/* eslint-disable @next/next/no-img-element -- Satori (ImageResponse) only
   renders raw <img>; next/image doesn't work inside OG image generation. */
/**
 * OG card for a single post.
 *
 * Renders a 1200×630 image with:
 *
 *   • The post caption (the quote) as the visual centrepiece, in
 *     serif-toned weight so it reads as a passage rather than UI chrome.
 *   • The source reference below — citation for the underlying scripture.
 *   • Author byline (avatar + name + @handle) bottom-left.
 *   • The post's first attached image as a dimmed background when
 *     available — same content the author sees on the card itself.
 *
 * Falls back to a flat cream background when the post has no images.
 * The light/dark text treatment swaps based on which surface is showing.
 */

import { ImageResponse } from "next/og";
import { readFile } from "node:fs/promises";
import { join } from "node:path";
import { bff } from "@/lib/bff";

export const runtime = "nodejs";

type PostImage = { id: string; url: string; position: number };
type Post = {
  id: string;
  user_id: string;
  caption: string;
  source_url: string;
  source_title: string;
  images: PostImage[];
  author_name?: string;
  author_handle?: string;
  author_avatar_url?: string | null;
};

let notoRegularData: Buffer | null = null;
let notoBoldData: Buffer | null = null;

async function loadFonts() {
  const fontsDir = join(process.cwd(), "public/fonts/Noto_Sans/static");
  if (!notoRegularData) {
    notoRegularData = await readFile(join(fontsDir, "NotoSans-Regular.ttf"));
  }
  if (!notoBoldData) {
    notoBoldData = await readFile(join(fontsDir, "NotoSans-Bold.ttf"));
  }
  return { regular: notoRegularData, bold: notoBoldData };
}

function initialsFor(name: string): string {
  return (
    name
      .split(/\s+/)
      .filter(Boolean)
      .map((p) => p[0])
      .slice(0, 2)
      .join("")
      .toUpperCase() || "?"
  );
}

export async function GET(
  _request: Request,
  context: { params: Promise<{ id: string }> },
) {
  try {
    const { id } = await context.params;
    const post = await bff<Post>(`/posts/${encodeURIComponent(id)}`, {
      revalidate: 60,
    }).catch(() => null);
    if (!post) {
      return new Response("Post not found", { status: 404 });
    }

    const fonts = await loadFonts();
    const caption = post.caption || "";
    const displayCaption =
      caption.length > 280 ? caption.slice(0, 277) + "…" : caption;
    const reference = post.source_title || "Source";
    const authorName = post.author_name || "Unknown";
    const authorHandle = post.author_handle ? `@${post.author_handle}` : "";
    const bgImageUrl = post.images?.[0]?.url ?? null;
    const hasImage = !!bgImageUrl;

    // Colour palette flips for image-backed cards so the caption stays
    // legible over the dimmed photo.
    const textPrimary = hasImage ? "#ffffff" : "#2d2418";
    const textSecondary = hasImage ? "rgba(255,255,255,0.85)" : "#5a4a3a";
    const accent = hasImage ? "#ffd9a8" : "#c47a5a";

    return new ImageResponse(
      (
        <div
          style={{
            width: 1200,
            height: 630,
            display: "flex",
            flexDirection: "column",
            backgroundColor: hasImage ? "#1a1410" : "#faf5f0",
            fontFamily: "Noto Sans, sans-serif",
            position: "relative",
            padding: 80,
          }}
        >
          {/* Background image + dimming overlay */}
          {hasImage ? (
            <>
              <img
                alt=""
                src={bgImageUrl}
                width={1200}
                height={630}
                style={{
                  position: "absolute",
                  top: 0,
                  left: 0,
                  width: 1200,
                  height: 630,
                  objectFit: "cover",
                  filter: "brightness(0.45)",
                }}
              />
              {/* Bottom-up gradient anchors the caption against the image */}
              <div
                style={{
                  position: "absolute",
                  top: 0,
                  left: 0,
                  width: 1200,
                  height: 630,
                  background:
                    "linear-gradient(to top, rgba(0,0,0,0.75), rgba(0,0,0,0.1))",
                }}
              />
            </>
          ) : null}

          {/* Caption — the centrepiece */}
          <div
            style={{
              display: "flex",
              fontSize: displayCaption.length > 160 ? 36 : 44,
              fontWeight: 700,
              color: textPrimary,
              lineHeight: 1.35,
              marginTop: 20,
              maxHeight: 380,
              overflow: "hidden",
              zIndex: 1,
            }}
          >
            “{displayCaption}”
          </div>

          {/* Reference (source citation) */}
          <div
            style={{
              display: "flex",
              fontSize: 22,
              fontWeight: 700,
              color: textSecondary,
              letterSpacing: 4,
              textTransform: "uppercase",
              marginTop: 28,
              zIndex: 1,
            }}
          >
            {reference}
          </div>

          {/* Spacer pushes the byline + branding to the bottom */}
          <div style={{ flex: 1, display: "flex" }} />

          {/* Bottom row: author + branding */}
          <div
            style={{
              display: "flex",
              flexDirection: "row",
              alignItems: "center",
              justifyContent: "space-between",
              zIndex: 1,
            }}
          >
            <div
              style={{
                display: "flex",
                flexDirection: "row",
                alignItems: "center",
                gap: 16,
              }}
            >
              {post.author_avatar_url ? (
                <img
                  alt=""
                  src={post.author_avatar_url}
                  width={64}
                  height={64}
                  style={{
                    width: 64,
                    height: 64,
                    borderRadius: 32,
                    objectFit: "cover",
                    border: `3px solid ${textPrimary}`,
                  }}
                />
              ) : (
                <div
                  style={{
                    width: 64,
                    height: 64,
                    borderRadius: 32,
                    backgroundColor: accent,
                    color: hasImage ? "#1a1410" : "#faf5f0",
                    display: "flex",
                    alignItems: "center",
                    justifyContent: "center",
                    fontSize: 28,
                    fontWeight: 700,
                  }}
                >
                  {initialsFor(authorName)}
                </div>
              )}
              <div
                style={{ display: "flex", flexDirection: "column", gap: 2 }}
              >
                <div
                  style={{
                    fontSize: 22,
                    fontWeight: 700,
                    color: textPrimary,
                    display: "flex",
                  }}
                >
                  {authorName}
                </div>
                {authorHandle ? (
                  <div
                    style={{
                      fontSize: 18,
                      color: textSecondary,
                      display: "flex",
                    }}
                  >
                    {authorHandle}
                  </div>
                ) : null}
              </div>
            </div>
            <div style={{ fontSize: 18, color: accent, fontWeight: 700 }}>
              prabhupadasays.org
            </div>
          </div>
        </div>
      ),
      {
        width: 1200,
        height: 630,
        fonts: [
          {
            name: "Noto Sans",
            data: fonts.regular,
            style: "normal" as const,
            weight: 400,
          },
          {
            name: "Noto Sans",
            data: fonts.bold,
            style: "normal" as const,
            weight: 700,
          },
        ],
      },
    );
  } catch (e) {
    console.error("Post OG image generation failed:", e);
    return new Response("Failed to generate OG image", { status: 500 });
  }
}