#!/bin/bash

echo
echo "A2SERVER fix: This utility will make a Raspberry Pi SD card boot if it"
echo "kernel panics (crashes) on startup after updating its operating system"
echo "while A2SERVER is installed."
echo
echo -n "Continue? "
read
doFix=
if [[ ${REPLY:0:1} == "y" || ${REPLY:0:1} == "Y" ]]; then
    while true; do
        echo
        echo "If attached, remove the Raspberry Pi's SD card from this computer."
        echo -n "Press return to continue..."; read; echo

        ls -1 /dev/sd? > /tmp/sd1 2> /dev/null

        echo "Insert the Raspberry Pi's SD card into this computer, using a USB"
        echo "reader if you don't have an SD slot. If this is a virtual machine,"
        echo "make sure you select the reader or SD slot from its USB menu."
        echo -n "Press return to continue..."; read; echo

        ls -1 /dev/sd? > /tmp/sd2 2> /dev/null
        
        # if exactly one drive has been inserted, exit loop
        if { ! diff /tmp/sd1 /tmp/sd2 &> /dev/null; }; then
            # files are different, get dev name
            if [[ $(wc -c /tmp/sd1 | cut -f 1 -d ' ') -eq 0 ]]; then
                if [[ $(wc -l /tmp/sd2 | cut -f 1 -d ' ') -eq 1 ]]; then
                    devName=$(cat /tmp/sd2)
                    break
                else
                    echo "More than one volume seems to have appeared. Trying again..."
                    echo
                fi
            else
                devName=$(grep -v "$(cat /tmp/sd1)" /tmp/sd2)
                if [[ $(wc -l <<< $devName) -eq 1 ]]; then
                    break
                else
                    echo "More than one volume seems to have appeared. Trying again..."
                    echo
                fi
            fi
        else
            echo "No SD card found. Trying again..."
            echo
        fi
        
    done
    
    mkdir -p /tmp/sd
    sudo mount ${devName}6 /tmp/sd

    raspbianDate=$(date -d "$(zcat /tmp/sd/usr/share/doc/raspberrypi-bootloader/changelog.Debian.gz | grep -m 1 ' --' | rev | cut -f 1-6 -d ' ' | rev)" +%s)
    doFix=
    if [[ $raspbianDate -lt 1403204265 ]]; then
        echo "This doesn't appear to be a version of Raspbian that requires fixing."
        echo -n "Are you sure you want to continue? "
        read
        if [[ ${REPLY:0:1} == "y" || ${REPLY:0:1} == "Y" ]]; then
            doFix=1
        fi
    else
        doFix=1
    fi

    if [[ $doFix ]]; then
        while read kernelRelease; do
            kernelReplaced=
            kernelMajorRelease=$(cut -d '.' -f 1  <<< $kernelRelease)
            kernelMinorRelease=$(cut -d '.' -f 2  <<< $kernelRelease | sed 's/\(^[0-9]*\)[^0-9].*$/\1/')
            kernelPatchRelease=$(cut -d '.' -f 3- <<< $kernelRelease | sed 's/\(^[0-9]*\)[^0-9].*$/\1/')
            # if kernel 3.12 below 3.12.25+, delete defective AppleTalk kernel
            if [[ $kernelMajorRelease -eq 3 && $kernelMinorRelease -eq 12 && $kernelPatchRelease -lt 25 ]]; then
                if [[ -f /tmp/sd/lib/modules/$kernelRelease/kernel/net/appletalk/appletalk.ko ]]; then
                    if [[ $(sha1sum /tmp/sd/lib/modules/$kernelRelease/kernel/net/appletalk/appletalk.ko | cut -f 1 -d ' ') != "ecb239fc084c36de93f6926e7749b80f6024f269" ]]; then
                        echo "Removing defective AppleTalk module from kernel $kernelRelease..."
                        sudo rm -rf /tmp/sd/lib/modules/$kernelRelease/kernel/net/appletalk 2> /dev/null
                        wget -qO /tmp/appletalk.ko.gz ${A2SERVER_SCRIPT_URL}files/appletalk-$kernelRelease.ko.gz
                        if [[ $? -eq 0 ]]; then
                            # if we found a prebuilt one on a2server site, so install it
                            gunzip -f /tmp/appletalk.ko.gz
                            sudo mkdir -p /tmp/sd/lib/modules/$kernelRelease/kernel/net/appletalk
                            sudo mv /tmp/appletalk.ko /tmp/sd/lib/modules/$kernelRelease/kernel/net/appletalk
                            echo "Installed fixed AppleTalk module for kernel $kernelRelease."
                            kernelReplaced=1
                        fi
                    fi
                fi
            fi
        done <<< "$(ls -1 /tmp/sd/lib/modules | sort -V)"
        sudo umount /tmp/sd
        
        echo kern:$kernelReplaced
        if [[ $kernelReplaced ]]; then
            echo
            echo "All set. Remove your SD card, put it back in your Pi, and boot it."
            echo
            echo "You should be able to connect from your Apple II, but if you can't,"
            echo "log in to your Pi and type 'a2server-setup' to complete the fix."
        else
            echo
            echo "Okey doke. Half done. Remove your SD card, and put it back in your Pi."
            echo "After it boots, log in and type 'a2server-setup' to complete the fix."
        fi        
        echo "See the A2SERVER web site at http://ivanx.com/a2server for more help."
        echo "(You can type 'sudo shutdown -h now' if you're done on this machine.)"
        echo
    fi
fi

rm fix &> /dev/null