/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt Creator.
**
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
****************************************************************************/

#include "cppselectionchanger.h"

#include <utils/textutils.h>
#include <utils/qtcassert.h>

#include <QDebug>
#include <QString>
#include <QTextBlock>
#include <QTextDocument>

using namespace CPlusPlus;
using namespace Utils::Text;

enum {
    debug = false
};

namespace CppEditor {

namespace Internal {
const int kChangeSelectionNodeIndexNotSet = -1;
const int kChangeSelectionNodeIndexWholeDocoument = -2;
} // namespace Internal
using namespace Internal;

CppSelectionChanger::CppSelectionChanger(QObject *parent)
    : QObject(parent)
    , m_changeSelectionNodeIndex(kChangeSelectionNodeIndexNotSet)
    , m_nodeCurrentStep(kChangeSelectionNodeIndexNotSet)
{
}

void CppSelectionChanger::onCursorPositionChanged(const QTextCursor &newCursor)
{
    // Reset the text cursor to be used for initial change selection behavior, only in the case
    // that the cursor is not being modified by the actual change selection methods.
    if (!m_inChangeSelection) {
        m_initialChangeSelectionCursor = newCursor;
        setNodeIndexAndStep(NodeIndexAndStepNotSet);
        if (debug)
            qDebug() << "Updating change selection cursor position:" << newCursor.position();
    }
}

namespace {

bool hasNoSelectionAndShrinking(
        CppSelectionChanger::Direction direction,
        const QTextCursor &cursor)
{
    if (direction == CppSelectionChanger::ShrinkSelection && !cursor.hasSelection()) {
        if (debug)
            qDebug() << "No selection to shrink, exiting early.";
        return true;
    }
    return false;
}

void ensureCursorSelectionIsNotFlipped(QTextCursor &cursor)
{
    if (cursor.hasSelection() && (cursor.anchor() > cursor.position()))
        cursor = flippedCursor(cursor);

    if (debug) {
        int l, c;
        convertPosition(cursor.document(), cursor.position(), &l, &c);

        qDebug() << "Cursor details: " << cursor.anchor() << cursor.position()
                 << " l,c:" << l << ":" << c;
    }
}

bool isDocumentAvailable(const CPlusPlus::Document::Ptr doc)
{
    if (!doc) {
        if (debug)
            qDebug() << "Document is not available.";
        return false;
    }
    return true;
}

QTextCursor getWholeDocumentCursor(const QTextCursor &cursor)
{
    QTextCursor newWholeDocumentCursor(cursor);
    newWholeDocumentCursor.setPosition(0, QTextCursor::MoveAnchor);
    newWholeDocumentCursor.setPosition(cursor.document()->characterCount() - 1,
                                       QTextCursor::KeepAnchor);
    return newWholeDocumentCursor;
}

bool isWholeDocumentSelectedAndExpanding(
        CppSelectionChanger::Direction direction,
        const QTextCursor &cursor)
{
    if (direction == CppSelectionChanger::ExpandSelection && cursor.hasSelection()) {
        const QTextCursor wholeDocumentCursor = getWholeDocumentCursor(cursor);
        if (wholeDocumentCursor == cursor) {
            if (debug)
                qDebug() << "Selection is whole document, nothing to expand, exiting early.";
            return true;
        }
    }
    return false;
}

} // end of anonymous namespace

int CppSelectionChanger::getTokenStartCursorPosition(
        unsigned tokenIndex,
        const QTextCursor &cursor) const
{
    int startLine, startColumn;
    m_unit->getTokenStartPosition(tokenIndex, &startLine, &startColumn);

    const QTextDocument *document = cursor.document();
    const int startPosition = document->findBlockByNumber(startLine - 1).position()
                                    + startColumn - 1;

    return startPosition;
}

int CppSelectionChanger::getTokenEndCursorPosition(
        unsigned tokenIndex,
        const QTextCursor &cursor) const
{
    int endLine, endColumn;
    m_unit->getTokenEndPosition(tokenIndex, &endLine, &endColumn);

    const QTextDocument *document = cursor.document();
    const int endPosition = document->findBlockByNumber(endLine - 1).position()
                                    + endColumn - 1;

    return endPosition;
}

void CppSelectionChanger::printTokenDebugInfo(
        unsigned tokenIndex,
        const QTextCursor &cursor,
        QString prefix) const
{
    int line, column;
    const Token token = m_unit->tokenAt(tokenIndex);
    m_unit->getTokenStartPosition(tokenIndex, &line, &column);
    const int startPos = getTokenStartCursorPosition(tokenIndex, cursor);
    const int endPos = getTokenEndCursorPosition(tokenIndex, cursor);

    qDebug() << qSetFieldWidth(20) << prefix << qSetFieldWidth(0)
             << token.spell() << tokenIndex
             << " l, c:" << line << ":" << column
             << " offset: " << token.utf16chars() << startPos << endPos;
}

bool CppSelectionChanger::shouldSkipASTNodeBasedOnPosition(
        const ASTNodePositions &positions,
        const QTextCursor &cursor) const
{
    bool shouldSkipNode = false;

    bool isEqual = cursor.anchor() == positions.astPosStart
                   && cursor.position() == positions.astPosEnd;

