#!/bin/bash

function helpexit() {
    echo "FolderSplitter:  copy files in this folder to subfolders in equal distribution"
    echo "usage: FolderSplitter [numberOfFolders] [rootFolder]"
    echo " If rootFolder omitted, current working directory used "
    exit
}
[[ -z "$1" ]] && helpexit
[[ "$1" = "-h" ]] && helpexit


if [ -z "$2" ]
then indir=$( pwd )
else
    if [ -d "$2" ]
    then indir="$2"
    else
        echo $2 does not exist.
        exit 1
    fi
fi
if [ -z "$1" ]
then echo need a number to how many folders to split.
     exit 1
fi
if [[ $1 == +([0-9]) ]] 
then n=$1
else
    echo $1 is not integer
    exit
fi

# make the list separator a rowchange
IFS=$'\n' 
# list files
pushd "$indir"
infiles=( $( ls ) )
fip=0
# create directories
for (( d=1; d<=$n; d++ ))
    do str="dir"$d
    mkdir "${str}" || echo error creating directory ${str}
done

perdir=$(( ${#infiles[@]} / $n ))

dip=1
fip=1
for (( f=0; f<${#infiles[@]}; f++ ))
    do cp -lav "${infiles[$f]}" dir"$dip"/ || echo error copying file ${infiles[$f]} 
    if (( $fip > $perdir ))
        then dip=$(($dip+1))
        fip=1
    else
        fip=$(($fip+1))
    fi
    if (( $dip > $n ))
        then dip=$n
    fi
done

for (( d=1; d<=$n; d++ ))
    do echo "dir"$d with $( ls dir"$d" | wc --lines ) files 
done