import path from "node:path";
import fs from "node:fs";
import { fileURLToPath } from "node:url";
import { crawl } from "../crawler.js"; 

const __dirname = path.dirname(fileURLToPath(import.meta.url));

const ts = () =>
  new Date().toISOString().replaceAll(":", "-").replaceAll(".", "-");

function attachJson(res, filename, obj) {
  const json = JSON.stringify(obj, null, 2);
  res.setHeader("Content-Type", "application/json; charset=utf-8");
  res.setHeader("Content-Disposition", `attachment; filename="${filename}"`);
  return res.send(json);
}
function isAbs(p) {
  try {
    return path.isAbsolute(p);
  } catch {
    return false;
  }
}

export async function crawlHandler(req, res) {
  try {
    const { url, max, stream, download, nostore } = req.query;
    if (!url) return res.status(400).json({ error: "Missing url param" });

    const target = new URL(String(url));
    const limit = Math.min(Math.max(parseInt(max ?? "50", 10), 1), 500);
    const wantsStream =
      String(stream) === "1" ||
      (req.get("accept") || "").includes("text/event-stream");

    /* ---------- SSE mode ---------- */
    if (wantsStream) {
      if (String(download) === "1") {
        return res.status(400).json({ error: "download not supported with stream=1" });
      }

      res.setHeader("Content-Type", "text/event-stream");
      res.setHeader("Cache-Control", "no-cache, no-transform");
      res.setHeader("Connection", "keep-alive");
      res.flushHeaders?.();

      const send = (obj, evt) => {
        if (evt) res.write(`event: ${evt}\n`);
        res.write(`data: ${JSON.stringify(obj)}\n\n`);
      };

      const heartbeat = setInterval(() => res.write(":\n\n"), 15000);
      let finished = false;

      req.on("close", () => {
        clearInterval(heartbeat);
        if (!finished) console.warn("SSE client disconnected.");
      });

      const onProgress = (tick) => send(tick, "tick");
      send({ ok: true, message: "Crawl started", url: target.toString(), limit }, "started");

      const result = await crawl(target.toString(), limit, onProgress, {
        persistReports: false,
        collectPages: true,
      });

      finished = true;
      clearInterval(heartbeat);
      send({ ok: true, done: true, result }, "done");
      return res.end();
    }

    /* ---------- Non-streaming mode ---------- */
    const preferMemory = String(nostore) === "1" || String(download) === "1";
    const result = await crawl(
      target.toString(),
      limit,
      undefined,
      preferMemory
        ? { persistReports: false, collectPages: true }
        : { persistReports: true, collectPages: true }
    );

    if (String(download) === "1") {
      const filename = `crawl-${ts()}.json`;

      if (Array.isArray(result?.results)) {
        return attachJson(res, filename, result.results);
      }

      const jsonPath = result?.files?.json;
      if (jsonPath) {
        const abs = isAbs(jsonPath) ? jsonPath : path.join(__dirname, jsonPath);
        if (fs.existsSync(abs)) {
          res.setHeader("Content-Type", "application/json; charset=utf-8");
          res.setHeader("Content-Disposition", `attachment; filename="${filename}"`);
          return fs.createReadStream(abs).pipe(res);
        }
      }
      return attachJson(res, filename, result ?? {});
    }

    return res.json({
      ok: true,
      message: "Crawl completed",
      url: target.toString(),
      limit,
      ...result,
    });
  } catch (err) {
    console.error("Crawl error:", err);
    res.status(500).json({ error: "Crawl failed", details: String(err?.message ?? err) });
  }
}