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

import getKubeConfig from "../../../../utils/config/kubernetes";
import { parseCpu, parseMemory } from "../../../../utils/kubernetes/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 } = req.query;

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

  try {
    const kc = getKubeConfig();
    const coreApi = kc.makeApiClient(CoreV1Api);
    const metricsApi = new Metrics(kc);
    const podsResponse = await coreApi.listNamespacedPod(namespace, null, null, null, null, labelSelector)
      .then((response) => response.body)
      .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: "not found"
      });
      return;
    }

    let cpuLimit = 0;
    let memLimit = 0;
    pods.forEach((pod) => {
      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 stats = await pods.map(async (pod) => {
      let depMem = 0;
      let depCpu = 0;
      const podMetrics = await metricsApi.getPodMetrics(namespace, pod.metadata.name)
        .then((response) => response)
        .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;
        });
      if (podMetrics) {
        podMetrics.containers.forEach((container) => {
          depMem += parseMemory(container.usage.memory);
          depCpu += parseCpu(container.usage.cpu);
        });
      }
      return {
        mem: depMem,
        cpu: depCpu
      };
    }).reduce(async (finalStats, podStatPromise) => {
        const podStats = await podStatPromise;
        return {
          mem: finalStats.mem + podStats.mem,
          cpu: finalStats.cpu + podStats.cpu
        };
      });
    stats.cpuLimit = cpuLimit;
    stats.memLimit = memLimit;
    stats.cpuUsage = cpuLimit ? stats.cpu / cpuLimit : 0;
    stats.memUsage = memLimit ? stats.mem / memLimit : 0;
    res.status(200).json({
      stats
    });
  } catch (e) {
    logger.error(e);
    res.status(500).send({
      error: "unknown error"
    });
  }
}