#include "dragabletable.h"
#include <QDrag>
#include <QMimeData>
#include <QUuid>
#include <QDebug>
#include <QtEvents>
#include <QPainter>
#include <QHeaderView>
#include "../PaintHelper/painthelper.h"

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

void DragableTable::SetDragEnable(bool value)
{
    setAcceptDrops(value);
    m_bDragEnable = value;
}
//某行之下或之上
void DragableTable::SetDragTargetRow(int row, bool isUpon)
{
    if(!m_bDragEnable) return;
    DragableTableDelegate *pDelegate = dynamic_cast<DragableTableDelegate*>(itemDelegate());
    if(pDelegate == nullptr) return;
    pDelegate->SetDragTarget(row, isUpon);
    
//    setProperty("dragTargetRow", row);
//    setProperty("isUpon", isUpon);
    m_nTargetRow = row;
    m_bIsUpon = isUpon;
    update();
}
void DragableTable::mouseMoveEvent(QMouseEvent *event)
{
    QTableView::mouseMoveEvent(event);
    if(!m_bDragEnable) return;
    if(!m_indexPressed.isValid()) return;
    //启动Drag事件
    QDrag *drag = new QDrag(this);
    QMimeData *mimeData = new QMimeData();
    mimeData->setText(m_UUID.toString());
    drag->setMimeData(mimeData);
    drag->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) return;
    const QMimeData *mimeData = event->mimeData();
    if(mimeData == nullptr || !mimeData->hasText()) return;
    if(event->mimeData()->text() != m_UUID.toString()) return;
    
    {//下面内容和dragMoveEvent里的一样, 避免dragMoveEvent未被调用而直接进入dropEvent
        QModelIndex index = indexAt(event->pos());
        int row = -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())
        {
            row = model()->rowCount() - 1;
            SetDragTargetRow(row, false);
        }
        else 
        {
            QRect indexRect = visualRect(index);
            int rowHeight = verticalHeader()->sectionSize(index.row());
            int center = indexRect.top() + rowHeight/2;
            SetDragTargetRow(index.row(), event->pos().y()<=center);
        }
    }
    event->accept();
}
void DragableTable::dragMoveEvent(QDragMoveEvent *event)
{
    if(!m_bDragEnable) return;
    QModelIndex index = indexAt(event->pos());
    int row = -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())
    {
        row = model()->rowCount() - 1;
        SetDragTargetRow(row, false);
    }
    else 
    {
        QRect indexRect = visualRect(index);
        int rowHeight = verticalHeader()->sectionSize(index.row());
        int center = indexRect.top() + rowHeight/2;
        SetDragTargetRow(index.row(), event->pos().y()<=center);
    }
}

void DragableTable::dropEvent(QDropEvent *event)
{
    if(!m_bDragEnable) return;
    /*----------------------------------------------------------------
     * 设置QDrag::exec()的返回值, 必须配合accept使用
     * 也可以直接调用acceptProposedAction方法来将返回值设为调用QDrag::exec时传入的defaultDropAction
     * event->setDropAction(Qt::MoveAction);
     * event->accept();
     * 不管之前执行了accept还是acceptProposedAction, 只要执行了event->ignore, QDrag::exec()的返回值都会是Qt::IgnoreAction
     * event->ignore();
    ----------------------------------------------------------------*/
    do
    {
        int sourceRow = m_indexPressed.row();
        if(m_nTargetRow == -1) break;
        if(sourceRow == m_nTargetRow) break;
        
        //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 insertedRow = m_nTargetRow + (m_bIsUpon?0:1) - ((sourceRow>m_nTargetRow)?0:1);
        if(sourceRow == insertedRow) break;
        
        //发送信号
        emit sig_Drop(sourceRow, insertedRow);
        if(m_bSignalOnly) break;
        
        QStandardItemModel *pModel = dynamic_cast<QStandardItemModel*>(model());
        if(pModel == nullptr) break;
        
