#!/bin/bash

ME=${0##*/}

PATH=$PATH:bin:/live/bin

CUSTOM_COMMENT="#--custom"
DEFAULT_RESOLUTION="1024x768"
DEFAULT_KERNEL="/antiX/vmlinuz"
DEFAULT_GRUB_CFG="/boot/grub/grub.cfg"
MENUS="menus"

usage() {
    local ret=${1:-0}

    cat <<Usage
Usage:  $ME [options] <file>

Assume <file> is a grub.cfg file.  Update the entries with titles that contain
"custom" or "menu" with all the /proc/cmdline boot parameters plus all the
trailing options on our command line.

First, make a backup of the file.  Then process the file by uncommenting
any lines that start with "#--custom" and removing all lines that set the
default entry.  Then create a new default entry that (eventually) points to
the custom entry that was created.

All entries that have "Custom" or "custom" in their title have their boot
parameters updated.  In addition all entries that have the "menus" boot
parameter also have their boot parameters updated.

Exceptions: only add the "menus" option to entries that already have it.
"menu".  Ignore any BOOT_IMAGE boot parameters and the "bootsave" and
"gfxsave" parameters.  If there isa BOOT_IMAGE boot parameter then it
is used in as the kernel in the custom entry we created/modify.

Options:
     --cheats="cheats"   Use "cheats" instead of /proc/cmdline
  -h --help              Show this usage
  -n --no-kernel         Use the default kernel
  -q --quiet             Print less
Usage

    exit $ret
}

main() {
    local param file fnct=0 cheats

    [ $# -eq 0 ] && usage

    for param; do
        case $param in
           --cheats=*) cheats=${param#--cheats=}        ;;
            -h|--help) usage                            ;;
       -n|--no-kernel) kernel=$DEFAULT_KERNEL           ;;
           -q|--quiet) QUIET=true                       ;;
                   -*) fatal "Unknown argument: $param" ;;
                    *) fcnt=$((fcnt + 1)); file=$param  ;;
        esac
    done

    case $fcnt in
        0) fatal "Expected one filename"            ;;
        1)                                          ;;
        *) fatal "Expected one filename. Got $fcnt" ;;
    esac

    test -d "$file" && file=${file%/}$DEFAULT_GRUB_CFG
    test -e "$file" || fatal "File $file does not exist"

    : ${cheats:=$(gather_params)}
    update_grub2 "$file" "$cheats"
   
}

update_grub2() {
    local file=$1
    shift
    local params="$*"

    test -e $file || fatal "File $file does not exist"
    test -w $file || fatal "Cannot write to file $file"

    local bak_file=$(backup_name $file .bak)
    cp $file $bak_file

    # We can do this the easy way ...
    local kernel=$(get_cmdline_vmlinuz)

    # ... or the hard way
    : ${kernel:=$(get_current_vmlinuz)}
    : ${kernel:=$DEFAULT_KERNEL}

    local resolution=$(get_fb_resolution)
    # : ${resolution:=$DEFAULT_RESOLUTION}

    local out line default_entry=0 entry_cnt=0 custom_cnt=0
    local is_custom is_blank
    while read line; do

        # Want to assume all lines we process are not zero-length
        if [ -z "$line" ]; then

            # Compress multiple blank lines into a single one
            [ "$is_blank" ] && continue
            is_blank=true
            out="$out\n"
            continue

        else
            is_blank=
        fi

        # Remove all lines that set the default
        [ -z "${line##set default=*}" ] && continue

        if [ -z "${line##menuentry *}" ]; then

            # Add default line before first menuentry
            [ $entry_cnt -eq 0 ] && out="${out}set default=%DEFAULT%\n\n"

            # Determine custom entries from the title
            is_custom=
            [ -z "${line##*[Cc]ustom*}" ] && is_custom=true

