using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace EthernetSwitcher
{
    public enum EthernetMode
    {
        Auto,
        Primary,
        Secondary,
        Disabled
    }

    public enum IpProtocol
    {
        IPv4,
        IPv6,
        IPv4_IPv6
    }

    public class Settings
    {
        private static readonly string SettingsFilePath = Path.Combine(Application.StartupPath, "settings.ini");
        
        public EthernetMode Mode { get; set; } = EthernetMode.Auto;
        public string PrimaryName { get; set; } = "";
        public string SecondaryName { get; set; } = "";
        public int CheckInterval { get; set; } = 5;
        public IpProtocol Protocol { get; set; } = IpProtocol.IPv4_IPv6;

        public static Settings Load()
        {
            var settings = new Settings();
            
            if (File.Exists(SettingsFilePath))
            {
                var mode = ReadIniValue("Settings", "Mode", "Auto");
                EthernetMode parsedMode;
                if (Enum.TryParse<EthernetMode>(mode, out parsedMode))
                {
                    settings.Mode = parsedMode;
                }
                
                settings.PrimaryName = ReadIniValue("Settings", "PrimaryName", "");
                settings.SecondaryName = ReadIniValue("Settings", "SecondaryName", "");
                
                var interval = ReadIniValue("Settings", "CheckInterval", "5");
                int parsedInterval;
                if (int.TryParse(interval, out parsedInterval))
                {
                    settings.CheckInterval = parsedInterval;
                }
                
                var protocol = ReadIniValue("Settings", "Protocol", "IPv4_IPv6");
                IpProtocol parsedProtocol;
                if (Enum.TryParse<IpProtocol>(protocol, out parsedProtocol))
                {
                    settings.Protocol = parsedProtocol;
                }
            }
            
            return settings;
        }

        public void Save()
        {
            WriteIniValue("Settings", "Mode", Mode.ToString());
            WriteIniValue("Settings", "PrimaryName", PrimaryName);
            WriteIniValue("Settings", "SecondaryName", SecondaryName);
            WriteIniValue("Settings", "CheckInterval", CheckInterval.ToString());
            WriteIniValue("Settings", "Protocol", Protocol.ToString());
        }

        [DllImport("kernel32", CharSet = CharSet.Unicode)]
        private static extern long WritePrivateProfileString(string section, string key, string value, string filePath);

        [DllImport("kernel32", CharSet = CharSet.Unicode)]
        private static extern int GetPrivateProfileString(string section, string key, string defaultValue, string returnedString, int size, string filePath);

        private static void WriteIniValue(string section, string key, string value)
        {
            WritePrivateProfileString(section, key, value, SettingsFilePath);
        }

        private static string ReadIniValue(string section, string key, string defaultValue)
        {
            var buffer = new string('\0', 256);
            var length = GetPrivateProfileString(section, key, defaultValue, buffer, buffer.Length, SettingsFilePath);
            return buffer.Substring(0, length);
        }
    }
}