#!/usr/bin/env bash
# -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*-
# ex: ts=8 sw=4 sts=4 et filetype=sh

COMMAND="$1"
KERNEL_VERSION="$2"
ENTRY_DIR_ABS="$3"
KERNEL_IMAGE="$4"
INITRD_OPTIONS_START="5"

if ! [[ $KERNEL_INSTALL_MACHINE_ID ]]; then
    exit 0
fi

if ! [[ -d "$ENTRY_DIR_ABS" ]]; then
    exit 0
fi

MACHINE_ID=$KERNEL_INSTALL_MACHINE_ID

BOOT_ROOT=${ENTRY_DIR_ABS%/$MACHINE_ID/$KERNEL_VERSION}
BOOT_MNT=$(stat -c %m $BOOT_ROOT)
ENTRY_DIR=${ENTRY_DIR_ABS#$BOOT_MNT}

if [[ $COMMAND == remove ]]; then
    rm -f "$BOOT_ROOT/loader/entries/$MACHINE_ID-$KERNEL_VERSION.conf"
    rm -f "$BOOT_ROOT/loader/entries/$MACHINE_ID-$KERNEL_VERSION+"*".conf"
    exit 0
fi

if ! [[ $COMMAND == add ]]; then
    exit 1
fi

if ! [[ $KERNEL_IMAGE ]]; then
    exit 1
fi

if [[ -f /etc/os-release ]]; then
    . /etc/os-release
elif [[ -f /usr/lib/os-release ]]; then
    . /usr/lib/os-release
fi

if ! [[ $PRETTY_NAME ]]; then
    PRETTY_NAME="Linux $KERNEL_VERSION"
fi

if [[ -f /etc/kernel/cmdline ]]; then
    read -r -d '' -a BOOT_OPTIONS < /etc/kernel/cmdline
elif [[ -f /usr/lib/kernel/cmdline ]]; then
    read -r -d '' -a BOOT_OPTIONS < /usr/lib/kernel/cmdline
else
    declare -a BOOT_OPTIONS

    read -r -d '' -a line < /proc/cmdline
    for i in "${line[@]}"; do
        [[ "${i#initrd=*}" != "$i" ]] && continue
        [[ "${i#BOOT_IMAGE=*}" != "$i" ]] && continue
        BOOT_OPTIONS+=("$i")
    done
fi

if [[ -f /etc/kernel/tries ]]; then
    read -r TRIES </etc/kernel/tries
    if ! [[ "$TRIES" =~ ^[0-9]+$ ]] ; then
        echo "/etc/kernel/tries does not contain an integer." >&2
        exit 1
    fi
    LOADER_ENTRY="$BOOT_ROOT/loader/entries/$MACHINE_ID-$KERNEL_VERSION+$TRIES.conf"
else
    LOADER_ENTRY="$BOOT_ROOT/loader/entries/$MACHINE_ID-$KERNEL_VERSION.conf"
fi

cp "$KERNEL_IMAGE" "$ENTRY_DIR_ABS/linux" &&
   chown root:root "$ENTRY_DIR_ABS/linux" &&
   chmod 0644 "$ENTRY_DIR_ABS/linux" || {
    echo "Could not copy '$KERNEL_IMAGE to '$ENTRY_DIR_ABS/linux'." >&2
    exit 1
}

INITRD_OPTIONS=( "${@:${INITRD_OPTIONS_START}}" )

for initrd in "${INITRD_OPTIONS[@]}"; do
    if [[ -f "${initrd}" ]]; then
        initrd_basename="$(basename ${initrd})"
        [ "$KERNEL_INSTALL_VERBOSE" -gt 0 ] && \
            echo "Installing $ENTRY_DIR_ABS/${initrd_basename}"
        cp "${initrd}" "$ENTRY_DIR_ABS/${initrd_basename}" &&
            chown root:root "$ENTRY_DIR_ABS/${initrd_basename}" &&
            chmod 0644 "$ENTRY_DIR_ABS/${initrd_basename}" || {
             echo "Could not copy '${initrd}' to '$ENTRY_DIR_ABS/${initrd_basename}'." >&2
             exit 1
        }
    fi
done

# If no initrd option is supplied, fall back to "initrd" which is
# the name used by dracut when generating it in its kernel-install hook
[[ ${#INITRD_OPTIONS[@]} == 0 ]] && INITRD_OPTIONS=( initrd )

mkdir -p "${LOADER_ENTRY%/*}" || {
    echo "Could not create loader entry directory '${LOADER_ENTRY%/*}'." >&2
    exit 1
}

[ "$KERNEL_INSTALL_VERBOSE" -gt 0 ] && \
    echo "Creating $LOADER_ENTRY"
{
    echo "title      $PRETTY_NAME"
    echo "version    $KERNEL_VERSION"
    echo "machine-id $MACHINE_ID"
    echo "options    ${BOOT_OPTIONS[*]}"
    echo "linux      $ENTRY_DIR/linux"
    for initrd in "${INITRD_OPTIONS[@]}"; do
        [[ -f $ENTRY_DIR_ABS/$(basename ${initrd}) ]] && \
            echo "initrd     $ENTRY_DIR/$(basename ${initrd})"
    done
    :
} > "$LOADER_ENTRY" || {
    echo "Could not create loader entry '$LOADER_ENTRY'." >&2
    exit 1
}
exit 0
