function sshkey () {
  local keys githubusername auth_files teams team_id members
  checkroot
  if [ "$1" == "add" ]; then
    checkargn $# 4
    shift
    temp_file=$(mktemp)
    echo "$@" >> $temp_file
    if ssh-keygen -l -f $temp_file 2>/dev/null <<< y >/dev/null; then
      rm $temp_file
      echo "$@" >> /root/.ssh/authorized_keys
      chmod 600 /root/.ssh/authorized_keys
      if [ "$(detectrpi)" != "nonrpi" ]; then
        mkdir -p /root/.ssh /home/pi/.ssh
        chmod 700 /root/.ssh /home/pi/.ssh
        echo "$@" >> /home/pi/.ssh/authorized_keys
        chmod 600 /home/pi/.ssh/authorized_keys
        chown -R pi:pi /home/pi/.ssh
        echo "====== Added to 'pi' and 'root' user's authorized_keys ======"
      else
        echo "====== Added to 'root' user's authorized_keys ======"
      fi
      echo "$@"
    else
      rm $temp_file
      log_and_exit1 "ERROR: invalid public key"
    fi
  elif [ "$1" == "list" ]; then
    checkargn $# 1
    echo "==== root keys ===="
    cat /root/.ssh/authorized_keys
    if [ "$(detectrpi)" != "nonrpi" ]; then
      echo "==== pi keys ===="
      cat /home/pi/.ssh/authorized_keys
    fi
  elif [ "$1" == "delete" ]; then
    checkargn $# 2
    if [ -z "$2" ]; then
      echo "Error: missing argument"
      log_and_exit1 "Usage: $BASENAME sshkey delete \"<key>\""
    fi
    keys="$(echo "$@" | sed 's/delete //')"
    if grep -Fxq "$keys" /root/.ssh/authorized_keys; then
      sed -i "\:$keys:d" /root/.ssh/authorized_keys
      echo "Key deleted from root keys."
    else
      echo "Key not found in root keys."
    fi
    if [ "$(detectrpi)" != "nonrpi" ]; then
      if grep -Fxq "$keys" /home/pi/.ssh/authorized_keys; then
        sed -i "\:$keys:d" /home/pi/.ssh/authorized_keys
        echo "Key deleted from pi keys."
      else
        echo "Key not found in pi keys."
      fi
    fi
  elif [ "$1" == "deleteall" ]; then
    checkargn $# 1
    rm /root/.ssh/authorized_keys
    if [ "$(detectrpi)" != "nonrpi" ]; then
      rm /home/pi/.ssh/authorized_keys
    fi
    echo "all sshkeys are deleted."
  elif [ "$1" == "github" ]; then
    if [ -z "$2" ]; then
      echo "Error: missing arguments"
      log_and_exit1 "Usage: $BASENAME sshkey github <adduser|deleteuser|addteam>"
    fi
    if [ "$2" == "adduser" ]; then
      if [ -z "$3" ]; then
        echo "Error: missing argument"
        log_and_exit1 "Usage: $BASENAME sshkey adduser <username>"
      fi
      shift; shift
      for user in "$@"; do
        echo "  Attempting to add the following user: $user"
        keys=$(curl -s "https://github.com/$user.keys")
        if [ ! -z "$keys" ]; then
          keys=$(sed 's#$# '$user'#' <<< $keys)
          sshkey add "$keys"
        fi
        echo "  Successfully added user: $user"
      done
    elif [ "$2" == "deleteuser" ]; then
      if [ -z "$3" ]; then
        echo "Error: missing argument"
        log_and_exit1 "Usage: $BASENAME sshkey deleteuser <username>"
      fi
      githubusername="$3"
      auth_files="/root/.ssh/authorized_keys /home/pi/.ssh/authorized_keys"
      for file in $auth_files; do
        if [ -f "$file" ]; then
          if grep -q " $githubusername$" $file; then
            sed -i "/ $githubusername$/d" $file
            echo "$githubusername's key(s) deleted from $file"
          else
            echo "$githubusername does not exist"
          fi
        else
          echo "$file does not exist."
        fi
      done
    elif [ "$2" == "addteam" ]; then
      checkargn $# 5
      if [ -z "$3" ] || [ -z "$4" ] || [ -z "$5" ]; then
        echo "Error: missing arguments"
        log_and_exit1 "Usage: $BASENAME sshkey github addteam <organization> <team_name> <access_token>"
      fi
      teams=$(curl -s -X GET "https://api.github.com/orgs/$3/teams" -H "Authorization: token $5")
      team_id=$(echo "$teams" | jq ".[] | select(.name==\"$4\").id")
      members=$(curl -s -X GET "https://api.github.com/teams/$team_id/members" -H "Authorization: token $5" | jq ".[].login" -r)
      while read -r member; do
        sshkey github adduser "$member"
      done <<< "$members"
    else
      echo "Error: unsupported command"
      log_and_exit1 "Usage: $BASENAME sshkey github <adduser|deleteuser|addteam>"
    fi
  else
    echo "Error: unsupported command"
    log_and_exit1 "Usage: $BASENAME sshkey <add|list|delete|deleteall|github>"
  fi
}

function sshkey_help () {
  echo
  echo "Usage: $BASENAME sshkey <add|list|delete|deleteall|github>"
  echo
  echo "Used for adding or removing ssh keys for authentication"
  echo
  echo "Example:"
  echo "  $BASENAME sshkey add \"\""
  echo "      The public key between quotes will be added to authorized_keys, so the user can login without a password for both 'pi' and 'root' user."
  echo
  echo "  $BASENAME sshkey list"
  echo "      Will output the content of the root and pi users keys"
  echo
  echo "  $BASENAME sshkey delete \"<key>\""
  echo "      Deletes the specified public key"
  echo
  echo "  $BASENAME sshkey deleteall"
  echo "      Deletes all ssh keys"
  echo
  echo "  $BASENAME sshkey github adduser|deleteuser <username>"
  echo "      Downloads or deletes the public keys of the github username from/to the authorized_keys file."
  echo
  echo "  $BASENAME sshkey github addteam <organization> <team_name> <access_token>"
  echo "      Downloads the public keys of the group members and adds them to authorized_keys"
  echo "      An access_token is required to make this work, it can be generated in the following link"
  echo "      https://github.com/settings/tokens"
  echo
}