set-gh-ssh-keys

#!/bin/bash

PROGNAME="$(basename $0)"

show_usage() {
	echo "$PROGNAME: Set SSH keys for a user"
	echo "Usage: $PROGNAME [ -h, --help | -s, --show | -c, --check | -g, --generate <email>]" 
	return
}

check_existing_ssh_key() {
	if [[ -f ~/.ssh/id_ed25519.pub ]]; then
		echo "SSH key already exists."
		exit 0
	else
		echo "No SSH key found."
		exit 1
	fi
}

show_ssh_key() {
	if [[ -f ~/.ssh/id_ed25519.pub ]]; then
		echo "Your SSH public key is:"
		cat ~/.ssh/id_ed25519.pub
	else
		echo "No SSH key found."
	fi
}

install_ssh_keygen() {
	if ! command -v ssh-keygen &>/dev/null; then
		echo "ssh-keygen is not installed. Please install it first. Do you want to install it now? (Y/n)"
		read -r install_ssh_keygen
		if [[ "$install_ssh_keygen" =~ ^[Yy]$ ]]; then
			sudo apt-get install openssh-client
		else
			echo "ssh-keygen is required to generate SSH keys. Exiting."
		exit 1
		fi
	fi
}

generate_ssh_key() {
	install_ssh_keygen

	if [[ -d ~/.ssh && -f ~/.ssh/id_ed25519.pub ]]; then
		echo "SSH key already exists. Please remove it before generating a new one."
		exit 1
	fi

	if [[ ! -d ~/.ssh ]]; then
		echo "Creating .ssh directory..."
		mkdir -p ~/.ssh
		chmod 700 ~/.ssh
	fi
	
	echo "Generating SSH key for $email..."
	ssh-keygen -t ed25519 -C "$email" -f ~/.ssh/id_ed25519 -N "" # -t is type -C is comment -f is file -N "" is no passphrase
	echo "SSH key generated successfully. Your public key is:"
	show_ssh_key

	add_to_agent
	
	exit 0
}

add_to_agent() {
	if ! pgrep -u "$USER" ssh-agent >/dev/null ; then
		eval "$(ssh-agent -s)" 
	fi

	echo "SSH key added to the agent."
	ssh-add ~/.ssh/id_ed25519
}

if [[ $# -eq 0 ]]; then
	show_usage
	exit 1
fi

case "$1" in
	-g|--generate)
	if [[ -z "$2" ]]; then
		echo "Error: No email provided."
		show_usage
		exit 1
	fi

	# Check if the email is valid
	if [[ ! "$2" =~ ^[^@]+@[^@]+\.[^@]+$ ]]; then
		echo "Error: Invalid email format."
		exit 1
	fi

	email="$2"
	generate_ssh_key
	exit 0
	;;
	-h | --help)
		show_usage
		exit 0
		;;
	-s | --show)
		show_ssh_key
		exit 0
		;;
	-c | --check)
		check_existing_ssh_key
		exit 0
		;;
	*)
		echo "Error: Invalid option."
		show_usage
		exit 1
		;;
esac