#!/bin/bash
time="$1"
if [ -z "$1" ]; then
    time="now"
fi

pushd . > /dev/null
cd /usr/share/zoneinfo/
tz="$(find | sed 's|^\./||' | fzf)"
popd > /dev/null

unix="$(TZ="$tz" date -d "$time" +%s)"
date -d "@${unix}"