#!/bin/bash

function usage()
{
    cat <<EOF
Usage: thorn-branch <command>

Available commands are:

    init   Set up a new <branch>_thorns branch in the current repository.
           Currently only Git repositories are supported, and there
           must be at least one commit in the repository.

    push   Clone a temporary copy of the current branch, run "make" in
           it, and commit the contents of the resulting thorns
           directory to the <branch>_thorns branch.  Push this branch
           and the current branch to origin.

EOF

}

set -e

if [ $# = 0 ]; then
    usage
    exit 1
fi

command="$1"

case "$command" in
    "help")
        usage
        ;;

    "push")
        BRANCH=$(git branch|grep '^\*'|awk '{print $2}')
        if [ -r ${BRANCH}_thorns ]; then
            echo "Existing directory ${BRANCH}_thorns: please remove before running thorn-branch init"
            exit 1
        fi
        if [ -r ${BRANCH} ]; then
            echo "Existing directory ${BRANCH}: please remove before running thorn-branch init"
            exit 1
        fi
        git fetch origin
        git branch -f ${BRANCH}_thorns remotes/origin/${BRANCH}_thorns
        git clone -b ${BRANCH} . ${BRANCH}
        make -C ${BRANCH}
        git clone -b ${BRANCH}_thorns . ${BRANCH}_thorns
        rsync -av --exclude=".git/*" --delete ${BRANCH}/thorns/ ${BRANCH}_thorns/
        git --git-dir ${PWD}/${BRANCH}_thorns/.git --work-tree ${PWD}/${BRANCH}_thorns add --all
        if git --git-dir ${PWD}/${BRANCH}_thorns/.git --work-tree ${PWD}/${BRANCH}_thorns commit -a -m "Updated from source"; then
            true
        fi
        git fetch ${BRANCH}_thorns "${BRANCH}_thorns:${BRANCH}_thorns"
        git push origin ${BRANCH} && git push origin ${BRANCH}_thorns
        rm -rf ${BRANCH} ${BRANCH}_thorns
        ;;
    
    "init")
        BRANCH=$(git branch|grep '^\*'|awk '{print $2}')
        if [ -r ${BRANCH}_thorns ]; then
            echo "Existing directory ${BRANCH}_thorns: please remove before running thorn-branch init"
            exit 1
        fi
        git clone -b ${BRANCH} . ${BRANCH}_thorns
        git --git-dir ${PWD}/${BRANCH}_thorns/.git --work-tree ${PWD}/${BRANCH}_thorns symbolic-ref HEAD refs/heads/master_thorns
        rm ${BRANCH}_thorns/.git/index
        git --git-dir ${PWD}/${BRANCH}_thorns/.git --work-tree ${PWD}/${BRANCH}_thorns clean -fdxq
        echo "This is the initial commit" > ${PWD}/${BRANCH}_thorns/README
        git --git-dir ${PWD}/${BRANCH}_thorns/.git --work-tree ${PWD}/${BRANCH}_thorns add ${PWD}/${BRANCH}_thorns/README
        git --git-dir ${PWD}/${BRANCH}_thorns/.git --work-tree ${PWD}/${BRANCH}_thorns commit -a -m "Initial thorns commit"
        git fetch ${BRANCH}_thorns "${BRANCH}_thorns:${BRANCH}_thorns"
        rm -rf ${BRANCH}_thorns
        ;;
    
    *)
        echo "thorn-branch: Command \'$command\' not recognised"
        exit 1
esac