#!/usr/bin/env bash

set -eo pipefail
shopt -s globstar

if [[ -n "$1" ]]; then cd "$1"; fi

declare -A occurences

for file in **/*; do
    if [[ ! -f "$file" || -L "$file" ]]; then continue; fi
    hash=$(xxh128sum "$file" | cut -f1 -d' ')
    occurence=${occurences[$hash]}
    if [[ -n "$occurence" ]]; then
        relpath=$(realpath -s --relative-to "$(dirname "$file")" "$occurence")
        ln -sf "$relpath" "$file"
        echo "symlinked ${file@Q} to ${relpath@Q}" >&2
    else
        echo "first occurence of $hash: ${file@Q}" >&2
        occurences[$hash]=$file
    fi
done