local pairs = pairs;
local setmetatable = setmetatable;
local st = require "prosody.util.stanza";
local util = module:require "muc/util";

local function get_filtered_presence(stanza)
	return util.filter_muc_x(st.clone(stanza));
end

local occupant_mt = {};
occupant_mt.__index = occupant_mt;

local function new_occupant(bare_real_jid, nick)
	return setmetatable({
		bare_jid = bare_real_jid;
		nick = nick; -- in-room jid
		sessions = {}; -- hash from real_jid to presence stanzas. stanzas should not be modified
		role = nil;
		jid = nil; -- Primary session
	}, occupant_mt);
end

-- Deep copy an occupant
local function copy_occupant(occupant)
	local sessions = {};
	for full_jid, session in pairs(occupant.sessions) do
		local presence_stanza = session.presence;
		-- Don't keep unavailable presences, as they'll accumulate; unless they're the primary session
		if presence_stanza.attr.type ~= "unavailable" or full_jid == occupant.jid then
			sessions[full_jid] = session;
		end
	end
	return setmetatable({
		bare_jid = occupant.bare_jid;
		nick = occupant.nick;
		sessions = sessions;
		role = occupant.role;
		jid = occupant.jid;
	}, occupant_mt);
end

-- finds another session to be the primary (there might not be one)
function occupant_mt:choose_new_primary()
	for jid, pr in self:each_session() do
		if pr.attr.type == nil then
			return jid;
		end
	end
	return nil;
end

function occupant_mt:get_session(real_jid)
	return self.sessions[real_jid];
end

function occupant_mt:set_session(real_jid, presence_stanza, replace_primary)
	local pr = get_filtered_presence(presence_stanza);
	pr.attr.from = self.nick;
	pr.attr.to = real_jid;

	self.sessions[real_jid] = { presence = pr };
	if replace_primary then
		self.jid = real_jid;
	elseif self.jid == nil or (pr.attr.type == "unavailable" and self.jid == real_jid) then
		-- Only leave an unavailable presence as primary when there are no other options
		self.jid = self:choose_new_primary() or real_jid;
	end
end

function occupant_mt:remove_session(real_jid)
	-- Delete original session
	self.sessions[real_jid] = nil;
	if self.jid == real_jid then
		self.jid = self:choose_new_primary();
	end
end

-- An iterator over self.sessions that returns (jid, presence, session)
local function _session_iter(s, var)
	local k = next(s, var);
	if k then
		local v = s[k];
		return k, v.presence, v;
	end
end

function occupant_mt:each_session()
	return _session_iter, self.sessions;
end

function occupant_mt:get_presence(real_jid)
	local session = self.sessions[real_jid or self.jid];
	if not session then return; end
	return session.presence;
end

return {
	new = new_occupant;
	copy = copy_occupant;
	mt = occupant_mt;
}