local session_dir = vim.env.HOME .. "/.local/share/nvim/sessions/"

local function session_file(workdir)
	local basename = workdir:gsub("([ \\%%~$])", "\\%1"):gsub("/", "\\%%")
	return session_dir .. basename
end

local function unescape(session)
	return session:sub(#session_dir+1):gsub("%%", "/")
end

local function save_session()
	vim.cmd("silent !mkdir -p " .. session_dir)
	vim.cmd("mksession! " .. session_file(vim.fn.getcwd()))
end

local function load_session(dir)
	vim.cmd.source(session_file(dir))
end

local function del_session(dir)
	vim.cmd("silent !rm " .. session_file(dir))
end

local function list_sessions()
	local sessions = vim.split(vim.fn.glob(session_dir .. "*"), '\n', { trimempty=true })
	local dated_sessions = {}
	for _, item in pairs(sessions) do
		table.insert(dated_sessions, { unescape(item), vim.fn.getftime(item) })
	end
	table.sort(dated_sessions, function(l, r) return l[2] > r[2] end)
	return dated_sessions
end

vim.api.nvim_create_autocmd({"BufWritePost"}, {
	callback = save_session
})

vim.api.nvim_create_user_command("SessionSave", function(opts) save_session(opts.args) end, { nargs=0 })
vim.api.nvim_create_user_command("SessionLoad", function(opts) load_session(opts.args) end, { nargs=1 })
vim.api.nvim_create_user_command("SessionDel", function(opts) del_session(opts.args) end, { nargs=1 })

return {
	load_session = load_session,
	save_session = save_session,
	list_sessions = list_sessions,
}