#ifndef CODEEDITOR_H
#define CODEEDITOR_H

#include <QSyntaxHighlighter>
#include <QPlainTextEdit>
#include <QObject>
#include <QRegularExpression>

class CodeEditorStyle;
class QPaintEvent;
class QResizeEvent;

class Highlighter : public QSyntaxHighlighter {
 Q_OBJECT

public:
 explicit Highlighter(QTextDocument *parent,
 CodeEditorStyle *widgetStyle);

 void setSymbols(const QStringList &symbols);

 void setStyle(const CodeEditorStyle &newStyle);

protected:
 void highlightBlock(const QString &text) override;

private:
 enum RuleRole {
 Keyword = 1,
 Class = 2,
 Comment = 3,
 Quote = 4,
 Symbol = 5
 };
 struct HighlightingRule {
 QRegularExpression pattern;
 QTextCharFormat format;
 RuleRole ruleRole;
 };

 void applyFormat(HighlightingRule &rule);

 QVector<HighlightingRule> mHighlightingRules;
 QVector<HighlightingRule> mHighlightingRulesWithSymbols;

 QRegularExpression mCommentStartExpression;
 QRegularExpression mCommentEndExpression;

 QTextCharFormat mKeywordFormat;
 QTextCharFormat mClassFormat;
 QTextCharFormat mSingleLineCommentFormat;
 QTextCharFormat mMultiLineCommentFormat;
 QTextCharFormat mQuotationFormat;
 QTextCharFormat mSymbolFormat;

 CodeEditorStyle *mWidgetStyle;
};

class CodeEditor : public QPlainTextEdit {
 Q_OBJECT

public:
 explicit CodeEditor(QWidget *parent);
 CodeEditor(const CodeEditor &) = delete;
 CodeEditor &operator=(const CodeEditor &) = delete;
 ~CodeEditor();

 void lineNumberAreaPaintEvent(QPaintEvent *event);
 int lineNumberAreaWidth();
 void setStyle(const CodeEditorStyle& newStyle);

 /**
 * Set source code to show, goto error line and highlight that line.
 * \param code The source code.
 * \param errorLine line number
 * \param symbols the related symbols, these are marked
 */
 void setError(const QString &code, int errorLine, const QStringList &symbols);

protected:
 void resizeEvent(QResizeEvent *event) override;

private slots:
 void updateLineNumberAreaWidth(int newBlockCount);
 void highlightErrorLine();
 void updateLineNumberArea(const QRect &, int);

private:
 QString generateStyleString();

private:
 QWidget *mLineNumberArea;
 Highlighter *mHighlighter;
 CodeEditorStyle *mWidgetStyle;
 int mErrorPosition;
};


class LineNumberArea : public QWidget {
public:
 explicit LineNumberArea(CodeEditor *editor) : QWidget(editor) {
 mCodeEditor = editor;
 }

 QSize sizeHint() const override {
 return QSize(mCodeEditor->lineNumberAreaWidth(), 0);
 }

protected:
 void paintEvent(QPaintEvent *event) override {
 mCodeEditor->lineNumberAreaPaintEvent(event);
 }

private:
 CodeEditor *mCodeEditor;
};

#endif // CODEEDITOR_H