Add /themes and /set_theme commands

Allowing the user to set their preferred theme!

init.lua

@@ -15,17 +15,22 @@
 
 fs_themes = {}
 fs_themes.themes = {}
-fs_themes.modpath = minetest.get_modpath(minetest.get_current_modname())
 
+local storage = minetest.get_mod_storage()
+local modpath = minetest.get_modpath(minetest.get_current_modname())
 
 -- Set a player’s theme by a registered theme’s name.
-function fs_themes.set_theme(player, theme_name)
+-- If dont_save is provided, the player’s default theme won’t change.
+function fs_themes.set_theme(player, theme_name, dont_save)
 	if not fs_themes.themes[theme_name] then
 		minetest.log("warning", string.format("Theme “%s” was not found.", theme_name))
-		return
+		return false
+	elseif not dont_save then
+		storage:set_string(player:get_player_name(), theme_name)
 	end
 
 	player:set_formspec_prepend(fs_themes.themes[theme_name])
+	return true
 end
 
 
@@ -34,25 +39,82 @@ function fs_themes.register_theme(name, formspecs_file_path)
 	local fs_file, open_err = io.open(formspecs_file_path, "r")
 	if fs_file == nil then
 		minetest.log("warning", string.format("Theme “%s” could not be opened: %s", name, open_err))
-		return
+		return false
 	end
 
 	local fs_file_contents = fs_file:read("*all")
 	fs_themes.themes[name] = fs_file_contents
+	return true
 end
 
 
--- Whenever a play joins, set their formspecs theme.
+minetest.register_chatcommand(
+	"themes",
+	{
+		description = "Lists available GUI (Formspecs) themes.",
+		func = function(name, param)
+			local ret = nil
+			for name,fs in pairs(fs_themes.themes) do
+				if ret == nil then
+					ret = name
+				else
+					ret = ret .. ", " .. name
+				end
+			end
+
+			if ret == nil then
+				ret = "No themes are installed!"
+			end
+
+			return true, ret
+		end
+	}
+)
+
+
+minetest.register_chatcommand(
+	"set_theme",
+	{
+		params = "<theme_name>",
+		description = "Sets your theme for GUI (Formspecs) windows.",
+		func = function(name, param)
+			if fs_themes.set_theme(minetest.get_player_by_name(name), param) then
+				return true, "Theme set!"
+			elseif param ~= "" then
+				return false, string.format("No such theme “%s”.", param)
+			else
+				return false
+			end
+		end
+	}
+)
+
+
+-- Whenever a player joins, set their formspecs theme.
 minetest.register_on_joinplayer(
 	function(player)
+		local player_name = player:get_player_name()
 		local default_theme = minetest.settings:get("fs_default_theme") or "restaurant"
-		fs_themes.set_theme(player, default_theme)
+		local player_theme = storage:get_string(player_name)
+
+		-- If a player has a preferred theme we cannot use, complain & use default.
+		if player_theme ~= "" and not fs_themes.set_theme(player, player_theme) then
+			minetest.chat_send_player(
+				player_name,
+				string.format("The theme “%s” no longer exists! Resetting preference.", player_theme))
+			player_theme = ""
+			storage:set_string(player_name, "")
+		end
+
+		if player_theme == "" then
+			fs_themes.set_theme(player, default_theme)
+		end
 	end
 )
 
 
 -- Register all themes in the ./themes/ directory, one by one.
-local theme_dir_path = fs_themes.modpath .. "/themes/"
+local theme_dir_path = modpath .. "/themes/"
 local theme_file_paths = minetest.get_dir_list(theme_dir_path, false)
 for _, file_name in pairs(theme_file_paths) do
 	fs_themes.register_theme(file_name, theme_dir_path .. file_name)