<!--
  - Copyright 2014-2018 the original author or authors.
  -
  - Licensed under the Apache License, Version 2.0 (the "License");
  - you may not use this file except in compliance with the License.
  - You may obtain a copy of the License at
  -
  -     http://www.apache.org/licenses/LICENSE-2.0
  -
  - Unless required by applicable law or agreed to in writing, software
  - distributed under the License is distributed on an "AS IS" BASIS,
  - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  - See the License for the specific language governing permissions and
  - limitations under the License.
  -->

<template>
  <sba-panel title="Garbage Collection Pauses" v-if="hasLoaded">
    <div>
      <div v-if="error" class="message is-danger">
        <div class="message-body">
          <strong>
            <font-awesome-icon class="has-text-danger" icon="exclamation-triangle"/>
            Fetching GC metrics failed.
          </strong>
          <p v-text="error.message"/>
        </div>
      </div>
      <div class="level" v-if="current">
        <div class="level-item has-text-centered">
          <div>
            <p class="heading">Count</p>
            <p v-text="current.count"/>
          </div>
        </div>
        <div class="level-item has-text-centered">
          <div>
            <p class="heading">Total time spent</p>
            <p v-text="`${current.total_time.asSeconds()}s`"/>
          </div>
        </div>
        <div class="level-item has-text-centered">
          <div>
            <p class="heading">Max time spent</p>
            <p v-text="`${current.max.asSeconds()}s`"/>
          </div>
        </div>
      </div>
    </div>
  </sba-panel>
</template>

<script>
  import subscribing from '@/mixins/subscribing';
  import Instance from '@/services/instance';
  import {concatMap, timer} from '@/utils/rxjs';
  import moment from 'moment';

  export default {
    props: {
      instance: {
        type: Instance,
        required: true
      }
    },
    mixins: [subscribing],
    data: () => ({
      hasLoaded: false,
      error: null,
      current: null,
    }),
    methods: {
      async fetchMetrics() {
        const response = await this.instance.fetchMetric('jvm.gc.pause');
        const measurements = response.data.measurements.reduce(
          (current, measurement) => ({
            ...current,
            [measurement.statistic.toLowerCase()]: measurement.value
          }), {}
        );
        return {
          ...measurements,
          total_time: moment.duration(Math.round(measurements.total_time * 1000)),
          max: moment.duration(Math.round(measurements.max * 1000)),
        };
      },
      createSubscription() {
        const vm = this;
        return timer(0, 2500)
          .pipe(concatMap(this.fetchMetrics))
          .subscribe({
            next: data => {
              vm.hasLoaded = true;
              vm.current = data;
            },
            error: error => {
              vm.hasLoaded = true;
              console.warn('Fetching GC metrics failed:', error);
              vm.error = error;
            }
          });
      }
    }
  }
</script>
