session-viewer/src/server/routes/sessions.ts

import { Router } from "express";
import { discoverSessions } from "../services/session-discovery.js";
import { parseSession } from "../services/session-parser.js";
import type { SessionEntry } from "../../shared/types.js";

export const sessionsRouter = Router();

// Simple cache to avoid re-discovering sessions on every detail request
let cachedSessions: SessionEntry[] = [];
let cacheTimestamp = 0;
const CACHE_TTL_MS = 30_000;

async function getCachedSessions(): Promise<SessionEntry[]> {
  const now = Date.now();
  if (now - cacheTimestamp > CACHE_TTL_MS) {
    cachedSessions = await discoverSessions();
    cacheTimestamp = now;
  }
  return cachedSessions;
}

sessionsRouter.get("/", async (req, res) => {
  try {
    if (req.query.refresh === "1") {
      cacheTimestamp = 0;
    }
    const sessions = await getCachedSessions();
    res.json({ sessions });
  } catch (err) {
    console.error("Failed to discover sessions:", err);
    res.status(500).json({ error: "Failed to discover sessions" });
  }
});

sessionsRouter.get("/:id", async (req, res) => {
  try {
    const sessions = await getCachedSessions();
    const entry = sessions.find((s) => s.id === req.params.id);
    if (!entry) {
      res.status(404).json({ error: "Session not found" });
      return;
    }
    const messages = await parseSession(entry.path);
    res.json({
      id: entry.id,
      project: entry.project,
      messages,
    });
  } catch (err) {
    console.error("Failed to load session:", err);
    res.status(500).json({ error: "Failed to load session" });
  }
});