#!/bin/bash
## Title      : ACHAR - Auto Completion of Hosts Add/Remove script
## Version    : 0.2.1
## GIT Repo   : https://git.zaks.web.za/zaks-web/achar
## Author     : Ze'ev Schurmann
## Company    : ZAKS Web
## Website    : https://www.zaks.web.za/
## Reddit     : https://www.reddit.com/r/ZAKSWeb
## License    : GPL3 or Later
## Description: This tool allows for the management of bash auto completion of
##              hostnames when using SSH or RSync in Bash.
##
## USAGE
##
## From the bash terminal, type:
##    $ achar {command} {context}
##
## COMMANDS
##
## add - adds a host to your list of common hosts
##    $ achar add username@hostname.domainname.tld
##    $ achar add username@1.2.3.4
##
## disable - disables auto completion of hostnames for current system user
##    $ achar disable
##      * does not delete the list of hosts stored at ~/.achar/hosts
##
## enable - enables auto completion of hostnames for current system user
##    $ achar enable
##
## help - displays this block of text
##    $ achar help
##
## license - displays the GPL3 and Later license
##    $ achar license
##
## list - list all existing hosts from your list of common hosts
##    $ achar list
##      * You can use context to search for a specific hostname or part there of
##    $ achar list username
##    $ achar list part-of-hostname
##
## remove - removes an existing host from your list of common hosts
##    $ achar remove username@hostname.domainname.tld
##    $ achar remove username@1.2.3.4
##
## reset - deletes all saved hosts
##    $ achar reset
##
## uninstall - uninstalls achar from your system
##    $ sudo achar uninstall
##    # achar uninstall
##      * does not delete the list of hosts stored at ~/.achar/hosts
##
## update - checks for an update to ACHAR and prompts you to install it
##    $ achar update

bashrc_array=("# enable host autocompletion for ssh and rsync" "[ -f ~/.achar/completions ] && [ -f ~/.achar/hosts ] && . ~/.achar/completions")
completions_array=("# Include existing rsync completions" ". /usr/share/bash-completion/completions/rsync" "" "# Include existing ssh completions" ". /usr/share/bash-completion/completions/ssh" "" "# Function to add custom user@hostname completions" "_custom_hosts()" "{" "    local cur=\"\${COMP_WORDS[COMP_CWORD]}\"" "    local hosts=\$(cat ~/.achar/hosts)" "    COMPREPLY=( \$(compgen -W \"\$hosts\" -- \"\$cur\") )" "}" "" "# Function to handle extended rsync completions" "_extended_rsync_completions()" "{" "    local cur=\"\${COMP_WORDS[COMP_CWORD]}\"" "" "    # Use custom host completions if '@' is detected" "    if [[ \"\$cur\" == *@* ]]; then" "        _custom_hosts" "    else" "        # Fallback to default rsync completion" "        _rsync" "    fi" "}" "" "# Extend the existing ssh completion function to include custom hosts" "_extended_ssh_completions()" "{" "    local cur=\"\${COMP_WORDS[COMP_CWORD]}\"" "" "    # Use custom host completions if '@' is detected" "    if [[ \"\$cur\" == *@* ]]; then" "        _custom_hosts" "    else" "        # Fallback to default ssh completion" "        _ssh" "    fi" "}" "" "# Preserve the original rsync completion function" "if declare -F _rsync &>/dev/null; then" "    complete -r rsync" "    complete -F _extended_rsync_completions rsync" "fi" "" "# Preserve the original ssh completion function" "if declare -F _ssh &>/dev/null; then" "    complete -r ssh" "    complete -F _extended_ssh_completions ssh" "fi")
completions_md5="a148257d1f32705ef2c1f292e72d528c"

function achar_add {

  local username_and_hostname

  username_and_hostname=$1
  validate_achar_installation hosts
  validate_host "$username_and_hostname"

  if [[ -z $(cat ~/.achar/hosts | grep "$username_and_hostname") ]]; then

    echo $username_and_hostname >> ~/.achar/hosts

  else

    echo "$username_and_hostname is already added!" >&2
    exit 1

  fi

}

function achar_disable {

  validate_achar_installation disabled

  rm ~/.achar/completions

  for ((i=0; i<${#bashrc_array[@]}; i++)); do

    line=$(echo "${bashrc_array[$i]}" | sed 's/[]\/$*.^|[]/\\&/g')
    sed -i "/^$line$/d" ~/.bashrc

  done

  echo "Please start a new Bash Terminal Session for the change to take affect."

}

function achar_enable {

  validate_achar_installation enabled

  if [[ ! -d ~/.achar ]]; then

    mkdir ~/.achar

  fi

  if [[ ! -f ~/.achar/hosts ]]; then

    touch ~/.achar/hosts

  fi

  touch ~/.achar/completions

  for ((i=0; i<${#completions_array[@]}; i++)); do

    echo "${completions_array[$i]}" >>  ~/.achar/completions

  done

  for ((i=0; i<${#bashrc_array[@]}; i++)); do

    echo "${bashrc_array[$i]}" >>  ~/.bashrc

  done

  echo "Please start a new Bash Terminal Session for the change to take affect."

