#!/bin/sh

find . -depth -name '*' -print0 | xargs -0 -n1 -P10 -I{} sh -c '
    generate_unique_name() {
        base_name="$1"; ext="$2"; dest_path="$3"; count=1
        [ -z "$ext" ] && new_name="$base_name" || new_name="${base_name}.${ext}"
        while [ -e "${dest_path}/${new_name}" ]; do
            [ -z "$ext" ] && new_name="${base_name}_${count}" || new_name="${base_name}_${count}.${ext}"
            count=$(( count + 1 ))
        done
        echo "$new_name"
    }

    process_item() {
        item_path="$1"; [ "$item_path" = "." ] && return
        dir_name=$(dirname "$item_path"); base_name=$(basename "$item_path")
        if [ -d "$item_path" ]; then
            new_name=$(echo "$base_name" | sed -E "s/[^a-zA-Z0-9 _.-]+//g; s/[ .-]+/_/g; s/_+/_/g; s/^_//; s/_$//; s/(.*)/\L\1/")
            [ -z "$new_name" ] && new_name="untitled"
        else
            file_ext="${base_name##*.}"
            base_name_no_ext="${base_name%.*}"
            new_base_name_no_ext=$(echo "$base_name_no_ext" | sed -E "s/[^a-zA-Z0-9 _.-]+//g; s/[ .-]+/_/g; s/_+/_/g; s/^_//; s/_$//; s/(.*)/\L\1/")
            [ -z "$new_base_name_no_ext" ] && new_base_name_no_ext="untitled"
            new_name="${new_base_name_no_ext}.${file_ext}"
        fi
        if [ "$base_name" != "$new_name" ]; then
            [ -e "${dir_name}/${new_name}" ] && new_name=$(generate_unique_name "${new_name%.*}" "${new_name##*.}" "$dir_name")
            mv "$item_path" "${dir_name}/${new_name}" 2>/dev/null || true
        fi
    }
    process_item "{}"
' 2>/dev/null