/*
 * Oak Video Editor - Non-Linear Video Editor
 * Copyright (C) 2025 Olive CE Team
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef VIEWERGLWIDGET_H
#define VIEWERGLWIDGET_H

#include <QMatrix4x4>
#include <QRubberBand>

#include "node/color/colormanager/colormanager.h"
#include "node/gizmo/text.h"
#include "node/node.h"
#include "node/output/track/tracklist.h"
#include "node/traverser.h"
#include "tool/tool.h"
#include "viewerplaybacktimer.h"
#include "viewerqueue.h"
#include "viewersafemargininfo.h"
#include "viewertexteditor.h"
#include "widget/manageddisplay/manageddisplay.h"
#include "widget/timetarget/timetarget.h"

namespace olive
{

/**
 * @brief The inner display/rendering widget of a Viewer class.
 *
 * Actual composition occurs elsewhere offscreen and
 * multithreaded, so its main purpose is receiving a finalized OpenGL texture and displaying it.
 *
 * The main entry point is SetTexture() which will receive an OpenGL texture ID, store it, and then call update() to
 * draw it on screen. The drawing function is in paintGL() (called during the update() process by Qt) and is fairly
 * simple OpenGL drawing code standardized around OpenGL ES 3.2 Core.
 *
 * If the texture has been modified and you're 100% sure this widget is using the same texture object, it's possible
 * to call update() directly to trigger a repaint, however this is not recommended. If you are not 100% sure it'll be
 * the same texture object, use SetTexture() since it will nearly always be faster to just set it than to check *and*
 * set it.
 */
class ViewerDisplayWidget : public ManagedDisplayWidget,
							public TimeTargetObject {
	Q_OBJECT
public:
	/**
   * @brief ViewerGLWidget Constructor
   *
   * @param parent
   *
   * QWidget parent.
   */
	ViewerDisplayWidget(QWidget *parent = nullptr);

	virtual ~ViewerDisplayWidget() override;

	const ViewerSafeMarginInfo &GetSafeMargin() const;
	void SetSafeMargins(const ViewerSafeMarginInfo &safe_margin);

	void SetGizmos(Node *node);

	const VideoParams &GetVideoParams() const
	{
		return gizmo_params_;
	}
	void SetVideoParams(const VideoParams &params);

	const AudioParams &GetAudioParams() const
	{
		return gizmo_audio_params_;
	}
	void SetAudioParams(const AudioParams &p);

	void SetTime(const rational &time);
	void SetSubtitleTracks(Sequence *list);

	void SetShowWidgetBackground(bool e)
	{
		show_widget_background_ = e;
		update();
	}

	/**
   * @brief Transform a point from viewer space to the buffer space.
   * Multiplies by the inverted transform matrix to undo the scaling and translation.
   */
	QPointF TransformViewerSpaceToBufferSpace(const QPointF &pos);

	bool IsDeinterlacing() const
	{
		return deinterlace_;
	}

	void ResetFPSTimer();

	bool GetShowFPS() const
	{
		return show_fps_;
	}

	bool GetShowSubtitles() const
	{
		return show_subtitles_;
	}
	void SetShowSubtitles(bool e)
	{
		show_subtitles_ = e;
		update();
	}

	void IncrementSkippedFrames();

	void IncrementFrameCount()
	{
		fps_timer_update_count_++;
	}

	TexturePtr GetCurrentTexture() const
	{
		return texture_;
	}

	void Play(const int64_t &start_timestamp, const int &playback_speed,
			  const rational &timebase, bool start_updating);

	void Pause();

	ViewerQueue *queue()
	{
		return &queue_;
	}

	ViewerPlaybackTimer *timer()
	{
		return &timer_;
	}

	QPointF ScreenToScenePoint(const QPoint &p);

	virtual bool eventFilter(QObject *o, QEvent *e) override;

public slots:
	/**
   * @brief Set the transformation matrix to draw with
   *
   * Set this if you want the drawing to pass through some sort of transform (most of the time you won't want this).
   */
	void SetMatrixTranslate(const QMatrix4x4 &mat);

