using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using System.Windows;
using System.Windows.Interop;
using FastSeekWpf.Core;
using FastSeekWpf.NativeInterop;

namespace FastSeekWpf;

public partial class App : Application
{
    private const string MutexName = "FastSeekWpf_SingleInstance_Mutex";
    private const uint WM_TOGGLE_WINDOW = Win32Api.WM_USER + 3;
    private Mutex? _mutex;
    private bool _ownsMutex;
    private volatile bool _shutdown;
    private MainWindow? _mainWindow;
    private Thread? _hotkeyThread;

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool AttachConsole(int dwProcessId);

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool AllocConsole();

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool FreeConsole();

    private const int ATTACH_PARENT_PROCESS = -1;

    private void OnStartup(object sender, StartupEventArgs e)
    {
        if (e.Args.Contains("--cli"))
        {
            RunCliMode();
            Shutdown();
            return;
        }

        if (e.Args.Contains("--clear-cache"))
        {
            RunClearCache();
            Shutdown();
            return;
        }

        Logger.Log("=== App startup ===");

        _mutex = new Mutex(true, MutexName, out bool createdNew);
        if (!createdNew)
        {
            IntPtr hwnd = Win32Api.FindWindowW(null, "FastSeek");
            if (hwnd != IntPtr.Zero)
                Win32Api.PostMessageW(hwnd, WM_TOGGLE_WINDOW, IntPtr.Zero, IntPtr.Zero);
            Shutdown();
            return;
        }
        _ownsMutex = true;

        _mainWindow = new MainWindow();
        _mainWindow.Show();

        _hotkeyThread = new Thread(HotkeyLoop)
        {
            IsBackground = true,
            Name = "HotkeyThread"
        };
        var helper = new WindowInteropHelper(_mainWindow);
        _hotkeyThread.Start(helper.Handle);
    }

    private static void EnsureConsole()
    {
        if (!AttachConsole(ATTACH_PARENT_PROCESS))
            AllocConsole();
        Console.OutputEncoding = Encoding.UTF8;
        var stdout = Console.OpenStandardOutput();
        var writer = new StreamWriter(stdout, Encoding.UTF8) { AutoFlush = true };
        Console.SetOut(writer);
        Console.SetError(writer);
    }

    private static void RunClearCache()
    {
        EnsureConsole();
        var cachePath = Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
            "FastSeek", "cache.dat");
        if (File.Exists(cachePath))
        {
            var size = new FileInfo(cachePath).Length;
            File.Delete(cachePath);
            Console.WriteLine($"Cache cleared ({size:N0} bytes)");
        }
        else
        {
            Console.WriteLine("No cache found.");
        }
        Console.WriteLine("Press Enter...");
        Console.ReadLine();
        FreeConsole();
    }

    private static void RunCliMode()
    {
        EnsureConsole();
        Console.Clear();

        PrintHeader("FastSeek CLI");
        Console.WriteLine();

        bool elevated = Elevation.IsElevated();
        if (elevated)
            PrintLine(ConsoleColor.Green, "Elevation", "Administrator ✓");
        else
        {
            PrintLine(ConsoleColor.Red, "Elevation", $"{Elevation.StatusText()} ✗");
            PrintError("NOT RUNNING AS ADMINISTRATOR — MFT read will fail.");
            PrintInfo("To fix: Build the project, then run the compiled .exe:");
            PrintDetail("  dotnet publish -c Release -r win-x64");
            PrintDetail("  .\\bin\\Release\\net8.0-windows\\win-x64\\FastSeekWpf.exe --cli");
            Console.WriteLine();
        }

        var drives = DriveDiscovery.GetNtfsDrives();
        PrintLine(ConsoleColor.Cyan, "Drives", $"{drives.Count} NTFS found");
        foreach (var d in drives) PrintDetail($"  {d.Letter}: {d.Root}");
        Console.WriteLine();

        if (drives.Count == 0)
        {
            PrintError("No NTFS drives found.");
            if (!elevated)
                PrintInfo("This is likely because you are not elevated. Try running as Administrator.");
            WaitExit();
            return;
        }

        if (!elevated)
            PrintInfo("Attempting scan anyway (will likely fail without elevation)...");

        PrintLine(ConsoleColor.Cyan, "Scan", "Reading MFT...");
        var index = new IndexStore();
        long totalRecords = 0;
        var sw = Stopwatch.StartNew();

        foreach (var drive in drives)
        {
            try
            {
                using var reader = new MftReader(drive);
                var (scan, method) = reader.ScanAny();

                if (scan.Records.Count > 0)
                {
                    index.PopulateFromScan(scan, drive.Root);
                    totalRecords += scan.Records.Count;
                    PrintLine(ConsoleColor.Green, $"  {drive.Letter}", $"{scan.Records.Count:N0} records ({method})");
                }
                else
                {
                    PrintError($"  {drive.Letter}: 0 records");
                    if (!elevated)
                        PrintInfo("    ↑ Expected when not running as Administrator.");
                }
            }
            catch (Exception ex)
            {
                PrintError($"  {drive.Letter}: {ex.Message}");
            }
        }

        index.Finalize();
        sw.Stop();

