module("pubsub", package.seeall);

local service = {};

local service_mt = { __index = service };

local default_config = {

	broadcaster = function () end;

	get_affiliation = function () end;

	capabilities = {};

};

function new(config)

	config = config or {};

	return setmetatable({

		config = setmetatable(config, { __index = default_config });

		affiliations = {};

		nodes = {};

	}, service_mt);

end

function service:may(node, actor, action)

	if actor == true then return true; end

	local node_obj = self.nodes[node];

	local node_aff = node_obj and node_obj.affiliations[actor];

	local service_aff = self.affiliations[actor]

	                 or self.config.get_affiliation(actor, node, action)

	                 or "none";

	local node_capabilities = node_obj and node_obj.capabilities;

	local service_capabilities = self.config.capabilities;

	-- Check if node allows/forbids it	

	if node_capabilities then

		local caps = node_capabilities[node_aff or service_aff];

		if caps then

			local can = caps[action];

			if can ~= nil then

				return can;

			end

		end

	end

	-- Check service-wide capabilities instead

	local caps = service_capabilities[node_aff or service_aff];

	if caps then

		local can = caps[action];

		if can ~= nil then

			return can;

		end

	end

	return false;

end

function service:set_affiliation(node, actor, jid, affiliation)

	-- Access checking

	if not self:may(node, actor, "set_affiliation") then

		return false, "forbidden";

	end

	--

	local node_obj = self.nodes[node];

	if not node_obj then

		return false, "item-not-found";

	end

	node_obj.affiliations[jid] = affiliation;

	local _, jid_sub = self:get_subscription(node, nil, jid);

	if not jid_sub and not self:may(node, jid, "be_unsubscribed") then

		local ok, err = self:add_subscription(node, nil, jid);

		if not ok then

			return ok, err;

		end

	elseif jid_sub and not self:may(node, jid, "be_subscribed") then

		local ok, err = self:add_subscription(node, nil, jid);

		if not ok then

			return ok, err;

		end

	end

	return true;

end

function service:add_subscription(node, actor, jid, options)

	-- Access checking

	local cap;

	if jid == actor or self.config.jids_equal(actor, jid) then

		cap = "subscribe";

	else

		cap = "subscribe_other";

	end

	if not self:may(node, actor, cap) then

		return false, "forbidden";

	end

	if not self:may(node, jid, "be_subscribed") then

		return false, "forbidden";

	end

	--

	local node_obj = self.nodes[node];

	if not node_obj then

		if not self.config.autocreate_on_subscribe then

			return false, "item-not-found";

		else

			local ok, err = self:create(node, actor);

			if not ok then

				return ok, err;

			end

		end

	end

	node_obj.subscribers[jid] = options or true;

	return true;

end

function service:remove_subscription(node, actor, jid)

	-- Access checking

	local cap;

	if jid == actor or self.config.jids_equal(actor, jid) then

		cap = "unsubscribe";

	else

		cap = "unsubscribe_other";

	end

	if not self:may(node, actor, cap) then

		return false, "forbidden";

	end

	if not self:may(node, jid, "be_unsubscribed") then

		return false, "forbidden";

	end

	--

	local node_obj = self.nodes[node];

	if not node_obj then

		return false, "item-not-found";

	end

	if not node_obj.subscribers[jid] then

		return false, "not-subscribed";

	end

	node_obj.subscribers[jid] = nil;

	return true;

end

function service:get_subscription(node, actor, jid)

	-- Access checking

	local cap;

	if jid == actor or self.config.jids_equal(actor, jid) then

		cap = "get_subscription";

	else

		cap = "get_subscription_other";

	end

	if not self:may(node, actor, cap) then

		return false, "forbidden";

	end

	--

	local node_obj = self.nodes[node];

	if node_obj then

		return true, node_obj.subscribers[jid];

	end

end

function service:create(node, actor)

	-- Access checking

	if not self:may(node, actor, "create") then

		return false, "forbidden";

	end

	--

	if self.nodes[node] then

		return false, "conflict";

	end

	self.nodes[node] = {

		name = node;

		subscribers = {};

		config = {};

		data = {};

		affiliations = {};

	};

	local ok, err = self:set_affiliation(node, true, actor, "owner");

	if not ok then

		self.nodes[node] = nil;

	end

	return ok, err;

end

function service:publish(node, actor, id, item)

	-- Access checking

	if not self:may(node, actor, "publish") then

		return false, "forbidden";

	end

	--

	local node_obj = self.nodes[node];

	if not node_obj then

		if not self.config.autocreate_on_publish then

			return false, "item-not-found";

		end

		local ok, err = self:create(node, actor);

		if not ok then

			return ok, err;

		end

		node_obj = self.nodes[node];

	end

	node_obj.data[id] = item;

	self.config.broadcaster(node, node_obj.subscribers, item);

	return true;

end

function service:retract(node, actor, id, retract)

	-- Access checking

	if not self:may(node, actor, "retract") then

		return false, "forbidden";

	end

	--

	local node_obj = self.nodes[node];

	if (not node_obj) or (not node_obj.data[id]) then

		return false, "item-not-found";

	end

	node_obj.data[id] = nil;

	if retract then

		self.config.broadcaster(node, node_obj.subscribers, retract);

	end

	return true

end

function service:get_items(node, actor, id)

	-- Access checking

	if not self:may(node, actor, "get_items") then

		return false, "forbidden";

	end

	--

	local node_obj = self.nodes[node];

	if not node_obj then

		return false, "item-not-found";

	end

	if id then -- Restrict results to a single specific item

		return true, { node_obj.data[id] };

	else

		return true, node_obj.data;

	end

end

function service:get_nodes(actor)

	-- Access checking

		return false, "forbidden";

	end

	--

	return true, self.nodes;

end

return _M;