{ pkgs, ... }:

{

  launchd.user.agents.locationchanger = {
    serviceConfig = {
      Label      = "org.nixos.locationchanger";
      RunAtLoad  = true;
      WatchPaths = [ "/Library/Preferences/SystemConfiguration" ];
    };
    script = ''
      # This script changes network location based on the name of Wi-Fi network.
      exec 2>&1 >> $HOME/Library/Logs/LocationChanger.log
      sleep 3

      ts() {
          date +"[%Y-%m-%d %H:%M] $*"
      }

      ID=`whoami`
      if [ "$ID" == "root" ]; then
          ts "Running as root will read a bad config, exiting."
          exit 1;
      fi

      SSID=`networksetup -listallhardwareports | awk '/Wi-Fi/{getline; print $2}' | xargs networksetup -getairportnetwork | awk '{print $NF}'`
      LOCATION_NAMES=`networksetup -listlocations`
      CURRENT_LOCATION=`networksetup -getcurrentlocation`
      CONFIG_FILE=$HOME/.locations/locations.conf

      ts "Connected to '$SSID'"
      ts "Probing '$CONFIG_FILE'"

      if [ -f $CONFIG_FILE ]; then
          ts "Reading to '$CONFIG_FILE'"
          ESSID=`echo "$SSID" | sed 's/[.[\*^$]/\\\\&/g'`
          NEW_SSID=`grep "^$ESSID=" $CONFIG_FILE | cut -d = -f 2`
          if [ "$NEW_SSID" != "" ]; then
              ts "Will switch the location to '$NEW_SSID' (configuration file)"
              SSID=$NEW_SSID
          else
              ts "Will switch the location to '$SSID'"
          fi
      fi

      ESSID=`echo "$SSID" | sed 's/[.[\*^$]/\\\\&/g'`

      if echo "$LOCATION_NAMES" | grep -q "^$ESSID$"; then
          NEW_LOCATION="$SSID"
      else
          if echo "$LOCATION_NAMES" | grep -q "^Automatic$"; then
              NEW_LOCATION=Automatic
              ts "Location '$SSID' was not found. Will default to 'Automatic'"
          else
              ts "Location '$SSID' was not found. The following locations are available: $LOCATION_NAMES"
              exit 1
          fi
      fi

      if [ "$NEW_LOCATION" != "" ]; then
          if [ "$NEW_LOCATION" != "$CURRENT_LOCATION" ]; then
              ts "Changing the location to '$NEW_LOCATION'"
              scselect "$NEW_LOCATION"
              SCRIPT="$HOME/.locations/$NEW_LOCATION"
              if [ -f "$SCRIPT" ]; then
                  ts "Running '$SCRIPT'"
                  "$SCRIPT"
              fi
          else
              ts "Already at '$NEW_LOCATION'"
          fi
      fi
    '';
  };

}