import { Router } from "@oak/oak";
import {
  fetchRichContent,
  fetchWithTimeout,
  isValidHttpUrl,
} from "../services/rich-content-service.ts";
import { APIErrorCode } from "../model/interfaces.ts";

const previewRouter = new Router();

previewRouter.get("/api/preview", async (ctx) => {
  const url = ctx.request.url.searchParams.get("url") ?? "";
  if (!isValidHttpUrl(url)) {
    ctx.response.status = 400;
    ctx.response.body = {
      success: false,
      error: { code: APIErrorCode.VALIDATION_ERROR, message: "Invalid URL" },
    };
    return;
  }
  const data = await fetchRichContent(url);
  ctx.response.body = { success: true, data: data ?? null };
});

/**
 * Proxy an external image through the server so HTTP thumbnail URLs don't
 * trigger mixed-content blocks when the frontend is served over HTTPS.
 */
previewRouter.get("/api/proxy-image", async (ctx) => {
  const url = ctx.request.url.searchParams.get("url") ?? "";
  if (!isValidHttpUrl(url)) {
    ctx.response.status = 400;
    return;
  }

  try {
    const res = await fetchWithTimeout(url, 8000);
    const contentType = res.headers.get("content-type") ?? "";
    if (!contentType.startsWith("image/")) {
      ctx.response.status = 400;
      return;
    }

    const MAX_SIZE = 5 * 1024 * 1024; // 5 MB
    const contentLength = Number(res.headers.get("content-length") ?? "0");
    if (contentLength > MAX_SIZE) {
      ctx.response.status = 400;
      return;
    }

    const bytes = new Uint8Array(await res.arrayBuffer());
    if (bytes.length > MAX_SIZE) {
      ctx.response.status = 400;
      return;
    }

    ctx.response.headers.set("Content-Type", contentType);
    ctx.response.headers.set("Cache-Control", "public, max-age=86400");
    ctx.response.body = bytes;
  } catch {
    ctx.response.status = 502;
  }
});

export default previewRouter;