#include "pagination.h"

#include <QVector>

#include <QComboBox>
#include <QDebug>
#include <QMouseEvent>
#include <QPainter>
#include <QPushButton>
#include <QStyleOptionButton>

enum PageNavigation {
    PreviousPage = -2,   // <
    NextPage = -1,       // >
    PreviousExPage = -4, // <<
    NextExPage = -3,     // >>
    NoSelection = 0
};

class PaginationPrivate
{
public:
    PaginationPrivate(QWidget *_q)
        : q(_q)
        , prevText("<")
        , nextText(">")
        , layout(static_cast<Pagination::Layout>(Pagination::TOTAL | Pagination::PREV
                                                 | Pagination::PAGER | Pagination::NEXT))
    {}
    QWidget *q;
    int total = 0;       //总数
    int pageCount = 0;   //页面数量
    int currentPage = 1; //当前页面
    int pagerCount = 7;  //翻页大小
    int pageSizes = 10;  //分页大小

    int defaultSize = 30; //控件默认大小
    int spacing = 5;      //控件默认间距

    int hoverNumber = PageNavigation::NoSelection; //焦点控件

    QString prevText; //上一页文本
    QString nextText; //下一页文本

    Pagination::Layout layout;

    QSize buttonSize(const QString &text)
    { //
        QMargins margins = q->contentsMargins();
        const QFontMetrics &met = q->fontMetrics();
#if QT_VERSION < QT_VERSION_CHECK(5, 11, 0)
        int w = met.width(text);
#else
        int w = met.horizontalAdvance(text);
#endif
        // 10 边距 但是获取不正确 先固定
        int width = std::max(defaultSize, w + margins.left() + margins.right() + 10);
        int height = std::max(defaultSize, met.height() + margins.top() + margins.bottom());
        // width = std::max(width, height);
        //qDebug() << text << QSize{width, height};
        return {width, height};
    }

    void drawNumber(const QRect &rect, int number, QPainter *painter)
    {
        QString text;
        if (PageNavigation::PreviousPage == number) {
            text = prevText;
        } else if (PageNavigation::NextPage == number) {
            text = nextText;
        } else if (PageNavigation::PreviousExPage == number) {
            if (hoverNumber == number) {
                text = "<<";
            } else {
                text = "...";
            }
        } else if (PageNavigation::NextExPage == number) {
            if (hoverNumber == number) {
                text = ">>";
            } else {
                text = "...";
            }
        } else {
            text = QString::number(number);
        }
        QStyleOptionButton opt;
        opt.initFrom(q);
        opt.text = text;
        opt.rect = rect;
        opt.state.setFlag(QStyle::State_MouseOver, hoverNumber == number);
        if (number > 0) {
            opt.state.setFlag(QStyle::State_On, currentPage == number);
            opt.state.setFlag(QStyle::State_Selected, currentPage == number);
        }
        q->style()->drawControl(QStyle::CE_PushButton, &opt, painter, q);
    }

    void drawText(const QRect &rect, const QString &text, QPainter *painter)
    {
        QStyle *style = q->style();
        QStyleOption opt;
        opt.initFrom(q);

        style->drawItemText(painter,
                            rect,
                            Qt::AlignCenter,
                            opt.palette,
                            true,
                            text,
                            q->foregroundRole());
    }

    QVector<int> numbers()
    {
        QVector<int> page;

        int halfPagerCount = (pagerCount - 1) / 2;
        bool showPrevMore = false;
        bool showNextMore = false;

        if (pageCount > pagerCount) {
            if (currentPage > pagerCount - halfPagerCount) {
                showPrevMore = true;
            }
            if (currentPage < pageCount - halfPagerCount) {
                showNextMore = true;
            }
        }
        if (pageCount > 0) {
            page.push_back(1);
        }
        if (showPrevMore && !showNextMore) {
            int startPage = pageCount - (pagerCount - 2);
            page.push_back(PageNavigation::PreviousExPage);
            for (int i = startPage; i < pageCount; ++i) {
                page.push_back(i);
            }
        } else if (!showPrevMore && showNextMore) {
            for (int i = 2; i < pagerCount; ++i) {
                page.push_back(i);
            }
            page.push_back(PageNavigation::NextExPage);
        } else if (showPrevMore && showNextMore) {
            int offset = pagerCount / 2 - 1;
            page.push_back(PageNavigation::PreviousExPage);
            for (int i = currentPage - offset; i <= currentPage + offset; ++i) {
                page.push_back(i);
            }
            page.push_back(PageNavigation::NextExPage);
        } else {
            for (int i = 2; i < pageCount; ++i) {
                page.push_back(i);
            }
        }
        if (pageCount > 1) {
            page.push_back(pageCount);
        }
        return page;
    }
};

