/***************************************************************************
 *   Copyright (c) 2004 Werner Mayer <wmayer[at]users.sourceforge.net>     *
 *                                                                         *
 *   This file is part of the FreeCAD CAx development system.              *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or         *
 *   modify it under the terms of the GNU Library General Public           *
 *   License as published by the Free Software Foundation; either          *
 *   version 2 of the License, or (at your option) any later version.      *
 *                                                                         *
 *   This library  is distributed in the hope that it will be useful,      *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU Library General Public License for more details.                  *
 *                                                                         *
 *   You should have received a copy of the GNU Library General Public     *
 *   License along with this library; see the file COPYING.LIB. If not,    *
 *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
 *   Suite 330, Boston, MA  02111-1307, USA                                *
 *                                                                         *
 ***************************************************************************/


#include <QContextMenuEvent>
#include <QMenu>
#include <QPainter>
#include <QRegularExpression>
#include <QShortcut>
#include <QTextCursor>


#include <Base/Parameter.h>
#include <Gui/Command.h>

#include "PythonEditor.h"
#include "Application.h"
#include "BitmapFactory.h"
#include "Macro.h"
#include "PythonDebugger.h"


using namespace Gui;

namespace Gui
{
struct PythonEditorP
{
    int debugLine {-1};
    QRect debugRect;
    QPixmap breakpoint;
    QPixmap debugMarker;
    QString filename;
    PythonDebugger* debugger;
    PythonEditorP()
        : breakpoint(BitmapFactory().iconFromTheme("breakpoint").pixmap(16, 16))
        , debugMarker(BitmapFactory().iconFromTheme("debug-marker").pixmap(16, 16))
    {
        debugger = Application::Instance->macroManager()->debugger();
    }
};
}  // namespace Gui

/* TRANSLATOR Gui::PythonEditor */

/**
 *  Constructs a PythonEditor which is a child of 'parent' and does the
 *  syntax highlighting for the Python language.
 */
PythonEditor::PythonEditor(QWidget* parent)
    : PythonTextEditor(parent)
{
    d = new PythonEditorP();
    this->setSyntaxHighlighter(new PythonSyntaxHighlighter(this));

    // set accelerators
    auto comment = new QShortcut(this);
    comment->setKey(QKeySequence(QStringLiteral("ALT+C")));

    auto uncomment = new QShortcut(this);
    uncomment->setKey(QKeySequence(QStringLiteral("ALT+U")));

    auto execInConsole = new QShortcut(this);
    execInConsole->setKey(QKeySequence(QStringLiteral("ALT+SHIFT+P")));

    connect(comment, &QShortcut::activated, this, &PythonEditor::onComment);
    connect(uncomment, &QShortcut::activated, this, &PythonEditor::onUncomment);
    connect(execInConsole, &QShortcut::activated, this, &PythonEditor::onExecuteInConsole);
}

/** Destroys the object and frees any allocated resources */
PythonEditor::~PythonEditor()
{
    delete d;
}

void PythonEditor::OnChange(Base::Subject<const char*>& rCaller, const char* sReason)
{
    const auto& rGrp = static_cast<ParameterGrp&>(rCaller);

    if (strcmp(sReason, "EnableBlockCursor") == 0 || strcmp(sReason, "FontSize") == 0
        || strcmp(sReason, "Font") == 0) {
        bool block = rGrp.GetBool("EnableBlockCursor", false);
        if (block) {
            setCursorWidth(QFontMetrics(font()).averageCharWidth());
        }
        else {
            setCursorWidth(1);
        }
    }