    // New selections should include initial selection.
    bool includesInitialSelection =
            m_initialChangeSelectionCursor.anchor() >= positions.astPosStart &&
            m_initialChangeSelectionCursor.position() <= positions.astPosEnd;

    // Prefer new selections to start with initial cursor if anchor == position.
    if (!m_initialChangeSelectionCursor.hasSelection()) {
        includesInitialSelection =
                m_initialChangeSelectionCursor.position() < positions.astPosEnd;
    }

    // When expanding: Skip if new selection is smaller than current cursor selection.
    // When shrinking: Skip if new selection is bigger than current cursor selection.
    bool isNewSelectionSmaller = positions.astPosStart > cursor.anchor()
                                 || positions.astPosEnd < cursor.position();
    bool isNewSelectionBigger = positions.astPosStart < cursor.anchor()
                                || positions.astPosEnd > cursor.position();

    if (m_direction == CppSelectionChanger::ExpandSelection
        && (isNewSelectionSmaller || isEqual || !includesInitialSelection)) {
        shouldSkipNode = true;
    } else if (m_direction == CppSelectionChanger::ShrinkSelection
               && (isNewSelectionBigger || isEqual || !includesInitialSelection)) {
        shouldSkipNode = true;
    }

    if (debug && shouldSkipNode) {
        qDebug() << "isEqual:" << isEqual << "includesInitialSelection:" << includesInitialSelection
                 << "isNewSelectionSmaller:" << isNewSelectionSmaller << "isNewSelectionBigger:"
                 << isNewSelectionBigger;
    }

    return shouldSkipNode;
}

ASTNodePositions CppSelectionChanger::getASTPositions(AST *ast, const QTextCursor &cursor) const
{
    ASTNodePositions positions(ast);

    // An AST node's contents is bound by its first token start position inclusively,
    // and its last token start position exclusively.
    // So we are also interested in the second to last token, which is actually
    // included in the bounds.
    positions.firstTokenIndex = ast->firstToken();
    positions.lastTokenIndex = ast->lastToken();
    positions.secondToLastTokenIndex = positions.lastTokenIndex - 1;

    // The AST position start is the start of the first token.
    positions.astPosStart = getTokenStartCursorPosition(positions.firstTokenIndex, cursor);

    // The end position depends on whether, there is only one token involved in the current AST
    // node or multiple ones.
    // Default we assume that there is only one token, so the end position of the AST node
    // is the start of the last token.
    // If there is more than one (second to last token will be different to the first token)
    // use the second to last token end position as the AST node end position.
    positions.astPosEnd = getTokenStartCursorPosition(positions.lastTokenIndex, cursor);
    if (positions.lastTokenIndex != positions.firstTokenIndex)
        positions.astPosEnd = getTokenEndCursorPosition(positions.secondToLastTokenIndex, cursor);

    if (debug) {
        qDebug() << "Token positions start and end:"
                 << positions.astPosStart << positions.astPosEnd;
    }

    return positions;
}

void CppSelectionChanger::updateCursorSelection(
        QTextCursor &cursorToModify,
        ASTNodePositions positions)
{
    m_workingCursor.setPosition(positions.astPosStart, QTextCursor::MoveAnchor);
    m_workingCursor.setPosition(positions.astPosEnd, QTextCursor::KeepAnchor);
    cursorToModify = m_workingCursor;

    if (debug) {
        printTokenDebugInfo(positions.firstTokenIndex, m_workingCursor,
                            QString::fromLatin1("First token:"));
        printTokenDebugInfo(positions.lastTokenIndex, m_workingCursor,
                            QString::fromLatin1("Last token:"));
        printTokenDebugInfo(positions.secondToLastTokenIndex, m_workingCursor,
                            QString::fromLatin1("Second to last:"));

        qDebug() << "Anchor is now: " << m_workingCursor.anchor();
        qDebug() << "Position is now: " << m_workingCursor.position();
    }
}

int CppSelectionChanger::getFirstCurrentStepForASTNode(AST *ast) const
{
    if (m_direction == ExpandSelection)
        return 1;
    else
        return possibleASTStepCount(ast);
}

bool CppSelectionChanger::isLastPossibleStepForASTNode(AST *ast) const
{
    if (m_direction == ExpandSelection)
        return currentASTStep() == possibleASTStepCount(ast);
    else
        return currentASTStep() == 1;
}

