# Creates an nginx configuration file so we serve HTTP/HTTPS on all
# domains for which a mail account has been set up.
########################################################################

import os, os.path, re, rtyaml

from mailconfig import get_mail_domains
from dns_update import get_custom_dns_config
from utils import shell, safe_domain_name, sort_domains

def get_web_domains(env):
	# What domains should we serve websites for?
	domains = set()

	# At the least it's the PRIMARY_HOSTNAME so we can serve webmail
	# as well as Z-Push for Exchange ActiveSync.
	domains.add(env['PRIMARY_HOSTNAME'])

	# Also serve web for all mail domains so that we might at least
	# provide Webfinger and ActiveSync auto-discover of email settings
	# (though the latter isn't really working). These will require that
	# an SSL cert be installed.
	domains |= get_mail_domains(env)

	# ...Unless the domain has an A/AAAA record that maps it to a different
	# IP address than this box. Remove those domains from our list.
	dns = get_custom_dns_config(env)
	for domain, value in dns.items():
		if domain not in domains: continue
		if (isinstance(value, str) and (value != "local")) \
		  or (isinstance(value, dict) and ("A" in value) and (value["A"] != "local")) \
		  or (isinstance(value, dict) and ("AAAA" in value) and (value["AAAA"] != "local")):
			domains.remove(domain)

	# Sort the list. Put PRIMARY_HOSTNAME first so it becomes the
	# default server (nginx's default_server).
	domains = sort_domains(domains, env)

	return domains
	
def do_web_update(env):
	# Build an nginx configuration file.
	nginx_conf = open(os.path.join(os.path.dirname(__file__), "../conf/nginx-top.conf")).read()

	# Add configuration for each web domain.
	template1 = open(os.path.join(os.path.dirname(__file__), "../conf/nginx.conf")).read()
	template2 = open(os.path.join(os.path.dirname(__file__), "../conf/nginx-primaryonly.conf")).read()
	for domain in get_web_domains(env):
		nginx_conf += make_domain_config(domain, template1, template2, env)

	# Did the file change? If not, don't bother writing & restarting nginx.
	nginx_conf_fn = "/etc/nginx/conf.d/local.conf"
	if os.path.exists(nginx_conf_fn):
		with open(nginx_conf_fn) as f:
			if f.read() == nginx_conf:
				return ""

	# Save the file.
	with open(nginx_conf_fn, "w") as f:
		f.write(nginx_conf)

	# Kick nginx.
	shell('check_call', ["/usr/sbin/service", "nginx", "restart"])

	return "web updated\n"

def make_domain_config(domain, template, template_for_primaryhost, env):
	# How will we configure this domain.

	# Where will its root directory be for static files?

	root = get_web_root(domain, env)

	# What private key and SSL certificate will we use for this domain?
	ssl_key, ssl_certificate, csr_path = get_domain_ssl_files(domain, env)

	# For hostnames created after the initial setup, ensure we have an SSL certificate
	# available. Make a self-signed one now if one doesn't exist.
	ensure_ssl_certificate_exists(domain, ssl_key, ssl_certificate, csr_path, env)

	# Put pieces together.
	nginx_conf_parts = re.split("\s*# ADDITIONAL DIRECTIVES HERE\s*", template)
	nginx_conf = nginx_conf_parts[0] + "\n"
	if domain == env['PRIMARY_HOSTNAME']:
		nginx_conf += template_for_primaryhost + "\n"

	# Replace substitution strings in the template & return.
	nginx_conf = nginx_conf.replace("$STORAGE_ROOT", env['STORAGE_ROOT'])
	nginx_conf = nginx_conf.replace("$HOSTNAME", domain)
	nginx_conf = nginx_conf.replace("$ROOT", root)
	nginx_conf = nginx_conf.replace("$SSL_KEY", ssl_key)
	nginx_conf = nginx_conf.replace("$SSL_CERTIFICATE", ssl_certificate)