}

function achar_help {

  local script_path

  script_path="${BASH_SOURCE[0]}"
  echo

  while read -r line; do

    if [[ ${line:0:2} == "##" ]]; then

      echo "${line:3}"

    elif [[ ${line:0:2} == "#!" ]]; then

      donothing=0

    else

      echo
      exit 0

    fi

  done < "$script_path"

}

function achar_license {

  echo
  curl -s https://git.zaks.web.za/zaks-web/achar/raw/branch/main/LICENSE | fmt

  if [[ $? != 0 ]]; then

    echo "Could not get the license file." >&2
    echo "Either you are not connected to the Internet or the update server is down." >&2
    exit 1

  fi

  echo

}

function achar_list {

  validate_achar_installation hosts

  if [[ -z $1 ]]; then

    cat ~/.achar/hosts | sort

  else

    cat ~/.achar/hosts | grep "$1" | sort

  fi

}

function achar_remove {

  local username_and_hostname

  username_and_hostname=$1
  validate_achar_installation hosts
  validate_host $username_and_hostname

  if [[ -z $(cat ~/.achar/hosts | grep "$username_and_hostname") ]]; then

    echo "$username_and_hostname is not there!" >&2
    exit 1

  else

    sed -i "/^$username_and_hostname$/d" ~/.achar/hosts

  fi

}

function achar_reset {

  validate_achar_installation hosts
  echo "This will delete all saved hosts and"
  echo "and start from scratch."
  echo
  echo "Press ENTER to continue or CTRL+C to STOP!"
  read text
  rm ~/.achar/hosts
  touch ~/.achar/hosts

}

function achar_uninstall {

  local script_path
  local text

  script_path="${BASH_SOURCE[0]}"

  if [[ $(whoami) == "root" ]]; then

    echo "You are about to uninstall ACHAR."
    echo
    echo "If you want to disable the autocompletions, then"
    echo "you must run \"achar disable\" for each user."
    echo "This is recommended if you are planning to install"
    echo "a new version."
    echo
    echo "Press ENTER to continue or CTRL+C to STOP!"
    read text
    rm $script_path

  else

    echo "Please run with root privilages (sudo) in order to uninstall."
    exit 1

  fi

}

function achar_update {

  local difference
  local script_path
  local stable_version_number
  local -a stable_version_number_array
  local test_stable
  local test_version
  local update_available
  local -a version_line
  local version_number
  local -a version_number_array

  script_path="${BASH_SOURCE[0]}"
  version_line=($(grep '^## Version' "$script_path"))
  version_number=${version_line[3]}
  stable_version_number=$(curl -s https://git.zaks.web.za/zaks-web/achar/raw/branch/main/stable_version)

  if [[ $? != 0 ]]; then
    echo "Could not check for latest version." >&2
    echo "Either you are not connected to the Internet or the update server is down." >&2
    exit 1
  fi

  oldIFS=$IFS
  IFS="."
  version_number_array=($version_number)
  stable_version_number_array=($stable_version_number)
  IFS=$oldIFS

  if [[ ${#version_number_array[@]} -gt ${#stable_version_number_array[@]} ]]; then

    difference=$((${#version_number_array[@]}-${#stable_version_number_array[@]}))

    for ((i=0; i<$differnce; i++)); do

      $stable_version_number_array[${#stable_version_number_array[@]}]=0

    done

  elif [[ ${#stable_version_number_array[@]} -gt ${#version_number_array[@]} ]]; then

    difference=$((${#version_number_array[@]}-${#stable_version_number_array[@]}))

    for ((i=0; i<$differnce; i++)); do

      $stable_version_number_array[${#stable_version_number_array[@]}]=0

    done

  fi

  echo "Current version is $version_number"
  echo "Latest version is $stable_version_number"
  update_available="false"

  for ((i=0; i<${#version_number_array[@]}; i++)); do

    if [[ $update_available == "false" ]]; then

      test_stable=${stable_version_number_array[$i]##+(0)}
      test_version=${version_number_array[$i]##+(0)}

      if [[ -z $test_stable ]]; then

        test_stable=0

      fi

      if [[ -z $test_version ]]; then

        test_version=0

      fi

      if [[ ${#stable_version_number_array[@]} -gt ${#version_number_array[@]} ]]; then

        update_available="true"

      fi

    fi

  done

  if [[ $update_available == "true" ]]; then

    echo "Update is avaiable!"
    echo
    echo "First run \"achar disable\" for all users."
    echo "Then run \"achar uninstall\" as root or sudo."
    echo "Lastly, follow the instructions at"
    echo "https://git.zaks.web.za/zaks-web/achar"
    echo "to install the latest version."

  else

    echo "You currently have the latest version!"

