#!/bin/bash

tryUpdateFromSd()
{
    local sd_name=$1
    # cut received line by / and take the third found result. (for /dev/sdb1 it's sdb1)
    local sd_folder_name=$(echo "${sd_name}" | cut -f 3 -d '/')
    exit_condition=false
    while [ "$exit_condition" == false ]
    do
        echo "Do you want to update from ${sd_name}? (Y/n)"
        read input_char
        if [ "$input_char" == "Y" ] || [ "$input_char" == "y" ]
        then
            echo " - Create /media/iso-$sd_folder_name"
            mkdir /media/iso-$sd_folder_name
            echo " - Mount ${sd_name} in /media/iso-$sd_folder_name"
            mount $sd_name /media/iso-$sd_folder_name
            echo " - Update the package manager."
            cp /etc/apt/sources.list /etc/apt/sources-backup.list
            mkdir /home/temp-apt
            mv /etc/apt/sources.list.d/* /home/temp-apt/
            echo "deb [trusted=yes] file:/media/iso-$sd_folder_name orel main contrib" > /etc/apt/sources.list
            echo " - Update packages."
            apt update
            apt upgrade
            echo " - Unmount ${sd_name}"
            umount /media/iso-$sd_folder_name
            rm -rf /media/iso-$sd_folder_name
            echo " - Restore the package manager."
            mv /etc/apt/sources-backup.list /etc/apt/sources.list
            mv /home/temp-apt/* /etc/apt/sources.list.d/
            rm -rf /home/temp-apt/
            exit_condition=true
            exit 0
        elif [ "$input_char" == "N" ] || [ "$input_char" == "n" ]
        then
            echo "Skip "${sd_name}""
            exit_condition=true
        else
            echo "Please, type Y to agree or N to decline."
            echo "Input Ctrl+C to exit."
        fi
    done
}

tryUpdateFromDrive()
{
    # Show devices with fdisk -l
    # Filter all lines which contain "sd*" (where * -- any latin letter from B to Z) except for "sd*:"
    # cut by space character and take the first found result
    # so it is: /dev/sdb1 , for example 
    sd_arr_raw=$(fdisk -l | egrep "sd[b-zB-Z][^:]" | cut -f 1 -d ' ')
    amount_of_sd=0
    for sd_raw in $sd_arr_raw
    do
        amount_of_sd=$(($amount_of_sd+1))
        echo "${sd_raw}; ID=${amount_of_sd}"
    done
    if (( $amount_of_sd < 1 ))
    then
        echo "Couldn't find external drives. Please, make sure they are connected and available."
        exit 1
    else
        for sd_raw in $sd_arr_raw
        do
            tryUpdateFromSd "${sd_raw}"
        done
        exot 0
    fi
}

tryUpdateFromFile()
{
    exit_condition=false
    while [ "$exit_condition" == false ]
    do
        echo "Do you want to update from ${filename}? (Y/n)"
        read input_char
        if [ "$input_char" == "y" ] || [ "$input_char" == "Y" ]
        then
            echo " - Create /media/iso-$filename"
            mkdir /media/iso-$filename
            echo " - Mount ${filename} in /media/iso-$filename"
            mount $filename /media/iso-$filename
            echo " - Update the package manager."
            cp /etc/apt/sources.list /etc/apt/sources-backup.list
            mkdir /home/temp-apt
            mv /etc/apt/sources.list.d/* /home/temp-apt/
            echo "deb [trusted=yes] file:/media/iso-$filename orel main contrib" > /etc/apt/sources.list
            echo " - Update packages."
            apt update
            apt upgrade
            echo " - Unmount ${filename}"
            umount /media/iso-$filename
            rm -rf /media/iso-$filename
            echo " - Restore the package manager."
            mv /etc/apt/sources-backup.list /etc/apt/sources.list
            mv /home/temp-apt/* /etc/apt/sources.list.d/
            rm -rf /home/temp-apt/
            exit_condition=true
            updated=true
            exit 0
        elif [ "$input_char" == "n" ] || [ "$input_char" == "N" ]
        then
            exit_condition=true
            exit 0
        else
            echo "Please, type Y to agree or N to decline."
            echo "Input Ctrl+C to exit."
        fi
    done
}

printHelp()
{
    echo "iso-updater - tool for updating OS packages by apt."
    echo " "
    echo "USAGE: iso-updater [-OPTIONS...] [ARGS]"
    echo " "
    echo "OPTIONS:"
    echo "-h, --help            Show brief instructions."
    echo " "
    echo "-d, --drive           Update the system from drive."
    echo "                      Make sure there is one and only one external drive "
    echo "                      connected. The program will read its partisions and "
    echo "                      try to upgrade the system from each of them."
    echo "                      Thoroughly follow all the instructions after launch."
    echo " "
    echo "-f, --file [PATH]     Update the system from an .iso file."
    echo "                      Make sure there is an .iso file needed to update "
    echo "                      the system from and that the file is being placed "
    echo "                      exactly at PATH. Thoroughly follow all "
    echo "                      the instructions after launch."
    echo " "
    echo "Example: sudo iso-updater --file /home/user/iso/very-very-cool-iso-file.iso"
    echo " "
    echo " "
    exit 0
}

while test $# -gt 0; do
    case "$1" in
    -h|--help)
        printHelp
        ;;
    -d|--drive)
        if [[ $UID != 0 ]]; then
            echo "Please, run with sudo:"
            echo "sudo $0 $*"
            exit 1
        fi
        tryUpdateFromDrive
        exit 0
        ;;
    -f|--file)
        if [[ $UID != 0 ]]; then
            echo "Please, run with sudo:"
            echo "sudo $0 $*"
            exit 1
        fi
        shift
        filename=$1
        if [ ! -f "$filename" ]
        then
            echo "Couldn't find $filename. Please, use correct filename and make sure it does exist."
            exit 1
        fi
        tryUpdateFromFile
        exit 0
        ;;
    esac
    echo "Couldn't recognize $1."
    echo " "
    shift
done

printHelp
exit 0