#include "MainWindow.h"

#include <QAction>
#include <QApplication>
#include <QFileDialog>
#include <QFileInfo>
#include <QImageReader>
#include <QImageWriter>
#include <QKeySequence>
#include <QMenuBar>
#include <QMessageBox>
#include <QMouseEvent>
#include <QSlider>
#include <QStatusBar>
#include <QToolBar>

#include <algorithm>
#include <cmath>

ImageLabel::ImageLabel(QWidget *parent)
    : QLabel(parent)
{
    setAlignment(Qt::AlignCenter);
    setBackgroundRole(QPalette::Base);
    setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
    setScaledContents(false);
    setMinimumSize(320, 240);
    setText(tr("打开一张图片开始查看"));
}

void ImageLabel::mouseDoubleClickEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        Q_EMIT doubleClicked();
    }
    QLabel::mouseDoubleClickEvent(event);
}

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    createActions();
    createMenus();
    createToolbar();
    createCentralWidget();
    updateActions();

    setWindowTitle(tr("chengnan 图片查看器"));
    resize(1100, 720);
    statusBar()->showMessage(tr("就绪"));
}

void MainWindow::createActions()
{
    openAction_ = new QAction(tr("打开(&O)"), this);
    openAction_->setShortcut(QKeySequence::Open);
    connect(openAction_, &QAction::triggered, this, &MainWindow::openImage);

    saveAction_ = new QAction(tr("保存(&S)"), this);
    saveAction_->setShortcut(QKeySequence::Save);
    connect(saveAction_, &QAction::triggered, this, &MainWindow::saveImage);

    saveAsAction_ = new QAction(tr("另存为(&A)"), this);
    saveAsAction_->setShortcut(QKeySequence::SaveAs);
    connect(saveAsAction_, &QAction::triggered, this, &MainWindow::saveImageAs);

    exitAction_ = new QAction(tr("退出(&X)"), this);
    exitAction_->setShortcut(QKeySequence::Quit);
    connect(exitAction_, &QAction::triggered, this, &QWidget::close);

    zoomInAction_ = new QAction(tr("放大"), this);
    zoomInAction_->setShortcut(QKeySequence::ZoomIn);
    connect(zoomInAction_, &QAction::triggered, this, &MainWindow::zoomIn);

    zoomOutAction_ = new QAction(tr("缩小"), this);
    zoomOutAction_->setShortcut(QKeySequence::ZoomOut);
    connect(zoomOutAction_, &QAction::triggered, this, &MainWindow::zoomOut);

    fitAction_ = new QAction(tr("适配窗口"), this);
    fitAction_->setShortcut(Qt::CTRL | Qt::Key_F);
    connect(fitAction_, &QAction::triggered, this, &MainWindow::fitToWindow);

    resetAction_ = new QAction(tr("原始大小"), this);
    resetAction_->setShortcut(Qt::CTRL | Qt::Key_0);
    connect(resetAction_, &QAction::triggered, this, &MainWindow::resetView);

    rotateLeftAction_ = new QAction(tr("左旋 90°"), this);
    connect(rotateLeftAction_, &QAction::triggered, this, &MainWindow::rotateLeft);

    rotateRightAction_ = new QAction(tr("右旋 90°"), this);
    connect(rotateRightAction_, &QAction::triggered, this, &MainWindow::rotateRight);

    flipHorizontalAction_ = new QAction(tr("水平翻转"), this);
    connect(flipHorizontalAction_, &QAction::triggered, this, &MainWindow::flipHorizontal);

    flipVerticalAction_ = new QAction(tr("垂直翻转"), this);
    connect(flipVerticalAction_, &QAction::triggered, this, &MainWindow::flipVertical);

    grayscaleAction_ = new QAction(tr("灰度化"), this);
    connect(grayscaleAction_, &QAction::triggered, this, &MainWindow::grayscale);

    invertAction_ = new QAction(tr("反色"), this);
    connect(invertAction_, &QAction::triggered, this, &MainWindow::invertColors);
}

void MainWindow::createMenus()
{
    QMenu *fileMenu = menuBar()->addMenu(tr("文件(&F)"));
    fileMenu->addAction(openAction_);
    fileMenu->addAction(saveAction_);
    fileMenu->addAction(saveAsAction_);
    fileMenu->addSeparator();
    fileMenu->addAction(exitAction_);

    QMenu *viewMenu = menuBar()->addMenu(tr("查看(&V)"));
    viewMenu->addAction(zoomInAction_);
    viewMenu->addAction(zoomOutAction_);
    viewMenu->addAction(fitAction_);
    viewMenu->addAction(resetAction_);