	# Add in any user customizations.
	nginx_conf_custom_fn = os.path.join(env["STORAGE_ROOT"], "www/custom.yaml")
	if os.path.exists(nginx_conf_custom_fn):
		yaml = rtyaml.load(open(nginx_conf_custom_fn))
		if domain in yaml:
			yaml = yaml[domain]
			if "proxy" in yaml:
				nginx_conf += "\tlocation / {\n\t\tproxy_pass %s;\n\t}\n" % yaml["proxy"]

	# Ending.
	nginx_conf += nginx_conf_parts[1]

	return nginx_conf

def get_web_root(domain, env):
	# Try STORAGE_ROOT/web/domain_name if it exists, but fall back to STORAGE_ROOT/web/default.
	for test_domain in (domain, 'default'):
		root = os.path.join(env["STORAGE_ROOT"], "www", safe_domain_name(test_domain))
		if os.path.exists(root): break
	return root

def get_domain_ssl_files(domain, env):
	# What SSL private key will we use? Allow the user to override this, but
	# in many cases using the same private key for all domains would be fine.
	# Don't allow the user to override the key for PRIMARY_HOSTNAME because
	# that's what's in the main file.
	ssl_key = os.path.join(env["STORAGE_ROOT"], 'ssl/ssl_private_key.pem')
	ssl_key_is_alt = False
	alt_key = os.path.join(env["STORAGE_ROOT"], 'ssl/%s/private_key.pem' % safe_domain_name(domain))
	if domain != env['PRIMARY_HOSTNAME'] and os.path.exists(alt_key):
		ssl_key = alt_key
		ssl_key_is_alt = True

	# What SSL certificate will we use?
	ssl_certificate_primary = os.path.join(env["STORAGE_ROOT"], 'ssl/ssl_certificate.pem')
	if domain == env['PRIMARY_HOSTNAME']:
		# For PRIMARY_HOSTNAME, use the one we generated at set-up time.
		ssl_certificate = ssl_certificate_primary
	else:
		# For other domains, we'll probably use a certificate in a different path.
		ssl_certificate = os.path.join(env["STORAGE_ROOT"], 'ssl/%s/ssl_certificate.pem' % safe_domain_name(domain))

		# But we can be smart and reuse the main SSL certificate if is has
		# a Subject Alternative Name matching this domain. Don't do this if
		# the user has uploaded a different private key for this domain.
		if not ssl_key_is_alt:
			from whats_next import check_certificate
			if check_certificate(domain, ssl_certificate_primary, None) == "OK":
				ssl_certificate = ssl_certificate_primary

	# Where would the CSR go? As with the SSL cert itself, the CSR must be
	# different for each domain name.
	if domain == env['PRIMARY_HOSTNAME']:
		csr_path = os.path.join(env["STORAGE_ROOT"], 'ssl/ssl_cert_sign_req.csr')
	else:
		csr_path = os.path.join(env["STORAGE_ROOT"], 'ssl/%s/certificate_signing_request.csr' % safe_domain_name(domain))

	return ssl_key, ssl_certificate, csr_path

def ensure_ssl_certificate_exists(domain, ssl_key, ssl_certificate, csr_path, env):
	# For domains besides PRIMARY_HOSTNAME, generate a self-signed certificate if
	# a certificate doesn't already exist. See setup/mail.sh for documentation.

	if domain == env['PRIMARY_HOSTNAME']:
		return

	# Sanity check. Shouldn't happen. A non-primary domain might use this
	# certificate (see above), but then the certificate should exist anyway.
	if ssl_certificate == os.path.join(env["STORAGE_ROOT"], 'ssl/ssl_certificate.pem'):
		return

	if os.path.exists(ssl_certificate):
		return

	os.makedirs(os.path.dirname(ssl_certificate), exist_ok=True)

	# Generate a new self-signed certificate using the same private key that we already have.

	# Start with a CSR.
	shell("check_call", [
		"openssl", "req", "-new",
		"-key", ssl_key,
		"-out",  csr_path,
		"-subj", "/C=%s/ST=/L=/O=/CN=%s" % (env["CSR_COUNTRY"], domain)])

	# And then make the certificate.
	shell("check_call", [
		"openssl", "x509", "-req",
		"-days", "365",
		"-in", csr_path,
		"-signkey", ssl_key,
		"-out", ssl_certificate])