    TextEditor::OnChange(rCaller, sReason);
}

void PythonEditor::setFileName(const QString& fn)
{
    d->filename = fn;
}

void PythonEditor::startDebug()
{
    if (d->debugger->start()) {
        d->debugger->runFile(d->filename);
        d->debugger->stop();
    }
}

void PythonEditor::toggleBreakpoint()
{
    QTextCursor cursor = textCursor();
    int line = cursor.blockNumber() + 1;
    d->debugger->toggleBreakpoint(line, d->filename);
    getMarker()->update();
}

void PythonEditor::showDebugMarker(int line)
{
    d->debugLine = line;
    getMarker()->update();
    QTextCursor cursor = textCursor();
    cursor.movePosition(QTextCursor::StartOfBlock);
    int cur = cursor.blockNumber() + 1;
    if (cur > line) {
        for (int i = line; i < cur; i++) {
            cursor.movePosition(QTextCursor::Up);
        }
    }
    else if (cur < line) {
        for (int i = cur; i < line; i++) {
            cursor.movePosition(QTextCursor::Down);
        }
    }
    setTextCursor(cursor);
}

void PythonEditor::hideDebugMarker()
{
    d->debugLine = -1;
    getMarker()->update();
}

void PythonEditor::drawMarker(int line, int x, int y, QPainter* p)
{
    Breakpoint bp = d->debugger->getBreakpoint(d->filename);
    if (bp.checkLine(line)) {
        p->drawPixmap(x, y, d->breakpoint);
    }
    if (d->debugLine == line) {
        p->drawPixmap(x, y + 2, d->debugMarker);
        d->debugRect = QRect(x, y + 2, d->debugMarker.width(), d->debugMarker.height());
    }
}

void PythonEditor::contextMenuEvent(QContextMenuEvent* e)
{
    QMenu* menu = createStandardContextMenu();
    if (!isReadOnly()) {
        menu->addSeparator();
        QAction* comment = menu->addAction(tr("Comment"), this, &PythonEditor::onComment);
        comment->setShortcut(QKeySequence(QStringLiteral("ALT+C")));
        QAction* uncomment = menu->addAction(tr("Uncomment"), this, &PythonEditor::onUncomment);
        uncomment->setShortcut(QKeySequence(QStringLiteral("ALT+U")));
        QAction* execInConsole
            = menu->addAction(tr("Execute in Console"), this, &PythonEditor::onExecuteInConsole);
        execInConsole->setShortcut(QKeySequence(QStringLiteral("ALT+Shift+P")));
    }

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

void PythonEditor::keyPressEvent(QKeyEvent* e)
{
    /** When the user presses enter the next line should match the current
     * indentation unless the line ends in a colon, where the next line
     * should have an additional indentation.  Shift+Enter should dedent
     * the next block 1 indentation from what it would have been, if possible.
     */
    if (e->key() == Qt::Key_Enter || e->key() == Qt::Key_Return) {
        bool shiftPressed = e->modifiers() & Qt::ShiftModifier;
        ParameterGrp::handle hPrefGrp = getWindowParameter();
        int indent = hPrefGrp->GetInt("IndentSize", 4);
        bool space = hPrefGrp->GetBool("Spaces", true);
        QString ch = space ? QStringLiteral(" ") : QStringLiteral("\t");

        QTextCursor cursor = textCursor();
        QString currentLineText = cursor.block().text();
        bool endsWithColon = currentLineText.endsWith(QLatin1Char(':'));
        int currentIndentation = 0;
        // count spaces/tabs at start of current line
        for (auto c : currentLineText) {
            if (c == ch) {
                currentIndentation++;
            }
            else {
                break;
            }
        }
        cursor.insertBlock();                            // new line
        cursor.movePosition(QTextCursor::StartOfBlock);  // carriage return
        // Shift+Enter means dedent, but ensure we are not at column 0
        if (shiftPressed && currentIndentation >= indent) {
            currentIndentation -= indent;
        }
        // insert appropriate number of spaces/tabs to match current indentation
        cursor.insertText(QString(currentIndentation, ch[0]));
        // if the line ended in a colon, then we need to add another tab or multiple spaces
        if (endsWithColon) {
            if (space) {
                cursor.insertText(QString(indent, ch[0]));  // 4 more spaces by default
            }
            else {
                cursor.insertText(ch);  // 1 more tab
            }
        }
        setTextCursor(cursor);
        return;  // skip default handler
    }
    PythonTextEditor::keyPressEvent(e);  // wasn't enter key, so let base class handle it
}

