#!/usr/bin/env bash
set -euo pipefail

MODE="${1:-}"
ROOT="${2:-}"

if [[ -z "$MODE" || -z "$ROOT" ]]; then
    echo "Usage: $0 <encode|decode> <root-folder>"
    exit 1
fi

cd "$ROOT"

ENC_SEP="__"   # Separator for encoding

encode() {
    find . -type f | while read -r file; do
        # Skip files already in root
        if [[ "$file" == "./"*"/"* ]]; then
            relpath="${file#./}"     # remove leading "./"
            dir=$(dirname "$relpath")
            base=$(basename "$relpath")

            # Encode: replace slashes with "__"
            encoded="${dir//$'/'/$ENC_SEP}__$base"

            # Avoid collision
            if [[ -e "$encoded" ]]; then
                i=1
                while [[ -e "${encoded%.*}_$i.${encoded##*.}" ]]; do
                    i=$((i+1))
                done
                encoded="${encoded%.*}_$i.${encoded##*.}"
            fi

            mv "$relpath" "$encoded"
        fi
    done

    # Remove empty dirs
    find . -type d -empty -delete
}

decode() {
    find . -maxdepth 1 -type f | while read -r f; do
        filename=$(basename "$f")

        # Split encoded name: dirparts__file.ext
        parts=(${filename//$ENC_SEP/ })

        # Last part is the real filename
        realfile="${parts[-1]}"
        unset 'parts[-1]'

        # Rebuild directory path
        dir=$(printf "/%s" "${parts[@]}")
        dir="${dir#/}"  # Remove leading slash

        if [[ -n "$dir" ]]; then
            mkdir -p "$dir"
            mv "$f" "$dir/$realfile"
        fi
    done
}

case "$MODE" in
    encode) encode ;;
    decode) decode ;;
    *) echo "Unknown mode: $MODE"; exit 1 ;;
esac