import EmberObject, { computed } from '@ember/object';
import { alias } from '@ember/object/computed';
import RollingArray from 'nomad-ui/utils/classes/rolling-array';
import AbstractStatsTracker from 'nomad-ui/utils/classes/abstract-stats-tracker';
import classic from 'ember-classic-decorator';

const percent = (numerator, denominator) => {
  if (!numerator || !denominator) {
    return 0;
  }
  return numerator / denominator;
};

const empty = (ts) => ({ timestamp: ts, used: null, percent: null });

@classic
class NodeStatsTracker extends EmberObject.extend(AbstractStatsTracker) {
  // Set via the stats computed property macro
  node = null;

  @computed('node.id')
  get url() {
    return `/v1/client/stats?node_id=${this.get('node.id')}`;
  }

  append(frame) {
    const timestamp = new Date(Math.floor(frame.Timestamp / 1000000));

    const cpuUsed = Math.floor(frame.CPUTicksConsumed) || 0;
    this.cpu.pushObject({
      timestamp,
      used: cpuUsed,
      percent: percent(cpuUsed, this.reservedCPU),
    });

    const memoryUsed = frame.Memory.Used;
    this.memory.pushObject({
      timestamp,
      used: memoryUsed,
      percent: percent(memoryUsed / 1024 / 1024, this.reservedMemory),
    });
  }

  pause() {
    const ts = new Date();
    this.memory.pushObject(empty(ts));
    this.cpu.pushObject(empty(ts));
  }

  // Static figures, denominators for stats
  @alias('node.resources.cpu') reservedCPU;
  @alias('node.resources.memory') reservedMemory;

  // Dynamic figures, collected over time
  // []{ timestamp: Date, used: Number, percent: Number }
  @computed('bufferSize', 'node')
  get cpu() {
    return RollingArray(this.bufferSize);
  }

  @computed('bufferSize', 'node')
  get memory() {
    return RollingArray(this.bufferSize);
  }
}

export default NodeStatsTracker;

export function stats(nodeProp, fetch) {
  return computed(nodeProp, function () {
    return NodeStatsTracker.create({
      fetch: fetch.call(this),
      node: this.get(nodeProp),
    });
  });
}
