using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Input;
using System.Windows.Interop;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Threading;
using FastSeekWpf.Core;
using FastSeekWpf.NativeInterop;

namespace FastSeekWpf;

public partial class MainWindow : Window, INotifyPropertyChanged
{
    public const uint WM_TOGGLE_WINDOW = Win32Api.WM_USER + 3;

    private IndexStore _index = new();
    private List<NtfsDrive> _drives = new();
    private readonly List<UsnWatcher> _watchers = new();
    private readonly object _indexLock = new();
    private readonly System.Collections.Concurrent.ConcurrentQueue<IndexEvent> _eventQueue = new();
    private CancellationTokenSource? _cts;
    private List<string> _excludedDirs = new();
    private int _selectedIndex;
    private bool _initialized;
    private bool _isVisible;

    private CancellationTokenSource? _searchDebounceCts;
    private readonly object _searchLock = new();

    public event PropertyChangedEventHandler? PropertyChanged;

    private List<ResultItem> _results = new();
    public List<ResultItem> Results
    {
        get => _results;
        set { _results = value; PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Results))); }
    }

    public MainWindow()
    {
        Logger.Log("MainWindow constructor");
        InitializeComponent();
        DataContext = this;
        _excludedDirs = CacheManager.LoadExclusions();

        Loaded += (s, e) =>
        {
            var helper = new WindowInteropHelper(this);
            var hwnd = helper.Handle;
            HwndSource.FromHwnd(hwnd)?.AddHook(WndProc);
            EnableDwmRoundedCorners(hwnd);
        };
    }

    private void EnableDwmRoundedCorners(IntPtr hwnd)
    {
        try
        {
            int cornerPref = Win32Api.DWMWCP_ROUND;
            Win32Api.DwmSetWindowAttribute(hwnd, Win32Api.DWMWA_WINDOW_CORNER_PREFERENCE, ref cornerPref, Marshal.SizeOf(cornerPref));
            int darkMode = 1;
            Win32Api.DwmSetWindowAttribute(hwnd, Win32Api.DWMWA_USE_IMMERSIVE_DARK_MODE, ref darkMode, Marshal.SizeOf(darkMode));
            Logger.Log("DWM rounded corners + dark mode enabled.");
        }
        catch (Exception ex)
        {
            Logger.Log($"DWM setup failed: {ex.Message}");
        }
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        Logger.Log("Window_Loaded");
        if (_initialized) return;
        _initialized = true;
        CenterWindow();
        ShowEmptyState();
        Task.Run(async () => await InitializeAsync());
    }

    private void ShowEmptyState()
    {
        Dispatcher.Invoke(() =>
        {
            ResultsScroll.Visibility = Visibility.Collapsed;
            EmptyHint.Visibility = Visibility.Visible;
            EmptyHint.Text = "Indexing...";
            StatusBar.Visibility = Visibility.Visible;
            StatusText.Text = "Starting scan...";
            SepLine.Visibility = Visibility.Collapsed;
        });
    }

    private async Task InitializeAsync()
    {
        Logger.Log("InitializeAsync start");
        try
        {
            _drives = DriveDiscovery.GetNtfsDrives();
            Logger.Log($"Found {_drives.Count} NTFS drives");

            if (_drives.Count == 0)
            {
                Dispatcher.Invoke(() =>
                {
                    EmptyHint.Text = "No NTFS drives found.\nRun as Administrator.";
                    StatusText.Text = "Error: no drives";
                });
                return;
            }

            bool needFullScan = true;
            var cache = CacheManager.LoadCache();
            if (cache != null)
            {
                Logger.Log($"Cache loaded: {cache.Entries.Count} entries");
                lock (_indexLock)
                {
                    _index = IndexStore.FromCache(cache);
                }
                Logger.Log($"Loaded cache: {_index.Count} files");