	/**
  * @brief Set the scale matrix.
  */
	void SetMatrixZoom(const QMatrix4x4 &mat);

	void SetMatrixCrop(const QMatrix4x4 &mat);

	/**
   * @brief Enables or disables whether this color at the cursor should be emitted
   *
   * Since tracking the mouse every movement, reading pixels, and doing color transforms are processor intensive, we
   * have an option for it. Ideally, this should be connected to a PixelSamplerPanel::visibilityChanged signal so that
   * it can automatically be enabled when the user is pixel sampling and disabled for optimization when they're not.
   */
	void SetSignalCursorColorEnabled(bool e);

	void SetImage(const QVariant &buffer);

	void SetBlank();

	/**
   * @brief Changes the pointer type if the tool is changed to the hand tool. Otherwise resets the pointer to it's
   * normal type.
   */
	void UpdateCursor();

	void ToolChanged();

	/**
   * @brief Enables/disables a basic deinterlace on the viewer
   */
	void SetDeinterlacing(bool e);

	void SetShowFPS(bool e);

	void RequestStartEditingText();

signals:
	/**
   * @brief Signal emitted when the user starts dragging from the viewer
   */
	void DragStarted(const QPoint &p);

	/**
   * @brief Signal emitted when a hand drag starts
   */
	void HandDragStarted();

	/**
   * @brief Signal emitted when a hand drag moves
   */
	void HandDragMoved(int x, int y);

	/**
   * @brief Signal emitted when a hand drag ends
   */
	void HandDragEnded();

	/**
   * @brief Signal emitted when cursor color is enabled and the user's mouse position changes
   */
	void CursorColor(const Color &reference, const Color &display);

	void DragEntered(QDragEnterEvent *event);

	void DragLeft(QDragLeaveEvent *event);

	void Dropped(QDropEvent *event);

	void TextureChanged(TexturePtr texture);

	void QueueStarved();

	void QueueNoLongerStarved();

	void CreateAddableAt(const QRectF &rect);

protected:
	QTransform GenerateWorldTransform();

	QTransform GenerateDisplayTransform();

	QTransform GenerateGizmoTransform(NodeTraverser &gt,
									  const TimeRange &range);
	QTransform GenerateGizmoTransform()
	{
		NodeTraverser t;
		t.SetCacheVideoParams(gizmo_params_);
		return GenerateGizmoTransform(t, GenerateGizmoTime());
	}

	TimeRange GenerateGizmoTime()
	{
		rational node_time = GetGizmoTime();
		return TimeRange(node_time,
						 node_time + gizmo_params_.frame_rate_as_time_base());
	}

	virtual TexturePtr LoadCustomTextureFromFrame(const QVariant &v)
	{
		return nullptr;
	}

protected slots:
	/**
   * @brief Paint function to display the texture (received in SetTexture()) on screen.
   *
   * Simple OpenGL drawing function for painting the texture on screen. Standardized around OpenGL ES 3.2 Core.
   */
	virtual void OnPaint() override;

	virtual void OnDestroy() override;

private:
	QPointF GetTexturePosition(const QPoint &screen_pos);
	QPointF GetTexturePosition(const QSize &size);
	QPointF GetTexturePosition(const double &x, const double &y);

	static void DrawTextWithCrudeShadow(QPainter *painter, const QRect &rect,
										const QString &text,
										const QTextOption &opt = QTextOption());

	rational GetGizmoTime();

	bool IsHandDrag(QMouseEvent *event) const;

	void UpdateMatrix();

	NodeGizmo *TryGizmoPress(const NodeValueRow &row, const QPointF &p);

	void OpenTextGizmo(TextGizmo *text, QMouseEvent *event = nullptr);

	bool OnMousePress(QMouseEvent *e);
	bool OnMouseMove(QMouseEvent *e);
	bool OnMouseRelease(QMouseEvent *e);
	bool OnMouseDoubleClick(QMouseEvent *e);

	bool OnKeyPress(QKeyEvent *e);
	bool OnKeyRelease(QKeyEvent *e);

	void EmitColorAtCursor(QMouseEvent *e);

	void DrawSubtitleTracks();

