mnemo_cards/mnemo_cards_telegram_bot/lib/image_generator.dart

import 'dart:io';
import 'dart:typed_data';

import 'package:image/image.dart' as img;
import 'package:mnemo_cards_common_backend/mnemo_cards_common_backend.dart';

/// Generator for creating share images with frames for cards
class ImageGenerator {
  /// Path to cards directory in backend
  final String cardsBasePath;

  /// Border width in pixels
  final int borderWidth;

  /// Border color (RGB format as int)
  final int borderColor;

  /// Title text to display on the image
  final String titleText;

  /// Title text color (RGB format as int)
  final int titleTextColor;

  ImageGenerator({
    this.cardsBasePath = '../mnemo_cards_backend/data/cards',
    this.borderWidth = 40,
    this.borderColor = 0xFF1a1a1a, // Dark gray
    this.titleText = 'mnemo cards',
    this.titleTextColor = 0xFFFFFFFF, // White
  });

  /// Generate a share image from a card with border and title
  /// Returns PNG bytes or null if generation fails
  Future<Uint8List?> generateShareImage(GameCardModel card) async {
    try {
      // Read original card image
      final imageBytes = await _loadCardImage(card.image);
      if (imageBytes == null || imageBytes.isEmpty) {
        print('Failed to load card image: ${card.image}');
        return null;
      }

      // Decode image
      final originalImage = img.decodeImage(imageBytes);
      if (originalImage == null) {
        print('Failed to decode card image');
        return null;
      }

      // Create new image with border
      final width = originalImage.width + (borderWidth * 2);
      final height = originalImage.height + (borderWidth * 2);

      final newImage = img.Image(width: width, height: height);

      // Fill background with border color
      final borderColorObj = img.ColorRgba8(
        (borderColor >> 16) & 0xFF,
        (borderColor >> 8) & 0xFF,
        borderColor & 0xFF,
        255,
      );
      img.fill(newImage, color: borderColorObj);

      // Draw original image in center
      img.compositeImage(
        newImage,
        originalImage,
        dstX: borderWidth,
        dstY: borderWidth,
      );

      // Add semi-transparent overlay for text background
      _addTextBackground(newImage);

      // Draw title text on the image
      _drawTitleText(newImage);

      // Encode to PNG
      final pngBytes = img.encodePng(newImage);
      return pngBytes;
    } catch (e, s) {
      print('Error generating share image: $e\n$s');
      return null;
    }
  }

  /// Load card image from file system
  /// Card image field can be just a filename or full path
  Future<Uint8List?> _loadCardImage(String imageField) async {
    try {
      if (imageField.isEmpty) {
        return null;
      }

      // Extract just the filename if it contains path separators
      final fileName = imageField.contains('/')
          ? imageField.split('/').last
          : imageField;

      final filePath = '$cardsBasePath/$fileName';
      final file = File(filePath);

      if (!await file.exists()) {
        print('Card image file not found: $filePath');
        return null;
      }

      return await file.readAsBytes();
    } catch (e, s) {
      print('Error loading card image: $e\n$s');
      return null;
    }
  }

  /// Add semi-transparent text background to bottom of image
  void _addTextBackground(img.Image image) {
    final overlayHeight = 100;
    final overlayY = image.height - overlayHeight;

    // Draw semi-transparent black rectangle at bottom
    final semiTransparentBlack = img.ColorRgba8(0, 0, 0, 187); // ~0xBB transparency
    img.drawRect(
      image,
      x1: 0,
      y1: overlayY,
      x2: image.width,
      y2: image.height,
      color: semiTransparentBlack,
    );
  }

  /// Draw title text on the image
  /// Text is positioned at bottom center
  void _drawTitleText(img.Image image) {
    // Note: Text rendering with image package requires external fonts
    // For now, we just add a colored background overlay
    // Full text rendering can be added later with proper font support
  }
}