                var checkpoints = new List<JournalCheckpoint>(cache.Checkpoints);
                bool deltaOk = true;
                foreach (var drive in _drives)
                {
                    var cp = checkpoints.FirstOrDefault(c => c.DriveLetter == drive.Letter);
                    if (cp != null)
                    {
                        try
                        {
                            var watcher = UsnWatcher.CreateForCheckpoint(drive, evt => _eventQueue.Enqueue(evt), cp);
                            watcher.Drain();
                            lock (_indexLock)
                            {
                                _index.Checkpoints.RemoveAll(c => c.DriveLetter == drive.Letter);
                                _index.Checkpoints.Add(watcher.Checkpoint());
                            }
                            _watchers.Add(watcher);
                            Logger.Log($"Delta catch-up OK for {drive.Letter}");
                        }
                        catch (Exception ex)
                        {
                            Logger.Log($"Delta catch-up failed: {ex.Message}");
                            deltaOk = false;
                            break;
                        }
                    }
                }

                if (deltaOk)
                {
                    needFullScan = false;
                    while (_eventQueue.TryDequeue(out var evt))
                        ApplyEvent(evt);
                    Logger.Log("Delta events applied.");
                }
                else
                {
                    Logger.Log("Delta failed, clearing cache.");
                    CacheManager.ClearCache();
                    _watchers.Clear();
                    _eventQueue.Clear();
                }
            }

            if (needFullScan)
            {
                Logger.Log("Starting full MFT scan...");
                lock (_indexLock)
                {
                    _index = new IndexStore();
                    long totalRecords = 0;
                    foreach (var drive in _drives)
                    {
                        try
                        {
                            Logger.Log($"Scanning {drive.Letter}...");
                            Dispatcher.Invoke(() => StatusText.Text = $"Scanning {drive.Letter}: ...");

                            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;
                                Logger.Log($"Scanned {drive.Letter}: {scan.Records.Count} files ({method})");
                                Dispatcher.Invoke(() => StatusText.Text = $"Scanned {drive.Letter}: {scan.Records.Count:N0} files");
                            }
                            else
                            {
                                Logger.Log($"Scan returned 0 records for {drive.Letter}");
                                Dispatcher.Invoke(() => StatusText.Text = $"Scan failed for {drive.Letter}");
                            }
                        }
                        catch (Exception ex)
                        {
                            Logger.Log($"Scan failed for {drive.Letter}: {ex}");
                        }
                    }
                    _index.Finalize();
                    Logger.Log($"Full scan complete. Total indexed: {_index.Count}");
                    CacheManager.SaveCache(_index);
                    Logger.Log("Cache saved.");
                }

                foreach (var drive in _drives)
                {
                    try
                    {
                        var watcher = new UsnWatcher(drive, evt => _eventQueue.Enqueue(evt), null);
                        _watchers.Add(watcher);
                        _ = watcher.RunAsync(CancellationToken.None);
                        Logger.Log($"USN watcher started for {drive.Letter}");
                    }
                    catch (Exception ex)
                    {
                        Logger.Log($"USN watcher failed for {drive.Letter}: {ex.Message}");
                    }
                }
            }

            _cts = new CancellationTokenSource();
            _ = Task.Run(() => LiveUpdateLoop(_cts.Token));

            Dispatcher.Invoke(() =>
            {
                if (_index.Count == 0)
                {
                    EmptyHint.Text = "Index is empty.\nRun CLI diagnostics: FastSeekWpf.exe --cli";
                    StatusText.Text = "0 files indexed — check diagnostics";
                }
                else
                {
                    EmptyHint.Text = "Start typing to search your files...";
                    StatusText.Text = $"{_index.Count:N0} files indexed";
                }
                StatusBar.Visibility = Visibility.Visible;
            });
            Logger.Log("InitializeAsync done.");
        }
        catch (Exception ex)
        {
            Logger.Log($"InitializeAsync fatal: {ex}");
            Dispatcher.Invoke(() =>
            {
                EmptyHint.Text = $"Initialization failed:\n{ex.Message}\n\nCheck log at %LOCALAPPDATA%\\FastSeek\\log.txt";
                StatusText.Text = "Error — check log";
            });
        }
    }

    private void LiveUpdateLoop(CancellationToken ct)
    {
        while (!ct.IsCancellationRequested)
        {
            int processed = 0;
            while (_eventQueue.TryDequeue(out var evt))
            {
                ApplyEvent(evt);
                processed++;
                if (processed > 100) break;
            }
            if (processed > 50)
                CacheManager.SaveCache(_index);
            Thread.Sleep(100);
        }
    }