Pagination::Pagination(QWidget *parent)
    : QWidget(parent)
    , d(new PaginationPrivate(this))
{
    setMouseTracking(true); // 启用鼠标跟踪
    setContentsMargins(7, 7, 7, 7);
}

Pagination::Pagination(int total, int pageSize, QWidget *parent)
    : QWidget(parent)
    , d(new PaginationPrivate(this))
{
    setMouseTracking(true); // 启用鼠标跟踪
    setContentsMargins(7, 7, 7, 7);

    d->total = total;
    d->pageSizes = pageSize;
    d->pageCount = (total + d->pageSizes - 1) / d->pageSizes;
}

Pagination::~Pagination()
{
    delete d;
}

int Pagination::currentPage() const
{
    return d->currentPage;
}
void Pagination::setCurrentPage(int page)
{
    d->currentPage = page;
    update();
}

QString Pagination::prevText() const
{
    return d->prevText;
}
void Pagination::setPrevText(const QString &text)
{
    d->prevText = text;
    update();
}

QString Pagination::nextText() const
{
    return d->nextText;
}
void Pagination::setNextText(const QString &text)
{
    d->nextText = text;
    update();
}

int Pagination::spacing() const
{
    return d->spacing;
}

void Pagination::setSpacing(int spacing)
{
    d->spacing = spacing;
}

Pagination::Layout Pagination::layout() const
{
    return d->layout;
}
void Pagination::setLayout(Pagination::Layout layout)
{
    d->layout = layout;
}

int Pagination::pagerCount() const
{
    return d->pagerCount;
}
void Pagination::setPagerCount(int count)
{
    if (count <= 0) {
        d->pagerCount = 7;
    } else {
        d->pagerCount = count;
    }
    update();
}

int Pagination::pageSizes() const
{
    return d->pageSizes;
}
void Pagination::setPageSizes(int count)
{
    d->pageSizes = count;
    d->pageCount = (d->total + d->pageSizes - 1) / d->pageSizes;
    update();
}

int Pagination::total() const
{
    return d->total;
}
void Pagination::setTotal(int count)
{
    d->total = count;
    d->pageCount = (count + d->pageSizes - 1) / d->pageSizes;
    update();
}

QSize Pagination::sizeHint() const
{
    QMargins margins = this->contentsMargins();
    const QFontMetrics &met = this->fontMetrics();

    int height = std::max(d->defaultSize, met.height() + margins.top() + margins.bottom());

    return QSize{150, height};
}

QSize Pagination::minimumSizeHint() const
{
    QMargins margins = this->contentsMargins();
    const QFontMetrics &met = this->fontMetrics();

    int height = std::max(d->defaultSize, met.height() + margins.top() + margins.bottom());

    return QSize{150, height};
}

void Pagination::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);

    const auto pages = d->numbers();
    int x = 0;
    int y = 0;
    if (d->layout & TOTAL) {
        const QString &text = QString(tr("Total:%1")).arg(d->total);
        QSize size = d->buttonSize(text);
        QRect rect(x, y, size.width(), size.height());
        d->drawText(rect, text, &painter);
        x = x + size.width() + d->spacing;
    }
    if (d->layout & PREV) {
        QSize size = d->buttonSize(d->prevText);
        QRect rect(x, y, size.width(), size.height());
        d->drawNumber(rect, PageNavigation::PreviousPage, &painter);
        x = x + size.width() + d->spacing;
    }
    if (d->layout & PAGER) {
        for (int p : pages) {
            QSize size = d->buttonSize(QString::number(p));
            QRect rect(x, y, size.width(), size.height());
            d->drawNumber(rect, p, &painter);
            x = x + size.width() + d->spacing;
        }
    }

    if (d->layout & NEXT) {
        QSize size = d->buttonSize(d->nextText);
        QRect rect(x, y, size.width(), size.height());
        d->drawNumber(rect, PageNavigation::NextPage, &painter);
        x = x + size.width() + d->spacing;
    }
    Q_UNUSED(x)
    setMinimumWidth(x);
    //painter.drawRect(rect());

    return QWidget::paintEvent(event);
}

void Pagination::mouseMoveEvent(QMouseEvent *event)
{
    const QPoint &point = event->pos();
    int x = 0;
    int y = 0;

