src/lib/services/picletExport.ts

import type { PicletInstance } from '$lib/db/schema';
import { embedPicletMetadata } from './picletMetadata';

/**
 * Generates a shareable image of a piclet with embedded metadata
 */
export async function generateShareableImage(piclet: PicletInstance): Promise<Blob> {
  // Create canvas
  const canvas = document.createElement('canvas');
  const ctx = canvas.getContext('2d');
  if (!ctx) throw new Error('Could not create canvas context');
  
  // Set canvas size to match original piclet resolution
  const canvasSize = 1024;
  canvas.width = canvasSize;
  canvas.height = canvasSize;
  
  // Fill background with solid sky blue
  ctx.fillStyle = '#87CEEB';
  ctx.fillRect(0, 0, canvasSize, canvasSize);
  
  // Load piclet image first to maintain original size
  const picletImg = await loadImage(piclet.imageData || piclet.imageUrl);
  const picletSize = 512; // Display at half the canvas size for better composition
  const picletX = (canvasSize - picletSize) / 2;
  const picletY = canvasSize / 2 - picletSize / 2 + 50; // Center with slight offset down
  
  // Load and draw grass platform positioned under the piclet
  const grassImg = await loadImage('/assets/grass.PNG');
  const platformSize = picletSize + 100; // Slightly larger than piclet
  const platformX = (canvasSize - platformSize) / 2;
  const platformY = picletY + picletSize - 150; // Position so piclet sits on platform
  ctx.drawImage(grassImg, platformX, platformY, platformSize, platformSize);
  
  // Draw piclet on top of platform
  ctx.drawImage(picletImg, picletX, picletY, picletSize, picletSize);
  
  // Add piclet name only (no level)
  ctx.fillStyle = 'white';
  ctx.strokeStyle = 'black';
  ctx.lineWidth = 6;
  ctx.font = 'bold 64px Arial';
  ctx.textAlign = 'center';
  
  const nameText = piclet.nickname || piclet.typeId;
  
  // Draw name with outline
  ctx.strokeText(nameText, canvasSize / 2, 120);
  ctx.fillText(nameText, canvasSize / 2, 120);
  
  // Load and draw translucent watermark
  const logoImg = await loadImage('/assets/snap_logo.png');
  const logoSize = 150;
  ctx.globalAlpha = 0.3; // More translucent
  ctx.drawImage(logoImg, canvasSize - logoSize - 30, canvasSize - logoSize - 30, logoSize, logoSize);
  ctx.globalAlpha = 1.0;
  
  // Get the image as blob
  const blob = await canvasToBlob(canvas);
  
  // Embed metadata in the blob
  return embedPicletMetadata(blob, piclet);
}

/**
 * Downloads a piclet card image
 */
export async function downloadPicletCard(piclet: PicletInstance, filename?: string): Promise<void> {
  const blob = await generateShareableImage(piclet);
  const url = URL.createObjectURL(blob);
  
  const a = document.createElement('a');
  a.href = url;
  a.download = filename || `Piclet_${piclet.nickname || piclet.typeId}_Lv${piclet.level}.png`;
  document.body.appendChild(a);
  a.click();
  document.body.removeChild(a);
  
  URL.revokeObjectURL(url);
}

/**
 * Helper to load an image
 */
function loadImage(src: string): Promise<HTMLImageElement> {
  return new Promise((resolve, reject) => {
    const img = new Image();
    img.crossOrigin = 'anonymous';
    img.onload = () => resolve(img);
    img.onerror = reject;
    img.src = src;
  });
}

/**
 * Convert canvas to blob
 */
function canvasToBlob(canvas: HTMLCanvasElement): Promise<Blob> {
  return new Promise((resolve, reject) => {
    canvas.toBlob((blob) => {
      if (blob) resolve(blob);
      else reject(new Error('Failed to create blob'));
    }, 'image/png');
  });
}