    private void ApplyEvent(IndexEvent evt)
    {
        lock (_indexLock)
        {
            switch (evt)
            {
                case IndexEvent.Created c:
                    _index.Insert(c.Record);
                    break;
                case IndexEvent.Deleted d:
                    _index.Remove(d.FileRef);
                    break;
                case IndexEvent.Renamed r:
                    _index.Rename(r.OldRef, r.NewRecord);
                    break;
                case IndexEvent.Moved m:
                    _index.ApplyMove(m.FileRef, m.NewParentRef, m.Name, m.Kind);
                    break;
            }
        }
    }

    private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
        if (msg == WM_TOGGLE_WINDOW)
        {
            Dispatcher.Invoke(ToggleVisibility);
            handled = true;
        }
        return IntPtr.Zero;
    }

    private void Window_Deactivated(object sender, EventArgs e) => FadeOutAndHide();

    private void Window_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if (e.ChangedButton == MouseButton.Left)
            DragMove();
    }

    private void FadeOutAndHide()
    {
        if (Resources["FadeAnim"] is Storyboard fade)
        {
            fade.Completed += (s, e) => { Hide(); _isVisible = false; };
            fade.Begin(this);
        }
        else
        {
            Hide();
            _isVisible = false;
        }
    }

    private void ToggleVisibility()
    {
        if (_isVisible)
            FadeOutAndHide();
        else
        {
            CenterWindow();
            SearchBox.Clear();
            Results = new List<ResultItem>();
            ShowEmptyState();
            Show();
            Activate();
            SearchBox.Focus();

            if (Resources["AppearAnim"] is Storyboard appear)
                appear.Begin(this);
            else
                Opacity = 1;
            _isVisible = true;
        }
    }

    private void CenterWindow()
    {
        var screenW = SystemParameters.PrimaryScreenWidth;
        var screenH = SystemParameters.PrimaryScreenHeight;
        Left = (screenW - Width) / 2;
        Top = screenH * 0.18;
    }

    private void Window_KeyDown(object sender, KeyEventArgs e)
    {
        switch (e.Key)
        {
            case Key.Escape:
                FadeOutAndHide();
                e.Handled = true;
                break;
            case Key.Down:
                if (ResultsList.Items.Count > 0 && ResultsList.SelectedIndex + 1 < ResultsList.Items.Count)
                {
                    ResultsList.SelectedIndex++;
                    ResultsList.ScrollIntoView(ResultsList.SelectedItem);
                    e.Handled = true;
                }
                break;
            case Key.Up:
                if (ResultsList.SelectedIndex > 0)
                {
                    ResultsList.SelectedIndex--;
                    ResultsList.ScrollIntoView(ResultsList.SelectedItem);
                    e.Handled = true;
                }
                break;
            case Key.Enter:
                OpenResult(e.KeyboardDevice.IsKeyDown(Key.LeftCtrl) || e.KeyboardDevice.IsKeyDown(Key.RightCtrl));
                e.Handled = true;
                break;
        }
    }

    private void SearchBox_Loaded(object sender, RoutedEventArgs e) => SearchBox.Focus();

    private void SearchBox_TextChanged(object sender, TextChangedEventArgs e)
    {
        var query = SearchBox.Text.Trim();
        Logger.Log($"SearchBox query: '{query}' (index={_index.Count:N0})");

        if (string.IsNullOrEmpty(query))
        {
            CancelPendingSearch();
            Dispatcher.Invoke(() =>
            {
                Results = new List<ResultItem>();
                ResultsScroll.Visibility = Visibility.Collapsed;
                EmptyHint.Visibility = Visibility.Visible;
                EmptyHint.Text = _index.Count == 0
                    ? "Index is empty.\nRun CLI diagnostics: FastSeekWpf.exe --cli"
                    : "Start typing to search your files...";
                SepLine.Visibility = Visibility.Collapsed;
                StatusText.Text = $"{_index.Count:N0} files indexed";
            });
            return;
        }

        CancelPendingSearch();

        var cts = new CancellationTokenSource();
        lock (_searchLock)
        {
            _searchDebounceCts = cts;
        }

        Task.Run(async () =>
        {
            try
            {
                await Task.Delay(25, cts.Token);
            }
            catch (TaskCanceledException)
            {
                return;
            }

            if (cts.IsCancellationRequested) return;

            List<SearchResult> results;
            lock (_indexLock)
            {
                results = SearchEngine.Search(_index, query, 50, false, _excludedDirs);
            }

