import { readFileSync } from 'fs';
import { join } from 'path';

/**
 * Loads the Inter fonts for use in Satori (Next.js OG Image generation).
 * Since we are using runtime = 'nodejs', we can read them from the filesystem.
 */
export async function getOgFonts() {
  const boldFontPath = join(process.cwd(), 'public/fonts/Inter-Bold.woff');
  const regularFontPath = join(process.cwd(), 'public/fonts/Inter-Regular.woff');

  try {
    console.log(`[OG] Loading fonts: bold=${boldFontPath}, regular=${regularFontPath}`);
    const boldFontBuffer = readFileSync(boldFontPath);
    const regularFontBuffer = readFileSync(regularFontPath);

    // Satori (Vercel OG) strictly requires an ArrayBuffer, not a Node Buffer view.
    const boldFont = boldFontBuffer.buffer.slice(
      boldFontBuffer.byteOffset,
      boldFontBuffer.byteOffset + boldFontBuffer.byteLength,
    );
    const regularFont = regularFontBuffer.buffer.slice(
      regularFontBuffer.byteOffset,
      regularFontBuffer.byteOffset + regularFontBuffer.byteLength,
    );

    console.log(
      `[OG] Fonts loaded successfully (${boldFont.byteLength} and ${regularFont.byteLength} bytes)`,
    );

    return [
      {
        name: 'Inter',
        data: boldFont,
        weight: 700 as const,
        style: 'normal' as const,
      },
      {
        name: 'Inter',
        data: regularFont,
        weight: 400 as const,
        style: 'normal' as const,
      },
    ];
  } catch (error) {
    console.error(`[OG] Failed to load fonts from ${process.cwd()}:`, error);
    return [];
  }
}

/**
 * Common configuration for OG images
 */
export const OG_IMAGE_SIZE = {
  width: 1200,
  height: 630,
};

/**
 * Loads a local image and converts it to a base64 data URI for Satori
 */
export function getLocalImageBase64(filename: string): string | undefined {
  try {
    const filePath = join(process.cwd(), 'public', filename);
    const buffer = readFileSync(filePath);
    const ext = filename.split('.').pop()?.toLowerCase();
    const mimeType =
      ext === 'png'
        ? 'image/png'
        : ext === 'jpg' || ext === 'jpeg'
          ? 'image/jpeg'
          : 'image/svg+xml';
    return `data:${mimeType};base64,${buffer.toString('base64')}`;
  } catch (error) {
    console.error(`[OG] Failed to load local image ${filename}:`, error);
    return undefined;
  }
}

/**
 * Returns standard assets for OG images
 */
export function getOgAssets() {
  return {
    logo: getLocalImageBase64('logo-white.png'),
    bgImage: getLocalImageBase64(
      'media/aerial-view-of-electricity-station-surrounded-with-2023-11-27-05-33-40-utc-scaled.jpg',
    ),
  };
}