        PrintLine(ConsoleColor.White, "Index", $"{index.Count:N0} entries  |  {sw.ElapsedMilliseconds}ms  |  {totalRecords / Math.Max(sw.ElapsedMilliseconds, 1):N0} rec/ms");
        Console.WriteLine();

        if (index.Count > 0)
        {
            var cacheSw = Stopwatch.StartNew();
            CacheManager.SaveCache(index);
            cacheSw.Stop();
            var cachePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "FastSeek", "cache.dat");
            long cacheSize = File.Exists(cachePath) ? new FileInfo(cachePath).Length : 0;
            PrintLine(ConsoleColor.Cyan, "Cache", $"saved {FormatBytes(cacheSize)} in {cacheSw.ElapsedMilliseconds}ms");
        }
        else
            PrintLine(ConsoleColor.DarkGray, "Cache", "skipped (empty index)");
        Console.WriteLine();

        if (index.Count > 0)
        {
            PrintLine(ConsoleColor.Cyan, "Benchmark", "1,000 random queries...");
            var benchSw = Stopwatch.StartNew();
            var rnd = new Random(42);
            var exclusions = CacheManager.LoadExclusions();
            long benchResults = 0;

            for (int i = 0; i < 1000; i++)
            {
                if (index.Entries.Count == 0) break;
                var entry = index.Entries[rnd.Next(index.Entries.Count)];
                var name = index.Name(entry);
                if (name.Length < 2) continue;
                int start = rnd.Next(name.Length - 1);
                int len = rnd.Next(1, Math.Min(name.Length - start, 6));
                var q = name.Substring(start, len).ToLowerInvariant();
                var r = SearchEngine.Search(index, q, 50, false, exclusions);
                benchResults += r.Count;
            }
            benchSw.Stop();

            double qps = 1000.0 / Math.Max(benchSw.ElapsedMilliseconds, 1) * 1000;
            PrintLine(ConsoleColor.White, "Result", $"{benchSw.ElapsedMilliseconds}ms total  |  {qps:N0} qps  |  {benchResults / 1000.0:F1} avg results");
        }
        else
            PrintLine(ConsoleColor.DarkGray, "Benchmark", "skipped (empty index)");
        Console.WriteLine();
        PrintDivider();
        Console.WriteLine();

        if (index.Count == 0)
        {
            PrintError("INDEX IS EMPTY — GUI will show no results.");
            if (!elevated)
            {
                PrintInfo("ROOT CAUSE: You must run the COMPILED .exe as Administrator.");
                PrintInfo("'dotnet run' does NOT trigger UAC elevation.");
                PrintInfo("Steps:");
                PrintDetail("  1. dotnet publish -c Release -r win-x64");
                PrintDetail("  2. .\\bin\\Release\\net8.0-windows\\win-x64\\FastSeekWpf.exe --cli");
                PrintDetail("  3. Accept the UAC prompt");
            }
            else
            {
                PrintInfo("Possible causes:");
                PrintDetail("  • MFT direct read blocked by antivirus/EDR");
                PrintDetail("  • Volume is ReFS/BitLocker/VM shared folder");
                PrintDetail("  • chkdsk / Windows Update holding volume lock");
            }
            Console.WriteLine();
        }

        if (index.Count > 0)
        {
            PrintHeader("Interactive Search (type 'exit' to quit)");
            Console.WriteLine();

            while (true)
            {
                Console.ForegroundColor = ConsoleColor.DarkGray;
                Console.Write("> ");
                Console.ResetColor();
                var query = Console.ReadLine()?.Trim();
                if (string.IsNullOrEmpty(query)) continue;
                if (query.Equals("exit", StringComparison.OrdinalIgnoreCase)) break;

                var searchSw = Stopwatch.StartNew();
                var exclusions = CacheManager.LoadExclusions();
                var results = SearchEngine.Search(index, query, 20, false, exclusions);
                searchSw.Stop();

