/*
    Copyright (C) 2016 Volker Krause <vkrause@kde.org>

    Permission is hereby granted, free of charge, to any person obtaining
    a copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:

    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
    IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
    CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
    TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#include "codeeditor.h"

#include <definition.h>
#include <foldingregion.h>
#include <syntaxhighlighter.h>
#include <theme.h>

#include <QApplication>
#include <QDebug>
#include <QFile>
#include <QFileDialog>
#include <QFontDatabase>
#include <QMenu>
#include <QPainter>
#include <QPalette>

class CodeEditorSidebar : public QWidget
{
    Q_OBJECT
public:
    explicit CodeEditorSidebar(CodeEditor *editor);
    QSize sizeHint() const override;

protected:
    void paintEvent(QPaintEvent *event) override;
    void mouseReleaseEvent(QMouseEvent *event) override;

private:
    CodeEditor *m_codeEditor;
};

CodeEditorSidebar::CodeEditorSidebar(CodeEditor *editor) :
    QWidget(editor),
    m_codeEditor(editor)
{
}

QSize CodeEditorSidebar::sizeHint() const
{
    return QSize(m_codeEditor->sidebarWidth(), 0);
}

void CodeEditorSidebar::paintEvent(QPaintEvent *event)
{
    m_codeEditor->sidebarPaintEvent(event);
}

void CodeEditorSidebar::mouseReleaseEvent(QMouseEvent *event)
{
    if (event->x() >= width() - m_codeEditor->fontMetrics().lineSpacing()) {
        auto block = m_codeEditor->blockAtPosition(event->y());
        if (!block.isValid() || !m_codeEditor->isFoldable(block))
            return;
        m_codeEditor->toggleFold(block);
    }
    QWidget::mouseReleaseEvent(event);
}


CodeEditor::CodeEditor(QWidget *parent) :
    QPlainTextEdit(parent),
    m_highlighter(new KSyntaxHighlighting::SyntaxHighlighter(document())),
    m_sideBar(new CodeEditorSidebar(this))
{
    setFont(QFontDatabase::systemFont(QFontDatabase::FixedFont));

    setTheme((palette().color(QPalette::Base).lightness() < 128)
        ? m_repository.defaultTheme(KSyntaxHighlighting::Repository::DarkTheme)
        : m_repository.defaultTheme(KSyntaxHighlighting::Repository::LightTheme));

    connect(this, &QPlainTextEdit::blockCountChanged, this, &CodeEditor::updateSidebarGeometry);
    connect(this, &QPlainTextEdit::updateRequest, this, &CodeEditor::updateSidebarArea);
    connect(this, &QPlainTextEdit::cursorPositionChanged, this, &CodeEditor::highlightCurrentLine);

    updateSidebarGeometry();
    highlightCurrentLine();
}

CodeEditor::~CodeEditor()
{
}

void CodeEditor::openFile(const QString& fileName)
{
    QFile f(fileName);
    if (!f.open(QFile::ReadOnly)) {
        qWarning() << "Failed to open" << fileName << ":" << f.errorString();
        return;
    }

    clear();

    const auto def = m_repository.definitionForFileName(fileName);
    m_highlighter->setDefinition(def);

    setWindowTitle(fileName);
    setPlainText(QString::fromUtf8(f.readAll()));
}

void CodeEditor::contextMenuEvent(QContextMenuEvent *event)
{
    auto menu = createStandardContextMenu(event->pos());
    menu->addSeparator();
    auto openAction = menu->addAction(QStringLiteral("Open File..."));
    connect(openAction, &QAction::triggered, this, [this]() {
        const auto fileName = QFileDialog::getOpenFileName(this, QStringLiteral("Open File"));
        if (!fileName.isEmpty())
            openFile(fileName);
    });

