#include <QtWidgets>
#include <QShortcut>
#include "codeeditor.h"
#include "codeeditorstyle.h"


Highlighter::Highlighter(QTextDocument *parent,
 CodeEditorStyle *widgetStyle) :
 QSyntaxHighlighter(parent),
 mWidgetStyle(widgetStyle)
{
 HighlightingRule rule;

 mKeywordFormat.setForeground(mWidgetStyle->keywordColor);
 mKeywordFormat.setFontWeight(mWidgetStyle->keywordWeight);
 QStringList keywordPatterns;
 keywordPatterns << "bool"
 << "break"
 << "case"
 << "char"
 << "class"
 << "const"
 << "continue"
 << "default"
 << "do"
 << "double"
 << "else"
 << "enum"
 << "explicit"
 << "for"
 << "friend"
 << "if"
 << "inline"
 << "int"
 << "long"
 << "namespace"
 << "operator"
 << "private"
 << "protected"
 << "public"
 << "return"
 << "short"
 << "signed"
 << "static"
 << "struct"
 << "switch"
 << "template"
 << "throw"
 << "typedef"
 << "typename"
 << "union"
 << "unsigned"
 << "virtual"
 << "void"
 << "volatile"
 << "while";
 foreach (const QString &pattern, keywordPatterns) {
 rule.pattern = QRegularExpression("\\b" + pattern + "\\b");
 rule.format = mKeywordFormat;
 rule.ruleRole = RuleRole::Keyword;
 mHighlightingRules.append(rule);
 }

 mClassFormat.setForeground(mWidgetStyle->classColor);
 mClassFormat.setFontWeight(mWidgetStyle->classWeight);
 rule.pattern = QRegularExpression("\\bQ[A-Za-z]+\\b");
 rule.format = mClassFormat;
 rule.ruleRole = RuleRole::Class;
 mHighlightingRules.append(rule);

 mQuotationFormat.setForeground(mWidgetStyle->quoteColor);
 mQuotationFormat.setFontWeight(mWidgetStyle->quoteWeight);
 rule.pattern = QRegularExpression("\".*\"");
 rule.format = mQuotationFormat;
 rule.ruleRole = RuleRole::Quote;
 mHighlightingRules.append(rule);

 mSingleLineCommentFormat.setForeground(mWidgetStyle->commentColor);
 mSingleLineCommentFormat.setFontWeight(mWidgetStyle->commentWeight);
 rule.pattern = QRegularExpression("//[^\n]*");
 rule.format = mSingleLineCommentFormat;
 rule.ruleRole = RuleRole::Comment;
 mHighlightingRules.append(rule);

 mHighlightingRulesWithSymbols = mHighlightingRules;

 mMultiLineCommentFormat.setForeground(mWidgetStyle->commentColor);
 mMultiLineCommentFormat.setFontWeight(mWidgetStyle->commentWeight);

 mSymbolFormat.setForeground(mWidgetStyle->symbolFGColor);
 mSymbolFormat.setBackground(mWidgetStyle->symbolBGColor);
 mSymbolFormat.setFontWeight(mWidgetStyle->symbolWeight);

 mCommentStartExpression = QRegularExpression("/\\*");
 mCommentEndExpression = QRegularExpression("\\*/");
}

void Highlighter::setSymbols(const QStringList &symbols)
{
 mHighlightingRulesWithSymbols = mHighlightingRules;
 foreach (const QString &sym, symbols) {
 HighlightingRule rule;
 rule.pattern = QRegularExpression("\\b" + sym + "\\b");
 rule.format = mSymbolFormat;
 rule.ruleRole = RuleRole::Symbol;
 mHighlightingRulesWithSymbols.append(rule);
 }
}

