#include "tagview.h"

#include <QWheelEvent>
#include <QScrollBar>
#include <cmath>
#include <QApplication>

TagView::TagView(QWidget *parent)
    : QGraphicsView(parent)
    , saveCenterTimer(this)
{
    setDragMode(QGraphicsView::RubberBandDrag);
    setScene(&m_scene);
    connect(&m_scene, &TagScene::tagDoubleClicked, this, &TagView::tagDoubleClicked);
    connect(&m_scene, &TagScene::imageLoaded, this, &TagView::zoomToFit);

    saveCenterTimer.setSingleShot(true);
    saveCenterTimer.setInterval(500);
    connect(&saveCenterTimer, &QTimer::timeout, this, &TagView::saveCenter);
}

TagView::~TagView()
{
    were_done = true;
}

void TagView::zoomToFit()
{
    QTransform tx = QTransform().rotate(-rotation);
    QRectF rect = tx.mapRect(m_scene.itemsBoundingRect());
    QRectF vp = viewport()->rect();

    setZoom(qMin(vp.width()/rect.width(), vp.height()/rect.height()));
    centerOn(m_scene.backgroundPixmapItem());
    qDebug() << "TagView::zoomToFit():" << sceneRect() << rect << viewport()->rect();
}

void TagView::setZoom(qreal zoom)
{
    this->zoom = zoom;
    if (m_proj)
        m_proj->setMeta("view_zoom", zoom);
    setTransform(QTransform::fromScale(zoom, zoom).rotate(rotation));
}

void TagView::zoomIn(qreal delta)
{
    setZoom(qMax(1.0/16, qMin(4.0, zoom * qPow(1.2, delta/120))));
}

void TagView::rotate(int angle)
{
    QGraphicsView::rotate(angle);
    int tmp = (rotation + angle) % 360;
    if (tmp < 0)
        tmp += 360;
    rotation = tmp;
    if (m_proj)
        m_proj->setMeta("view_rotation", rotation);
}

void TagView::setProject(SQLiteSaveFile *proj)
{
    m_proj = proj;
    m_scene.setProject(m_proj);
    restoreViewport();
}

void TagView::wheelEvent(QWheelEvent *evt)
{
    if (evt->modifiers() == Qt::ControlModifier) {
        zoomIn(evt->angleDelta().y());
    } else {
        if (qAbs(evt->angleDelta().x()) > qAbs(evt->angleDelta().y())) {
            QCoreApplication::sendEvent(horizontalScrollBar(), evt);
        } else {
            QCoreApplication::sendEvent(verticalScrollBar(), evt);
        }
    }
}

void TagView::scrollContentsBy(int dx, int dy)
{
    QGraphicsView::scrollContentsBy(dx, dy);
    /* Hackety hack: On object destruction this method is called downstream in the destructor chain. Prevent segfaults from calling an uninitialized timer. */
    if (!were_done)
        saveCenterTimer.start();
}

void TagView::keyPressEvent(QKeyEvent *event)
{
    if (event->modifiers() & Qt::ControlModifier)
        setDragMode(QGraphicsView::ScrollHandDrag);
    else
        setDragMode(QGraphicsView::RubberBandDrag);
}

void TagView::keyReleaseEvent(QKeyEvent *event)
{
    if (event->modifiers() & Qt::ControlModifier)
        setDragMode(QGraphicsView::ScrollHandDrag);
    else
        setDragMode(QGraphicsView::RubberBandDrag);
}

void TagView::focusInEvent(QFocusEvent *event)
{
    Q_UNUSED(event);
    if (QApplication::keyboardModifiers() & Qt::ControlModifier)
        setDragMode(QGraphicsView::ScrollHandDrag);
    else
        setDragMode(QGraphicsView::RubberBandDrag);
}

void TagView::saveCenter()
{
    QPointF p = mapToScene(viewport()->rect().center());
    if (m_proj)
        m_proj->setMeta("view_center", QJsonDocument(QJsonArray({p.x(), p.y()})).toJson());
}

void TagView::restoreViewport()
{
    if (!m_proj)
        return;

    QVariant v_rot = m_proj->getMeta("view_rotation");
    if (v_rot.isValid()) {
        rotation = v_rot.toInt();
    } else {
        rotation = 0;
    }

    QVariant v_zoom = m_proj->getMeta("view_zoom");
    if (v_zoom.isValid()) {
        zoom = v_zoom.toDouble();
        setTransform(QTransform::fromScale(zoom, zoom).rotate(rotation));
    } else {
        zoomToFit();
    }

    QVariant v_center = m_proj->getMeta("view_center");
    if (v_center.isValid()) {
        QJsonArray arr = QJsonDocument::fromJson(v_center.toByteArray()).toVariant().toJsonArray();
        assert(arr.size() == 2);
        assert(arr[0].isDouble() && arr[1].isDouble());
        centerOn(QPointF(arr[0].toDouble(), arr[1].toDouble()));
    } else {
        centerOn(m_scene.itemsBoundingRect().center());
    }
}