ASTNodePositions CppSelectionChanger::getFineTunedASTPositions(AST *ast,
                                                               const QTextCursor &cursor) const
{
    ASTNodePositions positions = getASTPositions(ast, cursor);
    fineTuneASTNodePositions(positions);
    return positions;
}

ASTNodePositions CppSelectionChanger::findRelevantASTPositionsFromCursor(
        const QList<AST *> &astPath,
        const QTextCursor &cursor,
        int startingFromNodeIndex)
{
    ASTNodePositions currentNodePositions;
    const int size = astPath.size();
    int currentAstIndex = m_direction == ExpandSelection ? size - 1 : 0;

    // Adjust starting node index, if a valid value was passed.
    if (startingFromNodeIndex != kChangeSelectionNodeIndexNotSet)
        currentAstIndex = startingFromNodeIndex;

    if (currentAstIndex < size && currentAstIndex >= 0) {
        AST *ast = astPath.at(currentAstIndex);
        m_changeSelectionNodeIndex = currentAstIndex;
        m_nodeCurrentStep = getFirstCurrentStepForASTNode(ast);
        currentNodePositions = getFineTunedASTPositions(ast, cursor);

        if (debug && startingFromNodeIndex == kChangeSelectionNodeIndexNotSet)
            qDebug() << "Setting AST index for the first time.";
    }

    if (!currentNodePositions.ast)
        setNodeIndexAndStep(NodeIndexAndStepNotSet);

    return currentNodePositions;
}

ASTNodePositions CppSelectionChanger::findRelevantASTPositionsFromCursorWhenNodeIndexNotSet(
        const QList<AST *> &astPath,
        const QTextCursor &cursor)
{
    // Find relevant AST node from cursor, when the user expands for the first time.
    return findRelevantASTPositionsFromCursor(astPath, cursor);
}

ASTNodePositions CppSelectionChanger::findRelevantASTPositionsFromCursorWhenWholeDocumentSelected(
        const QList<AST *> &astPath,
        const QTextCursor &cursor)
{
    // Can't expand more, because whole document is selected.
    if (m_direction == ExpandSelection)
        return {};

    // In case of shrink, select the next smaller selection.
    return findRelevantASTPositionsFromCursor(astPath, cursor);
}

ASTNodePositions CppSelectionChanger::findRelevantASTPositionsFromCursorFromPreviousNodeIndex(const QList<AST *> &astPath,
        const QTextCursor &cursor)
{
    ASTNodePositions nodePositions;

    // This is not the first expansion, use the previous node index.
    nodePositions.ast = astPath.at(m_changeSelectionNodeIndex);

    // We reached the last possible step for the current AST node, so we move to the
    // next / previous one depending on the direction.
    if (isLastPossibleStepForASTNode(nodePositions.ast)) {
        int newAstIndex = m_changeSelectionNodeIndex;
        if (m_direction == ExpandSelection)
            --newAstIndex;
        else
            ++newAstIndex;

        if (newAstIndex < 0 || newAstIndex >= astPath.count()) {
            if (debug)
                qDebug() << "Skipping expansion because there is no available next AST node.";
            return {};
        }

        // Switch to next AST and set the first step.
        nodePositions = findRelevantASTPositionsFromCursor(astPath, cursor, newAstIndex);
        if (!nodePositions)
            return {};

        if (debug)
            qDebug() << "Moved to next AST node.";
    } else {
        // There are possible steps available for current node, so move to the next / previous
        // step.
        if (m_direction == ExpandSelection)
            ++m_nodeCurrentStep;
        else
            --m_nodeCurrentStep;
        nodePositions = getFineTunedASTPositions(nodePositions.ast, cursor);

        if (debug)
            qDebug() << "Moved to next AST step.";
    }

    return nodePositions;
}

ASTNodePositions CppSelectionChanger::findNextASTStepPositions(const QTextCursor &cursor)
{
    // Find AST node path starting from the initial change selection cursor.
    // The ASTPath class, only takes into consideration the position of the cursor, but not the
    // anchor. We make up for that later in the code.
    QTextCursor cursorToStartFrom(m_initialChangeSelectionCursor);

    ASTPath astPathFinder(m_doc);
    const QList<AST *> astPath = astPathFinder(cursorToStartFrom);

#ifdef WITH_AST_PATH_DUMP
    if (debug)
        ASTPath::dump(astPath);
#endif

    if (astPath.size() == 0)
        return {};