    QMenu *processMenu = menuBar()->addMenu(tr("处理(&P)"));
    processMenu->addAction(rotateLeftAction_);
    processMenu->addAction(rotateRightAction_);
    processMenu->addAction(flipHorizontalAction_);
    processMenu->addAction(flipVerticalAction_);
    processMenu->addSeparator();
    processMenu->addAction(grayscaleAction_);
    processMenu->addAction(invertAction_);
}

void MainWindow::createToolbar()
{
    QToolBar *toolbar = addToolBar(tr("主工具栏"));
    toolbar->setMovable(false);
    toolbar->addAction(openAction_);
    toolbar->addAction(saveAction_);
    toolbar->addSeparator();
    toolbar->addAction(zoomOutAction_);

    zoomSlider_ = new QSlider(Qt::Horizontal, this);
    zoomSlider_->setRange(10, 400);
    zoomSlider_->setValue(100);
    zoomSlider_->setFixedWidth(180);
    zoomSlider_->setToolTip(tr("缩放比例"));
    connect(zoomSlider_, &QSlider::valueChanged, this, &MainWindow::updateZoomFromSlider);
    toolbar->addWidget(zoomSlider_);

    toolbar->addAction(zoomInAction_);
    toolbar->addAction(fitAction_);
    toolbar->addSeparator();
    toolbar->addAction(rotateLeftAction_);
    toolbar->addAction(rotateRightAction_);
    toolbar->addAction(grayscaleAction_);
    toolbar->addAction(invertAction_);
}

void MainWindow::createCentralWidget()
{
    imageLabel_ = new ImageLabel(this);
    connect(imageLabel_, &ImageLabel::doubleClicked, this, &MainWindow::fitToWindow);

    scrollArea_ = new QScrollArea(this);
    scrollArea_->setBackgroundRole(QPalette::Dark);
    scrollArea_->setWidget(imageLabel_);
    scrollArea_->setWidgetResizable(true);
    setCentralWidget(scrollArea_);
}

void MainWindow::openImage()
{
    const QString fileName = QFileDialog::getOpenFileName(
        this,
        tr("打开图片"),
        QString(),
        tr("图片文件 (*.png *.jpg *.jpeg *.bmp *.gif *.webp);;所有文件 (*.*)"));

    if (fileName.isEmpty()) {
        return;
    }

    QImageReader reader(fileName);
    reader.setAutoTransform(true);
    const QImage image = reader.read();
    if (image.isNull()) {
        QMessageBox::warning(this, tr("打开失败"), tr("无法读取图片：%1").arg(reader.errorString()));
        return;
    }

    setImage(image, fileName);
}

void MainWindow::saveImage()
{
    if (!ensureImageLoaded(tr("保存"))) {
        return;
    }

    if (currentPath_.isEmpty()) {
        saveImageAs();
        return;
    }

    writeImageToPath(currentPath_);
}

void MainWindow::saveImageAs()
{
    if (!ensureImageLoaded(tr("另存为"))) {
        return;
    }

    const QString fileName = QFileDialog::getSaveFileName(
        this,
        tr("另存为"),
        currentPath_.isEmpty() ? QStringLiteral("chengnan.png") : currentPath_,
        tr("PNG 图片 (*.png);;JPEG 图片 (*.jpg *.jpeg);;BMP 图片 (*.bmp);;所有文件 (*.*)"));

    if (!fileName.isEmpty()) {
        writeImageToPath(fileName);
    }
}

void MainWindow::zoomIn()
{
    setZoomFactor(zoomFactor_ * 1.25);
}

void MainWindow::zoomOut()
{
    setZoomFactor(zoomFactor_ / 1.25);
}

void MainWindow::fitToWindow()
{
    if (!ensureImageLoaded(tr("适配窗口"))) {
        return;
    }

    const QSize viewportSize = scrollArea_->viewport()->size();
    const QSize imageSize = currentImage_.size();
    if (imageSize.isEmpty()) {
        return;
    }

    const double xRatio = static_cast<double>(viewportSize.width()) / imageSize.width();
    const double yRatio = static_cast<double>(viewportSize.height()) / imageSize.height();
    setZoomFactor(std::min(xRatio, yRatio));
}

void MainWindow::resetView()
{
    setZoomFactor(1.0);
}

void MainWindow::rotateLeft()
{
    if (!ensureImageLoaded(tr("旋转"))) {
        return;
    }
    QTransform transform;
    transform.rotate(-90);
    applyTransformedImage(currentImage_.transformed(transform, Qt::SmoothTransformation));
}

void MainWindow::rotateRight()
{
    if (!ensureImageLoaded(tr("旋转"))) {
        return;
    }
    QTransform transform;
    transform.rotate(90);
    applyTransformedImage(currentImage_.transformed(transform, Qt::SmoothTransformation));
}

