import { ImageResponse } from "next/og";
import { allPosts } from "contentlayer/generated";
import { blogThumbnails } from "../../../src/components/blog/blogThumbnails";
import { BlogOGImageTemplate } from "../../../src/components/BlogOGImageTemplate";
import { getOgFonts, OG_IMAGE_SIZE } from "../../../src/lib/og-helper";
import * as fs from "node:fs/promises";
import * as path from "node:path";

export const size = OG_IMAGE_SIZE;
export const contentType = "image/png";
export const runtime = "nodejs";

export default async function Image({
  params,
}: {
  params: Promise<{ slug: string }>;
}) {
  const { slug } = await params;
  const post = allPosts.find((p) => p.slug === slug);

  let backgroundImageSrc: string | undefined = undefined;

  // If we have a custom generated thumbnail, convert it to a data URI for Satori
  if (post?.thumbnail) {
    try {
      const filePath = path.join(process.cwd(), "public", post.thumbnail);
      const fileBuffer = await fs.readFile(filePath);

      const ext = path.extname(post.thumbnail).substring(1).toLowerCase();
      const mimeType = ext === "jpg" || ext === "jpeg" ? "image/jpeg" : "image/png";

      backgroundImageSrc = `data:${mimeType};base64,${fileBuffer.toString("base64")}`;
    } catch (err) {
      console.warn(`[OG Image Generator] Could not read thumbnail file for ${slug} to use as background:`, err);
      // Fall through to standard plain background
    }
  }

  const thumbnail = blogThumbnails[slug];

  const title = post?.title || "Marc Mintel";
  const description =
    post?.description ||
    "Technical problem solver's blog - practical insights and learning notes";
  const label = post ? "Blog Post" : "Engineering";
  const accentColor = thumbnail?.accent;
  const keyword = thumbnail?.keyword;

  const fonts = await getOgFonts();

  return new ImageResponse(
    <BlogOGImageTemplate
      title={title}
      description={description}
      label={label}
      accentColor={accentColor}
      keyword={keyword}
      backgroundImageSrc={backgroundImageSrc}
    />,
    {
      ...OG_IMAGE_SIZE,
      fonts: fonts as any,
    },
  );
}
