Add substitutes

init.lua

@@ -37,6 +37,46 @@ local get_commands = function(itemstack)
 	return cmds
 end
 
+--[[ Takes a command and substitutes placeholders like “@playername” with the actual values.
+This operation might fail.
+Returns the substituted command on success.
+Returns false on failure. ]]
+local substitute_placeholders = function(command, itemstack, player, pointed_thing)
+	local pos_pt, pos_pl
+	pos_pl = player:get_pos()
+	if pointed_thing.type == "node" then
+		pos_pt = pointed_thing.under
+
+		command = string.gsub(command, "@ptx", pos_pt.x)
+		command = string.gsub(command, "@pty", pos_pt.y)
+		command = string.gsub(command, "@ptz", pos_pt.z)
+
+		local node = minetest.get_node(pos_pt)
+		command = string.gsub(command, "@nodename", node.name)
+		command = string.gsub(command, "@param2", node.param2)
+	else
+		-- If one of the coordinate parameters is in the command, but
+		-- the pointed thing is not a node, we have to fail as the placeholders
+		-- are meaningless.
+		local coord = {"@ptx", "@pty", "@ptz", "@nodename", "@param2", "@light"}
+		for c=1, #coord do
+			if string.find(command, coord[c]) ~= nil then
+				return false
+			end
+		end
+	end
+
+	command = string.gsub(command, "@plx", pos_pl.x)
+	command = string.gsub(command, "@ply", pos_pl.y)
+	command = string.gsub(command, "@plz", pos_pl.z)
+
+	command = string.gsub(command, "@playername", player:get_player_name())
+
+	command = string.gsub(command, "@@", "@")
+
+	return command
+end
+
 local execute_command = function(itemstack, player, pointed_thing)
 	local player_name = player:get_player_name()
 	local cmds = get_commands(itemstack)
@@ -46,6 +86,7 @@ local execute_command = function(itemstack, player, pointed_thing)
 	local player_privs = minetest.get_player_privs(player_name)
 	for c=1, #cmds do
 		local cmd = cmds[1]
+		-- Substitution successful?
 		-- Split command string into command name and parameters
 		local cmd_split = string.split(cmd, " ", false, 1)
 		local cmd_name
@@ -59,18 +100,25 @@ local execute_command = function(itemstack, player, pointed_thing)
 			if cmd_split[2] then
 				cmd_params = cmd_split[2]
 			end
+			cmd_params = substitute_placeholders(cmd_params, itemstack, player, pointed_thing)
 			local def = minetest.registered_chatcommands[cmd_name]
+			-- Command exists? Placeholder substitution successful?
 			if def then
-				local required_privs = def.privs
-				for priv, _ in pairs(required_privs) do
-					if player_privs[priv] ~= true then
-						minetest.chat_send_player(player_name, "Insufficient privileges for using command “"..cmd_name.."”! You need the “"..priv.."” privilege.")
-						return
+				if cmd_params then
+					local required_privs = def.privs
+					for priv, _ in pairs(required_privs) do
+						if player_privs[priv] ~= true then
+							minetest.chat_send_player(player_name, "Insufficient privileges for using command “"..cmd_name.."”! You need the “"..priv.."” privilege.")
+							return
+						end
 					end
+					-- All tests survived!
+					-- Call the command
+					def.func(player_name, cmd_params)
+				else
+					-- TODO: Rewrite error msg
+					minetest.chat_send_player(player_name, "Placeholders in command “"..cmd_name.."” do not apply!")
 				end
-				-- All tests survived!
-				-- Call the command
-				def.func(player_name, cmd_params)
 			else
 				minetest.chat_send_player(player_name, "The command “"..cmd_name.."” does not exist!")
 				return