        QList<QStandardItem*> targetRowItems = pModel->takeRow(sourceRow);
        if(!targetRowItems.isEmpty()) pModel->insertRow(insertedRow, targetRowItems);
        
        /*----------------------------------------------------------------
         * 另一种思路：先交换源行和目标行的数据, 交换后目标行去到了源行, 其他行不受影响; 再将目标行移到当前源行位置之后
        ----------------------------------------------------------------*/
        
    }while (false);
    
    m_indexPressed = QModelIndex();
    SetDragTargetRow(-1);
    event->acceptProposedAction();
}

DragableTableDelegate::DragableTableDelegate(QObject *parent)
    : BaseItemDelegate(parent)
//    , m_pTableView(parentTable)
    , m_nTargetRow(-1)
    , m_bIsUpon(false)
{
    
}

void DragableTableDelegate::SetDragTarget(int targetRow, bool isUpon)
{
    m_nTargetRow = targetRow;
    m_bIsUpon = isUpon;
}

void DragableTableDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    BaseItemDelegate::paint(painter,option,index);
    
    if(m_nTargetRow == -1) return;
    PainterEx *painterEx = static_cast<PainterEx*>(painter);
    
    //绘制第一列单元格圆圈和线
    if(index.row() == m_nTargetRow && index.column() == 0)
    {
        int y = m_bIsUpon?option.rect.top():option.rect.bottom();
        painterEx->DrawCircle(QPoint(km_nRadius, y), km_nRadius, Qt::transparent, QPen(QColor(86,135,228), 2));
        painterEx->setPen(QPen(QColor(86,135,228), 2));
        painterEx->drawLine(option.rect.left()+km_nRadius*2, y, option.rect.right(), y);
    }
    //如果指示器绘制在当前行的下方, 因为头部圆圈会跨到下一行, 所以在绘制下一行的时候, 又绘制一次
    if(!m_bIsUpon && (index.row() == m_nTargetRow+1) && index.column() == 0)
    {
        int y = option.rect.top() - 1;
        painterEx->DrawCircle(QPoint(km_nRadius, y), km_nRadius, Qt::transparent, QPen(QColor(86,135,228), 2));
        painterEx->setPen(QPen(QColor(86,135,228), 2));
        painterEx->drawLine(option.rect.left()+km_nRadius*2, y, option.rect.right(), y);
    }
    //绘制后面单元格的线
    if(index.row() == m_nTargetRow && index.column() != 0)
    {
        painterEx->DrawBorder(option.rect, QPen(QColor(86,135,228), 2), m_bIsUpon?PainterEx::RectBorderTop:PainterEx::RectBorderBottom);
    }
    
//    //绘制拖拽指示器(绘制2*列数次, 防止被覆盖)
//    if(index.row() == m_nTargetRow||index.row() == m_nTargetRow+1)
//    {
//        painter->setRenderHint(QPainter::Antialiasing);
//        painter->setPen(QPen(QColor(86,135,228), 2));
//        painter->setBrush(Qt::transparent);
        
//        //int rowCount = m_pTableView->model()->rowCount();
//        int colCount = m_pTableView->model()->columnCount();
//        QPoint targetRowRect_topLeft = m_pTableView->visualRect(m_pTableView->model()->index(row,0)).topLeft();
//        QPoint targetRowRect_bottomRight = m_pTableView->visualRect(m_pTableView->model()->index(row,colCount-1)).bottomRight();
//        QRect targetRowRect(targetRowRect_topLeft, targetRowRect_bottomRight);
        
//        //头部圆圈
//        int radius = 8;
//        int y = m_bIsUpon?targetRowRect.top():targetRowRect.bottom();
//        QPoint topleft = QPoint(targetRowRect.left(), y - radius);
//        painter->drawEllipse(QRect(topleft, QSize(radius*2, radius*2)));
//        painter->drawLine(targetRowRect.left()+radius*2, y, targetRowRect.right(), y);
    //    }
}