void PythonEditor::onComment()
{
    prepend(QStringLiteral("#"));
}

void PythonEditor::onUncomment()
{
    remove(QStringLiteral("#"));
}

void PythonEditor::onExecuteInConsole()
{
    QTextCursor cursor = textCursor();
    int selStart = cursor.selectionStart();
    int selEnd = cursor.selectionEnd();
    QTextBlock block;
    QString selectedCode;

    for (block = document()->begin(); block.isValid(); block = block.next()) {
        int pos = block.position();
        int off = block.length() - 1;
        if (pos >= selStart || pos + off >= selStart) {
            if (pos + 1 > selEnd) {
                break;
            }

            QString lineText = block.text();
            selectedCode.append(lineText + QLatin1String("\n"));
        }
    }

    if (!selectedCode.isEmpty()) {

        /** Dedent the block of code so that the first selected
         *  line has no indentation, but the remaining lines
         *  keep their indentation relative to that first line.
         */

        // get the leading whitespace of the first line
        QStringList lines = selectedCode.split(QLatin1Char('\n'));
        QString firstLineIndent;
        for (const QString& line : lines) {
            if (!line.isEmpty()) {
                int leadingWhitespace = line.indexOf(QRegularExpression(QLatin1String("\\S")));
                if (leadingWhitespace > 0) {
                    firstLineIndent = line.left(leadingWhitespace);
                }
                break;
            }
        }

        // remove that first line whitespace from all the lines
        for (QString& line : lines) {
            if (!line.isEmpty() && line.startsWith(firstLineIndent)) {
                line.remove(0, firstLineIndent.length());
            }
        }

        // join the lines into a single QString so we can execute as a single block
        QString dedentedCode = lines.join(QLatin1Char('\n'));

        if (!dedentedCode.isEmpty()) {
            try {
                Gui::Command::doCommand(Gui::Command::Doc, dedentedCode.toStdString().c_str());
            }
            catch (const Base::Exception& e) {
                QString errorMessage = QString::fromStdString(e.what());
                Base::Console().error(
                    "Error executing Python code:\n%s\n",
                    errorMessage.toUtf8().constData()
                );
            }
            catch (...) {
                Base::Console().error("An unknown error occurred while executing Python code.\n");
            }
        }
    }
}

// ------------------------------------------------------------------------

namespace Gui
{
class PythonSyntaxHighlighterP
{
public:
    PythonSyntaxHighlighterP()
    {
        keywords << QLatin1String("and") << QLatin1String("as") << QLatin1String("assert")
                 << QLatin1String("break") << QLatin1String("class") << QLatin1String("continue")
                 << QLatin1String("def") << QLatin1String("del") << QLatin1String("elif")
                 << QLatin1String("else") << QLatin1String("except") << QLatin1String("exec")
                 << QLatin1String("False") << QLatin1String("finally") << QLatin1String("for")
                 << QLatin1String("from") << QLatin1String("global") << QLatin1String("if")
                 << QLatin1String("import") << QLatin1String("in") << QLatin1String("is")
                 << QLatin1String("lambda") << QLatin1String("None") << QLatin1String("nonlocal")
                 << QLatin1String("not") << QLatin1String("or") << QLatin1String("pass")
                 << QLatin1String("print") << QLatin1String("raise") << QLatin1String("return")
                 << QLatin1String("True") << QLatin1String("try") << QLatin1String("while")
                 << QLatin1String("with") << QLatin1String("yield");
    }

