#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "item.h"

#include <QListWidgetItem>
#include <QMimeData>
#include <QDrag>
#include <QPainter>
#include <QMouseEvent>
#include <QDropEvent>
#include <QGraphicsView>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    /* 1. 场景 */
    m_scene = new QGraphicsScene(this);
    ui->graphicsView->setScene(m_scene);
    ui->graphicsView->setRenderHint(QPainter::Antialiasing);
    ui->graphicsView->setSceneRect(0, 0, 800, 600);
    ui->graphicsView->setAcceptDrops(true);
    ui->graphicsView->setFocus();

    /* 2. 列表 */
    ui->listWidget->setViewMode(QListView::IconMode);
    ui->listWidget->setIconSize(QSize(60, 30));
    ui->listWidget->setDragEnabled(false);
    ui->listWidget->viewport()->installEventFilter(this);

    /* 3. 填充列表 */
    createComponents();
}

MainWindow::~MainWindow()
{
    delete ui;
}

/* ---------- 拖拽核心 ---------- */
bool MainWindow::eventFilter(QObject *obj, QEvent *event)
{
    if (obj == ui->listWidget->viewport()) {
        static QListWidgetItem *dragItem = nullptr;
        static QPoint startPos;

        if (event->type() == QEvent::MouseButtonPress) {
            auto *me = static_cast<QMouseEvent*>(event);
            if (me->button() == Qt::LeftButton) {
                dragItem  = ui->listWidget->itemAt(me->pos());
                startPos  = me->pos();
            }
        } else if (event->type() == QEvent::MouseMove && dragItem) {
            auto *me = static_cast<QMouseEvent*>(event);
            if ((me->pos() - startPos).manhattanLength()
                    >= QApplication::startDragDistance()) {

                QString type = dragItem->data(Qt::UserRole).toString();

                QMimeData *mime = new QMimeData;
                mime->setData("application/x-component", type.toUtf8());

                QDrag *drag = new QDrag(this);
                drag->setMimeData(mime);
                drag->setPixmap(dragItem->icon().pixmap(ui->listWidget->iconSize()));
                drag->setHotSpot(drag->pixmap().rect().center());
                drag->exec(Qt::CopyAction);

                dragItem = nullptr;
            }
        } else if (event->type() == QEvent::MouseButtonRelease) {
            dragItem = nullptr;
        }
    }
    return QMainWindow::eventFilter(obj, event);
}

/* ---------- 填充列表 ---------- */
void MainWindow::createComponents()
{
    struct Comp { QString name; QColor color; };
    const QVector<Comp> comps = {
        {"常开",     Qt::blue},
        {"常闭",     Qt::red},
        {"比较指令", Qt::green},
        {"线圈",     Qt::darkYellow}
    };

    for (const Comp &c : comps) {
        QListWidgetItem *it = new QListWidgetItem(c.name, ui->listWidget);

        QPixmap pix(60, 30);
        pix.fill(Qt::white);
        QPainter p(&pix);
        p.setRenderHint(QPainter::Antialiasing);
        p.setBrush(c.color.lighter(150));
        p.setPen(QPen(c.color, 2));
        p.drawRoundedRect(QRect(5, 5, 50, 20), 3, 3);
        p.setPen(Qt::black);
        p.drawText(QRect(5, 5, 50, 20), Qt::AlignCenter, c.name);

        it->setIcon(QIcon(pix));
        it->setData(Qt::UserRole, c.name);
    }
}