#! /bin/bash
#Simple Login script made in $Bash!
#It has improved a lot than before, but still insecure :P
#Written by Sars!
#Version: 0.8

#Path where the valuables are stored.
pt=../usr/share/.login
#Path for temporarily storing unencrypted valuables.
opt=../usr/tmp/.tmplog

#Function for encrypting & decrypting cred.
encrypt() {
openssl enc -aes-256-cbc -pbkdf2 -salt -in $opt -out $pt -k $pf 2>/dev/null #Redirects error if any to /dev/null. Thanks to https://stackoverflow.com/a/25348167
chmod u-rw $pt
}

decrypt() {
chmod u+rw $pt
openssl enc -d -aes-256-cbc -pbkdf2 -salt -in $pt -out $opt -k $pss 2>/dev/null #Redirects bad-decrypts error if any to /dev/null. Thanks to https://stackoverflow.com/a/25348167
}

#Function that sets credentials.
st_crd() {
    read -p "Set Your Username: " un
    read -s -p "Set Your Password: " pf

    #rm the unencrypted cred file if it exists
    if [ -f $opt ];
    then
        rm $opt
    fi

    if [[ $un != "" && $pf != "" ]];
    then
        touch $pt
        echo -e "$un\n$pf" >> $opt
        echo -e "\nCredentials added!!"
        encrypt
        echo -e "\nExiting Termux, please restart it!"
        sleep 3
        kill -9 $PPID
    else
        echo -e '\nCredentials cannot be empty!'
        exit
    fi

}

#Function for re-setting credentials.
rst_crd() {
    read -p "Enter Old Password: " pss
    decrypt

    #Read the old pass.
    op=$( tail -n 1 $opt 2>/dev/null )

    if [[ $pss == "$op" && $pss != "" ]];
    then
        echo -e "\nClearing your Old Credentials..."
        rm -rf $pt
        echo -e "\nCleared! Please add your new credentials"
        st_crd

    else
        echo -e "\nOh, you remember your Credentials? :o"
        echo -e "\nClosing app, re-launch it please"
        chmod u-rw $pt
        sleep 3
        kill -9 $PPID
    fi
}

#Trap the intruder & check if user wants to reset Credentials ;)
int_trp() {
    echo -e "\nForgot your Credentials?"
    read ans

    if [[ $ans == "yes" || $ans == "y" || $ans == "Y" || $ans == "Yes" ]];
    then
        rst_crd

    else
        echo "Intruder Alert!!"
        chmod u-rw $pt
        sleep 3
        kill -9 $PPID
    fi
}

#Function for checking if the user is authorized.
chk_crd() {
    trap 'int_trp' INT
    chmod u+rw $pt

    echo "Enter Username"
    read n
    echo "Enter Passwd"
    read -s pss
    decrypt

    unm=$( head -n 1 $opt 2>/dev/null )
    p=$( tail -n 1 $opt 2>/dev/null )

    if [[ $n == "" || $pss == "" ]];
    then
        echo "Please Enter your Credentials... Exiting"
        sleep 3
        kill -9 $PPID

    elif [[ $n == "$unm" && $pss == "$p" ]];
    then
        echo "Welcome!"

    else
        echo "Un-Authorized User ..exiting"
        sleep 3
        kill -9 $PPID
    fi
    chmod u-rw $pt
    rm $opt
}

#Checks if the user is running the script for first time, it's not the proper way of doing this i guess but for now it works :P
if [ -f "$pt" ];
then
    chk_crd

else
    st_crd
fi

trap SIGINT