#!/bin/bash -e

# Deletes any local branches which are ancestors of origin/master,
# and also any branches in origin which are ancestors of
# origin/master and are named like $USER-*.

push_args=''

function is_merged {
    ! git rev-list -n 1 origin/master.."$1" | grep -q .
}

function clean_ref {
    ref="$1"
    case "$ref" in
        */master | */HEAD)
            return
            ;;

        refs/heads/*)
            if is_merged "$ref"; then
                echo -n "Deleting local branch $(echo "$ref" | sed 's!^refs/heads/!!')"
                echo " (was $(git rev-parse --short "$ref"))"
                git update-ref -d "$ref"
            fi
            ;;

        refs/remotes/origin/$USER-*)
            if is_merged "$ref"; then
                remote_name="$(echo "$ref" | sed 's!^refs/remotes/origin/!!')"
                echo -n "Deleting remote branch $remote_name"
                echo " (was $(git rev-parse --short "$ref"))"
                # NB: this won't handle spaces in ref names
                push_args="$push_args :$remote_name"
            fi
            ;;
    esac
}

if [ "$(git symbolic-ref HEAD)" != 'refs/heads/master' ]; then
    echo "Check out master before you run this script." >&2
    exit 1
fi

git fetch --prune origin

eval $(git for-each-ref --shell --format='clean_ref %(refname);')

if [ -n "$push_args" ]; then
    git push origin $push_args
fi