                Console.ForegroundColor = ConsoleColor.DarkGray;
                Console.WriteLine($"  {results.Count} results  |  {searchSw.Elapsed.TotalMilliseconds:F3}ms");
                Console.ResetColor();

                foreach (var r in results.Take(10))
                {
                    var color = r.Kind switch
                    {
                        ResultKind.App => ConsoleColor.Green,
                        ResultKind.Document => ConsoleColor.Yellow,
                        ResultKind.Image => ConsoleColor.Magenta,
                        ResultKind.Video => ConsoleColor.Red,
                        ResultKind.Audio => ConsoleColor.Blue,
                        ResultKind.Archive => ConsoleColor.DarkYellow,
                        ResultKind.Folder => ConsoleColor.Cyan,
                        _ => ConsoleColor.Gray
                    };
                    Console.ForegroundColor = color;
                    Console.Write($"  [{GetBadgeLabel(r.Kind),-4}] ");
                    Console.ResetColor();
                    Console.WriteLine($"{r.Name}  →  {r.FullPath}");
                }
                if (results.Count > 10)
                {
                    Console.ForegroundColor = ConsoleColor.DarkGray;
                    Console.WriteLine($"  ... and {results.Count - 10} more");
                    Console.ResetColor();
                }
                Console.WriteLine();
            }
        }

        WaitExit();
    }

    private static void WaitExit()
    {
        Console.WriteLine();
        Console.ForegroundColor = ConsoleColor.DarkGray;
        Console.WriteLine("Press Enter to exit...");
        Console.ResetColor();
        Console.ReadLine();
        FreeConsole();
    }

    private static void PrintHeader(string text)
    {
        Console.ForegroundColor = ConsoleColor.Cyan;
        Console.WriteLine($"━━━ {text} ━━━");
        Console.ResetColor();
    }

    private static void PrintDivider()
    {
        Console.ForegroundColor = ConsoleColor.DarkGray;
        Console.WriteLine(new string('─', 60));
        Console.ResetColor();
    }

    private static void PrintLine(ConsoleColor color, string label, string value)
    {
        Console.ForegroundColor = ConsoleColor.DarkGray;
        Console.Write($"{label,-10}: ");
        Console.ForegroundColor = color;
        Console.WriteLine(value);
        Console.ResetColor();
    }

    private static void PrintDetail(string text)
    {
        Console.ForegroundColor = ConsoleColor.DarkGray;
        Console.WriteLine(text);
        Console.ResetColor();
    }

    private static void PrintError(string text)
    {
        Console.ForegroundColor = ConsoleColor.Red;
        Console.WriteLine($"✗ {text}");
        Console.ResetColor();
    }

    private static void PrintInfo(string text)
    {
        Console.ForegroundColor = ConsoleColor.DarkCyan;
        Console.WriteLine($"ℹ {text}");
        Console.ResetColor();
    }

    private static string FormatBytes(long bytes)
    {
        if (bytes < 1024) return $"{bytes} B";
        if (bytes < 1024 * 1024) return $"{bytes / 1024.0:F1} KB";
        if (bytes < 1024 * 1024 * 1024) return $"{bytes / (1024.0 * 1024):F1} MB";
        return $"{bytes / (1024.0 * 1024 * 1024):F2} GB";
    }

    private static string GetBadgeLabel(ResultKind kind) => kind switch
    {
        ResultKind.App => "APP",
        ResultKind.Document => "DOC",
        ResultKind.Image => "IMG",
        ResultKind.Video => "VID",
        ResultKind.Audio => "AUD",
        ResultKind.Archive => "ZIP",
        ResultKind.Folder => "DIR",
        _ => "FILE"
    };

    private void OnExit(object sender, ExitEventArgs e)
    {
        _shutdown = true;
        _hotkeyThread?.Join(500);
        if (_ownsMutex)
            _mutex?.ReleaseMutex();
        _mutex?.Dispose();
        Logger.Log("=== App exit ===");
    }

    private void HotkeyLoop(object? param)
    {
        IntPtr targetHwnd = (IntPtr)(param ?? IntPtr.Zero);
        if (targetHwnd == IntPtr.Zero) return;

        uint modifiers = 0x0002 | 0x0004;
        if (!Win32Api.RegisterHotKey(IntPtr.Zero, 1, modifiers, 0x20))
        {
            Logger.Log($"RegisterHotKey failed: {Marshal.GetLastWin32Error()}");
            return;
        }

        try
        {
            while (!_shutdown)
            {
                int result = Win32Api.GetMessageW(out Win32Api.MSG msg, IntPtr.Zero, 0, 0);
                if (result == 0 || result == -1) break;

                if (msg.message == Win32Api.WM_HOTKEY)
                    Win32Api.PostMessageW(targetHwnd, WM_TOGGLE_WINDOW, IntPtr.Zero, IntPtr.Zero);
                else
                {
                    Win32Api.TranslateMessage(ref msg);
                    Win32Api.DispatchMessageW(ref msg);
                }
            }
        }
        finally
        {
            Win32Api.UnregisterHotKey(IntPtr.Zero, 1);
        }
    }
}