import { CoreV1Api, Metrics } from "@kubernetes/client-node";

import { getKubeConfig } from "../../../../utils/config/kubernetes";
import { parseCpu, parseMemory } from "../../../../utils/kubernetes/utils";
import createLogger from "../../../../utils/logger";

const logger = createLogger("kubernetesStatsService");

export default async function handler(req, res) {
  const APP_LABEL = "app.kubernetes.io/name";
  const { service, podSelector } = req.query;

  const [namespace, appName] = service;
  if (!namespace && !appName) {
    res.status(400).send({
      error: "kubernetes query parameters are required",
    });
    return;
  }
  const labelSelector = podSelector !== undefined ? podSelector : `${APP_LABEL}=${appName}`;

  try {
    const kc = getKubeConfig();
    if (!kc) {
      res.status(500).send({
        error: "No kubernetes configuration",
      });
      return;
    }
    const coreApi = kc.makeApiClient(CoreV1Api);
    const metricsApi = new Metrics(kc);
    const podsResponse = await coreApi
      .listNamespacedPod({
        namespace,
        labelSelector,
      })
      .catch((err) => {
        logger.error("Error getting pods: %d %s %s", err.statusCode, err.body, err.response);
        return null;
      });
    if (!podsResponse) {
      res.status(500).send({
        error: "Error communicating with kubernetes",
      });
      return;
    }
    const pods = podsResponse.items;

    if (pods.length === 0) {
      res.status(404).send({
        error: `no pods found with namespace=${namespace} and labelSelector=${labelSelector}`,
      });
      return;
    }

    const podNames = new Set();
    let cpuLimit = 0;
    let memLimit = 0;
    pods.forEach((pod) => {
      podNames.add(pod.metadata.name);
      pod.spec.containers.forEach((container) => {
        if (container?.resources?.limits?.cpu) {
          cpuLimit += parseCpu(container?.resources?.limits?.cpu);
        }
        if (container?.resources?.limits?.memory) {
          memLimit += parseMemory(container?.resources?.limits?.memory);
        }
      });
    });

    const namespaceMetrics = await metricsApi
      .getPodMetrics(namespace)
      .then((response) => response.items)
      .catch((err) => {
        // 404 generally means that the metrics have not been populated yet
        if (err.statusCode !== 404) {
          logger.error("Error getting pod metrics: %d %s %s", err.statusCode, err.body, err.response);
        }
        return null;
      });

    const stats = {
      mem: 0,
      cpu: 0,
    };

    if (namespaceMetrics) {
      const podMetrics = namespaceMetrics.filter((item) => podNames.has(item.metadata.name));
      podMetrics.forEach((metrics) => {
        metrics.containers.forEach((container) => {
          stats.mem += parseMemory(container.usage.memory);
          stats.cpu += parseCpu(container.usage.cpu);
        });
      });
    }

    stats.cpuLimit = cpuLimit;
    stats.memLimit = memLimit;
    stats.cpuUsage = cpuLimit ? 100 * (stats.cpu / cpuLimit) : 0;
    stats.memUsage = memLimit ? 100 * (stats.mem / memLimit) : 0;
    res.status(200).json({
      stats,
    });
  } catch (e) {
    if (e) logger.error(e);
    res.status(500).send({
      error: "unknown error",
    });
  }
}