    QStringList keywords;
};
}  // namespace Gui

/**
 * Constructs a Python syntax highlighter.
 */
PythonSyntaxHighlighter::PythonSyntaxHighlighter(QObject* parent)
    : SyntaxHighlighter(parent)
{
    d = new PythonSyntaxHighlighterP;
}

/** Destroys this object. */
PythonSyntaxHighlighter::~PythonSyntaxHighlighter()
{
    delete d;
}

/**
 * Detects all kinds of text to highlight them in the correct color.
 */
void PythonSyntaxHighlighter::highlightBlock(const QString& text)
{
    int i = 0;
    QChar prev, ch;

    const int Standard = 0;       // Standard text
    const int Digit = 1;          // Digits
    const int Comment = 2;        // Comment begins with #
    const int Literal1 = 3;       // String literal beginning with "
    const int Literal2 = 4;       // Other string literal beginning with '
    const int Blockcomment1 = 5;  // Block comments beginning and ending with """
    const int Blockcomment2 = 6;  // Other block comments beginning and ending with '''
    const int ClassName = 7;      // Text after the keyword class
    const int DefineName = 8;     // Text after the keyword def

    int endStateOfLastPara = previousBlockState();
    if (endStateOfLastPara < 0 || endStateOfLastPara > maximumUserState()) {
        endStateOfLastPara = Standard;
    }

    while (i < text.length()) {
        ch = text.at(i);

        switch (endStateOfLastPara) {
            case Standard: {
                switch (ch.unicode()) {
                    case '#': {
                        // begin a comment
                        setFormat(i, 1, this->colorByType(SyntaxHighlighter::Comment));
                        endStateOfLastPara = Comment;
                    } break;
                    case '"': {
                        // Begin either string literal or block comment
                        if ((i >= 2) && text.at(i - 1) == QLatin1Char('"')
                            && text.at(i - 2) == QLatin1Char('"')) {
                            setFormat(i - 2, 3, this->colorByType(SyntaxHighlighter::BlockComment));
                            endStateOfLastPara = Blockcomment1;
                        }
                        else {
                            setFormat(i, 1, this->colorByType(SyntaxHighlighter::String));
                            endStateOfLastPara = Literal1;
                        }
                    } break;
                    case '\'': {
                        // Begin either string literal or block comment
                        if ((i >= 2) && text.at(i - 1) == QLatin1Char('\'')
                            && text.at(i - 2) == QLatin1Char('\'')) {
                            setFormat(i - 2, 3, this->colorByType(SyntaxHighlighter::BlockComment));
                            endStateOfLastPara = Blockcomment2;
                        }
                        else {
                            setFormat(i, 1, this->colorByType(SyntaxHighlighter::String));
                            endStateOfLastPara = Literal2;
                        }
                    } break;
                    case ' ':
                    case '\t': {
                        // ignore whitespaces
                    } break;
                    case '(':
                    case ')':
                    case '[':
                    case ']':
                    case '+':
                    case '-':
                    case '*':
                    case '/':
                    case ':':
                    case '%':
                    case '^':
                    case '~':
                    case '!':
                    case '=':
                    case '<':
                    case '>':  // possibly two characters
                    {
                        setFormat(i, 1, this->colorByType(SyntaxHighlighter::Operator));
                        endStateOfLastPara = Standard;
                    } break;
                    default: {
                        // Check for normal text
                        if (ch.isLetter() || ch == QLatin1Char('_')) {
                            QString buffer;
                            int j = i;
                            while (ch.isLetterOrNumber() || ch == QLatin1Char('_')) {
                                buffer += ch;
                                ++j;
                                if (j >= text.length()) {
                                    break;  // end of text
                                }
                                ch = text.at(j);
                            }

                            if (d->keywords.contains(buffer) != 0) {
                                if (buffer == QLatin1String("def")) {
                                    endStateOfLastPara = DefineName;
                                }
                                else if (buffer == QLatin1String("class")) {
                                    endStateOfLastPara = ClassName;
                                }

