OpenCPN/check-pr

#!/bin/bash
#
# Check an OpenCPN pull request for whitespace errors.
#

function usage() {
cat << EOT
Usage:
    check-pr [-l | -h]  <<PR url> | <Repo url> <branch>>

Parameters:
    PR url:
        As copied from the Github UI, something like
        https://github.com/Github6am/OpenCPN/tree/opti_amerz
    Repo url:
        As of the Github UI, the Code button; something like
        https://github.com/Github6am/OpenCPN

Options:
    -l  Print a list of offending files rather than the complete diff.
    -h  Print this help message and exit
EOT
}


# Handle options and parameters
if [ "$1" = "-h" ]; then usage; exit 0; fi
if [ "$1" = "-l" ]; then list_opt='true'; shift; fi

if [ $# -eq 1 ]; then
    url=${1%%OpenCPN/*}/OpenCPN
    branch=${1##*/tree/}
elif [ $# -eq 2 ]; then
    url=$1
    branch=$2
else
    usage >&1
    exit 1
fi


# Set up the pr-tmp remote and the empty tree we compare against
if git config remote.pr-tmp.url >/dev/null; then
    git remote remove pr-tmp
fi
git remote add pr-tmp $url
git fetch pr-tmp $branch
empty_tree=$(git hash-object -t tree /dev/null)


# Do the check
if [ -n "$list_opt" ]; then
    exec > >(sed -e 's/:.*//' -e '/^+/d' | uniq)
fi
for f in $(git diff --name-only --diff-filter=ACMR HEAD pr-tmp/$branch); do
    git diff-tree --check $empty_tree pr-tmp/$branch $f
done


# Cleanup (stdout possibly redirected).
git remote remove pr-tmp