github-fork.sh

#! /usr/bin/env bash
#
# purpose: fork an already-cloned github repository from shell
#
# itch: You've made changes to someone else's repo that you've already
# cloned. Now you want to share them to github; but without all the
# silly gyrations.
#
# bug: it assumes you use ssh not https; and it creates/caches an api key
#
set -e

this=$(basename $0)
me=${1-dotysan}
now=$(date +%F)

url=$(git config --get remote.origin.url)
if [[ $url =~ .+github\.com.(.+)/(.+)\.git$ ]]
then    upstream_user="${BASH_REMATCH[1]}"
        repo="${BASH_REMATCH[2]}"
else    echo "ERROR: Remote origin is not on github."
        exit 1
fi >&2

if ! ghuser=$(git config --get github.user)
then    ghuser="$me"
        git config --global github.user "$ghuser"
fi

if [ "$upstream_user" = "$ghuser" ]
then    echo "ERROR: Can't fork your own repo."
        exit 1
fi >&2

gen_tok() {
        note="$USER@$HOSTNAME on $now using $this: https://gist.github.com/dotysan/8277858"
        data="{\"scopes\":[\"public_repo\"],\"note\":\"$note\"}"
        api=https://api.github.com/authorizations

        echo "Generating new access token..."
        # it will prompt for your github password here
        json=$(curl --silent --user "$ghuser" --data "$data" $api)

        re='"token": "([0-9a-f]{40})"'
        if [[ $json =~ $re ]]
        then tok="${BASH_REMATCH[1]}"
        else    echo "$json"
                echo "CRAP! Something went wrong."
                exit 1
        fi >&2

        git config --global github.token "$tok"
        git config --global github.toknote "$note"
}

# try and use an API token; otherwise create one and save
tok=$(git config --get github.token) ||gen_tok

do_fork() {
        post="https://$ghuser:$tok@api.github.com/repos/$upstream_user/$repo/forks"
        json=$(curl --silent --request POST "$post")
}

# TODO: check to see if the fork already exists before creating; in
# order to avoid collissions if the upstream isn't in sync
do_fork

# re-create/retry a failed/stale token
if grep -q '"message": "Bad credentials"' <<<"$json"
then    gen_tok
        do_fork
fi

# they say it's async...so just in case they're busy...
sleep 1

re="  \"ssh_url\": \"(git@github\.com:$ghuser/$repo\.git)\""
if [[ $json =~ $re ]]
then    origin="${BASH_REMATCH[1]}"
fi
if [ "$origin" != "git@github.com:$ghuser/$repo.git" ]
then    echo "$json"
        echo "CRAP! Something went wrong."
        exit 1
fi >&2

git remote set-url origin "$origin"
git remote add upstream "git@github.com:$upstream_user/$repo.git"

# alas! share local changes into the newly forked public repo
git push