    ASTNodePositions currentNodePositions;
    if (m_changeSelectionNodeIndex == kChangeSelectionNodeIndexNotSet) {
        currentNodePositions = findRelevantASTPositionsFromCursorWhenNodeIndexNotSet(astPath,
                                                                                     cursor);
    } else if (m_changeSelectionNodeIndex == kChangeSelectionNodeIndexWholeDocoument) {
        currentNodePositions = findRelevantASTPositionsFromCursorWhenWholeDocumentSelected(astPath,
                                                                                           cursor);
    } else {
        currentNodePositions = findRelevantASTPositionsFromCursorFromPreviousNodeIndex(astPath,
                                                                                       cursor);
    }

    if (debug) {
        qDebug() << "m_changeSelectionNodeIndex:" << m_changeSelectionNodeIndex
                 << "possible step count:" << possibleASTStepCount(currentNodePositions.ast)
                 << "current step:" << m_nodeCurrentStep;
    }

    QTC_ASSERT(m_nodeCurrentStep >= 1, return {});

    return currentNodePositions;
}

void CppSelectionChanger::fineTuneForStatementPositions(unsigned firstParenTokenIndex,
                                                        unsigned lastParenTokenIndex,
                                                        ASTNodePositions &positions) const
{
    Token firstParenToken = m_unit->tokenAt(firstParenTokenIndex);
    Token lastParenToken = m_unit->tokenAt(lastParenTokenIndex);
    if (debug) {
        qDebug() << "firstParenToken:" << firstParenToken.spell();
        qDebug() << "lastParenToken:" << lastParenToken.spell();
    }

    int newPosStart = getTokenStartCursorPosition(firstParenTokenIndex, m_workingCursor);
    int newPosEnd = getTokenEndCursorPosition(lastParenTokenIndex, m_workingCursor);

    bool isOutsideParen =
            m_initialChangeSelectionCursor.position() <= newPosStart;

    if (currentASTStep() == 1 && !isOutsideParen) {
        if (debug)
            qDebug() << "Selecting Paren contents of for statement.";
        positions.astPosStart = newPosStart + 1;
        positions.astPosEnd = newPosEnd - 1;
    }
    if (currentASTStep() == 2 && !isOutsideParen) {
        if (debug)
            qDebug() << "Selecting Paren of for statement together with contents.";
        positions.astPosStart = newPosStart;
        positions.astPosEnd = newPosEnd;
    }
}

void CppSelectionChanger::fineTuneASTNodePositions(ASTNodePositions &positions) const
{
    AST *ast = positions.ast;

    if (ast->asCompoundStatement()) {
        // Allow first selecting the contents of the scope, without selecting the braces, and
        // afterwards select the contents together with  braces.
        if (currentASTStep() == 1) {
            if (debug)
                qDebug() << "Selecting inner contents of compound statement.";

            unsigned firstInnerTokenIndex = positions.firstTokenIndex + 1;
            unsigned lastInnerTokenIndex = positions.lastTokenIndex - 2;
            Token firstInnerToken = m_unit->tokenAt(firstInnerTokenIndex);
            Token lastInnerToken = m_unit->tokenAt(lastInnerTokenIndex);
            if (debug) {
                qDebug() << "LastInnerToken:" << lastInnerToken.spell();
                qDebug() << "FirstInnerToken:" << firstInnerToken.spell();
            }

            // Check if compound statement is empty, then select just the blank space inside it.
            int newPosStart, newPosEnd;
            if (positions.secondToLastTokenIndex - positions.firstTokenIndex <= 1) {
                // TODO: If the empty space has a new tab character, or spaces, and the document is
                // not saved, the last semantic info is not updated, and the selection is not
                // properly computed. Figure out how to work around this.
                newPosStart = getTokenEndCursorPosition(positions.firstTokenIndex, m_workingCursor);
                newPosEnd = getTokenStartCursorPosition(positions.secondToLastTokenIndex,
                                                        m_workingCursor);
                if (debug)
                    qDebug() << "Selecting inner contents of compound statement which is empty.";
            } else {
                // Select the inner contents of the scope, without the braces.
                newPosStart = getTokenStartCursorPosition(firstInnerTokenIndex, m_workingCursor);
                newPosEnd = getTokenEndCursorPosition(lastInnerTokenIndex, m_workingCursor);
            }

            if (debug) {
                qDebug() << "New" << newPosStart << newPosEnd
                         << "Old" << m_workingCursor.anchor() << m_workingCursor.position();
            }

            positions.astPosStart = newPosStart;
            positions.astPosEnd = newPosEnd;
        }
        // Next time, we select the braces as well. Reverse for shrinking.
        // The positions already have the correct selection, so no need to set them.
    } else if (CallAST *callAST = ast->asCall()) {
        unsigned firstParenTokenIndex = callAST->lparen_token;
        unsigned lastParenTokenIndex = callAST->rparen_token;
        Token firstParenToken = m_unit->tokenAt(firstParenTokenIndex);
        Token lastParenToken = m_unit->tokenAt(lastParenTokenIndex);
        if (debug) {
            qDebug() << "firstParenToken:" << firstParenToken.spell();
            qDebug() << "lastParenToken:" << lastParenToken.spell();
        }