void Highlighter::setStyle(const CodeEditorStyle &newStyle)
{
 mKeywordFormat.setForeground(newStyle.keywordColor);
 mKeywordFormat.setFontWeight(newStyle.keywordWeight);
 mClassFormat.setForeground(newStyle.classColor);
 mClassFormat.setFontWeight(newStyle.classWeight);
 mSingleLineCommentFormat.setForeground(newStyle.commentColor);
 mSingleLineCommentFormat.setFontWeight(newStyle.commentWeight);
 mMultiLineCommentFormat.setForeground(newStyle.commentColor);
 mMultiLineCommentFormat.setFontWeight(newStyle.commentWeight);
 mQuotationFormat.setForeground(newStyle.quoteColor);
 mQuotationFormat.setFontWeight(newStyle.quoteWeight);
 mSymbolFormat.setForeground(newStyle.symbolFGColor);
 mSymbolFormat.setBackground(newStyle.symbolBGColor);
 mSymbolFormat.setFontWeight(newStyle.symbolWeight);
 for (HighlightingRule& rule : mHighlightingRules) {
 applyFormat(rule);
 }

 for (HighlightingRule& rule : mHighlightingRulesWithSymbols) {
 applyFormat(rule);
 }
}

void Highlighter::highlightBlock(const QString &text)
{
 foreach (const HighlightingRule &rule, mHighlightingRulesWithSymbols) {
 QRegularExpressionMatchIterator matchIterator = rule.pattern.globalMatch(text);
 while (matchIterator.hasNext()) {
 QRegularExpressionMatch match = matchIterator.next();
 setFormat(match.capturedStart(), match.capturedLength(), rule.format);
 }
 }

 setCurrentBlockState(0);

 int startIndex = 0;
 if (previousBlockState() != 1)
 startIndex = text.indexOf(mCommentStartExpression);

 while (startIndex >= 0) {
 QRegularExpressionMatch match = mCommentEndExpression.match(text, startIndex);
 int endIndex = match.capturedStart();
 int commentLength = 0;
 if (endIndex == -1) {
 setCurrentBlockState(1);
 commentLength = text.length() - startIndex;
 } else {
 commentLength = endIndex - startIndex
 + match.capturedLength();
 }
 setFormat(startIndex, commentLength, mMultiLineCommentFormat);
 startIndex = text.indexOf(mCommentStartExpression, startIndex + commentLength);
 }
}

void Highlighter::applyFormat(HighlightingRule &rule)
{
 switch (rule.ruleRole) {
 case RuleRole::Keyword:
 rule.format = mKeywordFormat;
 break;
 case RuleRole::Class:
 rule.format = mClassFormat;
 break;
 case RuleRole::Comment:
 rule.format = mSingleLineCommentFormat;
 break;
 case RuleRole::Quote:
 rule.format = mQuotationFormat;
 break;
 case RuleRole::Symbol:
 rule.format = mSymbolFormat;
 break;
 }
}

CodeEditor::CodeEditor(QWidget *parent) :
 QPlainTextEdit(parent),
 mWidgetStyle(new CodeEditorStyle(defaultStyleLight))
{
 mLineNumberArea = new LineNumberArea(this);
 mHighlighter = new Highlighter(document(), mWidgetStyle);
 mErrorPosition = -1;

 QFont font("Monospace");
 font.setStyleHint(QFont::TypeWriter);
 setFont(font);
 mLineNumberArea->setFont(font);

 // set widget coloring by overriding widget style sheet
 setObjectName("CodeEditor");
 setStyleSheet(generateStyleString());

 QShortcut *copyText = new QShortcut(QKeySequence(Qt::CTRL + Qt::Key_C),this);
 QShortcut *allText = new QShortcut(QKeySequence(Qt::CTRL + Qt::Key_A),this);

 connect(this, SIGNAL(blockCountChanged(int)), this, SLOT(updateLineNumberAreaWidth(int)));
 connect(this, SIGNAL(updateRequest(QRect,int)), this, SLOT(updateLineNumberArea(QRect,int)));
 connect(copyText, SIGNAL(activated()), this, SLOT(copy()));
 connect(allText, SIGNAL(activated()), this, SLOT(selectAll()));

 updateLineNumberAreaWidth(0);
}

CodeEditor::~CodeEditor()
{
 // NOTE: not a Qt Object - delete manually
 delete mWidgetStyle;
}

