elstat/priv/frontend/src/components/Dashboard.js

import React, { Component } from 'react'

import Service from './Service.js'
import ServicePlaceholder from './ServicePlaceholder.js'
import DegradedNotice from './DegradedNotice.js'
import StreamingClient from '../ws/client'
import Status from './Status'
import Page from './Page'
import { log, objectFromEntries, strictFetch } from '../util.js'
import { domain as DOMAIN } from '../config.json'

export default class Dashboard extends Component {
  client = null

  state = {
    loading: true,
    error: null,
    metrics: null,
    incident: null,
  }

  async componentDidMount () {
    try {
      await this.loadMetrics()
      await this.loadIncident()
    } catch (error) {
      this.setState({ error: error.toString() })
    }

    this.setState({ loading: false })
    if (this.state.error) {
      return
    }

    const endpoint = `${DOMAIN}/api/streaming`
      .replace('https', 'wss')
      .replace('http', 'ws')

    this.client = new StreamingClient(endpoint, this.state.metrics)
    this.client.connect()

    this.client.on('status', this.handleStatus.bind(this))
    this.client.on('latency', this.handleLatency.bind(this))

    this.client.on('incident_new', (incident) => {
      this.setState({ incident })
    })
    this.client.on('incident_update', (incident) => {
      this.setState({ incident })
    })
    this.client.on('incident_close', () => {
      this.setState({ incident: null })
    })
  }

  handleStatus (name, [, status]) {
    const { status: statuses } = this.state.metrics
    log('updating status on:', name)

    if (!(name in statuses)) {
      log(`failed to locate channel ${name} to update statuses`)
      return
    }

    if (statuses[name].status === status) {
      log(`ignoring stale status (${status}) for ${name}`)
      return
    }

    this.setState(({ metrics: old }, _props) => {
      const metrics = { ...old }
      metrics.status[name].status = status

      return { metrics }
    })
  }

  handleLatency (name, data) {
    const { metrics } = this.state

    log('adding latency entry:', data)

    // latency entries come in newest to oldest, so remove the oldest entry
    const graph = metrics.graph[name].slice(0, metrics.graph[name].length - 1)

    // make new data come in first
    const newGraph = [data, ...graph]

    this.setState(({ metrics: old }, _props) => {
      const metrics = { ...old }
      metrics.graph[name] = newGraph

      const [, latency] = data
      metrics.status[name].latency = latency

      return { metrics }
    })
  }

  async loadMetrics () {
    log('loading metrics')

    const resp = await strictFetch(`${DOMAIN}/api/status`)
    this.setState({ metrics: await resp.json() })
  }

  async loadIncident () {
    log('loading current incident')

    const resp = await strictFetch(`${DOMAIN}/api/incidents/current`)
    this.setState({ incident: await resp.json() })
  }

  renderNotice (services) {
    const down = services.filter(([, { status }]) => !status)

    // DegradedNotice should only be shown when there is no ongoing incident,
    // and any services are reported as down.
    if (!this.state.incident && down.length > 0) {
      return <DegradedNotice services={objectFromEntries(down)}/>
    }

    return <Status incident={this.state.incident}/>
  }

  renderServices (services) {
    const { graph: graphs } = this.state.metrics
    return services.map(([name, info]) => (
      <Service name={name} key={name} graph={graphs[name]} {...info}/>
    ))
  }

  renderPlaceholders () {
    return (
      <React.Fragment>
        <ServicePlaceholder/>
        <ServicePlaceholder/>
        <ServicePlaceholder/>
      </React.Fragment>
    )
  }

  renderDashboardContent () {
    if (this.state.error) {
      return <div className="error">{this.state.error}</div>
    }

    if (this.state.loading) {
      return this.renderPlaceholders()
    }

    const allServices = Object.entries(this.state.metrics.status)

    const services = this.renderServices(allServices)
    const notice = this.renderNotice(allServices)

    return (
      <React.Fragment>
        {notice}
        {services}
      </React.Fragment>
    )
  }

  render () {
    return (
      <Page>
        <h1>elstatus</h1>
        {this.renderDashboardContent()}
      </Page>
    )
  }
}