        // Select the parenthesis of the call, and everything between.
        int newPosStart = getTokenStartCursorPosition(firstParenTokenIndex, m_workingCursor);
        int newPosEnd = getTokenEndCursorPosition(lastParenTokenIndex, m_workingCursor);

        bool isInFunctionName =
                m_initialChangeSelectionCursor.position() <= newPosStart;

        // If cursor is inside the function name, select the name implicitly (because it's a
        // different AST node), and then the whole call expression (so just one step).
        // If cursor is inside parentheses, on first step select everything inside them,
        // on second step select the everything inside parentheses including them,
        // on third step select the whole call expression.
        if (currentASTStep() == 1 && !isInFunctionName) {
            if (debug)
                qDebug() << "Selecting everything inside parentheses.";
            positions.astPosStart = newPosStart + 1;
            positions.astPosEnd = newPosEnd - 1;
        }
        if (currentASTStep() == 2 && !isInFunctionName) {
            if (debug)
                qDebug() << "Selecting everything inside and including "
                            "the parentheses of the function call.";
            positions.astPosStart = newPosStart;
            positions.astPosEnd = newPosEnd;
        }
    } else if (StringLiteralAST *stringLiteralAST = ast->asStringLiteral()) {
        // Select literal without quotes on first step, and the whole literal on next step.
        if (currentASTStep() == 1) {
            Token firstToken = m_unit->tokenAt(stringLiteralAST->firstToken());
            bool isRawLiteral = firstToken.f.kind >= T_FIRST_RAW_STRING_LITERAL
                                && firstToken.f.kind <= T_RAW_UTF32_STRING_LITERAL;
            if (debug && isRawLiteral)
                qDebug() << "Is raw literal.";

            // Start from positions that include quotes.
            int newPosEnd = positions.astPosEnd;

            // Decrement last position to skip last quote.
            --newPosEnd;

            // If raw literal also skip parenthesis.
            if (isRawLiteral)
                --newPosEnd;

            // Start position will be the end position minus the size of the actual contents of the
            // literal.
            int newPosStart = newPosEnd - firstToken.string->size();

            // Skip raw literal parentheses.
            if (isRawLiteral)
                newPosStart += 2;

            positions.astPosStart = newPosStart;
            positions.astPosEnd = newPosEnd;
            if (debug)
                qDebug() << "Selecting inner contents of string literal.";
        }
    } else if (NumericLiteralAST *numericLiteralAST = ast->asNumericLiteral()) {
        Token firstToken = m_unit->tokenAt(numericLiteralAST->firstToken());
        // If char literal, select it without quotes on first step.
        if (firstToken.isCharLiteral()) {
            if (currentASTStep() == 1) {
                if (debug)
                    qDebug() << "Selecting inner contents of char literal.";

                positions.astPosEnd = positions.astPosEnd - 1;
                positions.astPosStart = positions.astPosEnd - firstToken.literal->size();
            }
        }
    } else if (ForStatementAST *forStatementAST = ast->asForStatement()) {
        unsigned firstParenTokenIndex = forStatementAST->lparen_token;
        unsigned lastParenTokenIndex = forStatementAST->rparen_token;
        fineTuneForStatementPositions(firstParenTokenIndex, lastParenTokenIndex, positions);
    } else if (RangeBasedForStatementAST *rangeForStatementAST = ast->asRangeBasedForStatement()) {
        unsigned firstParenTokenIndex = rangeForStatementAST->lparen_token;
        unsigned lastParenTokenIndex = rangeForStatementAST->rparen_token;
        fineTuneForStatementPositions(firstParenTokenIndex, lastParenTokenIndex, positions);
    } else if (ClassSpecifierAST *classSpecificerAST = ast->asClassSpecifier()) {

        unsigned firstBraceTokenIndex = classSpecificerAST->lbrace_token;
        unsigned lastBraceTokenIndex = classSpecificerAST->rbrace_token;
        unsigned classKeywordTokenIndex = classSpecificerAST->classkey_token;

        Token firstBraceToken = m_unit->tokenAt(firstBraceTokenIndex);
        Token lastBraceToken = m_unit->tokenAt(lastBraceTokenIndex);
        Token classKeywordToken = m_unit->tokenAt(classKeywordTokenIndex);

        if (debug) {
            qDebug() << "firstBraceToken:" << firstBraceToken.spell();
            qDebug() << "lastBraceToken:" << lastBraceToken.spell();
            qDebug() << "classKeywordToken:" << classKeywordToken.spell();

