# -*-eselect-*-  vim: ft=eselect
# Copyright 2004-2011 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2 or later
# $Id: $

DESCRIPTION="Switch bzImage default kernel by updating /boot/bzImage symlink"
MAINTAINER="stefan.cristian@rogentos.ro"
VERSION="0.1"

# Module variables
BOOT_DIR="${EROOT}/boot"
KERNEL_PREFIX="kernel-"
INITRAMFS_PREFIX="initramfs-"
BZIMAGE_SYM="${BOOT_DIR}/bzImage"
INITRD_SYM="${BOOT_DIR}/Initrd"

_is_kernel() {
    local f="${1}"
    outcome=$(LC_ALL=C /usr/bin/file --brief "${f}" 2> /dev/null | \
        grep -i -E "(boot executable bzImage|x86 boot sector)")
    [[ -n "${outcome}" ]] && return 0
    return 1
}

_get_initramfs() {
    local kernel_bn="${1}"
    echo "${kernel_bn/${KERNEL_PREFIX}/${INITRAMFS_PREFIX}}"
}

find_targets() {
    local f
    for f in "${BOOT_DIR}/"*; do
        # skip dirs
        [[ -d "${f}" ]] && continue
        # skip broken syms etc
        [[ ! -e "${f}" ]] && continue
        # skip non reg files
        [[ ! -f "${f}" ]] && continue
        _is_kernel "${f}" || continue
        basename "${f}"
    done
}

remove_symlink() {
    rm "${BZIMAGE_SYM}"
}

set_symlink() {
    local target="${1}"

    if is_number "${target}"; then
        local targets=( $(find_targets) )
        target=${targets[target-1]}
    fi

    [[ -z "${target}" || ! -f "${BOOT_DIR}/${target}" ]] \
        && die -q "Target \"${target}\" doesn't appear to be valid!"

    echo "Setting bzImage to ${target}"
    ln -sf "${target}" "${BZIMAGE_SYM}.tmp" || die "Cannot create symlink"
    mv "${BZIMAGE_SYM}.tmp" "${BZIMAGE_SYM}" || die "Cannot move symlink"

    local initramfs_target=$(_get_initramfs "${target}")
    if [ -f "${BOOT_DIR}/${initramfs_target}" ]; then
        echo "Setting Initrd to ${initramfs_target}"
        ln -sf "${initramfs_target}" "${INITRD_SYM}.tmp" || \
            die "Cannot create initrd symlink"
        mv "${INITRD_SYM}.tmp" "${INITRD_SYM}" || \
            "Cannot move initrd symlink"
    elif [ -L "${INITRD_SYM}" ]; then
        echo "No Initrd found, removing ${INITRD_SYM}"
        rm "${INITRD_SYM}"
    fi
}

### show action ###

describe_show() {
    echo "Show the current ${BZIMAGE_SYM} kernel and ${INITRD_SYM} initrd"
}

describe_show_options() {
    echo "--quiet  : only print the actual symlink value"
    echo "--silent : same as --quiet"
}

do_show() {
    local quiet=""

    while [[ $# -gt 0 ]]; do
        case ${1##--} in
            quiet|silent)
                quiet="1"
                ;;
        esac
        shift
    done

    [[ -z "${quiet}" ]] && write_list_start "Current kernel:"
    if [[ -L "${BZIMAGE_SYM}" ]] && [[ -e "${BZIMAGE_SYM}" ]]; then
        local kernel=$(canonicalise "${BZIMAGE_SYM}")
        local kernel_bn=$(basename "${kernel%/}")
        if [[ -n "${quiet}" ]]; then
            echo "${kernel_bn}"
        else
            write_kv_list_entry "${kernel_bn}" ""
        fi
    else
        if [[ -z "${quiet}" ]]; then
            write_kv_list_entry "(unset)" ""
        fi
    fi
}

### list action ###

describe_list() {
    echo "List available kernel bzImages"
}

describe_list_options() {
    echo "--quiet  : only print the actual symlink value"
    echo "--silent : same as --quiet"
}

do_list() {
    local quiet=""

    while [[ $# -gt 0 ]]; do
        case ${1##--} in
            quiet|silent)
                quiet="1"
                ;;
        esac
        shift
    done

    local i targets=( $(find_targets) )

    [[ -z "${quiet}" ]] && write_list_start "Available kernel targets:"
    for (( i = 0; i < ${#targets[@]}; i++ )); do
        if [[ -z "${quiet}" ]]; then
            # highlight the target where the symlink is pointing to
            [[ ${targets[i]} = \
                $(basename "$(canonicalise "${BZIMAGE_SYM}")") ]] \
                    && targets[i]=$(highlight_marker "${targets[i]}")
        else
            echo "${targets[i]}"
        fi
    done
    [[ -z "${quiet}" ]] && \
        write_numbered_list -m "(none found)" "${targets[@]}"
}

### set action ###
describe_set() {
    echo "Set a new kernel bzImage"
}

describe_set_parameters() {
    echo "<target>"
}

describe_set_options() {
    echo "target : Target name or number (from 'list' action)"
}

do_set() {
    [[ -z "${1}" ]] && die -q "You didn't tell me what to set the symlink to"
    [[ ${#} -gt 1 ]] && die -q "Too many parameters"

    if [[ -L "${BZIMAGE_SYM}" ]]; then
        # existing symlink
        remove_symlink || die -q "Couldn't remove existing symlink"
        set_symlink "$1" || die -q "Couldn't set a new symlink"
    elif [[ -e "${BZIMAGE_SYM}" ]]; then
        # we have something strange
        die -q "${BZIMAGE_SYM} exists but is not a symlink"
    else
        set_symlink "${1}" || die -q "Couldn't set a new symlink"
    fi
}