#!/bin/bash

function error_out {
    echo -en '\e[0;31m'
    echo "$1"
    echo -en '\e[0m'
    exit 1
}

status=$(git status --porcelain | grep -v '^??')
[ ! -z "$status" ] && error_out "Working directory or index not clean"

old_ref=$(git rev-list --max-count=1 HEAD)
branch=$1
branch_ref=$(git rev-list --max-count=1 "$branch")

[ $? -ne 0 ] && error_out "Unknown branch: $branch"

if [ "$old_ref" == "$branch_ref" ]; then
    new_ref=master
else
    ref_name=$(git describe --all --exact "$old_ref")
    if [ $? -eq 0 ]; then
        new_ref=$(echo "$ref_name" | perl -pe 's{^(heads|remotes)/}{}')
    else
        new_ref=$old_ref
    fi
fi

[ -z "$branch" ] && error_out "You must specify a branch name to deploy"

git fetch -p

git rebase origin/master "$branch"
[ $? -ne 0 ] && error_out "Rebase onto origin/master failed"

git push . HEAD:master
git push origin master
[ $? -ne 0 ] && error_out "Push of master to origin/master failed"

git checkout "$new_ref"
git branch -D "$branch"
git push origin ":$branch"