Validate input

init.lua

@@ -4,25 +4,37 @@ end
 
 minetest.register_chatcommand("report", {
 	func = function(name, param)
+		param = param:trim()
+		if param == "" then
+			return false, "Please add a message to your report. " ..
+				"If it's about (a) particular player(s), please also include their name(s)."
+		end
+		local _, count = string.gsub(param, " ", "")
+		if count == 0 then
+			minetest.chat_send_player(name, "If you're reporting a player, " ..
+				"you should also include a reason why. (Eg: swearing, sabotage)")
+		end
+
 		-- Send to online moderators / admins
 		-- Get comma separated list of online moderators and admins
-		local mods = ""
+		local mods = {}
 		for _, player in pairs(minetest.get_connected_players()) do
 			local name = player:get_player_name()
-			if minetest.check_player_privs(name, {kick=true,ban=true}) then
-				if mods ~= "" then
-					mods = mods .. ", "
-				end
-				mods = mods .. name
+			if minetest.check_player_privs(name, {kick = true, ban = true}) then
+				table.insert(mods, name)
 				minetest.chat_send_player(name, "-!- " .. name .. " reported: " .. param)
 			end
 		end
-		
-		-- I hope that none of the moderators are called "none"!
-		if mods == "" then
-			mods = "none"
+
+		if #mods > 0 then
+			mod_list = table.concat(mods, ", ")
+			chatplus.send_mail(name, minetest.setting_get("name"),
+				"Report: " .. param .. " (mods online: " .. mod_list .. ")")
+			return true, "Reported. Moderators currently online: " .. mod_list
+		else
+			chatplus.send_mail(name, minetest.setting_get("name"),
+				"Report: " .. param .. " (no mods online)")
+			return true, "Reported. We'll get back to you."
 		end
-		chatplus.send_mail(name, minetest.setting_get("name"),
-			"Report: " .. param .. " (mods online: " .. mods .. ")")
 	end
 })