#! @bash@/bin/sh -e

shopt -s nullglob

export PATH=/empty
for i in @path@; do PATH=$PATH:$i/bin; done

default=$1
if test -z "$1"; then
    echo "Syntax: grub-menu-builder.sh <DEFAULT-CONFIG>"
    exit 1
fi

bootMount="@bootMount@"
if test -z "$bootMount"; then bootMount=/boot; fi


target=/boot/grub/menu.lst
tmp=$target.tmp

cat > $tmp << GRUBEND
# Automatically generated.  DO NOT EDIT THIS FILE!
default 0
timeout 5
GRUBEND


if test -n "@grubSplashImage@"; then
    splashLocation=@grubSplashImage@
    # !!! image in /nix/store doesn't seem to work
    #if test -n "@copyKernels@"; then
	cp -f $splashLocation /boot/background.xpm.gz
	splashLocation="$bootMount/background.xpm.gz"
    #fi
    echo "splashimage $splashLocation" >> $tmp
fi

configurationCounter=0
configurationLimit="@configurationLimit@"
numAlienEntries=$(cat <<EOF | egrep '^[[:space:]]*title' | wc -l
@extraGrubEntries@
EOF)

if test $((configurationLimit+numAlienEntries)) -gt 190; then
	configurationLimit=$((190-numAlienEntries));
fi

addEntry() {
    local name="$1"
    local path="$2"
    local shortSuffix="$3"

    configurationCounter=$((configurationCounter + 1))
    if test $configurationCounter -gt @configurationLimit@ ; then
	    return
    fi;

    if ! test -e $path/kernel -a -e $path/initrd; then
        return
    fi

    local kernel=$(readlink -f $path/kernel)
    local initrd=$(readlink -f $path/initrd)

    if test "$path" = "$default"; then
	    cp "$kernel" /boot/nixos-kernel
	    cp "$initrd" /boot/nixos-initrd
	    cp "$(readlink -f "$path/init")" /boot/nixos-init
	    cat > /boot/nixos-grub-config <<EOF
	title Emergency boot
	kernel ${bootMount:-/boot}/nixos-kernel systemConfig=$(readlink -f "$path") init=/boot/nixos-init $(cat "$path/kernel-params")
	initrd ${bootMount:-/boot}/nixos-initrd
EOF
    fi

    if test -n "@copyKernels@"; then
        local kernel2=/boot/kernels/$(echo $kernel | sed 's^/^-^g')
        if ! test -e $kernel2; then
            cp $kernel $kernel2
        fi
        kernel=$kernel2

        local initrd2=/boot/kernels/$(echo $initrd | sed 's^/^-^g')
        if ! test -e $initrd2; then
            cp $initrd $initrd2
        fi
        initrd=$initrd2

        if test -n "$bootMount"; then
          kernel=$(echo $kernel2 | sed -e "s^/boot^$bootMount^")
          initrd=$(echo $initrd2 | sed -e "s^/boot^$bootMount^")
        fi
    fi
    
    local confName=$(if test -e $path/configuration-name; then 
	cat $path/configuration-name; 
    fi);
    if test -n "$confName" ; then
	name="$confName $3";
    fi;

    cat >> $tmp << GRUBEND

title $name
  kernel $kernel systemConfig=$(readlink -f $path) init=$(readlink -f $path/init) $(cat $path/kernel-params)
  initrd $initrd
GRUBEND
}


rm -rf /boot/kernels
if test -n "@copyKernels@"; then
    mkdir -p /boot/kernels
fi

# Additional entries specified verbatim by the configuration.
extraGrubEntries=$(cat <<EOF
@extraGrubEntries@
EOF
)

if test -n "@extraGrubEntriesBeforeNixos@"; then 
    echo "$extraGrubEntries" >> $tmp
fi

addEntry "NixOS - Default" $default ""

if test -z "@extraGrubEntriesBeforeNixos@"; then 
    echo "$extraGrubEntries" >> $tmp
fi

# Add all generations of the system profile to the menu, in reverse
# (most recent to least recent) order.
for link in $((ls -d $default/fine-tune/* ) | sort -n); do
    date=$(stat --printf="%y\n" $link | sed 's/\..*//')
    addEntry "NixOS - variation" $link ""
done
for generation in $(
    (cd /nix/var/nix/profiles && ls -d system-*-link) \
    | sed 's/system-\([0-9]\+\)-link/\1/' \
    | sort -n -r); do
    echo $generation
    link=/nix/var/nix/profiles/system-$generation-link
    date=$(stat --printf="%y\n" $link | sed 's/\..*//')
    addEntry "NixOS - Configuration $generation ($date)" $link "$generation ($date)"
done


cp $tmp $target