using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using Utils;

namespace HttpServer.App
{
    internal static class IpxeScriptManager
    {
        private static readonly string ScriptDir = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "IpxeScripts");

        private static readonly HashSet<char> InvalidFileNameChars = new HashSet<char>(Path.GetInvalidFileNameChars());

        private const string DefaultScript =
            "#!ipxe\r\n" +
            "echo Error: Boot script is no configured, please edit script file.";

        public static string GetInitScript(string url) =>
            "#!ipxe\r\n" +
            "chain " + url + "boot/ipxe/script?mac=${mac:hexhyp}";

        public static string GetScript(string mac)
        {
            var path = Path.Combine(ScriptDir, "MAC-" + FilterMac(mac) + ".txt");
            if (File.Exists(path)) return File.ReadAllText(path);

            if (false == Directory.Exists(ScriptDir)) Directory.CreateDirectory(ScriptDir);
            File.WriteAllText(path, DefaultScript);
            return File.ReadAllText(path);
        }

        private static string FilterMac(string mac)
        {
            var sb = new StringBuilder(mac);
            sb.FilterChars(InvalidFileNameChars);
            return sb.ToString();
        }
    }
}