local id = require "util.id";

local url = require "socket.url";

local jid_node = require "util.jid".node;

local invite_ttl = module:get_option_number("invite_expiry", 86400 * 7);

local token_storage = module:open_store("invite_token", "map");

local function get_uri(action, jid, token, params) --> string

	return url.build({

			scheme = "xmpp",

			path = jid,

			query = action..";preauth="..token..(params and (";"..params) or ""),

		});

end

local function create_invite(invite_action, invite_jid, allow_registration)

	local token = id.medium();

	local created_at = os.time();

	local expires = created_at + invite_ttl;

	local invite_params = (invite_action == "roster" and allow_registration) and "ibr=y" or nil;

	local invite = {

		type = invite_action;

		jid = invite_jid;

		token = token;

		allow_registration = allow_registration;

		uri = get_uri(invite_action, invite_jid, token, invite_params);

		created_at = created_at;

		expires = expires;

	};

	module:fire_event("invite-created", invite);

	if allow_registration then

		local ok, err = token_storage:set(nil, token, invite);

		if not ok then

			module:log("warn", "Failed to store account invite: %s", err);

			return nil, "internal-server-error";

		end

	end

	if invite_action == "roster" then

		local username = jid_node(invite_jid);

		local ok, err = token_storage:set(username, token, expires);

		if not ok then

			module:log("warn", "Failed to store subscription invite: %s", err);

			return nil, "internal-server-error";

		end

	end

	return invite;

end

-- Create invitation to register an account (optionally restricted to the specified username)

function create_account(account_username) --luacheck: ignore 131/create_account

	local jid = account_username and (account_username.."@"..module.host) or module.host;

	return create_invite("register", jid, true);

end

-- Create invitation to become a contact of a local user

function create_contact(username, allow_registration) --luacheck: ignore 131/create_contact

	return create_invite("roster", username.."@"..module.host, allow_registration);

end

local valid_invite_methods = {};

local valid_invite_mt = { __index = valid_invite_methods };

function valid_invite_methods:use()

	if self.username then

		-- Also remove the contact invite if present, on the

		-- assumption that they now have a mutual subscription

		token_storage:set(self.username, self.token, nil);

	end

	token_storage:set(nil, self.token, nil);

	return true;

end

-- Get a validated invite (or nil, err). Must call :use() on the

-- returned invite after it is actually successfully used

-- For "roster" invites, the username of the local user (who issued

-- the invite) must be passed.

-- If no username is passed, but the registration is a roster invite

-- from a local user, the "inviter" field of the returned invite will

-- be set to their username.

function get(token, username)

	if not token then

		return nil, "no-token";

	end

	local valid_until, inviter;

	if username then -- token being used for subscription

		-- Fetch from user store (subscription invite)

		valid_until = token_storage:get(username, token);

	else -- token being used for account creation

		-- Fetch from host store (account invite)

		local token_info = token_storage:get(nil, token);

		valid_until = token_info and token_info.expires;

		if token_info.type == "roster" then

			username = jid_node(token_info.jid);

			inviter = username;

		end

	end

	if not valid_until then

		module:log("debug", "Got unknown token: %s", token);

		return nil, "token-invalid";

	elseif os.time() > valid_until then

		module:log("debug", "Got expired token: %s", token);

		return nil, "token-expired";

	end

	return setmetatable({

		token = token;

		username = username;

		inviter = inviter;

	}, valid_invite_mt);

end

function use(token) --luacheck: ignore 131/use

	local invite = get(token);

	return invite and invite:use();

end