  fi

}

function validate_achar_installation {

  local achar_installation_error_code=""
  local what_test
  what_test=$1

  if [[ -d ~/.achar ]]; then

    achar_installation_error_code="A$achar_installation_error_code"

  else

    achar_installation_error_code="a$achar_installation_error_code"

  fi

  if [[ -f ~/.achar/hosts ]]; then

    achar_installation_error_code="H$achar_installation_error_code"

  else

    achar_installation_error_code="h$achar_installation_error_code"

  fi

  if [[ -f ~/.achar/completions ]]; then

    md5_test=$(cat ~/.achar/completions | md5sum)

    if [[ ${md5_test:0:32} == $completions_md5 ]]; then

      achar_installation_error_code="C$achar_installation_error_code"

    else

      echo "File corrupt: ~/.achar/completions" >&2
      exit 1

    fi

  else

    achar_installation_error_code="c$achar_installation_error_code"

  fi

  test=$(echo "${bashrc_array[1]}" | sed 's/[]\/$*.^|[]/\\&/g')

  if [[ -z $(cat ~/.bashrc | grep "${bashrc_array[0]}") ]] || [[ -z $(cat ~/.bashrc | grep "$test") ]]; then

    achar_installation_error_code="b$achar_installation_error_code"

  else

    achar_installation_error_code="B$achar_installation_error_code"

  fi

  if [[ $achar_installation_error_code == "BCHA" ]] && [[ $what_test == "enabled" ]]; then

    echo "ACHAR is already enabled!"
    exit 1

  elif [[ $achar_installation_error_code == "bcha" ]] && [[ $what_test == "disabled" ]]; then

    echo "ACHAR is already disabled!"
    exit 1

  elif [[ $achar_installation_error_code == "bcHA" ]] && [[ $what_test == "disabled" ]]; then

    echo "ACHAR is already disabled!"
    exit 1

  elif [[ $achar_installation_error_code == "bcha" ]] && [[ -z $what_test ]]; then

    echo "ACHAR is disabled!"
    exit 1

  elif [[ $achar_installation_error_code == "bcha" ]] && [[ $what_test == "hosts" ]]; then

    echo "ACHAR is disabled!"
    exit 1

  elif [[ $achar_installation_error_code != "BCHA" ]] && [[ $achar_installation_error_code != "bcha" ]] && [[ -z $what_test ]]; then

    echo "Something is wrong with your setup!" >&2

    if [[ ${achar_installation_error_code:0:1} == "b" ]]; then

      echo "Required code missing from ~/.bashrc" >&2

    fi

    if [[ ${achar_installation_error_code:1:1} == "c" ]]; then

      echo "File missing: ~/.achar/completions" >&2

    fi

    if [[ ${achar_installation_error_code:2:1} == "h" ]]; then

      echo "File missing: ~/.achar/hosts" >&2

    fi

    if [[ ${achar_installation_error_code:3:1} == "a" ]]; then

      echo "Folder missing: ~/.achar/" >&2

    fi

    exit 1

  fi

}

function validate_host {

  local hostname
  local -a temp_array
  local username_and_hostname
  local username

  if [[ -z $1 ]]; then

    echo "Unexpected Error!"
    exit 1

  fi

  username_and_hostname="$1"
  temp_array=($username_and_hostname)

  if [[ ${#temp_array[@]} != 1 ]]; then

    echo "Invalid Hostname!"
    exit 1

  fi

  old_ifs=$IFS
  IFS="@"
  temp_array=($username_and_hostname)
  IFS=$old_ifs

  if [[ ${#temp_array[@]} != 2 ]]; then

    echo "Invalid Hostname!"
    exit 1

  fi

  username=${temp_array[0]}
  hostname=${temp_array[1]}

  if [[ $hostname =~ ^([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])$ ]]; then

    donothing=0

  elif nslookup "$hostname" > /dev/null 2>&1; then

    donothing=0

  else

    echo "Invalid Domain Name or IP address!"
    exit 1

  fi

  if [[ ${username:0:1} =~ ^[0-9]$ ]] || [[ ! $username =~ ^[A-Za-z0-9_.-]+$ ]]; then

    echo "Username is not a valid format!"
    echo "Must contain \"A-Z\", \"a-z\", \"0-9\", \"_\", \".\" and \"-\"."
    exit 1

  fi

}

if [[ -z $1 ]]; then

  achar_help

elif [[ ${1,,} == "add" ]]; then

  if [[ -z $2 ]]; then

    echo "Please include a username@hostname" >&2
    exit 1

  else

    achar_add $2

  fi

elif [[ ${1,,} == "disable" ]]; then

  achar_disable

elif [[ ${1,,} == "enable" ]]; then

  achar_enable

elif [[ ${1,,} == "help" ]]; then

  achar_help

elif [[ ${1,,} == "license" ]]; then

  achar_license

elif [[ ${1,,} == "list" ]]; then

  if [[ -z $2 ]]; then

    achar_list

  else

    achar_list $2

  fi

elif [[ ${1,,} == "remove" ]]; then

  if [[ -z $2 ]]; then

    echo "Please include a username@hostname" >&2
    exit 1

  else

    achar_remove $2

  fi

elif [[ ${1,,} == "reset" ]]; then

  achar_reset

elif [[ ${1,,} == "uninstall" ]]; then

  achar_uninstall

elif [[ ${1,,} == "update" ]]; then

  achar_update

else

  achar_help

fi

exit 0