-- Copyright 2025 David Vazgenovich Shakaryan

local mp_utils = require('mp.utils')

local downloader = {}
local mt = {}
mt.__index = mt

function downloader.new()
	return setmetatable({
		pending = {},
		running = false,
	}, mt)
end

function mt:exec(url, file, cb)
	if mp_utils.file_info(file) then
		self:exec_next()
		return
	end

	local tmp = file .. '.tmp'
	local cmd = {'curl', '-sSfLo', tmp, url}
	print('downloading ' .. url)

	self.running = true
	mp.command_native_async({
		name = 'subprocess',
		args = cmd,
		playback_only = false,
	}, function(success, res)
		self.running = false
		self:exec_next()
		if success and res.status == 0 then
			os.rename(tmp, file)
			if cb then
				cb(url, file)
			end
		else
			os.remove(tmp)
		end
	end)
end

function mt:exec_next()
	if #self.pending > 0 then
		self:exec(unpack(table.remove(self.pending)))
	end
end

-- more recently requested downloads are executed first, as they are more
-- likely to be used for the current display state
function mt:schedule(...)
	if self.running then
		self.pending[#self.pending+1] = {...}
	else
		self:exec(...)
	end
end

return downloader