#!/opt/homebrew/bin/bash
#
# x.sh — sanitize filenames: lowercase, replace non-alnum/dot with underscores,
# collapse runs of underscores, trim, and never overwrite a *different* existing file.
#
shopt -s globstar
SAVEIFS=$IFS
IFS=$'\n'      # only split on newlines

sanitize() {
  local name="$1"
  # 1) lowercase
  name="${name,,}"
  # 2) anything not a–z, 0–9, or dot → underscore
  name="${name//[^a-z0-9.]/_}"
  # 3) collapse multiple underscores → one underscore
  name="$(echo "$name" | sed -E 's/_+/_/g')"
  # 4) remove underscore adjacent to dots
  name="$(echo "$name" | sed -E 's/_\.|\._/./g')"
  # 5) trim leading/trailing underscores
  name="$(echo "$name" | sed -E 's/^_+|_+$//g')"
  printf '%s' "$name"
}

export -f sanitize

# depth-first traversal so directories are renamed after their contents
find . -depth -print0 | while IFS= read -r -d '' src; do
  dir=$(dirname  "$src")
  base=$(basename  "$src")
  dst=$(sanitize  "$base")

  if [[ "$base" != "$dst" ]]; then
    target="$dir/$dst"
    if [[ -e "$target" ]]; then
      # If the only difference is case (macOS/APFS), allow it:
      if [[ "${src,,}" = "${target,,}" ]]; then
        mv -v "$src" "$target"
      else
        echo "Skipping: '$src' → '$target' (target exists)"
      fi
    else
      mv -v "$src" "$target"
    fi
  fi
done

IFS=$SAVEIFS