#!/bin/bash

if [ ! -d "./.git" ]; then
    echo "missing .git dir!"
    exit 1
fi

last_commit() {
    printf "Last commit date: %s\n" "$(git log | grep 'Date' | cut -d ' ' -f 4- | head -1)"
}

help() {
    echo "gdt: Commit with fake date"
    echo
    echo "USAGE"
    echo "    $0 -[dl] <git command>"
    echo
    echo "ARGS"
    echo "    -d, --date    Sets commit and author date"
    echo "    -h, --help    Prints this message"
}

die() {
    echo "ERROR: $1"
    echo
    help >&2
    exit 1
}

case "$1" in
    "-d"|"--date")
        shift
        [ -n "$1" ] && date="$1" || die "Missing date"
        shift
    ;;
    "-h"|"--help")
        help
        exit
    ;;
    *)
        last_commit
        exit
    ;;
esac

if [ "$#" -lt "1" ]; then
    die "Missing commit message!"
fi

export GIT_AUTHOR_DATE="${date}"
export GIT_COMMITTER_DATE="${date}"

git commit -am "$@"