using System;
using System.IO;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Linq;
using Editor;
using Sandbox;

using Button = Editor.Button;
using Label = Editor.Label;
using Checkbox = Editor.Checkbox;
using LineEdit = Editor.LineEdit;

/// <summary>
/// Git Version Control widget for s&box editor.
/// Provides UI for repository management, file change tracking, commit history, and remote synchronization.
/// </summary>
[Dock( "Editor", "Version Control", "account_tree" )]
public partial class LocalControlWidget : Widget
{
	private const int MAX_FILES_DISPLAYED = 50;
	private const float REFRESH_DEBOUNCE_TIME = 0.5f;
	private const int FILE_WATCHER_BUFFER_SIZE = 65536;

	private Widget _changesView;
	private Widget _historyView;
	private Widget _noGitView;

	private ScrollArea _changesScroll;
	private ScrollArea _historyScroll;

	private TextEdit _commitMessage;
	private LineEdit _gitRemoteUrl;
	private Button _commitBtn;
	private Button _changesTabBtn;
	private Button _historyTabBtn;

	private bool _showChangesTab = true;
	private bool _needsRefresh = false;
	private bool _gitOperationInProgress = false;
	private FileSystemWatcher _watcher;
	private TimeSince _lastRefresh = 0;

	private class ChangeRow
	{
		public string FilePath;
		public Checkbox Toggle;
	}
	private List<ChangeRow> _trackedRows = new();

	public LocalControlWidget( Widget parent ) : base( parent )
	{
		MinimumSize = new Vector2( 200, 500 );
		Layout = Layout.Column();
		Layout.Margin = 10;
		Layout.Spacing = 8;

		BuildTopBar();
		Layout.AddSeparator();

		_noGitView = new Widget( this );
		_noGitView.Layout = Layout.Column();

		_changesView = new Widget( this );
		_changesView.Layout = Layout.Column();
		_changesView.Visible = false;

		_historyView = new Widget( this );
		_historyView.Layout = Layout.Column();
		_historyView.Visible = false;

		Layout.Add( _noGitView );
		Layout.Add( _changesView );
		Layout.Add( _historyView );

		BuildNoGitView();
		BuildChangesArea();
		BuildHistoryArea();

		SetupAutoRefresh();
		UpdateRootView();

		TryPopulateGitRemoteUrlFromOrigin();
	}

	private void BuildTopBar()
	{
		var topBar = Layout.AddRow();
		topBar.Spacing = 5;

		_changesTabBtn = new Button( "📝 Changes" );
		_changesTabBtn.Clicked += () => ShowTab( true );
		topBar.Add( _changesTabBtn );

		_historyTabBtn = new Button( "🕒 History" );
		_historyTabBtn.Clicked += () => ShowTab( false );
		topBar.Add( _historyTabBtn );

		topBar.AddStretchCell();

		var refreshBtn = new Button( string.Empty, "refresh" );
		refreshBtn.ToolTip = "Refresh View";
		refreshBtn.Clicked += OnRefreshClicked;
		topBar.Add( refreshBtn );
	}

	// --- first run view ---

	private void BuildNoGitView()
	{
		_noGitView.Layout.Margin = 16;
		_noGitView.Layout.Spacing = 12;

		_noGitView.Layout.Add( new Label( "<big><b>⚠ Git Not Found</b></big>" ) );

		var desc = new Label(
			"This Library uses Git for version control. Git does not appear to be installed or is not available in your system PATH.\n\n" +
			"Git stores your project history locally — no account or internet connection is required. You can optionally push to GitHub later.",
			_noGitView
		);
		desc.WordWrap = true;
		_noGitView.Layout.Add( desc );

		_noGitView.Layout.AddSeparator();

		_noGitView.Layout.Add( new Label( "<b>To get started:</b>" ) );

		var steps = new Label(
			"1. Download and install Git from  git-scm.com/download/win\n" +
			"2. Restart s&box after installing\n" +
			"3. Click Refresh above — the panel will activate automatically",
			_noGitView
		);
		steps.WordWrap = true;
		_noGitView.Layout.Add( steps );

		_noGitView.Layout.AddSeparator();

		var footer = new Label( "<font color='#888'>Once Git is installed, this panel will let you commit, view history, restore previous versions, and optionally push to GitHub.</font>", _noGitView );
		footer.WordWrap = true;
		_noGitView.Layout.Add( footer );