	QPointF GetVirtualPosForTextEdit(const QPointF &p)
	{
		return text_transform_inverted_.map(p) - text_edit_pos_;
	}

	template <typename T> void ForwardDragEventToTextEdit(T *event);

	bool ForwardMouseEventToTextEdit(QMouseEvent *event,
									 bool check_if_outside = false);
	bool ForwardEventToTextEdit(QEvent *event);

	QPointF AdjustPosByVAlign(QPointF p);

	void CloseTextEditor();

	void GenerateGizmoTransforms();

	void DrawBlank(const VideoParams &device_params);

	/**
   * @brief Internal reference to the OpenGL texture to draw. Set in SetTexture() and used in paintGL().
   */
	TexturePtr texture_;

	/**
   * @brief Internal texture to deinterlace to
   */
	TexturePtr deinterlace_texture_;

	/**
   * @brief Deinterlace shader
   */
	QVariant deinterlace_shader_;

	/**
   * @brief Blank shader
   */
	QVariant blank_shader_;

	/**
   * @brief Translation only matrix (defaults to identity).
   */
	QMatrix4x4 translate_matrix_;

	/**
   * @brief Scale only matrix.
   */
	QMatrix4x4 scale_matrix_;

	/**
   * @brief Crop only matrix
   */
	QMatrix4x4 crop_matrix_;

	/**
   * @brief Cached result of translate_matrix_ and scale_matrix_ multiplied
   */
	QMatrix4x4 combined_matrix_;
	QMatrix4x4 combined_matrix_flipped_;

	bool signal_cursor_color_;

	ViewerSafeMarginInfo safe_margin_;

	Node *gizmos_;
	NodeValueRow gizmo_db_;
	VideoParams gizmo_params_;
	AudioParams gizmo_audio_params_;
	QPoint gizmo_start_drag_;
	QPoint gizmo_last_drag_;
	TimeRange gizmo_draw_time_;
	NodeGizmo *current_gizmo_;
	bool gizmo_drag_started_;
	QTransform gizmo_last_draw_transform_;
	QTransform gizmo_last_draw_transform_inverted_;

	bool show_subtitles_;
	Sequence *subtitle_tracks_;

	rational time_;

	/**
   * @brief Position of mouse to calculate delta from.
   */
	QPoint hand_last_drag_pos_;
	bool hand_dragging_;

	bool deinterlace_;

	qint64 fps_timer_start_;
	int fps_timer_update_count_;

	bool show_fps_;
	int frames_skipped_;

	QVector<double> frame_rate_averages_;
	int frame_rate_average_count_;

	bool show_widget_background_;

	QVariant load_frame_;

	int playback_speed_;

	enum PushMode {
		/// New frame to push to internal texture
		kPushFrame,

		/// Internal texture reference is up to date, keep showing it
		kPushUnnecessary,

		/// Draw blank/black screen
		kPushBlank,

		/// Draw nothing (not even a black frame)
		kPushNull,
	};

	PushMode push_mode_;

	// Playback
	ViewerQueue queue_;

	ViewerPlaybackTimer timer_;

	rational playback_timebase_;

	bool add_band_;
	QPoint add_band_start_;
	QPoint add_band_end_;

	bool queue_starved_;

	TextGizmo *active_text_gizmo_;
	QPointF text_edit_pos_;
	ViewerTextEditor *text_edit_;
	ViewerTextEditorToolBar *text_toolbar_;
	QTransform text_transform_;
	QTransform text_transform_inverted_;

private slots:
	void UpdateFromQueue();

	void TextEditChanged();
	void TextEditDestroyed();

	void SubtitlesChanged(const TimeRange &r);

	void FocusChanged(QWidget *old, QWidget *now);

	QRectF UpdateActiveTextGizmoSize();
};

}

#endif // VIEWERGLWIDGET_H