void MainWindow::flipHorizontal()
{
    if (!ensureImageLoaded(tr("翻转"))) {
        return;
    }
    applyTransformedImage(currentImage_.mirrored(true, false));
}

void MainWindow::flipVertical()
{
    if (!ensureImageLoaded(tr("翻转"))) {
        return;
    }
    applyTransformedImage(currentImage_.mirrored(false, true));
}

void MainWindow::grayscale()
{
    if (!ensureImageLoaded(tr("灰度化"))) {
        return;
    }
    applyTransformedImage(currentImage_.convertToFormat(QImage::Format_Grayscale8));
}

void MainWindow::invertColors()
{
    if (!ensureImageLoaded(tr("反色"))) {
        return;
    }
    QImage image = currentImage_.convertToFormat(QImage::Format_ARGB32);
    image.invertPixels(QImage::InvertRgb);
    applyTransformedImage(image);
}

void MainWindow::updateZoomFromSlider(int value)
{
    const double factor = static_cast<double>(value) / 100.0;
    if (std::abs(factor - zoomFactor_) > 0.001) {
        zoomFactor_ = factor;
        updateImageView();
    }
}

void MainWindow::setImage(const QImage &image, const QString &path)
{
    currentImage_ = image.convertToFormat(QImage::Format_ARGB32);
    currentPath_ = path;
    setZoomFactor(1.0);
    updateActions();

    const QFileInfo info(path);
    setWindowTitle(path.isEmpty()
        ? tr("chengnan 图片查看器")
        : tr("%1 - chengnan 图片查看器").arg(info.fileName()));
    statusBar()->showMessage(tr("已加载：%1 × %2").arg(currentImage_.width()).arg(currentImage_.height()), 5000);
}

void MainWindow::updateImageView()
{
    if (currentImage_.isNull()) {
        imageLabel_->setPixmap(QPixmap());
        imageLabel_->setText(tr("打开一张图片开始查看"));
        return;
    }

    const QSize scaledSize = currentImage_.size() * zoomFactor_;
    const QPixmap pixmap = QPixmap::fromImage(currentImage_).scaled(
        scaledSize,
        Qt::KeepAspectRatio,
        Qt::SmoothTransformation);

    imageLabel_->setText(QString());
    imageLabel_->setPixmap(pixmap);
    imageLabel_->resize(pixmap.size());

    if (zoomSlider_->value() != static_cast<int>(zoomFactor_ * 100.0)) {
        zoomSlider_->blockSignals(true);
        zoomSlider_->setValue(static_cast<int>(zoomFactor_ * 100.0));
        zoomSlider_->blockSignals(false);
    }

    statusBar()->showMessage(tr("缩放：%1%").arg(static_cast<int>(zoomFactor_ * 100.0)));
}

void MainWindow::setZoomFactor(double factor)
{
    zoomFactor_ = std::clamp(factor, 0.10, 4.00);
    updateImageView();
}

void MainWindow::applyTransformedImage(const QImage &image)
{
    currentImage_ = image.convertToFormat(QImage::Format_ARGB32);
    updateImageView();
    updateActions();
    statusBar()->showMessage(tr("处理完成，可保存结果"), 3000);
}

void MainWindow::updateActions()
{
    const bool hasImage = !currentImage_.isNull();
    saveAction_->setEnabled(hasImage);
    saveAsAction_->setEnabled(hasImage);
    zoomInAction_->setEnabled(hasImage);
    zoomOutAction_->setEnabled(hasImage);
    fitAction_->setEnabled(hasImage);
    resetAction_->setEnabled(hasImage);
    rotateLeftAction_->setEnabled(hasImage);
    rotateRightAction_->setEnabled(hasImage);
    flipHorizontalAction_->setEnabled(hasImage);
    flipVerticalAction_->setEnabled(hasImage);
    grayscaleAction_->setEnabled(hasImage);
    invertAction_->setEnabled(hasImage);
    zoomSlider_->setEnabled(hasImage);
}

bool MainWindow::ensureImageLoaded(const QString &actionName) const
{
    if (!currentImage_.isNull()) {
        return true;
    }

    QMessageBox::information(nullptr, actionName, tr("请先打开一张图片。"));
    return false;
}

bool MainWindow::writeImageToPath(const QString &path)
{
    QImageWriter writer(path);
    if (!writer.write(currentImage_)) {
        QMessageBox::warning(this, tr("保存失败"), tr("无法保存图片：%1").arg(writer.errorString()));
        return false;
    }

    currentPath_ = path;
    setWindowTitle(tr("%1 - chengnan 图片查看器").arg(QFileInfo(path).fileName()));
    statusBar()->showMessage(tr("已保存：%1").arg(path), 5000);
    return true;
}