using Microsoft.Win32;
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Security.Principal;
using System.Threading;

namespace Bedtimer
{
    public sealed class Config
    {
        public int BedMinutes { get; set; } = 22 * 60 + 30; // 10:30 PM
        public int WarnLead { get; set; } = 60;
        public int FlashLead { get; set; } = 20;
        public int LockDelay { get; set; } = 5;

        private const string RegPath = @"SOFTWARE\Whitlocktech\Bedtimer";

        // --- Public API -------------------------------------------------------

        public static Config LoadOrCreate()
        {
            // Read only; do NOT write defaults here.
            using var k = OpenHKLM().OpenSubKey(RegPath, writable: false);
            if (k == null) return new Config(); // defaults in memory only

            int Get(string n, int d) => (k.GetValue(n) is int v) ? v : d;

            return new Config
            {
                BedMinutes = Get(nameof(BedMinutes), 22 * 60 + 30),
                WarnLead = Get(nameof(WarnLead), 60),
                FlashLead = Get(nameof(FlashLead), 20),
                LockDelay = Get(nameof(LockDelay), 5),
            };
        }

        public void Save()
        {
            try
            {
                using var root = OpenHKLM();
                using var k = root.CreateSubKey(RegPath, writable: true);
                k.SetValue(nameof(BedMinutes), BedMinutes, RegistryValueKind.DWord);
                k.SetValue(nameof(WarnLead), WarnLead, RegistryValueKind.DWord);
                k.SetValue(nameof(FlashLead), FlashLead, RegistryValueKind.DWord);
                k.SetValue(nameof(LockDelay), LockDelay, RegistryValueKind.DWord);
                Signals.RaiseConfigChanged();
            }
            catch (UnauthorizedAccessException)
            {
                // Relaunch self elevated to write HKLM in the SAME registry view
                var exe = Environment.ProcessPath!;
                var args = $"--save-admin {BedMinutes} {WarnLead} {FlashLead} {LockDelay}";
                Process.Start(new ProcessStartInfo(exe, args)
                {
                    UseShellExecute = true,
                    Verb = "runas"
                });
            }
        }

        public static void SaveFromArgs(string[] args)
        {
            // Accept: Bedtimer.exe --save-admin <bed> <warn> <flash> <delay>
            // Find the flag and read the 4 numbers after it.
            int i = Array.FindIndex(args, a => string.Equals(a, "--save-admin", StringComparison.OrdinalIgnoreCase));
            if (i < 0 || args.Length < i + 5) return;

            var cfg = new Config
            {
                BedMinutes = int.Parse(args[i + 1]),
                WarnLead = int.Parse(args[i + 2]),
                FlashLead = int.Parse(args[i + 3]),
                LockDelay = int.Parse(args[i + 4]),
            };

            using var root = OpenHKLM();
            using var k = root.CreateSubKey(RegPath, writable: true);
            k.SetValue(nameof(BedMinutes), cfg.BedMinutes, RegistryValueKind.DWord);
            k.SetValue(nameof(WarnLead), cfg.WarnLead, RegistryValueKind.DWord);
            k.SetValue(nameof(FlashLead), cfg.FlashLead, RegistryValueKind.DWord);
            k.SetValue(nameof(LockDelay), cfg.LockDelay, RegistryValueKind.DWord);
            Signals.RaiseConfigChanged();
        }


        // Keep %AppData% for state/logs
        public static string Dir => System.IO.Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
            "Whitlocktech", "Bedtimer");

        // --- Helpers ----------------------------------------------------------

        private static RegistryKey OpenHKLM()
        {
            // Always open the correct view explicitly to avoid WOW6432 redirection issues
            var view = Environment.Is64BitOperatingSystem ? RegistryView.Registry64 : RegistryView.Registry32;
            return RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, view);
        }

        public static bool IsProcessElevated()
        {
            using var id = WindowsIdentity.GetCurrent();
            var p = new WindowsPrincipal(id);
            return p.IsInRole(WindowsBuiltInRole.Administrator);
        }
    }

    public static class Signals
    {
        public const string ConfigChangedName = @"Local\Bedtimer_Config_Changed";
        public static void RaiseConfigChanged()
        {
            using var ev = new EventWaitHandle(false, EventResetMode.AutoReset, ConfigChangedName);
            ev.Set();
        }
        public static EventWaitHandle SubscribeConfigChanged()
            => new EventWaitHandle(false, EventResetMode.AutoReset, ConfigChangedName);
    }
}