#!/usr/bin/env bash
#
# usage: ./generate_ssh_keys.sh --type "host" --username "root" --hostname "hostname"
#

while [[ $# -gt 0 ]]
do
    key="$1"

    case $key in
        --type)
            type="$2"
            shift # past argument
            shift # past value
            ;;
        --username)
            username="$2"
            shift # past argument
            shift # past value
            ;;
        --hostname)
            hostname="$2"
            shift # past argument
            shift # past value
            ;;
        *)    # unknown option
            echo "Unknown option $1"
            exit 1
            ;;
    esac
done

if [[ -z "$type" || -z "$username" || -z "$hostname" ]]; then
    echo "All arguments are not specified."
    exit 1
fi

if [[ $type != "user" && $type != "host" ]]; then
    echo "Invalid type. It should be either 'user' or 'host'"
    exit 1
fi

HOST_KEY_DIR="$HOME/keys/hosts/$hostname"
USER_KEY_DIR="$HOME/keys/users/$username"
mkdir -p "$HOST_KEY_DIR" "$USER_KEY_DIR"

if [[ $type == "user" ]]; then
    keyfile="id_ed25519"
    name="$username"
else
    keyfile="ssh_host_ed25519_key"
    name="root@$hostname"
fi

keydir=$([[ $type == "user" ]] && echo "$USER_KEY_DIR" || echo "$HOST_KEY_DIR")
fullpath="$keydir/$keyfile"
overwrite=""
[ -f "$fullpath" ] && read -p "Target key '$fullpath' already exists, would you like to overwrite it? (yes|no) " overwrite
[ "$overwrite" = "yes" ] || [ -z "$overwrite" ] && ssh-keygen -t ed25519 -f "$fullpath" -C "$name" -N ""