#!/bin/bash
# Author: Alexander Epstein https://github.com/alexanderepstein

currentVersion="1.11.1"
state=""

checkOpenSSL()
{
  if  ! command -v openssl &>/dev/null ;then
    echo "Error: to use this tool openssl must be installed" >&2
    return 1
  else
    return 0
  fi
}
## uses openssl aes 256 cbc encryption to encrypt file salting it with password designated by user
encrypt()
{
  echo "Encrypting $1..."
  openssl enc -aes-256-cbc -salt -a -in $1 -out $2 || { echo "File not found"; return 1; }
  echo "Successfully encrypted"
}

## uses openssl aes 256 cbc decryption to decrypt file
decrypt()
{
  echo "Decrypting $1..."
  openssl enc -aes-256-cbc -d -a -in $1 -out $2 || { echo "File not found"; return 1; }
  echo "Successfully decrypted"
}

update()
{
  # Author: Alexander Epstein https://github.com/alexanderepstein
  # Update utility version 1.2.0
  # To test the tool enter in the defualt values that are in the examples for each variable
  repositoryName="Bash-Snippets" #Name of repostiory to be updated ex. Sandman-Lite
  githubUserName="alexanderepstein" #username that hosts the repostiory ex. alexanderepstein
  nameOfInstallFile="install.sh" # change this if the installer file has a different name be sure to include file extension if there is one
  latestVersion=$(curl -s https://api.github.com/repos/$githubUserName/$repositoryName/tags | grep -Eo '"name":.*?[^\\]",'| head -1 | grep -Eo "[0-9.]+" ) #always grabs the tag without the v option

  if [[ $currentVersion == "" || $repositoryName == "" || $githubUserName == "" || $nameOfInstallFile == "" ]];then
    echo "Error: update utility has not been configured correctly." >&2
    exit 1
  elif [[ $latestVersion == "" ]];then
    echo "Error: no active internet connection" >&2
    exit 1
  else
    if [[ "$latestVersion" != "$currentVersion" ]]; then
      echo "Version $latestVersion available"
      echo -n "Do you wish to update $repositoryName [Y/n]: "
      read -r answer
      if [[ "$answer" == "Y" || "$answer" == "y" ]] ;then
        cd  ~ || { echo 'Update Failed' ; exit 1 ; }
        if [[ -d  ~/$repositoryName ]]; then rm -r -f $repositoryName  ||  { echo "Permissions Error: try running the update as sudo"; exit 1; } ; fi
        git clone "https://github.com/$githubUserName/$repositoryName" || { echo "Couldn't download latest version" ; exit 1; }
        cd $repositoryName ||  { echo 'Update Failed' ; exit 1 ;}
        git checkout "v$latestVersion" 2> /dev/null || git checkout "$latestVersion" 2> /dev/null || echo "Couldn't git checkout to stable release, updating to latest commit."
        chmod a+x install.sh #this might be necessary in your case but wasnt in mine.
        ./$nameOfInstallFile "update" || exit 1
        cd ..
        rm -r -f $repositoryName ||  { echo "Permissions Error: update succesfull but cannot delete temp files located at ~/$repositoryName delete this directory with sudo"; exit 1; }
      else
        exit 1
      fi
    else
      echo "$repositoryName is already the latest version"
    fi
  fi

}


usage()
{
  echo "Crypt"
  echo "Description: A wrapper around openssl that facilitates encrypting and decrypting files."
  echo "Usage: crypt [flag] [inputFile] [outputFile]"
  echo "  -e Encrypt the inputFile and store it in the outputFile"
  echo "  -d Decrypt the inputFile and store it in the outputFile"
  echo "  -u Update Bash-Snippet Tools"
  echo "  -h Show the help"
  echo "  -v Get the tool version"
  echo "Examples:"
  echo "  crypt -e mySecretFile.txt myEncryptedFile.jpg (change filetype so default program is incorrect)"
  echo "  crypt -d myEncryptedFile.jpg thisIsNowDecrypted.txt (change filetype back so now default program is correct)"
}

checkOpenSSL || exit 1

while getopts "huve:d:" opt; do ## alows for using options in bash
  case $opt in
    e) ## when trying to encrypt run this
      if [[ $state != "decrypt" ]];then
        state="encrypt"
      else
        echo "Error: the -d and -e options are mutally exclusive" >&2
        exit 1
      fi
      if [[ $# -ne 3 ]]; then
        echo "Option -e needs and only accepts two arguments [file to encrypt] [output file]" >&2
        exit 1
      fi

    ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      exit 1
    ;;
    d) ## when trying to decrypt run this
      if [[ $state != "encrypt" ]];then
        state="decrypt"
      else
        echo "Error: the -e and -d options are mutally exclusive" >&2
        exit 1
      fi
      if [[ $# -ne 3 ]]; then
        echo "Option -d needs and only accepts two arguments [file to decrypt] [output file]" >&2
        exit 1
      fi
    ;;
    u)
      update
      exit 0
    ;;
    h)
      usage
      exit 0
    ;;
    v)
      echo "Version $currentVersion"
      exit 0
    ;;
    :) ## will run when no arguments are provided to to e or d options
      echo "Option -$OPTARG requires an argument." >&2
      exit 1
    ;;
  esac
done

if [[ $# == 0 ]]; then
  usage
  exit 0
elif [[ $1 == "update" ]];then
  update
  exit 0
elif [[ $1 == "help" ]];then
  usage
  exit 0
elif [[ $state == "encrypt" ]];then
  encrypt $2 $3 || exit 1
  exit 0
elif [[ $state == "decrypt" ]];then
  decrypt $2 $3 || exit 1
  exit 0
fi