        }

        int newPosStart = getTokenStartCursorPosition(firstBraceTokenIndex, m_workingCursor);
        int newPosEnd = getTokenEndCursorPosition(lastBraceTokenIndex, m_workingCursor);

        bool isOutsideBraces =
                m_initialChangeSelectionCursor.position() <= newPosStart;
        bool isInsideBraces = !isOutsideBraces;

        int classKeywordPosStart = getTokenStartCursorPosition(classKeywordTokenIndex,
                                                               m_workingCursor);

        int classKeywordPosEnd = getTokenEndCursorPosition(classKeywordTokenIndex, m_workingCursor);

        bool isInClassKeyword = m_initialChangeSelectionCursor.anchor() >= classKeywordPosStart &&
                                m_initialChangeSelectionCursor.position() <= classKeywordPosEnd;

        bool isInClassName = false;
        int classNamePosEnd = newPosEnd;
        NameAST *nameAST = classSpecificerAST->name;
        if (nameAST) {
            SimpleNameAST *classNameAST = nameAST->asSimpleName();
            if (classNameAST) {
                unsigned identifierTokenIndex = classNameAST->identifier_token;
                Token identifierToken = m_unit->tokenAt(identifierTokenIndex);
                if (debug)
                    qDebug() << "identifierToken:" << identifierToken.spell();

                int classNamePosStart = getTokenStartCursorPosition(identifierTokenIndex,
                                                                    m_workingCursor);
                classNamePosEnd = getTokenEndCursorPosition(identifierTokenIndex,
                                                            m_workingCursor);

                isInClassName = m_initialChangeSelectionCursor.anchor() >= classNamePosStart &&
                                m_initialChangeSelectionCursor.position() <= classNamePosEnd;
            }
        }

        if (currentASTStep() == 1 && isInsideBraces) {
            if (debug)
                qDebug() << "Selecting everything inside braces of class statement.";
            positions.astPosStart = newPosStart + 1;
            positions.astPosEnd = newPosEnd - 1;
        }
        if (currentASTStep() == 2 && isInsideBraces) {
            if (debug)
                qDebug() << "Selecting braces of class statement.";
            positions.astPosStart = newPosStart;
            positions.astPosEnd = newPosEnd;
        }
        if (currentASTStep() == 1 && isInClassKeyword) {
            if (debug)
                qDebug() << "Selecting class keyword.";
            positions.astPosStart = classKeywordPosStart;
            positions.astPosEnd = classKeywordPosEnd;
        }
        if (currentASTStep() == 2 && isInClassKeyword) {
            if (debug)
                qDebug() << "Selecting class keyword and name.";
            positions.astPosStart = classKeywordPosStart;
            positions.astPosEnd = classNamePosEnd;
        }
        if (currentASTStep() == 1 && isInClassName) {
            if (debug)
                qDebug() << "Selecting class keyword and name.";
            positions.astPosStart = classKeywordPosStart;
            positions.astPosEnd = classNamePosEnd;
        }
    } else if (NamespaceAST *namespaceAST = ast->asNamespace()) {
        unsigned namespaceTokenIndex = namespaceAST->namespace_token;
        unsigned identifierTokenIndex = namespaceAST->identifier_token;
        Token namespaceToken = m_unit->tokenAt(namespaceTokenIndex);
        Token identifierToken = m_unit->tokenAt(identifierTokenIndex);
        if (debug) {
            qDebug() << "namespace token:" << namespaceToken.spell();
            qDebug() << "identifier token:" << identifierToken.spell();
        }

        int namespacePosStart = getTokenStartCursorPosition(namespaceTokenIndex, m_workingCursor);
        int namespacePosEnd = getTokenEndCursorPosition(namespaceTokenIndex, m_workingCursor);

        int identifierPosStart = getTokenStartCursorPosition(identifierTokenIndex, m_workingCursor);
        int identifierPosEnd = getTokenEndCursorPosition(identifierTokenIndex, m_workingCursor);

        bool isInNamespaceKeyword =
                m_initialChangeSelectionCursor.position() <= namespacePosEnd;

        bool isInNamespaceIdentifier =
                m_initialChangeSelectionCursor.anchor() >= identifierPosStart &&
                m_initialChangeSelectionCursor.position() <= identifierPosEnd;

        if (currentASTStep() == 1) {
            if (isInNamespaceKeyword) {
                if (debug)
                    qDebug() << "Selecting namespace keyword.";
                positions.astPosStart = namespacePosStart;
                positions.astPosEnd = namespacePosEnd;
            }
            else if (isInNamespaceIdentifier) {
                if (debug)
                    qDebug() << "Selecting namespace identifier.";
                positions.astPosStart = identifierPosStart;
                positions.astPosEnd = identifierPosEnd;
            }
        }
        else if (currentASTStep() == 2) {
            if (isInNamespaceKeyword || isInNamespaceIdentifier) {
                if (debug)
                    qDebug() << "Selecting namespace keyword and identifier.";
                positions.astPosStart = namespacePosStart;
                positions.astPosEnd = identifierPosEnd;

