/***

  Olive - Non-Linear Video Editor
  Copyright (C) 2022 Olive Team
  Modifications Copyright (C) 2025 mikesolar

  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/>.

***/

#include "timebasedview.h"

#include <QGraphicsRectItem>
#include <QMouseEvent>
#include <QScrollBar>
#include <QTimer>

#include "widget/timebased/timebasedwidget.h"
#include "oakengine/events.h"
#include "oakengine/viewer.h"

namespace olive
{

TimeBasedView::TimeBasedView(QWidget *parent)
	: HandMovableView(parent)
	, playhead_scene_left_(-1)
	, playhead_scene_right_(-1)
	, dragging_playhead_(false)
	, snapped_(false)
	, snap_service_(nullptr)
	, y_axis_enabled_(false)
	, y_scale_(1.0)
	, viewer_(nullptr)
{
	// Sets scene to our scene
	setScene(&scene_);

	// Set default scale (ensures non-zero scale from beginning)
	set_scale(1.0);

	// Default to no default drag mode
	set_default_drag_mode(NoDrag);

	// Signal to update bounding rect when the scene changes
	connect(&scene_, &QGraphicsScene::changed, this,
			&TimeBasedView::update_scene_rect);

	// Workaround for Qt drawing issues with the default MinimalViewportUpdate. While this might be
	// slower (Qt documentation says it may actually be faster in some situations),
	// MinimalViewportUpdate causes all sorts of graphical crud building up in the scene
	setViewportUpdateMode(QGraphicsView::FullViewportUpdate);
}

void TimeBasedView::TimebaseChangedEvent(const Rational &)
{
	// Timebase influences position/visibility of playhead
	viewport()->update();
}

void TimeBasedView::enable_snap(const std::vector<Rational> &points)
{
	snapped_ = true;
	snap_time_ = points;

	viewport()->update();
}

void TimeBasedView::disable_snap()
{
	snapped_ = false;

	viewport()->update();
}

const double &TimeBasedView::get_y_scale() const
{
	return y_scale_;
}

void TimeBasedView::VerticalScaleChangedEvent(double)
{
}

void TimeBasedView::zoom_into_cursor_position(QWheelEvent *event,
										   double scale_multiplier,
										   const QPointF &cursor_pos)
{
	// If CTRL is held (or a preference is set to swap CTRL behavior), we zoom instead of scrolling
	bool only_vertical = false;
	bool only_horizontal = false;

	// Ctrl+Shift limits to only one axis
	// Alt switches between horizontal only (alt held) or vertical only (alt not held)
	if (y_axis_enabled_) {
		if (event->modifiers() & Qt::ShiftModifier) {
			if (event->modifiers() & Qt::AltModifier) {
				only_horizontal = true;
			} else {
				only_vertical = true;
			}
		}
	} else {
		only_horizontal = true;
	}

	if (!only_vertical) {
		double old_scroll = horizontalScrollBar()->value();

		double old_scale = get_scale();
		emit scale_changed(old_scale * scale_multiplier);

		// Use GetScale so that if this value was clamped, we don't erroneously use an unclamped value
		int new_x_scroll =
			qRound((cursor_pos.x() + old_scroll) / old_scale * get_scale() -
				   cursor_pos.x());
		horizontalScrollBar()->setValue(new_x_scroll);
	}

	if (!only_horizontal) {
		double old_y_scroll = verticalScrollBar()->value();

		double old_y_scale = get_y_scale();
		set_y_scale(old_y_scale * scale_multiplier);

		// Use GetYScale so that if this value was clamped, we don't erroneously use an unclamped value
		int new_y_scroll =
			qRound((cursor_pos.y() + old_y_scroll) / old_y_scale * get_y_scale() -
				   cursor_pos.y());
		verticalScrollBar()->setValue(new_y_scroll);
	}
}

void TimeBasedView::set_y_scale(const double &y_scale)
{
	Q_ASSERT(y_scale > 0);

	y_scale_ = y_scale;

	if (y_axis_enabled_) {
		VerticalScaleChangedEvent(y_scale_);

		viewport()->update();
	}
}

void TimeBasedView::set_viewer_node(ViewerOutput *v)
{
	if (viewer_) {
		oakengine_event_unsubscribe(viewer_sub_);
		viewer_sub_ = 0;
	}

	viewer_ = v;

	if (viewer_) {
		viewer_sub_ = oakengine_event_subscribe(
			viewer_,
			OAKENGINE_EVENT_VIEWER_PLAYHEAD_CHANGED,
			[](const oakengine_event *, void *userdata) {
				static_cast<TimeBasedView *>(userdata)->viewport()->update();
			},
			this);
	}
}

