#!/bin/sh
#
# Convert a patch-queue branch into a patch series in debian/patches and vice
# versa.
#
# assumes you have your quilt patch queue for $branch on patch-queue/$branch
#
# See: https://honk.sigxcpu.org/piki/development/debian_packages_in_git/

is_patch_queue()
{
    local branch=$1

    if expr $branch : patch-queue/ >/dev/null; then
         return 0
    else
         return 1
    fi
}

pq_export()
{
    local branch=$1
    local pq="patch-queue/$branch"

    if is_patch_queue $branch; then
        echo "On a patch-queue branch, can't redo patches."
        return 1
    fi

    rm -f debian/patches/*
    PATCHES=`git format-patch -N -o debian/patches $branch...$pq`
    if [ -n "$PATCHES" ]; then
        echo "Regenerationg patch queue in \"debian/patches\"."
        > debian/patches/series
        for PATCH in $PATCHES; do
	    # delete the first line (from sha1) and last two lines (git version
	    # info) of the patch file
            sed -i -e '1d' -e 'N;$!P;$!D;$d' $PATCH
            sed -i -e 's/^-- \n[0-9\.]+$//' $PATCH
            echo $PATCH | sed -e 's%debian/patches/%%' >> debian/patches/series
        done
        git status -- debian/patches
    else
        echo "No patches on \"$pq\"."
    fi
}

pq_rebase()
{
    local branch=$1
    local pq="patch-queue/$branch"

    if ! is_patch_queue $branch; then
	echo "Switching to \"$pq\""
        git checkout $pq
    else
        echo "Already on \"$branch\""
    fi
    git rebase $branch
}

pq_import()
{
    local branch=$1
    local pq="patch-queue/$branch"
    local patches=debian/patches/

    if is_patch_queue $branch; then
        echo "Already on a patch-queue branch \"$branch\" - doing nothing."
        return 1
    fi

    if [ ! -r ${patches}series ]; then
        echo "Found no series file at \"$patches\"."
        return 1
    fi

    if ! git checkout -b $pq; then
        echo "Cannot create patch-queue branch \"$pq\"."
	return 1
    fi
    QUILT_PATCHES=$patches git quiltimport
} 

usage ()
{
    cat <<EOF
$0 [ACTION]

Options:
	export		Export the associated patch-queue branch into
                        debian/patches and update the series file.

	import		Create a patch-queue branch from debian/patches.

	rebase		Switch to associated patch-queue branch and rebase
                        against current branch.
EOF
}

branch=$(git branch --no-color | awk '/^\*/ { print $2 }')

case "$1" in
    export)
        pq_export $branch
        ;;
    import)
	pq_import $branch
	;;
    rebase)
        pq_rebase $branch
        ;;
    *)
	usage
	exit 1
	;;
esac