#!/usr/bin/env bash

set -e

usage() {
    cat <<EOF >&2
Usage: $0 --email=admin@example.com [--method={webroot|standalone}] \
hostname.example.com [another.example.com]
EOF
    exit 1
}

if [ "$EUID" -ne 0 ]; then
    echo "Error: This script must be run as root" >&2
    exit 1
fi

method=webroot
args="$(getopt -o '' --long help,email:,method:,skip-symlink,agree-tos -n "$0" -- "$@")"
eval "set -- $args"
while true; do
    case "$1" in
        --email)
            EMAIL="$2"
            shift
            shift
            ;;
        --method)
            method="$2"
            shift
            shift
            ;;
        --skip-symlink)
            skip_symlink=1
            shift
            ;;
        --agree-tos)
            agree_tos=--agree-tos
            shift
            ;;
        --help)
            show_help=1
            shift
            ;;
        --)
            shift
            break
            ;;
    esac
done

# Parse the remaining arguments as Subject Alternative Names to pass to certbot
HOSTNAMES=()
for arg; do
    HOSTNAMES+=(-d "$arg")
done
DOMAIN=$1

if [ -n "$show_help" ]; then
    usage
fi

if [ -z "$DOMAIN" ] || [ -z "$EMAIL" ]; then
    usage
fi

case "$method" in
    standalone)
        method_args=(--standalone --no-directory-hooks)
        ;;
    webroot)
        method_args=(--webroot '--webroot-path=/var/lib/zulip/certbot-webroot/')
        ;;
    *)
        usage
        ;;
esac

# Check for a supported OS release.
if [ -f /etc/os-release ]; then
    os_info="$(
        . /etc/os-release
        printf '%s\n' "$ID" "$ID_LIKE"
    )"
    {
        read -r os_id
        read -r os_id_like || true
    } <<<"$os_info"
fi

set -x

case " $os_id $os_id_like " in
    *' debian '*)
        apt-get update
        apt-get install -y certbot
        ;;
    *' rhel '*)
        yum install -y certbot
        ;;
esac

# We don't use --no-interactive, because certbot needs to ask the user
# to agree to the Let's Encrypt Subscriber Agreement (aka ToS).
# Passing --force-interactive suppresses a warning, but also brings up
# an annoying prompt we stifle with --no-eff-email.
certbot certonly "${method_args[@]}" \
    "${HOSTNAMES[@]}" -m "$EMAIL" \
    $agree_tos \
    --force-interactive --no-eff-email

symlink_with_backup() {
    if [ -e "$2" ]; then
        # If the user is setting up our automatic certbot-management on a
        # system that already has certs for Zulip, use some extra caution
        # to keep the old certs available.
        mv -f --backup=numbered "$2" "$2".setup-certbot || true
    fi
    ln -nsf "$1" "$2"
}

if [ -z "$skip_symlink" ]; then
    CERT_DIR=/etc/letsencrypt/live/"$DOMAIN"
    symlink_with_backup "$CERT_DIR"/privkey.pem /etc/ssl/private/zulip.key
    symlink_with_backup "$CERT_DIR"/fullchain.pem /etc/ssl/certs/zulip.combined-chain.crt
fi

# "certbot certonly" does not run deploy hooks, so reload nginx if
# need be to pick up the new certificate.
case "$method" in
    webroot)
        service nginx reload
        ;;
esac

echo "Certbot SSL certificate configuration succeeded."