-- Copyright © 2024 Jaidyn Ann <jadedctrl@posteo.at>
--
-- This program is free software: you can redistribute it and/or
-- modify it under the terms of the GNU Lesser General Public License
-- as published by the Free Software Foundation, either version 3 of
-- the License, or (at your option) any later version.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-- GNU Lesser General Public License for more details.
--
-- You should have received a copy of the GNU Lesser General Public License
-- along with this program. If not, see <https://www.gnu.org/licenses/>.

fs_themes = {}
fs_themes.themes = {}

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.
-- 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 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


-- Register a theme, given a name and a formspec string.
function fs_themes.register_theme(name, formspec_str)
	fs_themes.themes[name] = formspec_str
	return true
end


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")
		local player_theme = storage:get_string(player_name)

		-- Set the “default” theme (inherited from whatever mods load before fs_themes)
		if not fs_themes.themes["default"] then
			fs_themes.themes["default"] = player:get_formspec_prepend()
		end

		-- 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 == "" and default_theme and default_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 = modpath .. "/themes/"
local theme_file_paths = minetest.get_dir_list(theme_dir_path, false)
for _, file_name in pairs(theme_file_paths) do
	local fs_file, open_err = io.open(theme_dir_path .. file_name, "r")
	if fs_file == nil then
		minetest.log("warning", string.format("Theme “%s” could not be opened: %s", name, open_err))
		return false
	end

	local fs_file_contents = fs_file:read("*all")
	fs_themes.register_theme(file_name, fs_file_contents)
end