            }
        }
    } else if (ExpressionListParenAST *parenAST = ast->asExpressionListParen()) {
        unsigned firstParenTokenIndex = parenAST->lparen_token;
        unsigned lastParenTokenIndex = parenAST->rparen_token;
        Token firstParenToken = m_unit->tokenAt(firstParenTokenIndex);
        Token lastParenToken = m_unit->tokenAt(lastParenTokenIndex);
        if (debug) {
            qDebug() << "firstParenToken:" << firstParenToken.spell();
            qDebug() << "lastParenToken:" << lastParenToken.spell();
        }

        // Select the parentheses, and everything between.
        int newPosStart = getTokenStartCursorPosition(firstParenTokenIndex, m_workingCursor);
        int newPosEnd = getTokenEndCursorPosition(lastParenTokenIndex, m_workingCursor);

        if (currentASTStep() == 1) {
            if (debug)
                qDebug() << "Selecting everything inside parentheses.";
            positions.astPosStart = newPosStart + 1;
            positions.astPosEnd = newPosEnd - 1;
        }
        if (currentASTStep() == 2) {
            if (debug)
                qDebug() << "Selecting everything inside including the parentheses.";
            positions.astPosStart = newPosStart;
            positions.astPosEnd = newPosEnd;
        }
    } else if (FunctionDeclaratorAST* functionDeclaratorAST = ast->asFunctionDeclarator()) {
        unsigned firstParenTokenIndex = functionDeclaratorAST->lparen_token;
        unsigned lastParenTokenIndex = functionDeclaratorAST->rparen_token;
        Token firstParenToken = m_unit->tokenAt(firstParenTokenIndex);
        Token lastParenToken = m_unit->tokenAt(lastParenTokenIndex);
        if (debug) {
            qDebug() << "firstParenToken:" << firstParenToken.spell();
            qDebug() << "lastParenToken:" << lastParenToken.spell();
        }

        int newPosStart = getTokenStartCursorPosition(firstParenTokenIndex, m_workingCursor);
        int newPosEnd = getTokenEndCursorPosition(lastParenTokenIndex, m_workingCursor);

        if (currentASTStep() == 1) {
            if (debug)
                qDebug() << "Selecting everything inside and including the parentheses.";
            positions.astPosStart = newPosStart;
            positions.astPosEnd = newPosEnd;
        }
    } else if (FunctionDefinitionAST *functionDefinitionAST = ast->asFunctionDefinition()) {
        if (!functionDefinitionAST->function_body)
            return;

        CompoundStatementAST *compoundStatementAST =
                functionDefinitionAST->function_body->asCompoundStatement();
        if (!compoundStatementAST)
            return;

        if (!functionDefinitionAST->decl_specifier_list
                || !functionDefinitionAST->decl_specifier_list->value)
            return;

        SimpleSpecifierAST *simpleSpecifierAST =
                functionDefinitionAST->decl_specifier_list->value->asSimpleSpecifier();
        if (!simpleSpecifierAST)
            return;

        unsigned firstBraceTokenIndex = compoundStatementAST->lbrace_token;
        unsigned specifierTokenIndex = simpleSpecifierAST->firstToken();
        Token firstBraceToken = m_unit->tokenAt(firstBraceTokenIndex);
        Token specifierToken = m_unit->tokenAt(specifierTokenIndex);
        if (debug) {
            qDebug() << "firstBraceToken:" << firstBraceToken.spell();
            qDebug() << "specifierToken:" << specifierToken.spell();
        }

        int firstBracePosEnd = getTokenStartCursorPosition(firstBraceTokenIndex, m_workingCursor);

        bool isOutsideBraces =
                m_initialChangeSelectionCursor.position() <= firstBracePosEnd;

        if (currentASTStep() == 1 && isOutsideBraces) {
            int newPosStart = getTokenStartCursorPosition(specifierTokenIndex, m_workingCursor);

            if (debug)
                qDebug() << "Selecting everything to the left of the function braces.";
            positions.astPosStart = newPosStart;
            positions.astPosEnd = firstBracePosEnd - 1;
        }
    } else if (DeclaratorAST *declaratorAST = ast->asDeclarator()) {
        PostfixDeclaratorListAST *list = declaratorAST->postfix_declarator_list;
        if (!list)
            return;

        PostfixDeclaratorAST *postfixDeclarator = list->value;
        if (!postfixDeclarator)
            return;

        FunctionDeclaratorAST *functionDeclarator = postfixDeclarator->asFunctionDeclarator();
        if (!functionDeclarator)
            return;

        SpecifierListAST *cv_list = functionDeclarator->cv_qualifier_list;
        if (!cv_list)
            return;

