#include "dragabletable.h"
#include <QDrag>
#include <QMimeData>
#include <QDebug>
#include <QtEvents>
#include <QHeaderView>
#include "Modules/GroupScreen/groupscreendelegate.h"

DragableTable::DragableTable(QWidget *parent)
    : TableViewEx(parent)
    , m_UUID(QUuid::createUuid())
    , m_bDragEnable(true)
    , m_nTargetRow(-1)
    , m_bIsUpon(false)
{
    SetDragTargetRow(-1);
    setAcceptDrops(true);
}

//某行之下或之上
void DragableTable::SetDragTargetRow(int nRow, bool bIsUpOn)
{
    if(!m_bDragEnable) return;
    GroupScreenDelegate *pDelegate = dynamic_cast<GroupScreenDelegate*>(itemDelegate());
    if(pDelegate == nullptr) return;
    pDelegate->SetDragTarget(nRow, bIsUpOn);

    m_nTargetRow = nRow;
    m_bIsUpon = bIsUpOn;
    update();
}
void DragableTable::mouseMoveEvent(QMouseEvent *event)
{
    QTableView::mouseMoveEvent(event);
    if(!m_bDragEnable) return;
    if(!m_indexPressed.isValid()) return;
    //启动Drag事件
    QDrag *pDrag = new QDrag(this);
    QMimeData *pMimeData = new QMimeData();
    pMimeData->setText(m_UUID.toString());
    pDrag->setMimeData(pMimeData);
    pDrag->exec(Qt::MoveAction, Qt::CopyAction);
    m_indexPressed = QModelIndex();
    SetDragTargetRow(-1);
}

void DragableTable::mousePressEvent(QMouseEvent *event)
{
    QTableView::mousePressEvent(event);
    if(!m_bDragEnable) return;
    // 只允许左键按住
    if(event->button() != Qt::LeftButton) return;

    // 根据触发鼠标位置获得QModelIndex
    m_indexPressed = indexAt(event->pos());
}

void DragableTable::mouseReleaseEvent(QMouseEvent *event)
{
    QTableView::mouseReleaseEvent(event);
    if(!m_bDragEnable) return;
    m_indexPressed = QModelIndex();
    SetDragTargetRow(-1);
}

void DragableTable::dragEnterEvent(QDragEnterEvent *event)
{
    if(!m_bDragEnable)
    {
        event->ignore();
    }
    else
    {
        const QMimeData *pMimeData = event->mimeData();
        if(!pMimeData || !pMimeData->hasText() || event->mimeData()->text() != m_UUID.toString())
        {
            event->ignore();
        }
        else
        {
            QModelIndex index = indexAt(event->pos());
            int nRow = -1;
            // 如拖拽到表格的空白位置, 视为目标是最后一行之下
            if(!index.isValid())
            {
                nRow = model()->rowCount() - 1;
                SetDragTargetRow(nRow, false);
            }
            else
            {
                QRect indexRect = visualRect(index);
                int nRowHeight = verticalHeader()->sectionSize(index.row());
                int nCenter = indexRect.top() + nRowHeight / 2;
                SetDragTargetRow(index.row(), event->pos().y() <= nCenter);
            }
            event->accept();
        }
    }
}
void DragableTable::dragMoveEvent(QDragMoveEvent *event)
{
    if(!m_bDragEnable)
    {
        event->ignore();
    }
    else
    {
        QModelIndex index = indexAt(event->pos());
        int nRow = -1;
        //如拖拽到表格的空白位置, 视为目标是最后一行之下
        if(!index.isValid())
        {
            nRow = model()->rowCount() - 1;
            SetDragTargetRow(nRow, false);
        }
        else
        {
            QRect indexRect = visualRect(index);
            int nRowHeight = verticalHeader()->sectionSize(index.row());
            int nCenter = indexRect.top() + nRowHeight/2;
            SetDragTargetRow(index.row(), event->pos().y() <= nCenter);
        }
        event->accept();
    }
}

void DragableTable::dropEvent(QDropEvent *event)
{
    if(!m_bDragEnable)
    {
        event->ignore();
    }
    else
    {
        int nSourceRow = m_indexPressed.row();
        if(m_nTargetRow != -1 && nSourceRow != m_nTargetRow)
        {
            // 计算实际要插入到的行: 如果是插入到"之下", 则要加1; 如果把上方的行往下移, 则要减1
            int nInsertedRow = m_nTargetRow + (m_bIsUpon ? 0 : 1) - ((nSourceRow > m_nTargetRow) ? 0 : 1);
            if(nSourceRow != nInsertedRow)
            {
                QStandardItemModel *pModel = dynamic_cast<QStandardItemModel*>(model());
                if(pModel)
                {
                    QList<QStandardItem*> targetRowItems = pModel->takeRow(nSourceRow);
                    if(!targetRowItems.isEmpty()) pModel->insertRow(nInsertedRow, targetRowItems);

                    selectRow(nInsertedRow);
                }
                // 发送信号
                emit SignalDrop(nSourceRow, nInsertedRow);
            }
        }
        m_indexPressed = QModelIndex();
        SetDragTargetRow(-1);
        event->acceptProposedAction();
    }
}