    // syntax selection
    auto hlActionGroup = new QActionGroup(menu);
    hlActionGroup->setExclusive(true);
    auto hlGroupMenu = menu->addMenu(QStringLiteral("Syntax"));
    QMenu *hlSubMenu = hlGroupMenu;
    QString currentGroup;
    for (const auto &def : m_repository.definitions()) {
        if (def.isHidden())
            continue;
        if (currentGroup != def.section()) {
            currentGroup = def.section();
            hlSubMenu = hlGroupMenu->addMenu(def.translatedSection());
        }

        Q_ASSERT(hlSubMenu);
        auto action = hlSubMenu->addAction(def.translatedName());
        action->setCheckable(true);
        action->setData(def.name());
        hlActionGroup->addAction(action);
        if (def.name() == m_highlighter->definition().name())
            action->setChecked(true);
    }
    connect(hlActionGroup, &QActionGroup::triggered, this, [this](QAction *action) {
        const auto defName = action->data().toString();
        const auto def = m_repository.definitionForName(defName);
        m_highlighter->setDefinition(def);
    });

    // theme selection
    auto themeGroup = new QActionGroup(menu);
    themeGroup->setExclusive(true);
    auto themeMenu = menu->addMenu(QStringLiteral("Theme"));
    for (const auto &theme : m_repository.themes()) {
        auto action = themeMenu->addAction(theme.translatedName());
        action->setCheckable(true);
        action->setData(theme.name());
        themeGroup->addAction(action);
        if (theme.name() == m_highlighter->theme().name())
            action->setChecked(true);
    }
    connect(themeGroup, &QActionGroup::triggered, this, [this](QAction *action) {
        const auto themeName = action->data().toString();
        const auto theme = m_repository.theme(themeName);
        setTheme(theme);
    });

    menu->exec(event->globalPos());
    delete menu;
}

void CodeEditor::resizeEvent(QResizeEvent *event)
{
    QPlainTextEdit::resizeEvent(event);
    updateSidebarGeometry();
}

void CodeEditor::setTheme(const KSyntaxHighlighting::Theme &theme)
{
    auto pal = qApp->palette();
    if (theme.isValid()) {
        pal.setColor(QPalette::Base, theme.editorColor(KSyntaxHighlighting::Theme::BackgroundColor));
        pal.setColor(QPalette::Highlight, theme.editorColor(KSyntaxHighlighting::Theme::TextSelection));
    }
    setPalette(pal);

    m_highlighter->setTheme(theme);
    m_highlighter->rehighlight();
    highlightCurrentLine();
}

int CodeEditor::sidebarWidth() const
{
    int digits = 1;
    auto count = blockCount();
    while (count >= 10) {
        ++digits;
        count /= 10;
    }
    return 4 + fontMetrics().horizontalAdvance(QLatin1Char('9')) * digits + fontMetrics().lineSpacing();
}

void CodeEditor::sidebarPaintEvent(QPaintEvent *event)
{
    QPainter painter(m_sideBar);
    painter.fillRect(event->rect(), m_highlighter->theme().editorColor(KSyntaxHighlighting::Theme::IconBorder));

    auto block = firstVisibleBlock();
    auto blockNumber = block.blockNumber();
    int top = blockBoundingGeometry(block).translated(contentOffset()).top();
    int bottom = top + blockBoundingRect(block).height();
    const int currentBlockNumber = textCursor().blockNumber();

    const auto foldingMarkerSize = fontMetrics().lineSpacing();

    while (block.isValid() && top <= event->rect().bottom()) {
        if (block.isVisible() && bottom >= event->rect().top()) {
            const auto number = QString::number(blockNumber + 1);
            painter.setPen(m_highlighter->theme().editorColor(
                (blockNumber == currentBlockNumber) ? KSyntaxHighlighting::Theme::CurrentLineNumber
                                                    : KSyntaxHighlighting::Theme::LineNumbers));
            painter.drawText(0, top, m_sideBar->width() - 2 - foldingMarkerSize, fontMetrics().height(), Qt::AlignRight, number);
        }

