git-add

#!/usr/bin/env bash

###
### git-add: Add convenience options to git-add(1).
###

BASENAME="$(basename $0)"
ERR_NOTREPO="Not a Git repository."

ARGV=()
FILES=()
REGEX='^%[0-9]+$'
STAGEABLE=()

while [[ $# -gt 0 ]]; do
	case $1 in
		-h|--help)
			exec $GIT add --help

			exit 0
		;;
		%*)
			if [[ ! "$($GIT rev-parse --is-inside-work-tree)" ]] 2>/dev/null; then
				printf '%s\n' "$ERR_NOTREPO"

				exit 1
			fi

			# Unstaged, untracked files.
			STAGEABLE+=($($GIT status --porcelain=v1 | grep -E '^(\w|\s)(A|C|D|M|R|U)\s+' | awk '{$1=$1};1' | cut -d' ' -f2))
			STAGEABLE+=($($GIT status --porcelain=v1 | grep '??' | cut -d' ' -f2))

			INDEX="$1"

			if [[ ! "$INDEX" =~ $REGEX ]]; then
				printf '%s: %s is not a valid number.\n' "$BASENAME" "$INDEX"

				exit 1
			fi

			INDEX="$(( $(echo $INDEX | tr -d '%') - 1 ))"

			if [[ $INDEX -lt 0 ]] || \
			   [[ $(expr $INDEX + 1) -gt ${#STAGEABLE[@]} ]]; then
				printf '%s: %s is not a valid index.\n' "$BASENAME" "$(expr $INDEX + 1)"

				exit 1
			fi

			FILES+=("${STAGEABLE[$INDEX]}")

			shift
		;;
		*)
			ARGV+=("$1")

			shift
		;;
	esac
done

exec $GIT add "${ARGV[@]}" "${FILES[@]}"