		_noGitView.Layout.AddStretchCell();
	}

	// --- Changes area ---

	private Label _syncStatusLabel;
	private void BuildChangesArea()
	{
		_changesView.Layout.Add( new Label( "<big><b>Uncommitted Changes:</b></big>" ) );

		_syncStatusLabel = new Label( "<font color='#888'>Checking sync status...</font>", _changesView );
		_changesView.Layout.Add( _syncStatusLabel );

		var spacer1 = new Widget( _changesView );
		spacer1.MinimumSize = new Vector2( 0, 8 );
		_changesView.Layout.Add( spacer1 );

		_changesScroll = new ScrollArea( _changesView );
		_changesView.Layout.Add( _changesScroll );

		_changesView.Layout.AddSeparator();

		var spacer2 = new Widget( _changesView );
		spacer2.MinimumSize = new Vector2( 0, 8 );
		_changesView.Layout.Add( spacer2 );

		_changesView.Layout.Add( new Label( "<big><b>Commit Message:</b></big>" ) );

		var textSpacer = new Widget( _changesView );
		textSpacer.MinimumSize = new Vector2( 0, 4 );
		_changesView.Layout.Add( textSpacer );

		_commitMessage = new TextEdit(_changesView);
		_commitMessage.MinimumSize = new Vector2(0, 80);
		_commitMessage.MaximumSize = new Vector2(9999, 80);
		_commitMessage.PlaceholderText = "Enter commit message... (Leave blank for default)";

		_changesView.Layout.Add(_commitMessage);

		_commitBtn = new Button( "Commit", "check_circle" );
		_commitBtn.Clicked += OnCommitClicked;
		_changesView.Layout.Add( _commitBtn );

		var remoteSpacer = new Widget( _changesView );
		remoteSpacer.MinimumSize = new Vector2( 0, 12 );
		_changesView.Layout.Add( remoteSpacer );

		// Remote / push-pull section
		var remoteSection = new Widget( _changesView );
		remoteSection.Layout = Layout.Column();
		remoteSection.Layout.Spacing = 5;
		_changesView.Layout.Add( remoteSection );

		remoteSection.Layout.Add( new Label( "<b>Remote URL (optional):</b>" ) );

		_gitRemoteUrl = new LineEdit();
		_gitRemoteUrl.PlaceholderText = "https://github.com/user/repo.git";
		_gitRemoteUrl.MinimumSize = new Vector2( 0, 24 );
		_gitRemoteUrl.MaximumSize = new Vector2( 9999, 24 );
		remoteSection.Layout.Add( _gitRemoteUrl );

		var spacer = new Widget( remoteSection );
		spacer.MinimumSize = new Vector2( 0, 2 );
		remoteSection.Layout.Add( spacer );

		var row1 = remoteSection.Layout.AddRow();
		row1.Spacing = 5;

		var initBtn = new Button( "Init Git", "create_new_folder" );
		initBtn.ToolTip = "Initialize a new Git repository in this project folder";
		initBtn.Clicked += OnInitGitClicked;
		row1.Add( initBtn, 1 );

		var connectBtn = new Button( "Set Remote", "hub" );
		connectBtn.ToolTip = "Set the remote repository URL for this project";
		connectBtn.Clicked += OnConnectOriginClicked;
		row1.Add( connectBtn, 1 );

		var row2 = remoteSection.Layout.AddRow();
		row2.Spacing = 5;

		var pullBtn = new Button( "Pull", "download" );
		pullBtn.ToolTip = "Pull changes from the remote repository. Make sure to commit or stash your local changes first!";
		pullBtn.Clicked += OnPullClicked;
		row2.Add( pullBtn, 1 );

		var pushBtn = new Button( "Push", "upload" );
		pushBtn.ToolTip = "Push your committed changes to the remote repository.";
		pushBtn.Clicked += OnPushClicked;
		row2.Add( pushBtn, 1 );
	}

	// --- History area ---

	private void BuildHistoryArea()
	{
		_historyView.Layout.Add( new Label( "<big><b>Commit History:</b></big>" ) );

		var spacer = new Widget( _historyView );
		spacer.MinimumSize = new Vector2( 0, 8 );
		_historyView.Layout.Add( spacer );

		_historyScroll = new ScrollArea( _historyView );
		_historyView.Layout.Add( _historyScroll );
	}

