pre-push

#!/usr/bin/env bash

set -euo pipefail

#
# Capture the pre-push context.
#
# From githooks(5):
#
#   Information about what is to be pushed is provided on the hook's standard
#   input with lines of the form:
#
#     <local ref> SP <local sha1> SP <remote ref> SP <remote sha1> LF
#
#   For instance, if the command git push origin master:foreign were run the
#   hook would receive a line like the following:
#
#     refs/heads/master 67890 refs/heads/foreign 12345
#

mapfile -t input

dump-input() {
    # Reproduce the input for use with another command.
    printf '%s\n' "${input[@]}"
}

#
# Check if pushing to a "protected" branch was intended.
#

check-input-for-protected-branch-name() {
    local line remote_ref
    for line in "${input[@]}"
    do
        read -r _ _ remote_ref _ <<< "$line"
        check-ref-for-protected-branch-name "$remote_ref" || return $?
    done
}

check-ref-for-protected-branch-name() {
    local remote_ref="$1" answer
    # Prevent accidental pushes to "protected" branches.
    if [[ $remote_ref =~ /(master|production|staging) ]]
    then
        printf "You're about to push to %q.\n" "$remote_ref" >&2
        read -p "Is that what you intended? [y|N] " -n 1 -s -r answer >&2 < /dev/tty
        echo >&2
        if [[ $answer != [yY] ]]
        then
            return 2  # prevents push.
        fi
    fi
}

check-input-for-protected-branch-name || exit $?

#
# LFS.
#

if type -P git-lfs &> /dev/null
then
    dump-input | git lfs pre-push "$@"
else
    echo "This repository is configured for Git LFS but 'git-lfs' was not found on your path." >&2
    exit 2  # prevents push.
fi

# End.