#!/bin/bash

FILE_REPO="/mnt/perfmount/file_repo"
TEST=0
DD_BS=512
RAND_SCALE=20

function usage()
{
        echo "usage: $1 <thread_count> <file_count>"
        exit 1
}

function create_files()
{
        tid=$1
        count=$2
        start=$((tid*count))

        if [ $TEST -eq "1" ]; then
                for ((i=0; i<${count}; i++)); do
                        outfile=$FILE_REPO/tid${tid}_file$((start+i))
                        echo "dd if=/dev/urandom of=$outfile bs=1b count=$((RANDOM*20))"
                done
        else
                for ((i=0; i<${count}; i++)); do
                        filesize=$((RANDOM*RAND_SCALE))
                        dd_count=$((filesize/DD_BS))
                        outfile=$FILE_REPO/tid${tid}_file$((start+i))
                        dd if=/dev/zero of=$outfile bs=1b count=$dd_count > /dev/null 2>&1
                        echo "$tid $i"
                done
        fi
}

function Not_A_Number()
{
        echo $1$2 | grep ^[0-9]*$ > /dev/null
        return $?
}

function main()
{
        if [ $# -ne 2 ]; then
                usage $0
        fi

        if ! Not_A_Number $1 $2; then
                echo "Invalid input. Enter only numbers."
                usage
        fi

        if [ $2 -lt $1 ]; then
                echo "Number of files cannot be less than number of threads"
                usage $0
        fi

        mkdir -p $FILE_REPO

        nthr=$1
        fc=$2
        files_per_thr=$((fc/nthr))
        
        for i in `seq 0 $((nthr-1))`; do
                create_files $i $files_per_thr &
        done    

        wait
}

main $@