>`
                  : ''
              )
              .join('')
          )
          .join('')}
      </svg>
    `;

    const blob = new Blob([svgContent], { type: 'image/svg+xml' });
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = `qr-${qrData.plantId || qrData.batchId || 'code'}.svg`;
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    URL.revokeObjectURL(url);

    setDownloading(false);
  };

  const formatDate = (dateString: string) => {
    return new Date(dateString).toLocaleDateString('en-US', {
      year: 'numeric',
      month: 'short',
      day: 'numeric',
    });
  };

  return (
    <div className="bg-white rounded-lg shadow-lg overflow-hidden">
      {/* Header */}
      <div className="bg-gradient-to-r from-purple-600 to-indigo-600 text-white p-4">
        <h3 className="text-lg font-bold">Traceability QR Code</h3>
        <p className="text-purple-200 text-sm">Scan to verify authenticity</p>
      </div>

      <div className="p-6">
        {/* QR Code */}
        <div className="flex justify-center mb-6">
          <div className="p-4 bg-white border-2 border-gray-200 rounded-lg shadow-inner">
            <svg width={size} height={size} viewBox={`0 0 ${size} ${size}`}>
              <rect width="100%" height="100%" fill="white" />
              {matrix.map((row, i) =>
                row.map((cell, j) =>
                  cell ? (
                    <rect
                      key={`${i}-${j}`}
                      x={j * cellSize}
                      y={i * cellSize}
                      width={cellSize}
                      height={cellSize}
                      fill="black"
                    />
                  ) : null
                )
              )}
            </svg>
          </div>
        </div>

        {/* Action buttons */}
        <div className="flex gap-3 mb-6">
          <button
            onClick={handleCopyLink}
            className="flex-1 px-4 py-2 bg-gray-100 hover:bg-gray-200 text-gray-700 rounded-lg font-medium transition flex items-center justify-center gap-2"
          >
            {copied ? (
              <>
                <span className="text-green-600">✓</span> Copied!
              </>
            ) : (
              <>
                <span>📋</span> Copy Link
              </>
            )}
          </button>
          <button
            onClick={handleDownload}
            disabled={downloading}
            className="flex-1 px-4 py-2 bg-purple-600 hover:bg-purple-700 text-white rounded-lg font-medium transition flex items-center justify-center gap-2 disabled:opacity-50"
          >
            {downloading ? (
              <>Downloading...</>
            ) : (
              <>
                <span>⬇️</span> Download
              </>
            )}
          </button>
        </div>

        {/* Details */}
        {showDetails && (
          <div className="space-y-3 border-t border-gray-200 pt-4">
            {qrData.plantId && (
              <div className="flex justify-between items-center">
                <span className="text-sm text-gray-500">Plant ID</span>
                <span className="text-sm font-mono text-gray-900">{qrData.plantId.slice(0, 12)}...</span>
              </div>
            )}
            {qrData.batchId && (
              <div className="flex justify-between items-center">
                <span className="text-sm text-gray-500">Batch ID</span>
                <span className="text-sm font-mono text-gray-900">{qrData.batchId.slice(0, 12)}...</span>
              </div>
            )}
            <div className="flex justify-between items-center">
              <span className="text-sm text-gray-500">Last Event</span>
              <span className="text-sm text-gray-900 capitalize">
                {qrData.lastEventType.replace(/_/g, ' ')}
              </span>
            </div>
            <div className="flex justify-between items-center">
              <span className="text-sm text-gray-500">Last Updated</span>
              <span className="text-sm text-gray-900">{formatDate(qrData.lastEventTimestamp)}</span>
            </div>
            <div className="flex justify-between items-center">
              <span className="text-sm text-gray-500">Current Custodian</span>
              <span className="text-sm text-gray-900">{qrData.currentCustodian}</span>
            </div>
            <div className="flex justify-between items-center">
              <span className="text-sm text-gray-500">Verification Code</span>
              <span className="text-sm font-mono text-green-600">{qrData.verificationCode}</span>
            </div>
          </div>
        )}

        {/* Blockchain info */}
        <div className="mt-4 p-3 bg-gray-50 rounded-lg">
          <div className="flex items-center gap-2 text-sm text-gray-600">
            <span>🔗</span>
            <span className="font-medium">Blockchain Verified</span>
          </div>
          <p className="text-xs text-gray-400 mt-1 font-mono break-all">
            {qrData.blockchainAddress}
          </p>
        </div>
      </div>
    </div>
  );
}