	// --- View switching ---

	private void UpdateRootView()
	{
		bool gitReady = IsGitAvailable();

		_noGitView.Visible = !gitReady;
		_changesTabBtn.Enabled = gitReady;
		_historyTabBtn.Enabled = gitReady;

		if ( gitReady )
		{
			ShowTab( _showChangesTab );
		}
		else
		{
			_changesView.Visible = false;
			_historyView.Visible = false;
		}
	}

	private void ShowTab( bool showChanges )
	{
		_showChangesTab = showChanges;
		_changesView.Visible = showChanges;
		_historyView.Visible = !showChanges;
		_noGitView.Visible = false;

		if ( showChanges )
		{
			OnRefreshClicked();
		}
		else
		{
			RefreshHistoryUI();
		}
	}

	// --- Helpers ---

	private void AddChangeItem( Widget parentCanvas, string filePath, string status )
	{
		var row = parentCanvas.Layout.AddRow();
		row.Spacing = 5;

		var cb = new Checkbox { Value = true };
		row.Add( cb );

		var fileLabel = new ClickableLabel( filePath, parentCanvas );
		fileLabel.ToolTip = "Double-click to view diff";
		fileLabel.DoubleClicked += () => OpenDiffWindow( filePath );
		fileLabel.RightClicked += pos => ShowChangeItemContextMenu( filePath, pos );

		row.Add( fileLabel );
		row.AddStretchCell();
		row.Add( new Label( status ) );

		_trackedRows.Add( new ChangeRow { FilePath = filePath, Toggle = cb } );
	}

	private void ShowChangeItemContextMenu( string filePath, Vector2 screenPosition )
	{
		var menu = new ContextMenu( this );
		var normalizedFilePath = filePath.Replace( "\\", "/" ).Trim();

		menu.AddOption( $"Ignore File: {normalizedFilePath}", "block", () =>
		{
			if ( AddToGitIgnore( normalizedFilePath ) )
			{
				OnRefreshClicked();
			}
		} );

		var folderPath = GetFolderIgnorePath( normalizedFilePath );
		if ( !string.IsNullOrWhiteSpace( folderPath ) )
		{
			menu.AddOption( $"Ignore Folder: {folderPath}", "folder_off", () =>
			{
				if ( AddToGitIgnore( folderPath ) )
				{
					OnRefreshClicked();
				}
			} );
		}

		menu.AddOption( "Discard Changes", "history", () =>
		{
			Editor.Dialog.AskConfirm(
				() => PerformDiscard( normalizedFilePath ),
				$"Are you sure you want to permanently discard changes to '{normalizedFilePath}'? \n\nThis cannot be undone.",
				"Discard Changes?"
			);
		} );

		menu.OpenAt( screenPosition, false );
	}

	private void PerformDiscard( string path )
	{
		var (ok, _, err) = RunGitCommand( $"restore {QuoteArg( path )}" );
		if ( ok )
		{
			Log.Info( $"Discarded changes to: {path}" );
			OnRefreshClicked();
		}
		else
		{
			Log.Error( $"Discard failed: {err}" );
		}
	}

	private static string GetFolderIgnorePath( string filePath )
	{
		var dir = Path.GetDirectoryName( filePath )?.Replace( "\\", "/" );
		if ( string.IsNullOrWhiteSpace( dir ) )
		{
			return null;
		}

		return dir.EndsWith( "/" ) ? dir : dir + "/";
	}

	private bool AddToGitIgnore( string entry )
	{
		if ( string.IsNullOrWhiteSpace( entry ) )
		{
			return false;
		}

		try
		{
			var gitIgnorePath = Path.Combine( Project.Current.GetRootPath(), ".gitignore" );
			var normalizedEntry = entry.Replace( "\\", "/" ).Trim();

			var lines = File.Exists( gitIgnorePath )
				? File.ReadAllLines( gitIgnorePath ).ToList()
				: new List<string>();

			if ( lines.Any( x => string.Equals( x.Trim(), normalizedEntry, StringComparison.Ordinal ) ) )
			{
				Log.Info( $"Already in .gitignore: {normalizedEntry}" );
				return false;
			}

			lines.Add( normalizedEntry );
			File.WriteAllLines( gitIgnorePath, lines );
			Log.Info( $"Added to .gitignore: {normalizedEntry}" );
			return true;
		}
		catch ( Exception e )
		{
			Log.Error( $"Failed to add to .gitignore: {e.Message}" );
			return false;
		}
	}

