setcasefold

#!/bin/bash

folder="$(pwd)"

# Check if a folder argument is provided
if [ $# -gt 0 ]; then
    # Assign the full path to a variable and remove trailing slash
    folder="$(readlink -f -- "${1%/}")"
fi

# Check if the folder exists
if [ ! -d "$folder" ]; then
    echo "Error: The specified folder '$folder' does not exist."
    exit 1
fi

# Ask for confirmation
read -r -p "Are you sure you want to apply the +F flag to all directories in '$folder' and its subdirectories? (yes/no): " confirmation

if [[ ! "$confirmation" =~ ^([yY][eE][sS]|[yY])$ ]]; then
    echo "Operation cancelled."
    exit 1
fi

# Check if the filesystem supports case-folding
filesystem=$(df -P "$folder" | awk 'NR==2 {print $1}')
if ! sudo tune2fs -l "$filesystem" | grep -q "casefold"; then
    echo "Error: The filesystem containing '$folder' does not support case-folding."
    exit 1
fi

# Parent directory of the target folder
parent_dir="$(dirname -- "$folder")"

# Create a temporary working directory next to the target
if ! temp_dir=$(mktemp -d -p "$parent_dir" 2>/dev/null); then
    echo "Error: Failed to create temporary directory in '$parent_dir'!"
    exit 1
fi

# Move the original folder into the temporary location
mv "$folder" "$temp_dir/" 2>/dev/null

# Recreate directory tree and apply +F to each directory
while IFS= read -r -d '' dir; do
    rel_path="${dir#"$temp_dir/"}"
    target_path="$parent_dir/$rel_path"

    mkdir -p -- "$target_path"
    sudo chattr +F -- "$target_path"
done < <(find "$temp_dir" -mindepth 1 -type d -print0)

# Root path of the moved original tree
moved_root="$temp_dir/$(basename -- "$folder")"

# Copy files back into the recreated directories
rsync -a -- "$moved_root/" "$folder/"

# Clean up temporary directory
rm -rf -- "$temp_dir"

echo "Operation completed."