local lfs = require "lfs";

local pctl = require "util.prosodyctl";

local configmanager = require "core.configmanager";

local openssl;

local cert_commands = {};

-- If a file already exists, ask if the user wants to use it or replace it

-- Backups the old file if replaced

local function use_existing(filename)

	local attrs = lfs.attributes(filename);

	if attrs then

		if pctl.show_yesno(filename .. " exists, do you want to replace it? [y/n]") then

			local backup = filename..".bkp~"..os.date("%FT%T", attrs.change);

			os.rename(filename, backup);

			pctl.show_message("%s backed up to %s", filename, backup);

		else

			-- Use the existing file

			return true;

		end

	end

end

local have_pposix, pposix = pcall(require, "util.pposix");

local cert_basedir = prosody.paths.data == "." and "./certs" or prosody.paths.data;

if have_pposix and pposix.getuid() == 0 then

	-- FIXME should be enough to check if this directory is writable

	local cert_dir = configmanager.get("*", "certificates") or "certs";

	cert_basedir = configmanager.resolve_relative_path(prosody.paths.config, cert_dir);

end

function cert_commands.config(arg)

	if #arg >= 1 and arg[1] ~= "--help" then

		local conf_filename = cert_basedir .. "/" .. arg[1] .. ".cnf";

		if use_existing(conf_filename) then

			return nil, conf_filename;

		end

		local distinguished_name;

		if arg[#arg]:find("^/") then

			distinguished_name = table.remove(arg);

		end

		local conf = openssl.config.new();

		conf:from_prosody(prosody.hosts, configmanager, arg);

		if distinguished_name then

			local dn = {};

			for k, v in distinguished_name:gmatch("/([^=/]+)=([^/]+)") do

				table.insert(dn, k);

				dn[k] = v;

			end

			conf.distinguished_name = dn;

		else

			pctl.show_message("Please provide details to include in the certificate config file.");

			pctl.show_message("Leave the field empty to use the default value or '.' to exclude the field.")

			for _, k in ipairs(openssl._DN_order) do

				local v = conf.distinguished_name[k];

				if v then

					local nv = nil;

					if k == "commonName" then

						v = arg[1]

					elseif k == "emailAddress" then

						v = "xmpp@" .. arg[1];

					elseif k == "countryName" then

						local tld = arg[1]:match"%.([a-z]+)$";

						if tld and #tld == 2 and tld ~= "uk" then

							v = tld:upper();

						end

					end

					nv = pctl.show_prompt(("%s (%s):"):format(k, nv or v));

					nv = (not nv or nv == "") and v or nv;

					if nv:find"[\192-\252][\128-\191]+" then

						conf.req.string_mask = "utf8only"

					end

					conf.distinguished_name[k] = nv ~= "." and nv or nil;

				end

			end

		end

		local conf_file, err = io.open(conf_filename, "w");

		if not conf_file then

			pctl.show_warning("Could not open OpenSSL config file for writing");

			pctl.show_warning(err);

			os.exit(1);

		end

		conf_file:write(conf:serialize());

		conf_file:close();

		print("");

		pctl.show_message("Config written to %s", conf_filename);

		return nil, conf_filename;

	else

		pctl.show_usage("cert config HOSTNAME [HOSTNAME+]", "Builds a certificate config file covering the supplied hostname(s)")

	end

end

function cert_commands.key(arg)

	if #arg >= 1 and arg[1] ~= "--help" then

		local key_filename = cert_basedir .. "/" .. arg[1] .. ".key";

		if use_existing(key_filename) then

			return nil, key_filename;

		end

		os.remove(key_filename); -- This file, if it exists is unlikely to have write permissions

		local key_size = tonumber(arg[2] or pctl.show_prompt("Choose key size (2048):") or 2048);

		local old_umask = pposix.umask("0377");

		if openssl.genrsa{out=key_filename, key_size} then

			os.execute(("chmod 400 '%s'"):format(key_filename));

			pctl.show_message("Key written to %s", key_filename);

			pposix.umask(old_umask);

			return nil, key_filename;

		end

		pctl.show_message("There was a problem, see OpenSSL output");

	else

		pctl.show_usage("cert key HOSTNAME <bits>", "Generates a RSA key named HOSTNAME.key\n "

		.."Prompts for a key size if none given")

	end

end

function cert_commands.request(arg)

	if #arg >= 1 and arg[1] ~= "--help" then

		local req_filename = cert_basedir .. "/" .. arg[1] .. ".req";

		if use_existing(req_filename) then

			return nil, req_filename;

		end

		local _, key_filename = cert_commands.key({arg[1]});

		local _, conf_filename = cert_commands.config(arg);

		if openssl.req{new=true, key=key_filename, utf8=true, sha256=true, config=conf_filename, out=req_filename} then

			pctl.show_message("Certificate request written to %s", req_filename);

		else

			pctl.show_message("There was a problem, see OpenSSL output");

		end

	else

		pctl.show_usage("cert request HOSTNAME [HOSTNAME+]", "Generates a certificate request for the supplied hostname(s)")

	end

end

function cert_commands.generate(arg)

	if #arg >= 1 and arg[1] ~= "--help" then

		local cert_filename = cert_basedir .. "/" .. arg[1] .. ".crt";

		if use_existing(cert_filename) then

			return nil, cert_filename;

		end

		local _, key_filename = cert_commands.key({arg[1]});

		local _, conf_filename = cert_commands.config(arg);

		if key_filename and conf_filename and cert_filename

			and openssl.req{new=true, x509=true, nodes=true, key=key_filename,

				days=365, sha256=true, utf8=true, config=conf_filename, out=cert_filename} then

			pctl.show_message("Certificate written to %s", cert_filename);

			print();

		else

			pctl.show_message("There was a problem, see OpenSSL output");

		end

	else

		pctl.show_usage("cert generate HOSTNAME [HOSTNAME+]", "Generates a self-signed certificate for the current hostname(s)")

	end

end

local function sh_esc(s)

	return "'" .. s:gsub("'", "'\\''") .. "'";

end

local function copy(from, to, umask, owner, group)

	local old_umask = umask and pposix.umask(umask);

	local attrs = lfs.attributes(to);

	if attrs then -- Move old file out of the way

		local backup = to..".bkp~"..os.date("%FT%T", attrs.change);

		os.rename(to, backup);

	end

	-- FIXME friendlier error handling, maybe move above backup back?