            Logger.Log($"Search '{query}': {results.Count} results returned to UI");

            var items = results.Select((r, i) => new ResultItem
            {
                FullPath = r.FullPath,
                DisplayName = Path.GetFileNameWithoutExtension(r.FullPath),
                IsSelected = i == 0,
                IsHovered = false,
                Kind = r.Kind,
                IconGlyph = GetIconGlyph(r.Kind),
                BadgeLabel = GetBadgeLabel(r.Kind),
                BadgeColor = GetBadgeColor(r.Kind)
            }).ToList();

            Dispatcher.Invoke(() =>
            {
                if (cts.IsCancellationRequested) return;
                _selectedIndex = 0;
                Results = items;

                if (items.Count > 0)
                {
                    ResultsScroll.Visibility = Visibility.Visible;
                    EmptyHint.Visibility = Visibility.Collapsed;
                    SepLine.Visibility = Visibility.Visible;
                    ResultsList.SelectedIndex = 0;
                }
                else
                {
                    ResultsScroll.Visibility = Visibility.Collapsed;
                    EmptyHint.Visibility = Visibility.Visible;
                    EmptyHint.Text = $"No results for \"{query}\"";
                    SepLine.Visibility = Visibility.Collapsed;
                }

                StatusText.Text = $"{items.Count} results";
                StatusBar.Visibility = Visibility.Visible;
            });
        });
    }

    private void ResultsList_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        _selectedIndex = ResultsList.SelectedIndex;
    }

    private void CancelPendingSearch()
    {
        lock (_searchLock)
        {
            _searchDebounceCts?.Cancel();
            _searchDebounceCts?.Dispose();
            _searchDebounceCts = null;
        }
    }

    private void ResultItem_Click(object sender, MouseButtonEventArgs e)
    {
        if (sender is Border border && border.DataContext is ResultItem item)
        {
            int idx = Results.IndexOf(item);
            if (idx >= 0)
            {
                ResultsList.SelectedIndex = idx;
                OpenResult(false);
            }
        }
    }

    private void OpenResult(bool folderOnly)
    {
        if (ResultsList.SelectedItem is not ResultItem item) return;
        string target = folderOnly
            ? (Directory.Exists(item.FullPath) ? item.FullPath : Path.GetDirectoryName(item.FullPath) ?? item.FullPath)
            : item.FullPath;

        Win32Api.ShellExecuteW(IntPtr.Zero, "open", target, null, null, 1);
        FadeOutAndHide();
    }

    private static string GetIconGlyph(ResultKind kind) => kind switch
    {
        ResultKind.App => "\uE7E8",
        ResultKind.Document => "\uE8A5",
        ResultKind.Image => "\uE91B",
        ResultKind.Video => "\uE714",
        ResultKind.Audio => "\uE8D6",
        ResultKind.Archive => "\uE7B8",
        ResultKind.Folder => "\uE8B7",
        _ => "\uE7C3"
    };

    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 static Color GetBadgeColor(ResultKind kind) => kind switch
    {
        ResultKind.App => Color.FromRgb(60, 200, 120),
        ResultKind.Document => Color.FromRgb(240, 140, 60),
        ResultKind.Image => Color.FromRgb(180, 80, 220),
        ResultKind.Video => Color.FromRgb(220, 60, 80),
        ResultKind.Audio => Color.FromRgb(60, 160, 240),
        ResultKind.Archive => Color.FromRgb(200, 160, 40),
        ResultKind.Folder => Color.FromRgb(80, 120, 220),
        _ => Color.FromRgb(100, 100, 130)
    };

    protected override void OnClosing(CancelEventArgs e)
    {
        _cts?.Cancel();
        CancelPendingSearch();
        foreach (var w in _watchers) w.Dispose();
        _watchers.Clear();
        CacheManager.SaveCache(_index);
        base.OnClosing(e);
    }
}

public record ResultItem
{
    public string FullPath { get; init; } = "";
    public string DisplayName { get; init; } = "";
    public bool IsSelected { get; init; }
    public bool IsHovered { get; init; }
    public ResultKind Kind { get; init; }
    public string IconGlyph { get; init; } = "";
    public string BadgeLabel { get; init; } = "";
    public Color BadgeColor { get; init; }
}