	private void OpenDiffWindow( string relativePath )
	{
		string currentPath = Path.Combine( Project.Current.GetRootPath(), relativePath );
		string currentContent = File.Exists( currentPath ) ? File.ReadAllText( currentPath ) : "[File is missing in current workspace]";
		string oldContent = ReadGitFileAtRevision( "HEAD", relativePath );

		var diff = new DiffWindow( relativePath, oldContent, currentContent );
		diff.Show();
	}

	private void RefreshHistoryUI()
	{
		try
		{
			_historyScroll.Canvas?.Destroy();
			
			var canvas = new Widget( _historyScroll );
			canvas.Layout = Layout.Column();
			_historyScroll.Canvas = canvas;

			RefreshGitHistoryUI( canvas );
		}
		catch ( Exception e )
		{
			Log.Error( $"Failed to refresh history UI: {e.Message}" );
		}
	}

	private void OnRefreshClicked()
	{
		if ( !IsGitAvailable() )
		{
			UpdateRootView();
			return;
		}

		try
		{
			_changesScroll.Canvas?.Destroy();

			var canvas = new Widget( _changesScroll );
			canvas.Layout = Layout.Column();
			_changesScroll.Canvas = canvas;

			_trackedRows.Clear();

			RefreshGitChanges( canvas );

			_ = UpdateSyncStatusAsync();

			canvas.Layout.AddStretchCell();
		}
		catch ( Exception e )
		{
			Log.Error( $"Failed to refresh changes UI: {e.Message}" );
		}
	}

	private void OnCommitClicked()
	{
		_ = CommitGitChanges();
	}

	// --- Autorefresh lifecycle ---

	private void SetupAutoRefresh()
	{
		if (_watcher != null)
		{
			_watcher.EnableRaisingEvents = false;
			_watcher.Dispose();
		}

		_watcher = new FileSystemWatcher(Project.Current.GetRootPath());
		_watcher.IncludeSubdirectories = true;

		_watcher.InternalBufferSize = FILE_WATCHER_BUFFER_SIZE;

		_watcher.NotifyFilter = NotifyFilters.LastWrite
							  | NotifyFilters.FileName
							  | NotifyFilters.DirectoryName
							  | NotifyFilters.Size
							  | NotifyFilters.CreationTime;

		_watcher.Changed += OnFileChanged;
		_watcher.Created += OnFileChanged;
		_watcher.Deleted += OnFileChanged;
		_watcher.Renamed += OnFileChanged;

		_watcher.Error += OnWatcherError;

		_watcher.EnableRaisingEvents = true;
	}

	private void OnWatcherError(object sender, ErrorEventArgs e)
	{
		Log.Warning($"Version Control Watcher error: {e.GetException().Message}. Restarting...");

		_ = Task.Run(async () =>
		{
			await Task.Delay(1000);
			SetupAutoRefresh();
		});
	}

	private void OnFileChanged( object sender, FileSystemEventArgs e )
	{
		if ( IsInternalToolPath( e.FullPath ) )
		{
			return;
		}

		_needsRefresh = true;
		_lastRefresh = 0;
	}

	private static bool IsInternalToolPath( string fullPath )
	{
		if ( string.IsNullOrWhiteSpace( fullPath ) )
		{
			return false;
		}

		var normalized = fullPath.Replace( '\\', '/' );
		return normalized.Contains( "/.git/", StringComparison.OrdinalIgnoreCase )
			|| normalized.EndsWith( "/.git", StringComparison.OrdinalIgnoreCase );
	}

	[EditorEvent.Frame]
	public void FrameUpdate()
	{
		if (_needsRefresh && _lastRefresh > REFRESH_DEBOUNCE_TIME && !_gitOperationInProgress)
		{
			_needsRefresh = false;
			_lastRefresh = 0;

			if (_changesView.Visible)
			{
				OnRefreshClicked();
			}
		}
	}

	public override void OnDestroyed()
	{
		if ( _watcher != null )
		{
			_watcher.EnableRaisingEvents = false;
			_watcher.Changed -= OnFileChanged;
			_watcher.Created -= OnFileChanged;
			_watcher.Deleted -= OnFileChanged;
			_watcher.Renamed -= OnFileChanged;
			_watcher.Dispose();
			_watcher = null;
		}

		base.OnDestroyed();
	}
}