#include "mygraphicsview.h"
#include <QMimeData>
#include <QCursor>
#include <QGraphicsScene>
#include <QDebug>

MyGraphicsView::MyGraphicsView(QWidget *parent)
    : QGraphicsView(parent)
{
    setAcceptDrops(true);
    viewport()->setAcceptDrops(true);
    setRenderHint(QPainter::Antialiasing);
    setFocusPolicy(Qt::StrongFocus);
}

void MyGraphicsView::dragEnterEvent(QDragEnterEvent *event)
{
    if (event->mimeData()->hasFormat("application/x-component"))
        event->acceptProposedAction();
    else
        event->ignore();
}

void MyGraphicsView::dragMoveEvent(QDragMoveEvent *event)
{
    if (event->mimeData()->hasFormat("application/x-component"))
        event->acceptProposedAction();
    else
        event->ignore();
}

void MyGraphicsView::dropEvent(QDropEvent *event)
{
    if (!event->mimeData()->hasFormat("application/x-component")) {
        event->ignore();
        return;
    }

    QString type = QString::fromUtf8(event->mimeData()->data("application/x-component"));

    QPointF scenePos = mapToScene(event->pos());
    Item *item = new Item(type);
    item->setPos(scenePos);

    if (scene())
        scene()->addItem(item);

    event->acceptProposedAction();
}

void MyGraphicsView::keyPressEvent(QKeyEvent *event)
{
    if (event->key() == Qt::Key_Delete && scene()) {
        QList<QGraphicsItem*> selectedItems = scene()->selectedItems();
        for (QGraphicsItem* item : selectedItems) {
            // 如果是Item，顺便删除其连线
            if (auto node = dynamic_cast<Item*>(item)) {
                QList<Connection*> conns = node->connections();
                for (Connection* conn : conns) {
                    scene()->removeItem(conn);
                    conn->from_->removeConnection(conn);
                    conn->to_->removeConnection(conn);
                    delete conn;
                }
            }
            scene()->removeItem(item);
            delete item;
        }
    } else {
        QGraphicsView::keyPressEvent(event);
    }
}

// ----------- 连线交互 ------------

Item* MyGraphicsView::anchorItemAt(const QPoint& viewPos, Item::AnchorType& anchorType)
{
    QPointF scenePos = mapToScene(viewPos);
    for (QGraphicsItem* item : scene()->items(scenePos)) {
        if (Item* node = dynamic_cast<Item*>(item)) {
            QRectF r = node->boundingRect();
            QPointF local = node->mapFromScene(scenePos);
            if (QLineF(local, QPointF(r.left(), r.center().y())).length() < 10) {
                anchorType = Item::Left;
                return node;
            }
            if (QLineF(local, QPointF(r.right(), r.center().y())).length() < 10) {
                anchorType = Item::Right;
                return node;
            }
        }
    }
    return nullptr;
}

void MyGraphicsView::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        Item::AnchorType anchor;
        Item* node = anchorItemAt(event->pos(), anchor);
        if (node) {
            drawingConnection_ = true;
            startItem_ = node;
            startAnchor_ = anchor;
            tempLine_ = scene()->addLine(QLineF(node->anchorPos(anchor), mapToScene(event->pos())),
                                         QPen(Qt::darkGray, 2, Qt::DashLine));
            return;
        }
    }
    QGraphicsView::mousePressEvent(event);
}

void MyGraphicsView::mouseMoveEvent(QMouseEvent *event)
{
    if (drawingConnection_ && tempLine_) {
        QLineF l = tempLine_->line();
        l.setP2(mapToScene(event->pos()));
        tempLine_->setLine(l);
        return;
    }
    QGraphicsView::mouseMoveEvent(event);
}

void MyGraphicsView::mouseReleaseEvent(QMouseEvent *event)
{
    if (drawingConnection_ && tempLine_) {
        // 检查鼠标释放点是否在某个Item boundingRect内
        QPointF scenePos = mapToScene(event->pos());
        for (QGraphicsItem* item : scene()->items(scenePos)) {
            if (Item* node = dynamic_cast<Item*>(item)) {
                QRectF r = node->boundingRect();
                QPointF local = node->mapFromScene(scenePos);
                // 计算落点距离左右端点
                double distLeft = QLineF(local, QPointF(r.left(), r.center().y())).length();
                double distRight = QLineF(local, QPointF(r.right(), r.center().y())).length();
                Item::AnchorType anchor = (distLeft < distRight) ? Item::Left : Item::Right;
                // 生成连线
                Connection* conn = new Connection(startItem_, startAnchor_, node, anchor);
                scene()->addItem(conn);
                break;
            }
        }
        // 清除临时线
        scene()->removeItem(tempLine_);
        delete tempLine_;
        tempLine_ = nullptr;
        drawingConnection_ = false;
        startItem_ = nullptr;
        return;
    }
    QGraphicsView::mouseReleaseEvent(event);
}