#!/bin/bash

set -e

top=$(pwd)

# parameters
kernel_submodule=
kernel_patchdir=
new_tag=
rebase=

# generated based on new_tag
pq_branch=
# previously checked out in submodule
old_ref=

function cleanup_pq_branch {
    if [[ -n $pq_branch ]]; then
	echo "cleaning up PQ branch '$pq_branch'"
	cd "${top}/${kernel_submodule}"
	git checkout --quiet $old_ref
	git reset --hard
	git branch -D "$pq_branch"
    fi
}

function error_exit {
    echo "$1"
    set +e

    cleanup_pq_branch

    cd "${top}"

    exit 1
}

if [[ "$#" -lt 3 || "$#" -gt 4 ]]; then
    echo "USAGE: $0 submodule patchdir tag [rebase]"
    echo "\t fetches and checks out 'tag' in 'submodule'"
    echo "\t if 'rebase' is given, imports, rebases and exports patchqueue from 'patchdir' as well"
    exit 1
fi

kernel_submodule=$1
if [ ! -d "${kernel_submodule}" ]; then
    error_exit "'${kernel_submodule}' must be a directory!"
fi

kernel_patchdir=$2
if [ ! -d "${kernel_patchdir}" ]; then
    error_exit "'${kernel_patchdir}' must be a directory!"
fi

new_tag=$3
rebase=$4

if [[ -n $(git status --untracked-files=no --porcelain) ]]; then
    error_exit "working directory unclean, aborting"
fi


cd "${kernel_submodule}"
## check for tag and fetch if needed
echo "checking for tag '${new_tag}'"
if [[ -z $(git tag -l "${new_tag}") ]]; then
    echo "tag not found, fetching and retrying"
    git fetch --tags
fi
if [[ -z $(git tag -l "${new_tag}") ]]; then
    error_exit "tag not found, aborting"
fi
echo "tag found"
cd "${top}"

if [[ -n "$rebase" ]]; then
    echo ""
    echo "automatic patchqueue rebase enabled"
    cd "${kernel_submodule}"
    ## preparing patch queue branch
    old_ref=$(git rev-parse HEAD)
    pq_branch="auto_pq/${new_tag}"
    cd "${top}"

    echo "previous HEAD: ${old_ref}"

    echo ""
    "${top}/debian/scripts/import-patchqueue" "${kernel_submodule}" "${kernel_patchdir}" "${pq_branch}" || error_exit "failed to import patchqueue"

    cd "${kernel_submodule}"
    ## rebase patches
    echo ""
    echo "rebasing patchqueue on top of '${new_tag}'"
    git rebase "${new_tag}"
    cd "${top}"

    ## regenerate exported patch queue
    echo ""
    "${top}/debian/scripts/export-patchqueue" "${kernel_submodule}" "${kernel_patchdir}" "${new_tag}" || error_exit "failed to export patchqueue"

    cleanup_pq_branch
    cd "${top}"
    pq_branch=
fi

cd "${kernel_submodule}"
echo ""
echo "checking out '${new_tag}' in submodule"
git checkout --quiet "${new_tag}"
cd "${top}"

echo ""
echo "committing results"
git commit --verbose -s -m "update sources to ${new_tag}" -m "(generated with debian/scripts/import-upstream-tag)" "${kernel_submodule}"
if [[ -n "$rebase" ]]; then
    git add "${kernel_patchdir}"
    git commit --verbose -s -m "rebase patches on top of ${new_tag}" -m "(generated with debian/scripts/import-upstream-tag)" "${kernel_patchdir}"
fi