auto-save-state.lua

-- Runs write-watch-later-config periodically

local options = require 'mp.options'
local o = { save_interval = 60 }
options.read_options(o)

local function save()
	if mp.get_property_bool("resume-playback") then
		mp.command("write-watch-later-config")
	end
end

local function save_on_file_loaded()
	if mp.get_property_number("playlist-pos") == 0 then
		return -- no point saving here
	end
	save()
end

local function save_if_pause(_, pause)
	if pause then save() end
end

local function pause_timer_while_paused(_, pause)
	if pause then timer:stop() else timer:resume() end
end

-- This function runs on file-loaded, registers two callback functions, and 
-- then they run delete-watch-later-config when appropriate.
local function delete_watch_later(event)
	local path = mp.get_property("path")

	-- Temporarily disables save-position-on-quit while eof-reached is true, so 
	-- state isn't saved at EOF when keep-open=yes
	local function eof_reached(_, eof)
		if not can_delete then
			return
		elseif eof then
			print("Deleting state (eof-reached)")
			mp.commandv("delete-watch-later-config", path)
			mp.set_property("save-position-on-quit", "no")
		else
			mp.set_property("save-position-on-quit", "yes")
		end
	end

	local function end_file(event)
		mp.unregister_event(end_file)
		mp.unobserve_property(eof_reached)

		if not can_delete then
			can_delete = true
		elseif event["reason"] == "eof" or event["reason"] == "stop" then
			print("Deleting state (end-file "..event["reason"]..")")
			mp.commandv("delete-watch-later-config", path)
		end
	end

	mp.observe_property("eof-reached", "bool", eof_reached)
	mp.register_event("end-file", end_file)
end

mp.set_property("save-position-on-quit", "yes")

can_delete = true
mp.register_script_message("skip-delete-state", function() can_delete = false end)

timer = mp.add_periodic_timer(o.save_interval, save)
mp.observe_property("pause", "bool", pause_timer_while_paused)

mp.observe_property("pause", "bool", save_if_pause)
mp.register_event("file-loaded", delete_watch_later)
mp.register_event("file-loaded", save_on_file_loaded)