newline pre-commit

#!/bin/sh

# Get list of added/modified files (not deleted) in the index
files=$(git diff --cached --name-only --diff-filter=ACM)

for f in $files
do
  # Skip if file doesn't exist (e.g., deleted or renamed away)
  [ -f "$f" ] || continue

  # Check if file is a text file using `file --mime`
  mimetype=$(file --mime-type -b "$f")
  case "$mimetype" in
    text/*)
      # Ensure file ends in newline
      if [ "$(tail -c1 "$f")" != "" ]; then
        echo >> "$f"
        git add "$f"
      fi

      # Remove trailing whitespace
      if grep -q "[[:blank:]]$" "$f"; then
        # macOS uses BSD `sed`, so adjust the `-i` flag accordingly
        if sed --version >/dev/null 2>&1; then
          # GNU sed (Linux)
          sed -i -e 's/[[:blank:]]\+$//' "$f"
        else
          # BSD sed (macOS)
          sed -i '' -e 's/[[:blank:]]\+$//' "$f"
        fi
        git add "$f"
      fi
      ;;
    *)
      # Skip binary files
      ;;
  esac
done