#!/usr/bin/env bash

extract () {
  if [ -f $1 ] ; then
    case $1 in
      *.tar.bz2)   tar xvjf $1    ;;
      *.tar.gz)    tar xvzf $1    ;;
      *.bz2)       bunzip2 $1     ;;
      *.rar)       unrar x $1     ;;
      *.gz)        gunzip $1      ;;
      *.tar)       tar xvf $1     ;;
      *.tbz2)      tar xvjf $1    ;;
      *.tgz)       tar xvzf $1    ;;
      *.zip)       unzip $1       ;;
      *.Z)         uncompress $1  ;;
      *.7z)        7z x $1        ;;
      *.xz)        unxz $1        ;;
      *)           echo "don't know how to extract '$1'..." ;;
    esac
  else
    echo "'$1' is not a valid file!"
  fi
}

merkle-tree () {
  dirname="${1-.}"
  find "$dirname" -type f | \ # get all files in the $dirname tree
    sort                  | \ # sort them to get the same result on different filesystems
    xargs sha256sum       | \ # compute the SHA256 of each file, BONUS it outputs the filename, so if the content does not change but the filename does, the end hash will be different
    sha256sum             | \ # compute the final hash
    awk '{print $1}'          # omit the filename, which is `-` as stdin in this case
}