using Microsoft.Win32;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace TWASys_App.Models.ServerInfo
{
    public record OsInfo(string Platform, string Name, string Version, string Kernel, string Architecture);

    public class OsInfoReader
    {
        public static OsInfo Get()
        {
            var arch = RuntimeInformation.OSArchitecture.ToString();

            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
                return GetWindows(arch);
            if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
                return GetLinux(arch);
            if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
                return GetMac(arch);

            return new OsInfo(RuntimeInformation.OSDescription, "Unknown", "Unknown", "Unknown", arch);
        }

        // ---------- Windows ----------
        static OsInfo GetWindows(string arch)
        {
            string name = "Windows";
            string version = "Unknown";
            try
            {
                using var k = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion");
                var productName = k?.GetValue("ProductName")?.ToString();
                var displayVer = k?.GetValue("DisplayVersion")?.ToString() ?? k?.GetValue("ReleaseId")?.ToString();
                var build = k?.GetValue("CurrentBuildNumber")?.ToString();
                var ubrObj = k?.GetValue("UBR");
                var ubr = ubrObj is int i ? i.ToString() : ubrObj?.ToString();

                name = productName ?? "Windows";
                if (!string.IsNullOrWhiteSpace(build))
                    version = $"{(displayVer ?? "")}".Trim();
                if (!string.IsNullOrWhiteSpace(build))
                    version = string.IsNullOrWhiteSpace(version) ? $"Build {build}.{ubr}" : $"{version} (Build {build}.{ubr})";
            }
            catch { /* fallback below */ }

            var kernel = RuntimeInformation.OSDescription; // e.g. "Microsoft Windows 10.0.19045"
            return new OsInfo("Windows", name, version, kernel, arch);
        }

        // ---------- Linux ----------
        static OsInfo GetLinux(string arch)
        {
            string name = "Linux";
            string version = "Unknown";

            try
            {
                var dict = ParseKeyValueFile("/etc/os-release"); // NAME, PRETTY_NAME, VERSION_ID...
                if (dict.TryGetValue("NAME", out var n)) name = TrimQuotes(n);
                if (dict.TryGetValue("PRETTY_NAME", out var pretty)) version = TrimQuotes(pretty);
                else if (dict.TryGetValue("VERSION", out var v)) version = TrimQuotes(v);
                else if (dict.TryGetValue("VERSION_ID", out var vid)) version = TrimQuotes(vid);
            }
            catch { /* ignore */ }

            var kernel = Run("uname", "-sr"); // e.g. "Linux 6.8.0-40-generic"
            if (string.IsNullOrWhiteSpace(kernel)) kernel = RuntimeInformation.OSDescription;

            return new OsInfo("Linux", name, version, kernel, arch);
        }

        // ---------- macOS ----------
        static OsInfo GetMac(string arch)
        {
            var name = Run("sw_vers", "-productName");    // "macOS"
            var version = Run("sw_vers", "-productVersion"); // "14.6.1"
            if (string.IsNullOrWhiteSpace(name)) name = "macOS";
            if (string.IsNullOrWhiteSpace(version)) version = "Unknown";

            var kernel = Run("uname", "-sr"); // "Darwin 23.6.0"
            if (string.IsNullOrWhiteSpace(kernel)) kernel = RuntimeInformation.OSDescription;

            return new OsInfo("macOS", name.Trim(), version.Trim(), kernel.Trim(), arch);
        }

        // ---------- helpers ----------
        static Dictionary<string, string> ParseKeyValueFile(string path)
        {
            var d = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
            if (!File.Exists(path)) return d;
            foreach (var raw in File.ReadAllLines(path))
            {
                var line = raw.Trim();
                if (line.Length == 0 || line.StartsWith("#")) continue;
                var i = line.IndexOf('=');
                if (i <= 0) continue;
                d[line[..i]] = line[(i + 1)..];
            }
            return d;
        }
        static string TrimQuotes(string s) => s.Trim().Trim('"');

        static string Run(string file, string args)
        {
            try
            {
                var p = new Process
                {
                    StartInfo = new ProcessStartInfo
                    {
                        FileName = file,
                        Arguments = args,
                        RedirectStandardOutput = true,
                        RedirectStandardError = true,
                        UseShellExecute = false,
                        CreateNoWindow = true
                    }
                };
                p.Start();
                var s = p.StandardOutput.ReadToEnd().Trim();
                p.WaitForExit(1500);
                return s;
            }
            catch { return ""; }
        }
    }
}