#!/bin/bash
# 

CONTEXT="$(kubectl config current-context)"
CUR_NAMESPACE=$(kubectl config get-contexts | grep "*" | awk '{ print $5 }')
NEW_NAMESPACE=
LIST_OBJECTS=

while :; do
  case $1 in
    -h|-\?|--help)
cat << EOF
Usage: ${0##*/} [-h] [-l|--list] [NAMESPACE]
Change current Kubernetes namespace, and optionally list objects.

    -h          display this help and exit
    -l          list objects after changing namespace
EOF
      exit
      ;;
    -l|--list)
      LIST_OBJECTS=1
      ;;
    *)
      if [[ -n "$1" ]]; then
        NEW_NAMESPACE="$1"
      fi
  esac
  shift
  if [[ -z $1 ]]; then
    break;
  fi
done

if [ -z "$NEW_NAMESPACE" ]; then
  echo "Select a new namespace:"
  echo
  NAMESPACES=( )
  kubectl get namespace 2>/dev/null >/dev/null
  if [ $? -eq 0 ]; then
    # Our account can list cluster namespaces
    NAMESPACES=( $(kubectl get namespace -o name | awk -F "/" '{ print $2 }' | sort) )
  else
    # Our account can NOT list cluster namespaces - they must be configured in the kubeconfig
    NAMESPACES=( $(kubectl config get-contexts -o name | sort) )
  fi
  NS_OPTS=()
  NS_LABELS=()
  for NS in "${NAMESPACES[@]}"; do
    NS_OPTS+=("$NS")
    if [[ $NS == $CUR_NAMESPACE ]]; then
      NS_LABELS+=("$(tput setaf 6)$NS$(tput sgr0) (current)")
    else
      NS_LABELS+=("$NS")
    fi
  done

  I=0
  for LABEL in "${NS_LABELS[@]}"; do
    printf '%s\n' "$((++I))) $LABEL"
  done >&2

  NUM_ITEMS=${#NS_LABELS[@]}
  PS3="$(tput setaf 6)  > Namespace: $(tput sgr0)"
  while :; do
    printf %s "${PS3}" >&2
    read -r INDEX
    # Make sure that the input is either empty or that a valid index was entered.
    [[ -z $INDEX ]] && break  # empty input
    (( INDEX >= 1 && INDEX <= NUM_ITEMS )) 2>/dev/null || { continue; }
    break
  done

  if [[ -n $INDEX ]]; then
    NEW_NAMESPACE="${NS_OPTS[$INDEX - 1]}"
  else
    NEW_NAMESPACE=$CUR_NAMESPACE
  fi
fi

if [[ -n $NEW_NAMESPACE ]]; then
  if [[ $CUR_NAMESPACE != $NEW_NAMESPACE ]]; then
    kubectl config set-context $CONTEXT --namespace=$NEW_NAMESPACE > /dev/null
    echo "Set namespace to $(tput setaf 6)$NEW_NAMESPACE$(tput sgr0)"
  else
    echo "Current namespace $(tput setaf 6)$CUR_NAMESPACE$(tput sgr0) (not changed)"
  fi
  echo
fi

if [[ -z $LIST_OBJECTS ]]; then
  printf %s "List objects? [Y/n]" >&2
  read -r LIST_OBJECTS
fi
if [[ $LIST_OBJECTS != 'n' ]]; then
  echo
  echo "----- $(tput setaf 6)Deployments$(tput sgr0) -----"
  kubectl get deployments
  echo
  echo "----- $(tput setaf 6)Pods$(tput sgr0) -----"
  kubectl get pods
  echo
  echo "----- $(tput setaf 6)Services$(tput sgr0) -----"
  kubectl get services
  echo
  echo "----- $(tput setaf 6)Ingress$(tput sgr0) -----"
  kubectl get ingress
  echo
  echo "----- $(tput setaf 6)Secrets$(tput sgr0) -----"
  kubectl get secrets
  echo
  echo "----- $(tput setaf 6)Config Maps$(tput sgr0) -----"
  kubectl get configmap
  echo
fi