#!/hint/bash -euE
# Copyright (C) 2023  Umorpha Systems
# SPDX-License-Identifier: AGPL-3.0-or-later

load_module "$(dirname -- "${BASH_SOURCE[0]}")/base-nginx.sh"

packages+=(
	certbot
	sudo
)

post_install+=(30:acme:post_install) # must be after '20:nginx:post_install' and '10:osi-mk:hostname'
acme:post_install() {
	local arg_mountpoint=$1

	########################################################################
	# First up, we're going to run a separate nginx instance from          #
	# the main one to handle ACME HTTP-01 challenges.                      #
	########################################################################
	# Inspired by https://xyrillian.de/thoughts/posts/how-i-run-certbot.html
	cat >"$arg_mountpoint/etc/nginx/nginx-cleartext.conf" <<-'EOF'
		# -*- mode: nginx; nginx-indent-level: 4; intent-tabs-mode: nil -*-

		pid /run/nginx-cleartext.pid;

		worker_processes  1;

		error_log /var/log/nginx/cleartext-error.log error;

		events {
		    worker_connections  1024;
		}

		http {
		    error_log  /var/log/nginx/cleartext-error.http.log  error;
		    access_log /var/log/nginx/cleartext-access.http.log combined;

		    types_hash_max_size 4096;
		    include       mime.types;
		    default_type  application/octet-stream;

		    sendfile           on;
		    keepalive_timeout  65;

		    gzip  on;

		    server {
		        listen 80 default_server;
		        listen [::]:80 default_server;
		
		        location / {
		            return 301 https://$host$request_uri;
		        }
		
		        location /.well-known/acme-challenge {
		            root /var/lib/letsencrypt;
		            default_type "text/plain";
		        }
		    }
		}
	EOF

	mkdir -p "$arg_mountpoint/etc/systemd/system/nginx-cleartext.service.d"
	echo '[Unit]' >"$arg_mountpoint/etc/systemd/system/nginx-cleartext.service"
	ln -sT /usr/lib/systemd/system/nginx.service "$arg_mountpoint/etc/systemd/system/nginx-cleartext.service.d/00-base.conf"
	cat >"$arg_mountpoint/etc/systemd/system/nginx-cleartext.service.d/01-base.conf" <<-EOF
		[Service]
		PIDFile=/run/nginx-cleartext.pid
		ExecStart=
		ExecStart=/usr/bin/nginx -c /etc/nginx/nginx-cleartext.conf
		ExecReload=
		ExecReload=/usr/bin/nginx -c /etc/nginx/nginx-cleartext.conf -s reload
	EOF

	systemctl --root="$arg_mountpoint" enable nginx-cleartext.service

	########################################################################
	# Set up Certbot+SSL for the system                                    #
	########################################################################

	# General SSL
	curl https://ssl-config.mozilla.org/ffdhe2048.txt > "$arg_mountpoint/etc/ssl/private/dhparam.pem"
	ln -sT "../../letsencrypt/live/$(cat "$arg_mountpoint/etc/hostname")" "$arg_mountpoint/etc/ssl/private/myhostname"

	# Have Certbot run as non-root
	install -Dm644 /dev/stdin "$arg_mountpoint"/etc/sysusers.d/certbot.conf <<-EOF
		u keys - "Certbot" /etc/ssl
	EOF
	install -Dm644 /dev/stdin "$arg_mountpoint"/etc/tmpfiles.d/certbot.conf <<-EOF
		d /etc/letsencrypt         0755 keys keys
		d /etc/letsencrypt/archive 0750 keys keys
		d /etc/letsencrypt/live    0750 keys keys
		d /var/lib/letsencrypt     0755 keys keys
		d /var/log/letsencrypt     0700 keys keys
	EOF
	install -Dm644 /dev/stdin "$arg_mountpoint/etc/systemd/system/certbot-renew.service.d/user.conf" <<-EOF
		[Service]
		User=keys
		UMask=0027
	EOF
	install -Dm644 /dev/stdin "$arg_mountpoint/etc/sudoers.d/10-certbot" <<-EOF
		keys ALL=(ALL) NOPASSWD: /etc/ssl/misc/certbot-hook
	EOF

