// proxy/backoneAgentFetcher.js
// ─────────────────────────────────────────────────────────────────────────────
// Fetches active agents from BackOne API.
// Uses a two-strategy approach to handle endpoints that may timeout (Source 2).
// ─────────────────────────────────────────────────────────────────────────────

const { backoneFetch, agentMap } = require('./backoneClientCore');

// Strategy 1 timeout: 15s (agent/download can be slow on small deployments)
const PRIMARY_TIMEOUT_MS = 15000;

async function fetchAgents(siteUuid = null) {
  // Strategy 1: Use /assets/agents (reliable, returns id+uuid+uuid)
  try {
    const data = await backoneFetch('/assets/agents', {}, null, siteUuid);
    if (data && Array.isArray(data) && data.length > 0) {
      const list = data.map(r => ({
        id:           r.id || r.uuid,
        uuid:         r.uuid,
        serial:       r.uuid,
        label:        r.label || r.uuid,
        provisioned:  true,
        activated:    true,
        last_seen_at: r.last_seen ? new Date(r.last_seen * 1000) : null,
      })).filter(a => a.uuid);

      // Populate agentMap (uuid → id) for downstream filter_agents usage
      for (const a of list) {
        if (a.uuid) agentMap[a.uuid] = a.id || a.uuid;
      }
      console.log(`[fetchAgents] Got ${list.length} agents from /assets/agents.`);
      return list;
    }
  } catch (e) {
    console.error('[fetchAgents] /assets/agents failed:', e.message);
  }


  // Strategy 2: Fallback — discover agents from /data/flows
  // Useful for Source 2 where /data/stats/top/agent/download consistently times out.
  console.log('[fetchAgents] Primary endpoint timeout/empty. Using flows-based agent discovery...');
  try {
    const flowData = await backoneFetch('/data/flows', {
      settings_limit: 100,
    }, null, siteUuid);

    if (!flowData || !Array.isArray(flowData)) return [];

    // Extract unique agent_uuids from flow records
    const seen = new Set();
    const agentList = [];
    for (const flow of flowData) {
      const uuid = flow.agent_uuid;
      if (uuid && !seen.has(uuid)) {
        seen.add(uuid);
        agentList.push({
          id:           null,
          uuid:         uuid,
          serial:       uuid,
          label:        uuid,
          provisioned:  true,
          activated:    true,
          last_seen_at: flow.last_seen_at ?? null,
        });
      }
    }

    console.log(`[fetchAgents] Fallback discovered ${agentList.length} agent(s) from flows.`);
    return agentList;
  } catch (e) {
    console.error('[fetchAgents] Fallback also failed:', e.message);
    return [];
  }
}

module.exports = { fetchAgents };