	local input = assert(io.open(from));

	local output = assert(io.open(to, "w"));

	local data = input:read(2^11);

	while data and output:write(data) do

		data = input:read(2^11);

	end

	assert(input:close());

	assert(output:close());

	if not prosody.installed then

		-- FIXME this is possibly specific to GNU chown

		os.execute(("chown -c --reference=%s %s"):format(sh_esc(cert_basedir), sh_esc(to)));

	elseif owner and group then

		local ok = os.execute(("chown %s:%s %s"):format(sh_esc(owner), sh_esc(group), sh_esc(to)));

		assert(ok == true or ok == 0, "Failed to change ownership of "..to);

	end

	if old_umask then pposix.umask(old_umask); end

	return true;

end

function cert_commands.import(arg)

	local hostnames = {};

	-- Move hostname arguments out of arg, the rest should be a list of paths

	while arg[1] and prosody.hosts[ arg[1] ] do

		table.insert(hostnames, table.remove(arg, 1));

	end

	if hostnames[1] == nil then

		local domains = os.getenv"RENEWED_DOMAINS"; -- Set if invoked via certbot

		if domains then

			for host in domains:gmatch("%S+") do

				table.insert(hostnames, host);

			end

		else

			for host in pairs(prosody.hosts) do

				if host ~= "*" and configmanager.get(host, "enabled") ~= false then

					table.insert(hostnames, host);

				end

			end

		end

	end

	if not arg[1] or arg[1] == "--help" then -- Probably forgot the path

		pctl.show_usage("cert import [HOSTNAME+] /path/to/certs [/other/paths/]+",

			"Copies certificates to "..cert_basedir);

		return 1;

	end

	local owner, group;

	if pposix.getuid() == 0 then -- We need root to change ownership

		owner = configmanager.get("*", "prosody_user") or "prosody";

		group = configmanager.get("*", "prosody_group") or owner;

	end

	local cm = require "core.certmanager";

	local imported = {};

	for _, host in ipairs(hostnames) do

		for _, dir in ipairs(arg) do

			local paths = cm.find_cert(dir, host);

			if paths then

				copy(paths.certificate, cert_basedir .. "/" .. host .. ".crt", nil, owner, group);

				copy(paths.key, cert_basedir .. "/" .. host .. ".key", "0377", owner, group);

				table.insert(imported, host);

			else

				-- TODO Say where we looked

				pctl.show_warning("No certificate for host "..host.." found :(");

			end

			-- TODO Additional checks

			-- Certificate names matches the hostname

			-- Private key matches public key in certificate

		end

	end

	if imported[1] then

		pctl.show_message("Imported certificate and key for hosts %s", table.concat(imported, ", "));

		local ok, err = pctl.reload();

		if not ok and err ~= "not-running" then

			pctl.show_message(pctl.error_messages[err]);

		end

	else

		pctl.show_warning("No certificates imported :(");

		return 1;

	end

end

local function cert(arg)

	if #arg >= 1 and arg[1] ~= "--help" then

		openssl = require "util.openssl";

		lfs = require "lfs";

		local cert_dir_attrs = lfs.attributes(cert_basedir);

		if not cert_dir_attrs then

			pctl.show_warning("The directory "..cert_basedir.." does not exist");

			return 1; -- TODO Should we create it?

		end

		local uid = pposix.getuid();

		if uid ~= 0 and uid ~= cert_dir_attrs.uid then

			pctl.show_warning("The directory "..cert_basedir.." is not owned by the current user, won't be able to write files to it");

			return 1;

		elseif not cert_dir_attrs.permissions then -- COMPAT with LuaFilesystem < 1.6.2 (hey CentOS!)

			pctl.show_message("Unable to check permissions on %s (LuaFilesystem 1.6.2+ required)", cert_basedir);

			pctl.show_message("Please confirm that Prosody (and only Prosody) can write to this directory)");

		elseif cert_dir_attrs.permissions:match("^%.w..%-..%-.$") then

			pctl.show_warning("The directory "..cert_basedir.." not only writable by its owner");

			return 1;

		end

		local subcmd = table.remove(arg, 1);

		if type(cert_commands[subcmd]) == "function" then

			if subcmd ~= "import" then -- hostnames are optional for import

				if not arg[1] then

					pctl.show_message"You need to supply at least one hostname"

					arg = { "--help" };

				end

				if arg[1] ~= "--help" and not prosody.hosts[arg[1]] then

					pctl.show_message(pctl.error_messages["no-such-host"]);

					return 1;

				end

			end

			return cert_commands[subcmd](arg);

		elseif subcmd == "check" then

			return require "util.prosodyctl.check".check({"certs"});

		end

	end

	pctl.show_usage("cert config|request|generate|key|import", "Helpers for generating X.509 certificates and keys.")

	for _, cmd in pairs(cert_commands) do

		print()

		cmd{ "--help" }

	end

end

return {

	cert = cert;

};