#!/bin/zsh

SCRIPTNAME="~/chm.sh"
ALIASNAME="chm"

_help() {

echo -n "chm: performs chmod recursively on specified folder with specified values for folder and files. Executable permissions will be set for all folders\n\n"
echo "Usage: $SCRIPTNAME <octalvalue> <folder>
  or:       $ALIASNAME <octalvalue> <folder>
octalvalue : this is the FILE permissions to be set in the specified folder and its subfolders. Use the same octal value you would use as a chmod argument
folder     : this is the folder on which to execute the command

Example:
  $SCRIPTNAME 664 ./testfolder          ; this will set testfolder and its subfolders to 775 and files in those subfolders to 664
  $SCRIPTNAME 764 ./testfolder          ; this will set testfolder and its subfolders to 775 and files in those subfolders to 764
"
}

_process() {
        folder=$2
        declare -i val=$1
        declare -i rwmask=8#111
        declare -i dirval=$val\|$rwmask
        filevalstr=$(printf "%03o" $val)
        dirvalstr=$(printf "%03o" $dirval)
        echo chmod -R $dirvalstr "'"$folder"'"
        find "$folder" -type d -exec chmod $dirvalstr {} \;
        echo chmod -R $filevalstr "'"$folder"'"
        find "$folder" -type f -exec chmod $filevalstr {} \;
}

main() {
        [[ -z "$1" ]] && _help && return
        if [[ $# -lt 2 ]]; then
                _help
                return
        fi
        declare -i modval=0
        { # try
                let modval=8#$1 &&
                _process $modval "$2"
        } || { # catch
                echo 'ERROR: Check if the first argument is a proper octal value!'
                echo 'If not, fix the value and try again.'
        }
}

main "$@"