            # Re-write title of first custom entry and record its position
            if [ "$is_custom" ]; then
                custom_cnt=$((custom_cnt + 1))
                if [ $custom_cnt -eq 1 ]; then
                    line="menuentry \"Custom ($(date '+%e %B %Y'))\" {"
                    default_entry=$entry_cnt
                fi
            fi

            entry_cnt=$((entry_cnt + 1))

        # Fill in the first and only the first "custom" entry
        elif [ -n "$is_custom" -a $custom_cnt -eq 1 ]; then

            if [ -z "${line##linux *}" ]; then
                line=$(echo "$line" | sed -r "s|^(linux\s).*|\1$kernel $params|")

            elif [ -n "$resolution" -a -z "${line##gfxpayload=*}" ]; then
                line="gfxpayload=$resolution"
            fi

        # Add our parameters to every entry that already has the "menus" parameter
        elif [ -z "${line##linux *}" ]; then

            if echo "$line" | grep -q "\<menus\>"; then
                line=$(echo "$line" | sed -r "s|^(linux\s*[^ ]+).*|\1 $params $MENUS|")
            fi

        fi

        out="$out$line\n"

    # the sed uncomments our custom entry (if needed) and remove any existing default lines
    done<<Read_File
$(sed -e "s/^\s*$CUSTOM_COMMENT\s*//" -e "s/\s+$//" -e "/\s*(set\s+)?default\>.*/d" $file)
Read_File

    # Fill in the number for the first Custom entry as the default entry
    # local tmp_file=$(backup_name $file .tmp)
    echo -e "$out" | sed -r "s/(default=)%DEFAULT%/\1$default_entry/" > $file

    printf "    Updated file %s\n" $file
    printf "    With: %s\n" "$params"
    sleep 1
}

gather_params() {
    local p out
    for p in $(cat /live/config/proc-cmdline /live/config/cmdline 2>/dev/null) $*; do
        case $p in
                  menus|menus=*) MENUS=$p ;;
              gfxsave|gfxsave=*)  ;;
            bootsave|bootsave=*)  ;;
                   BOOT_IMAGE=*)  ;;
          savestate|nosavestate)  ;;
                nostore|dostore)  ;;
               checkmd5|checkfs)  ;;
              automount|mount=*)  ;;
                      hwclock=*)  ;;
                      desktop=*)  ;;
                              *) out=$out${out:+ }$p
        esac
    done
    echo $out
}

get_current_vmlinuz() {
    local initrd_file=/live/config/initrd.out
    test -r $initrd_file                  || return 1

    eval $(egrep -r "^(BOOT_MP|SQFILE_DIR)=" $initrd_file)
    [ -z "$BOOT_MP" -o -z "$SQFILE_DIR" ] && return 2
    test -d $SQFILE_DIR                   || return 3

    local vmlinuz=$(vmlinuz-version --current $SQFILE_DIR/*)
    [ -z "$vmlinuz" -o -n "${vmlinuz##$BOOT_MP*}" ] && return 4
    echo ${vmlinuz#$BOOT_MP}
}

get_cmdline_vmlinuz() {
    sed -rn "s/.*\<BOOT_IMAGE=([^ ]+).*/\1/p" /proc/cmdline
}

get_fb_resolution() {
    local dir=/sys/class/graphics/fb0
    local name rez
    read name 2>/dev/null <$dir/name
    read rez  2>/dev/null <$dir/virtual_size
    #[ "$name" = "simple" ] || return 1
    [ ${#rez} -gt 5 ]      || return 1
    echo ${rez/,/x}
    return 0
}

backup_name() {
    local file=$1 ext=${2:-.bak}

    [ -n "$file" ] || fatal "Can't make a backup name of an empty string"

    local dir=$(dirname $file)  base=$(basename $file)
    local new=${base%.*}
    echo $dir/$new$ext
}

fatal() {
    [ -z "$QUIET" ] && echo "$ME fatal error: $*"
    exit 2
}

main "$@"