#!/usr/bin/env bash

# Variables
script="$(basename "$0")"
hostsfile=/etc/hosts
default_ip="127.0.0.1"

## Colors
red=31
green=32
yellow=33

## Detect platform
case "$(uname -s)" in
  Linux)
    platform="linux";;
  Darwin)
    platform="macos";;
  CYGWIN*|MINGW*|MSYS*)
    platform="windows";;
  *)
    platform="other";;
esac


# Utils
mc_is_windows() {
  [ "$platform" == "windows" ]
}

mc_is_linux() {
  [ "$platform" == "linux" ]
}

mc_is_macos() {
  [ "$platform" == "macos" ]
}

mc_print_color() {
  printf "\e[%sm%s\e[m" "$1" "$2"
}

mc_prepend() {
  color="${2-$yellow}"
  prefix="$(mc_print_color "$color" "$(printf "%-3s | " "${1-EMCEE}")")"
  while IFS= read -r line; do
    echo -e "${prefix}${line}"
  done
}

mc_error() {
  printf '\a%s\n' "$1" | mc_prepend "ERROR" $red >&2
}

mc_done() {
  printf '\a%s\n' "$1" | mc_prepend "DONE!" $green >&2
}

mc_die() {
  mc_error "$1"
  exit 1
}

if mc_is_windows; then
  # Path to windows hosts file
  hostsfile="$(cmd //C echo %WINDIR%)\System32\drivers\etc\hosts"
fi

mc_win_run_as_admin() {
  command="$1"
  [ -z "$command" ] && mc_die "Run_as_admin missing command argument"

  echo "Running command with privileges, prepare for UAC popup (if enabled)..." | mc_prepend
  powershell -Command "Start-Process cmd -ArgumentList  \"/c\",\"$command\" -Verb RunAs" -windowstyle hidden
  # Add slight delay to avoid out-of-sync issues (e.g. grep still seeing the host in hostsfile)
  sleep 0.1
}

mc_find_in_hosts() {
  pattern="$1"
  pattern="${pattern//\*/\\*}"
  pattern="${pattern//\./\\.}"
  awk "/[ 	]+$pattern[ 	]*$/" "$hostsfile"
}

mc_help() {
  echo "emcee - Master of Ceremonies: add and remove entries in your /etc/hosts file" | mc_prepend
  echo "~~~~~" | mc_prepend
  echo "" | mc_prepend
  echo "Usage:" | mc_prepend
  echo "    $script add <hostname> [<ip>]      (ip is optional, defaults to $default_ip)" | mc_prepend
  echo "    $script remove <hostname>" | mc_prepend
  echo "    $script -h or --help               Show this message" | mc_prepend
  exit 0
}


# Commands
remove() {
  hostname="$1"
  if [ -n "$(mc_find_in_hosts "$hostname")" ]; then
    echo "$hostname found in your $hostsfile, removing..." | mc_prepend
    if mc_is_windows; then
      # findstr cannot write back to the same file, so create a .tmp first and remove it
      command="(copy /Y $hostsfile $hostsfile.tmp 1>NUL) && (findstr /V $hostname $hostsfile.tmp > $hostsfile) && (del $hostsfile.tmp)"
      mc_win_run_as_admin "$command"
    else
      sudo sed -i".bak" -E "/[ 	]+${hostname}[ 	]*$/d" "$hostsfile"
    fi

    if [ -z "$(mc_find_in_hosts "$hostname")" ]; then
      mc_done "$hostname was removed succesfully"
    else
      mc_die "Failed to remove $hostname"
    fi
  else
    echo "$hostname was not found in your $hostsfile" | mc_prepend
  fi
}

add() {
  hostname="$1"
  ip="${2-$default_ip}"
  if [ -n "$(mc_find_in_hosts "$hostname")" ]; then
    echo "$hostname already exists:" | mc_prepend
    mc_find_in_hosts "$hostname" | mc_prepend
  else
    echo "Adding $hostname to your $hostsfile" | mc_prepend
    if mc_is_windows; then
      # Notes for Batch commands:
      #  - `echo(` echos a new line
      #  - don't put spaces between operators, they will be echo'd too
      command="(echo(&&echo $(printf '%s\t%s' "$ip" "$hostname"))>>$hostsfile"
      mc_win_run_as_admin "$command"
    else
      printf '%s\t%s\n' "$ip" "$hostname" | sudo tee -a "$hostsfile" > /dev/null
    fi

    if [ -n "$(mc_find_in_hosts "$hostname")" ]; then
      mc_done "$hostname was added succesfully:"
      mc_done "$(mc_find_in_hosts "$hostname")"
    else
      mc_die "Failed to add $hostname"
    fi
  fi
}

show() {
  hostname="$1"
  found="$(mc_find_in_hosts "$hostname")"
  if [ -n "$found" ]; then
    echo "$hostname found:" | mc_prepend
    mc_find_in_hosts "$hostname" | mc_prepend
  else
    mc_die "$hostname not found"
  fi
}


# Execution
[[ "$1" =~ ^(-h|--help)$ ]] && mc_help

# Test if first argument is a function
if [[ "$1" =~ ^(add|remove|show)$ ]] ; then
  [ -z "$2" ] && mc_die "Missing hostname"

  # Execute arguments
  "$@"
else
  mc_die "Unknown option '$1'"
fi
echo