-- Copyright 2025 David Vazgenovich Shakaryan

local util = require('util')

local mp_utils = require('mp.utils')

local cacher = {}

local function exec(obj, opts, call_opts, func, func_name, ...)
	local call_opts = call_opts or {}
	local fn = table.concat({opts.prefix, func_name, ...}, '.')
	local path = mp_utils.join_path(opts.directory, fn)
	local f = mp_utils.file_info(path)
	local data
	local miss = call_opts.force or not f or
		os.time() - f.mtime > opts.time

	if miss then
		if call_opts.before_miss then
			call_opts.before_miss()
		end

		data = func(obj, ...)
		if data then
			util.write_json_file(path, data)
		end
	else
		if call_opts.before_hit then
			call_opts.before_hit()
		end
	end

	if f and not data then
		print('using cached ' .. fn)
		data = util.read_json_file(path)
	end

	if miss then
		if call_opts.after_miss then
			call_opts.after_miss()
		end
	else
		if call_opts.after_hit then
			call_opts.after_hit()
		end
	end

	return data
end

function cacher.wrap(obj, opts)
	local proxy = {}

	function proxy:with_opts(f, ...)
		local n = select('#', ...)
		local args = {...}
		return exec(
			obj, opts, args[n], obj[f], f, unpack(args, 1, n - 1))
	end

	setmetatable(proxy, {
		__index = function(t, k)
			local v = obj[k]
			if type(v) ~= 'function' or not opts.functions[k] then
				return v
			end

			local fn = function(_, ...)
				return exec(obj, opts, nil, v, k, ...)
			end

			t[k] = fn

			return fn
		end,
	})

	return proxy
end

return cacher