	# Have the normal certbot-renew.service handle changing lists of domains.
	install -Dm755 /dev/stdin "$arg_mountpoint/etc/ssl/misc/certbot-init" <<-'EOF'
		#!/usr/bin/env bash

		set -eu

		if [[ "$(whoami)" != keys ]]; then
			echo "$0: this script must be run as user 'keys'" >&2
			exit 1
		fi

		cd /

		# The first name listed should be the canonical host name
		domains=(
			$(cat /etc/hostname)
			$(find -L /etc/ssl/misc/certbot-domains.d -type f -executable -exec {} \;)
		)

		cmd=(
			certbot certonly

			--keep-until-expiring # only renew if nescessary

			--non-interactive
			--agree-tos

			--cert-name "${domains[0]}"
			--email "$(whoami)@${domains[0]}"
			--webroot -w /var/lib/letsencrypt
		)

		for domain in "${domains[@]}"; do
			cmd+=(-d "$domain")
		done

		umask 0027
		"${cmd[@]}"
	EOF
	install -Dm755 /dev/stdin "$arg_mountpoint/etc/ssl/misc/certbot-renew" <<-'EOF'
		#!/usr/bin/env bash
		set -eu
		. /etc/ssl/misc/certbot-init
		sudo /etc/ssl/misc/certbot-hook
	EOF
	install -Dm644 /dev/stdin "$arg_mountpoint/etc/systemd/system/certbot-renew.service.d/10-custom.conf" <<-EOF
		# Use our wrapper script to handle changing lists of
		# domains and call our post-renew hooks.
		[Service]
		ExecStart=
		ExecStart=/etc/ssl/misc/certbot-renew

		# Add the dependencies with how we have it configured.
		[Unit]
		After=network-online.target nginx-cleartext.service
		Wants=network-online.target nginx-cleartext.service
	EOF

	systemctl --root="$arg_mountpoint" enable certbot-renew.timer

	# Create a variant service for use at system boot.
	install -Dm644 /dev/stdin "$arg_mountpoint/etc/systemd/system/certbot-init.service" <<-EOF
		[Unit]
	EOF
	install -d "$arg_mountpoint/etc/systemd/system/certbot-init.service.d"
	ln -s /usr/lib/systemd/system/certbot-renew.service "$arg_mountpoint/etc/systemd/system/certbot-init.service.d/00-base.conf"
	ln -s ../certbot-renew.service.d/10-custom.conf     "$arg_mountpoint/etc/systemd/system/certbot-init.service.d/10-custom.conf"

	########################################################################
	# Configure the main nginx to play nice                                #
	########################################################################

	install -Dm644 /dev/stdin "$arg_mountpoint"/etc/sysusers.d/nginx.conf <<-EOF
		m nginx keys
	EOF
	sed -i 's|/var/log/nginx/http\.|/var/log/nginx/https.|' "$arg_mountpoint/etc/nginx/nginx.conf"

	install -Dm644 /dev/stdin "$arg_mountpoint/etc/systemd/system/nginx.service.d/10-certbot.conf" <<-EOF
		[Unit]
		After=certbot-init.service
		Wants=certbot-init.service
	EOF

	cat >"$arg_mountpoint/etc/nginx/snippets/listen.conf" <<-'EOF'
		# -*- mode: nginx -*-
		listen 443 ssl http2;
		listen [::]:443 ssl http2;

		access_log /var/log/nginx/main-access.http.$server_name.log combined;

		# generated 2023-10-28, Mozilla Guideline v5.7, nginx 1.24.0, OpenSSL 3.1.4, intermediate configuration
		# https://ssl-config.mozilla.org/#server=nginx&version=1.24.0&config=intermediate&openssl=3.1.4&guideline=5.7

		ssl_certificate     /etc/ssl/private/myhostname/fullchain.pem;
		ssl_certificate_key /etc/ssl/private/myhostname/privkey.pem;
		ssl_session_timeout 1d;
		ssl_session_cache shared:MozSSL:10m;  # about 40000 sessions
		ssl_session_tickets off;

		ssl_dhparam /etc/ssl/private/dhparam.pem;

		# intermediate configuration
		ssl_protocols TLSv1.2 TLSv1.3;
		ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-CHACHA20-POLY1305;
		ssl_prefer_server_ciphers off;

		# HSTS (ngx_http_headers_module is required) (63072000 seconds)
		add_header Strict-Transport-Security "max-age=63072000" always;

		# OCSP stapling
		ssl_stapling on;
		ssl_stapling_verify on;

		# verify chain of trust of OCSP response using Root CA and Intermediate certs
		ssl_trusted_certificate /etc/ssl/private/myhostname/chain.pem;
	EOF

	install -Dm755 /dev/stdin "$arg_mountpoint/etc/ssl/misc/certbot-domains.d/10-nginx-auto" <<-'EOF'
		#!/bin/sh
		grep -hoE 'server_name\s+([-.a-z0-9]+)\s*;' /etc/nginx/sites/*.conf | sed -E -e 's/server_name\s+//' -e 's/\s*;//'
	EOF
	install -Dm755 /dev/stdin "$arg_mountpoint/etc/ssl/misc/certbot-hook" <<-'EOF'
		#!/bin/sh
		if systemctl is-active nginx.service; then
		    systemctl reload nginx.service
		fi
	EOF
}