static int getPos(const QString &fileData, int lineNumber)
{
 if (lineNumber <= 1)
 return 0;
 for (int pos = 0, line = 1; pos < fileData.size(); ++pos) {
 if (fileData[pos] != '\n')
 continue;
 ++line;
 if (line >= lineNumber)
 return pos + 1;
 }
 return fileData.size();
}

void CodeEditor::setStyle(const CodeEditorStyle& newStyle)
{
 *mWidgetStyle = newStyle;
 // apply new styling
 setStyleSheet(generateStyleString());
 mHighlighter->setStyle(newStyle);
 mHighlighter->rehighlight();
 highlightErrorLine();
}

void CodeEditor::setError(const QString &code, int errorLine, const QStringList &symbols)
{
 mHighlighter->setSymbols(symbols);

 setPlainText(code);

 mErrorPosition = getPos(code, errorLine);
 QTextCursor tc = textCursor();
 tc.setPosition(mErrorPosition);
 setTextCursor(tc);
 centerCursor();

 highlightErrorLine();
}

int CodeEditor::lineNumberAreaWidth()
{
 int digits = 1;
 int max = qMax(1, blockCount());
 while (max >= 10) {
 max /= 10;
 ++digits;
 }

 int space = 3 + fontMetrics().width(QLatin1Char('9')) * digits;
 return space;
}

void CodeEditor::updateLineNumberAreaWidth(int /* newBlockCount */)
{
 setViewportMargins(lineNumberAreaWidth(), 0, 0, 0);
}

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

 if (rect.contains(viewport()->rect()))
 updateLineNumberAreaWidth(0);
}

void CodeEditor::resizeEvent(QResizeEvent *event)
{
 QPlainTextEdit::resizeEvent(event);
 QRect cr = contentsRect();
 mLineNumberArea->setGeometry(QRect(cr.left(), cr.top(), lineNumberAreaWidth(), cr.height()));
}

void CodeEditor::highlightErrorLine()
{
 QList<QTextEdit::ExtraSelection> extraSelections;

 QTextEdit::ExtraSelection selection;

 selection.format.setBackground(mWidgetStyle->highlightBGColor);
 selection.format.setProperty(QTextFormat::FullWidthSelection, true);
 selection.cursor = QTextCursor(document());
 if (mErrorPosition >= 0) {
 selection.cursor.setPosition(mErrorPosition);
 } else {
 selection.cursor.setPosition(0);
 }
 selection.cursor.clearSelection();
 extraSelections.append(selection);

 setExtraSelections(extraSelections);
}

void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
{
 QPainter painter(mLineNumberArea);
 painter.fillRect(event->rect(), mWidgetStyle->lineNumBGColor);

 QTextBlock block = firstVisibleBlock();
 int blockNumber = block.blockNumber();
 int top = (int) blockBoundingGeometry(block).translated(contentOffset()).top();
 int bottom = top + (int) blockBoundingRect(block).height();

 while (block.isValid() && top <= event->rect().bottom()) {
 if (block.isVisible() && bottom >= event->rect().top()) {
 QString number = QString::number(blockNumber + 1);
 painter.setPen(mWidgetStyle->lineNumFGColor);
 painter.drawText(0, top, mLineNumberArea->width(), fontMetrics().height(),
 Qt::AlignRight, number);
 }

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

QString CodeEditor::generateStyleString()
{
 QString bgcolor = QString("background:rgb(%1,%2,%3);")
 .arg(mWidgetStyle->widgetBGColor.red())
 .arg(mWidgetStyle->widgetBGColor.green())
 .arg(mWidgetStyle->widgetBGColor.blue());
 QString fgcolor = QString("color:rgb(%1,%2,%3);")
 .arg(mWidgetStyle->widgetFGColor.red())
 .arg(mWidgetStyle->widgetFGColor.green())
 .arg(mWidgetStyle->widgetFGColor.blue());
 QString style = QString("%1 %2")
 .arg(bgcolor)
 .arg(fgcolor);
 return style;
}