    if (d->layout & TOTAL) {
        const QString &text = QString(tr("Total:%1")).arg(d->total);
        QSize size = d->buttonSize(text);
        QRect rect(x, y, size.width(), size.height());
        x = x + size.width() + d->spacing;
        if (rect.contains(point)) {
            d->hoverNumber = PageNavigation::NoSelection;
            update();
            return QWidget::mouseMoveEvent(event);
        }
    }
    if (d->layout & PREV) {
        QSize size = d->buttonSize(d->prevText);
        QRect rect(x, y, size.width(), size.height());
        x = x + size.width() + d->spacing;
        if (rect.contains(point)) {
            d->hoverNumber = PageNavigation::PreviousPage;
            update();
            return QWidget::mouseMoveEvent(event);
        }
    }
    if (d->layout & PAGER) {
        const auto pages = d->numbers();
        for (int p : pages) {
            QSize size = d->buttonSize(QString::number(p));
            QRect rect(x, y, size.width(), size.height());
            x = x + size.width() + d->spacing;
            if (rect.contains(point)) {
                d->hoverNumber = p;
                update();
                return QWidget::mouseMoveEvent(event);
            }
        }
    }

    if (d->layout & NEXT) {
        QSize size = d->buttonSize(d->nextText);
        QRect rect(x, y, size.width(), size.height());
        x = x + size.width() + d->spacing;
        if (rect.contains(point)) {
            d->hoverNumber = PageNavigation::NextPage;
            update();
            return QWidget::mouseMoveEvent(event);
        }
    }
    Q_UNUSED(x)
    return QWidget::mouseMoveEvent(event);
}

void Pagination::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        const QPoint &point = event->pos();
        int x = 0;
        int y = 0;

        if (d->layout & TOTAL) {
            const QString &text = QString(tr("Total:%1")).arg(d->total);
            QSize size = d->buttonSize(text);
            QRect rect(x, y, size.width(), size.height());
            x = x + size.width() + d->spacing;
            if (rect.contains(point)) {
                update();
                return QWidget::mouseMoveEvent(event);
            }
        }
        if (d->layout & PREV) {
            QSize size = d->buttonSize(d->prevText);
            QRect rect(x, y, size.width(), size.height());
            x = x + size.width() + d->spacing;
            if (rect.contains(point)) {
                int newPage = d->currentPage - 1;
                if (newPage < 1) {
                    newPage = 1;
                }
                if (newPage > d->pageCount) {
                    newPage = d->pageCount;
                }
                //发送信号
                if (d->currentPage != newPage) {
                    d->currentPage = newPage;
                    emit valueChanged(d->currentPage);
                }
                update();
                return QWidget::mouseMoveEvent(event);
            }
        }
        if (d->layout & PAGER) {
            const auto pages = d->numbers();
            for (int p : pages) {
                QSize size = d->buttonSize(QString::number(p));
                QRect rect(x, y, size.width(), size.height());
                x = x + size.width() + d->spacing;
                if (rect.contains(point)) {
                    int newPage = d->currentPage;
                    if (p > 0) {
                        newPage = p;
                    } else {
                        const int pagerCountOffset = d->pagerCount - 2;
                        if (p == PageNavigation::PreviousExPage) {
                            newPage = d->currentPage - pagerCountOffset;
                        } else if (p == PageNavigation::NextExPage) {
                            newPage = d->currentPage + pagerCountOffset;
                        } else if (p == PageNavigation::PreviousExPage) {
                            newPage = d->currentPage - 1;
                        } else if (p == PageNavigation::NextPage) {
                            newPage = d->currentPage + 1;
                        }
                    }
                    if (newPage < 1) {
                        newPage = 1;
                    }
                    if (newPage > d->pageCount) {
                        newPage = d->pageCount;
                    }
                    //发送信号
                    if (d->currentPage != newPage) {
                        d->currentPage = newPage;
                        emit valueChanged(d->currentPage);
                    }
                    update();
                    return QWidget::mouseMoveEvent(event);
                }
            }
        }

        if (d->layout & NEXT) {
            QSize size = d->buttonSize(d->nextText);
            QRect rect(x, y, size.width(), size.height());
            x = x + size.width() + d->spacing;
            if (rect.contains(point)) {
                int newPage = d->currentPage + 1;
                if (newPage < 1) {
                    newPage = 1;
                }
                if (newPage > d->pageCount) {
                    newPage = d->pageCount;
                }
                //发送信号
                if (d->currentPage != newPage) {
                    d->currentPage = newPage;
                    emit valueChanged(d->currentPage);
                }
                update();
                return QWidget::mouseMoveEvent(event);
            }
        }
        Q_UNUSED(x)
    }
    QWidget::mousePressEvent(event);
}
void Pagination::leaveEvent(QEvent *event)
{
    d->hoverNumber = PageNavigation::NoSelection;
    update();
    QWidget::leaveEvent(event);
}