        // folding marker
        if (block.isVisible() && isFoldable(block)) {
            QPolygonF polygon;
            if (isFolded(block)) {
                polygon << QPointF(foldingMarkerSize * 0.4, foldingMarkerSize * 0.25);
                polygon << QPointF(foldingMarkerSize * 0.4, foldingMarkerSize * 0.75);
                polygon << QPointF(foldingMarkerSize * 0.8, foldingMarkerSize * 0.5);
            } else {
                polygon << QPointF(foldingMarkerSize * 0.25, foldingMarkerSize * 0.4);
                polygon << QPointF(foldingMarkerSize * 0.75, foldingMarkerSize * 0.4);
                polygon << QPointF(foldingMarkerSize * 0.5, foldingMarkerSize * 0.8);
            }
            painter.save();
            painter.setRenderHint(QPainter::Antialiasing);
            painter.setPen(Qt::NoPen);
            painter.setBrush(QColor(m_highlighter->theme().editorColor(KSyntaxHighlighting::Theme::CodeFolding)));
            painter.translate(m_sideBar->width() - foldingMarkerSize, top);
            painter.drawPolygon(polygon);
            painter.restore();
        }

        block = block.next();
        top = bottom;
        bottom = top + blockBoundingRect(block).height();
        ++blockNumber;
    }
}

void CodeEditor::updateSidebarGeometry()
{
    setViewportMargins(sidebarWidth(), 0, 0, 0);
    const auto r = contentsRect();
    m_sideBar->setGeometry(QRect(r.left(), r.top(), sidebarWidth(), r.height()));
}

void CodeEditor::updateSidebarArea(const QRect& rect, int dy)
{
    if (dy)
        m_sideBar->scroll(0, dy);
    else
        m_sideBar->update(0, rect.y(), m_sideBar->width(), rect.height());
}

void CodeEditor::highlightCurrentLine()
{
    QTextEdit::ExtraSelection selection;
    selection.format.setBackground(QColor(m_highlighter->theme().editorColor(KSyntaxHighlighting::Theme::CurrentLine)));
    selection.format.setProperty(QTextFormat::FullWidthSelection, true);
    selection.cursor = textCursor();
    selection.cursor.clearSelection();

    QList<QTextEdit::ExtraSelection> extraSelections;
    extraSelections.append(selection);
    setExtraSelections(extraSelections);
}

QTextBlock CodeEditor::blockAtPosition(int y) const
{
    auto block = firstVisibleBlock();
    if (!block.isValid())
        return QTextBlock();

    int top = blockBoundingGeometry(block).translated(contentOffset()).top();
    int bottom = top + blockBoundingRect(block).height();
    do {
        if (top <= y && y <= bottom)
            return block;
        block = block.next();
        top = bottom;
        bottom = top + blockBoundingRect(block).height();
    } while (block.isValid());
    return QTextBlock();
}

bool CodeEditor::isFoldable(const QTextBlock &block) const
{
    return m_highlighter->startsFoldingRegion(block);
}

bool CodeEditor::isFolded(const QTextBlock &block) const
{
    if (!block.isValid())
        return false;
    const auto nextBlock = block.next();
    if (!nextBlock.isValid())
        return false;
    return !nextBlock.isVisible();
}

void CodeEditor::toggleFold(const QTextBlock &startBlock)
{
    // we also want to fold the last line of the region, therefore the ".next()"
    const auto endBlock = m_highlighter->findFoldingRegionEnd(startBlock).next();

    if (isFolded(startBlock)) {
        // unfold
        auto block = startBlock.next();
        while (block.isValid() && !block.isVisible()) {
            block.setVisible(true);
            block.setLineCount(block.layout()->lineCount());
            block = block.next();
        }

    } else {
        // fold
        auto block = startBlock.next();
        while (block.isValid() && block != endBlock) {
            block.setVisible(false);
            block.setLineCount(0);
            block = block.next();
        }
    }

    // redraw document
    document()->markContentsDirty(startBlock.position(), endBlock.position() - startBlock.position() + 1);

    // update scrollbars
    emit document()->documentLayout()->documentSizeChanged(document()->documentLayout()->documentSize());
}

#include "codeeditor.moc"
