local interval_ms = 30 * 60 * 1000
local interval_s = interval_ms / 1000
local state_file = vim.fn.stdpath("state") .. "/config-update-last-check"
local config_dir = vim.uv.fs_realpath(vim.fn.stdpath("config")) or vim.fn.stdpath("config")
local running = false

local function last_check()
	local f = io.open(state_file, "r")
	if not f then
		return 0
	end
	local n = tonumber(f:read("*l"))
	f:close()
	return n or 0
end

local function mark_checked()
	vim.fn.mkdir(vim.fn.fnamemodify(state_file, ":h"), "p")
	local f = io.open(state_file, "w")
	if f then
		f:write(tostring(os.time()))
		f:close()
	end
end

local function notify()
	local msg = "---------- notice ----------\nconfig update! restart now\n--------------"
	pcall(function()
		require("lz.n").trigger_load("fidget.nvim")
	end)
	local ok = pcall(function()
		require("fidget").notify(msg, vim.log.levels.ERROR, { annote = "", ttl = 600 })
	end)
	if not ok then
		vim.notify(msg, vim.log.levels.ERROR)
	end
end

local function git(args, cb)
	local cmd = { "git", "-C", config_dir }
	vim.list_extend(cmd, args)
	local env = { GIT_TERMINAL_PROMPT = "0" }
	if not vim.env.GIT_SSH_COMMAND then
		env.GIT_SSH_COMMAND = "ssh -o BatchMode=yes -o ConnectTimeout=10"
	end
	local ok = pcall(vim.system, cmd, { text = true, env = env, timeout = 60000 }, function(res)
		vim.schedule(function()
			cb(res)
		end)
	end)
	if not ok then
		running = false
	end
end

local function finish()
	running = false
end

local function check()
	if running or vim.fn.executable("git") ~= 1 then
		return
	end
	running = true
	mark_checked()
	git({ "fetch", "--quiet" }, function(fetched)
		if fetched.code ~= 0 then
			return finish()
		end
		git({ "rev-list", "--count", "HEAD..@{u}" }, function(counted)
			if counted.code ~= 0 or (tonumber(vim.trim(counted.stdout or "")) or 0) == 0 then
				return finish()
			end
			git({ "merge", "--ff-only", "--quiet", "@{u}" }, function(merged)
				finish()
				if merged.code == 0 then
					notify()
				end
			end)
		end)
	end)
end

vim.api.nvim_create_autocmd("UIEnter", {
	once = true,
	callback = function()
		vim.schedule(function()
			if os.time() - last_check() >= interval_s then
				check()
			end
		end)
	end,
})

local timer = vim.uv.new_timer()
if timer then
	timer:start(interval_ms, interval_ms, function()
		vim.schedule(check)
	end)
end