local id = require "util.id";

local jid = require "util.jid";

local promise = require "util.promise";

local rm = require "core.rostermanager";

local st = require "util.stanza";

local errors = require "util.error".init(module.name, {

	["statement-not-found"] = { type = "cancel", condition = "item-not-found" };

	["statement-mismatch"] = { type = "cancel", condition = "conlict" };

});

module:hook("presence/bare", function (event)

	local origin, stanza = event.origin, event.stanza;

	if stanza.attr.type ~= "subscribe" then

		return; -- We're only interested in subscription requests

	end

	local moved = stanza:get_child("moved", "urn:xmpp:moved:1");

	if not moved then

		return; -- We're only interested in stanzas with a moved notification

	end

	local verification = stanza:get_child("moved-verification", "https://prosody.im/protocol/moved");

	if verification then

		return; -- We already attempted to verify this stanza

	end

	module:log("debug", "Received moved notification from %s", stanza.attr.from);

	local old_jid = moved:get_child_text("old-jid");

	if not old_jid then

		return; -- Failed to read old JID

	end

	local to_user = jid.node(stanza.attr.to);

	local new_jid_unverified = jid.bare(stanza.attr.from);

	if not rm.is_contact_subscribed(to_user, module.host, old_jid) then

		return; -- Old JID was not an existing contact, ignore

	end

	if rm.is_contact_pending_in(to_user, module.host, new_jid_unverified)

	or rm.is_contact_subscribed(to_user, module.host, new_jid_unverified) then

		return; -- New JID already subscribed or pending, ignore

	end

	local moved_statement_query = st.iq({ to = old_jid, type = "get", id = id.short() })

		:tag("pubsub", { xmlns = "http://jabber.org/protocol/pubsub" })

			:tag("items", { node = "urn:xmpp:moved:1" })

				:tag("item", { id = "current" }):up()

			:up()

		:up();

	-- TODO: Catch and handle <gone/> errors per note in XEP-0283.

	module:send_iq(moved_statement_query):next(function (reply)

		module:log("debug", "Statement reply: %s", reply.stanza);

		local moved_statement = reply.stanza:find("{http://jabber.org/protocol/pubsub}pubsub/items/{http://jabber.org/protocol/pubsub}item/{urn:xmpp:moved:1}moved");

		if not moved_statement then

			return promise.reject(errors.new("statement-not-found")); -- No statement found

		end

		local new_jid = jid.prep(moved_statement:get_child_text("new-jid"));

		if new_jid ~= new_jid_unverified then

			return promise.reject(errors.new("statement-mismatch")); -- Verification failed; JIDs do not match

		end

		-- Verified!

		module:log("info", "Verified moved notification <%s> -> <%s>", old_jid, new_jid);

		-- Add incoming subscription and respond

		rm.set_contact_pending_in(to_user, module.host, new_jid);

		rm.subscribed(to_user, module.host, new_jid);

		module:send(st.presence({ to = new_jid, from = to_user.."@"..module.host, type = "subscribed" }));

		rm.roster_push(to_user, module.host, new_jid);

		-- Request outgoing subscription if old JID had one

		if rm.is_user_subscribed(to_user, module.host, old_jid) then

			module:log("debug", "Requesting subscription to new JID");

			rm.set_contact_pending_out(to_user, module.host, new_jid);

			module:send(st.presence({ to = new_jid, from = to_user.."@"..module.host, type = "subscribe" }));

		end

	end):catch(function (err)

		module:log("debug", "Failed to verify moved statement for <%s> -> <%s>: %s", old_jid, new_jid_unverified, require "util.serialization".serialize(err, "debug"));

		stanza:reset()

			:tag("moved-verification", { xmlns = "https://prosody.im/protocol/moved", status = "failed" })

			:up();

		module:send(stanza, origin);

	end);

	-- Halt processing of the stanza, for now

	return true;

end, 1);