QPointF TimeBasedView::scale_point(const QPointF &p) const
{
	return QPointF(p.x() * get_scale(), p.y() * get_y_scale());
}

QPointF TimeBasedView::unscale_point(const QPointF &p) const
{
	return QPointF(p.x() / get_scale(), p.y() / get_y_scale());
}

void TimeBasedView::drawForeground(QPainter *painter, const QRectF &rect)
{
	QGraphicsView::drawForeground(painter, rect);

	if (!timebase().isNull()) {
		double width = time_to_scene(timebase());

		playhead_scene_left_ = get_playhead_x();
		playhead_scene_right_ = playhead_scene_left_ + width;

		QRectF playhead_rect(playhead_scene_left_, rect.top(), width,
							 rect.height());

		// Get playhead highlight color
		QColor highlight = palette().text().color();
		highlight.setAlpha(32);
		painter->setPen(Qt::NoPen);
		painter->setBrush(highlight);
		painter->drawRect(playhead_rect);

		// FIXME: Hardcoded...
		painter->setPen(PLAYHEAD_COLOR);
		painter->setBrush(Qt::NoBrush);
		painter->drawLine(
			QLineF(playhead_rect.topLeft(), playhead_rect.bottomLeft()));
	}

	if (snapped_) {
		painter->setPen(palette().text().color());

		foreach (const Rational &r, snap_time_) {
			double x = time_to_scene(r);

			painter->drawLine(x, rect.top(), x, rect.height());
		}
	}
}

bool TimeBasedView::playhead_press(QMouseEvent *event)
{
	QPointF scene_pos = mapToScene(event->pos());

	dragging_playhead_ = (event->button() == Qt::LeftButton &&
						  scene_pos.x() >= playhead_scene_left_ &&
						  scene_pos.x() < playhead_scene_right_);

	return dragging_playhead_;
}

bool TimeBasedView::playhead_move(QMouseEvent *event)
{
	if (!dragging_playhead_) {
		return false;
	}

	if (viewer_) {
		QPointF scene_pos = mapToScene(event->pos());
		Rational mouse_time = qMax(Rational(0), scene_to_time(scene_pos.x()));

		if (Core::instance()->snapping() && snap_service_) {
			Rational movement;

			snap_service_->snap_point({ mouse_time }, &movement,
									 TimeBasedWidget::k_snap_all &
										 ~TimeBasedWidget::k_snap_to_playhead);

			mouse_time += movement;
		}

		oakengine_viewer_set_playhead(
			reinterpret_cast<OakEngineNode *>(viewer_),
			mouse_time.numerator(), mouse_time.denominator());
	}

	return true;
}

bool TimeBasedView::playhead_release(QMouseEvent *)
{
	if (dragging_playhead_) {
		dragging_playhead_ = false;

		if (snap_service_) {
			snap_service_->hide_snaps();
		}

		return true;
	}

	return false;
}

qreal TimeBasedView::get_playhead_x()
{
	if (viewer_) {
		int64_t pn, pd;
		oakengine_viewer_get_playhead(
			reinterpret_cast<OakEngineNode *>(viewer_), &pn, &pd);
		return time_to_scene(Rational(pn, pd));
	} else {
		return 0;
	}
}

void TimeBasedView::set_end_time(const Rational &length)
{
	end_time_ = length;

	update_scene_rect();
}

void TimeBasedView::update_scene_rect()
{
	QRectF bounding_rect = scene_.itemsBoundingRect();

	// There's no need for a timeline to ever go below 0 on the X scale
	bounding_rect.setLeft(0);

	// Ensure the scene is always the full length of the timeline with a gap at the end to work with
	bounding_rect.setRight(time_to_scene(end_time_) + width());

	// Any further rect processing from derivatives can be done here
	SceneRectUpdateEvent(bounding_rect);

	// If the scene is already this rect, do nothing
	if (scene_.sceneRect() != bounding_rect) {
		scene_.setSceneRect(bounding_rect);
	}
}

void TimeBasedView::resizeEvent(QResizeEvent *event)
{
	QGraphicsView::resizeEvent(event);

	update_scene_rect();
}

void TimeBasedView::ScaleChangedEvent(const double &scale)
{
	TimeScaledObject::ScaleChangedEvent(scale);

	// Update scene rect
	update_scene_rect();

	// Force redraw for playhead if the above function didn't do it
	viewport()->update();
}

}