#!/bin/bash

# A bash scripts that processes a directory in three deferent ways
# Author : Obada Alabbadi

# displays Information about using this script
usage()
{
    cat <<EOF
    usage: dirproc DIRECTORY ana REGEX
    or:    dirproc DIRECTORY del MAXSIZE
    or:    dirproc DIRECTORY arr FILETYPE

    This script processes a directory in three deferent ways, DIRECTORY can be a relative or absolute path

    dirproc DIRECTORY ana REGEX
    recursivly searches for and displays all files in DIRECTORY that match the regular expresion REGEX, also prints the number of matches

    dirproc DIRECTORY del MAXSIZE
    recursivly searches for all files in DIRECTORY that are larger than MAXSIZE bytes, where MAXSIZE is an unsigned integer, the user must confirm before deleting by typing
    y : delete this file
    yall : delete this file and all next matches
        n : do not delete this file
    nall : do not delete this file and all next matches

    dirproc DIRECTORY arr FILETYPE
    creates a directory in the pwd named "all FILETYPE files" (if it doesn't already exist), then recursivly searches for all files in DIRECTORY that have an extension of FILETYPE and copies them to the created directory
EOF
    exit 1
}

# process a specific file depending on the arguments, the first argument is the file path
process()
{
    # file info
    filename=$(basename -- "$1")
    extension="${filename##*.}"
    filename="${filename%.*}"

    filesize=$(stat -c%s "$1")

    if [ -n "$ana" ] && [[ "$filename" =~ $regex ]] # found a matching regex
    then
        echo "Found match : $filename"
        count=`expr $count + 1`
    elif [ -n "$del" ] && [[ $filesize -gt $mxsize ]] && ! [ -n "$nall" ] # found a file with big size
    then
        #if the user already choose "yall" remove the file immediately
        if [ -n "$yall" ]
        then
            rm "$1"
            return
        fi

        echo "file : $item"
        echo "size : $filesize"

        #prompt the user for confirmation
        echo "are you sure you want to delete this file? [y/n/yall/nall]"
        read reply

        if [ "$reply" = "yall" ]
        then
            yall=1
            rm "$1"
        elif [ "$reply" = "nall" ]
        then
            nall=1
        elif [ "$reply" = "y" ]
        then
            rm "$1"
            echo "succesfully removed"
        else
            echo "file not removed"
        fi
        echo
    elif [ -n "$arr" ] && [[ "$extension" = "$type" ]] # found a file with the extension
    then
        cp "$1" "$PWD/all $type files"
    fi
}

# recursivly process a directory (the first parameter)
search()
{
    # iterate over all directories and files
    for item in "$1"/*
    do
                if [ -d "$item" ] # another directory, search inside it
        then
            search "$item"
        elif [ -f "$item" ]
        then
            process "$item" # a file, process it
        fi
        done
}

# needed variables

ana=
count=0
regex=

del=
mxsize=
numregex='^[0-9]+$'
yall=
nall=

arr=
type=

# get the abolute path
absolute=
case $1 in
  /*) absolute=$1;;
  *) absolute=$PWD/$1;;
esac

if ! [ -d $absolute ] # invalid directory, display usage and exit
then
    usage
elif [ "$2" = "ana" ] && [ -n "$3" ] # first option
then
    ana=1
    regex=$3
elif [ "$2" = "del" ] && [[ "$3" =~ $numregex ]] # second option
then
    del=1
    mxsize=$3
elif [ "$2" = "arr" ] && [ -n "$3" ] # third option
then
    arr=1
    type=$3
    if ! [ -d "$PWD/all $type files" ]
    then
        mkdir "all $type files"
    fi
else # invalid arguments, display usage
    usage
fi

# search recursivly
search "$absolute"

# display number of matches for REGEX
if [ -n "$ana" ]
then
    echo "$count matching files"
fi