                                QTextCharFormat keywordFormat;
                                keywordFormat.setForeground(
                                    this->colorByType(SyntaxHighlighter::Keyword)
                                );
                                keywordFormat.setFontWeight(QFont::Bold);
                                setFormat(i, buffer.length(), keywordFormat);
                            }
                            else {
                                setFormat(i, buffer.length(), this->colorByType(SyntaxHighlighter::Text));
                            }

                            // increment i
                            if (!buffer.isEmpty()) {
                                i = j - 1;
                            }
                        }
                        // this is the beginning of a number
                        else if (ch.isDigit()) {
                            setFormat(i, 1, this->colorByType(SyntaxHighlighter::Number));
                            endStateOfLastPara = Digit;
                        }
                        // probably an operator
                        else if (ch.isSymbol() || ch.isPunct()) {
                            setFormat(i, 1, this->colorByType(SyntaxHighlighter::Operator));
                        }
                    }
                }
            } break;
            case Comment: {
                setFormat(i, 1, this->colorByType(SyntaxHighlighter::Comment));
            } break;
            case Literal1: {
                setFormat(i, 1, this->colorByType(SyntaxHighlighter::String));
                if (ch == QLatin1Char('"')) {
                    endStateOfLastPara = Standard;
                }
            } break;
            case Literal2: {
                setFormat(i, 1, this->colorByType(SyntaxHighlighter::String));
                if (ch == QLatin1Char('\'')) {
                    endStateOfLastPara = Standard;
                }
            } break;
            case Blockcomment1: {
                setFormat(i, 1, this->colorByType(SyntaxHighlighter::BlockComment));
                if (i >= 2 && ch == QLatin1Char('"') && text.at(i - 1) == QLatin1Char('"')
                    && text.at(i - 2) == QLatin1Char('"')) {
                    endStateOfLastPara = Standard;
                }
            } break;
            case Blockcomment2: {
                setFormat(i, 1, this->colorByType(SyntaxHighlighter::BlockComment));
                if (i >= 2 && ch == QLatin1Char('\'') && text.at(i - 1) == QLatin1Char('\'')
                    && text.at(i - 2) == QLatin1Char('\'')) {
                    endStateOfLastPara = Standard;
                }
            } break;
            case DefineName: {
                if (ch.isLetterOrNumber() || ch == QLatin1Char(' ') || ch == QLatin1Char('_')) {
                    setFormat(i, 1, this->colorByType(SyntaxHighlighter::Defname));
                }
                else {
                    if (ch.isSymbol() || ch.isPunct()) {
                        setFormat(i, 1, this->colorByType(SyntaxHighlighter::Operator));
                    }
                    endStateOfLastPara = Standard;
                }
            } break;
            case ClassName: {
                if (ch.isLetterOrNumber() || ch == QLatin1Char(' ') || ch == QLatin1Char('_')) {
                    setFormat(i, 1, this->colorByType(SyntaxHighlighter::Classname));
                }
                else {
                    if (ch.isSymbol() || ch.isPunct()) {
                        setFormat(i, 1, this->colorByType(SyntaxHighlighter::Operator));
                    }
                    endStateOfLastPara = Standard;
                }
            } break;
            case Digit: {
                if (ch.isDigit() || ch == QLatin1Char('.')) {
                    setFormat(i, 1, this->colorByType(SyntaxHighlighter::Number));
                }
                else {
                    if (ch.isSymbol() || ch.isPunct()) {
                        setFormat(i, 1, this->colorByType(SyntaxHighlighter::Operator));
                    }
                    endStateOfLastPara = Standard;
                }
            } break;
        }

        prev = ch;
        i++;
    }

    // only block comments can have several lines
    if (endStateOfLastPara != Blockcomment1 && endStateOfLastPara != Blockcomment2) {
        endStateOfLastPara = Standard;
    }

    setCurrentBlockState(endStateOfLastPara);
}

#include "moc_PythonEditor.cpp"