const eventSource = new EventSource("/api/events")

let prevCPUIdle = 0
let prevCPUKernel = 0
let prevCPUUser = 0

eventSource.onmessage = function (event) {
  const data = JSON.parse(event.data)

  const GB = 1024 * 1024 * 1024

  let currentCPUIdle = data.processor_info.IdleTimeSinceBoot
  let currentCPUKernel = data.processor_info.KernelTimeSinceBoot
  let currentCPUUser = data.processor_info.UserTimeSinceBoot

  document.getElementById("cpu-load").innerText = data.load_average.Load1.toFixed(2) + " " + data.load_average.Load5.toFixed(2) + " " + data.load_average.Load15.toFixed(2)
  document.getElementById("cpu-usage").innerText = calculateCPUUsage(currentCPUIdle, currentCPUKernel, currentCPUUser).toFixed(2) + "%"
  document.getElementById("memory").innerText = ((data.memory_info.SystemMemory - data.memory_info.AvailableMemory) / GB).toFixed(2) + "/" + (data.memory_info.SystemMemory / GB).toFixed(2)
  document.getElementById("temperature").innerText = checkTemperatureAvailability(data.temperature_info)
  document.getElementById("uptime").innerText = formatUptime(data.uptime_info)
}

function calculateCPUUsage(currentIdle, currentKernel, currentUser) {
  if (prevCPUIdle === 0 || prevCPUKernel === 0 || prevCPUUser === 0) {
    prevCPUIdle = currentIdle
    prevCPUKernel = currentKernel
    prevCPUUser = currentUser

    return 0
  }

  deltaIdle = currentIdle - prevCPUIdle
  deltaKernel = currentKernel - prevCPUKernel
  deltaUser = currentUser - prevCPUUser

  deltaTotal = deltaIdle + deltaKernel + deltaUser

  totalCPUUsage = ((deltaKernel + deltaUser) / deltaTotal) * 100

  prevCPUIdle = currentIdle
  prevCPUKernel = currentKernel
  prevCPUUser = currentUser

  return totalCPUUsage
}

function checkTemperatureAvailability(temperatureStruct) {
  if (temperatureStruct.Supported) {
    return temperatureStruct.Celsius + "C°"
  } else {
    return "Unsupported"
  }
}

function formatUptime(uptimeStruct) {
  total = Math.round(uptimeStruct.Uptime)
  if (total < 60) {
    return Math.floor(total)
  }
  s = total % 60
  m = (total / 60) % 60

  if (total < 3000) {
    return Math.floor(m)+":"+String(Math.floor(s)).padStart(2, '0')
  }

  h = (total / 3600) % 24
  if (total < 86400) {
    return Math.floor(h)+":"+String(Math.floor(m)).padStart(2, '0')+":"+String(Math.floor(s)).padStart(2, '0')
  }

  d = total / 86400
  return  Math.floor(d)+":"+String(Math.floor(h)).padStart(2, '0')+":"+String(Math.floor(m)).padStart(2, '0')+":"+String(Math.floor(s)).padStart(2, '0')
}