var channels = {}

// cf [wlan channels frequency](https://en.wikipedia.org/wiki/List_of_WLAN_channels)

var frequency = 2412

for (var i = 1; i < 15; i++) {
  channels[i] = frequency.toString()
  frequency = frequency + 5
}

frequency = 5180

for(var i = 36 ; i <= 64 ; i+=2){
  channels[i] = frequency.toString()
  frequency += 10
}

frequency = 5500

for(var i = 100 ; i <= 144 ; i+=2){
  channels[i] = frequency.toString()
  frequency += 10
}

frequency = 5745

for(var i = 149 ; i <= 161 ; i+=2){
  channels[i] = frequency.toString()
  frequency += 10
}

frequency = 5825

for(var i = 165 ; i <= 173 ; i+=4){
  channels[i] = frequency.toString()
  frequency += 20
}


function frequencyFromChannel(channelId) {
  return channels[parseInt(channelId)]
}

function dBFromQuality(quality) {
  return (parseFloat(quality)/2 - 100)
}


exports.frequencyFromChannel = frequencyFromChannel
exports.dBFromQuality = dBFromQuality