        SpecifierAST *first_cv = cv_list->value;
        if (!first_cv)
            return;

        unsigned firstCVTokenIndex = first_cv->firstToken();
        Token firstCVToken = m_unit->tokenAt(firstCVTokenIndex);
        if (debug) {
            qDebug() << "firstCVTokenIndex:" << firstCVToken.spell();
        }

        int cvPosStart = getTokenStartCursorPosition(firstCVTokenIndex, m_workingCursor);
        bool isBeforeCVList = m_initialChangeSelectionCursor.position() < cvPosStart;

        if (currentASTStep() == 1 && isBeforeCVList) {
            if (debug)
                qDebug() << "Selecting function declarator without CV qualifiers.";

            int newPosEnd = cvPosStart;
            positions.astPosEnd = newPosEnd - 1;
        }

    } else if (TemplateIdAST *templateIdAST = ast->asTemplateId()) {
        unsigned identifierTokenIndex = templateIdAST->identifier_token;
        Token identifierToken = m_unit->tokenAt(identifierTokenIndex);
        if (debug) {
            qDebug() << "identifierTokenIndex:" << identifierToken.spell();
        }

        int newPosStart = getTokenStartCursorPosition(identifierTokenIndex, m_workingCursor);
        int newPosEnd = getTokenEndCursorPosition(identifierTokenIndex, m_workingCursor);

        bool isInsideIdentifier = m_initialChangeSelectionCursor.anchor() >= newPosStart &&
                                  m_initialChangeSelectionCursor.position() <= newPosEnd;

        if (currentASTStep() == 1 && isInsideIdentifier) {
            if (debug)
                qDebug() << "Selecting just identifier before selecting template id.";
            positions.astPosStart = newPosStart;
            positions.astPosEnd = newPosEnd;
        }
    } else if (TemplateDeclarationAST *templateDeclarationAST = ast->asTemplateDeclaration()) {
        unsigned templateKeywordTokenIndex = templateDeclarationAST->template_token;
        unsigned greaterTokenIndex = templateDeclarationAST->greater_token;
        Token templateKeywordToken = m_unit->tokenAt(templateKeywordTokenIndex);
        Token greaterToken = m_unit->tokenAt(greaterTokenIndex);
        if (debug) {
            qDebug() << "templateKeywordTokenIndex:" << templateKeywordToken.spell();
            qDebug() << "greaterTokenIndex:" << greaterToken.spell();
        }

        int templateKeywordPosStart = getTokenStartCursorPosition(templateKeywordTokenIndex,
                                                                  m_workingCursor);
        int templateKeywordPosEnd = getTokenEndCursorPosition(templateKeywordTokenIndex,
                                                              m_workingCursor);

        int templateParametersPosEnd = getTokenEndCursorPosition(greaterTokenIndex,
                                                                 m_workingCursor);

        bool isInsideTemplateKeyword =
                m_initialChangeSelectionCursor.anchor() >= templateKeywordPosStart &&
                m_initialChangeSelectionCursor.position() <= templateKeywordPosEnd;

        if (currentASTStep() == 1 && isInsideTemplateKeyword) {
            if (debug)
                qDebug() << "Selecting template keyword.";
            positions.astPosStart = templateKeywordPosStart;
            positions.astPosEnd = templateKeywordPosEnd;
        }
        if (currentASTStep() == 2 && isInsideTemplateKeyword) {
            if (debug)
                qDebug() << "Selecting template keyword and parameters.";
            positions.astPosStart = templateKeywordPosStart;
            positions.astPosEnd = templateParametersPosEnd;
        }
    } else if (LambdaExpressionAST *lambdaExpressionAST = ast->asLambdaExpression()) {
        // TODO: Fix more lambda cases.
        LambdaIntroducerAST *lambdaIntroducerAST = lambdaExpressionAST->lambda_introducer;
        LambdaDeclaratorAST *lambdaDeclaratorAST = lambdaExpressionAST->lambda_declarator;
        if (!lambdaDeclaratorAST)
            return;

        TrailingReturnTypeAST *trailingReturnTypeAST = lambdaDeclaratorAST->trailing_return_type;
        unsigned firstSquareBracketTokenIndex = lambdaIntroducerAST->lbracket_token;
        unsigned lastParenTokenIndex = lambdaDeclaratorAST->rparen_token;

        Token firstSquareBracketToken = m_unit->tokenAt(firstSquareBracketTokenIndex);
        Token lastParenToken = m_unit->tokenAt(lastParenTokenIndex);
        if (debug) {
            qDebug() << "firstSquareBracketToken:" << firstSquareBracketToken.spell();
            qDebug() << "lastParenToken:" << lastParenToken.spell();
        }

        int firstSquareBracketPosStart = getTokenStartCursorPosition(firstSquareBracketTokenIndex,
                                                                     m_workingCursor);
        int lastParenPosEnd = getTokenEndCursorPosition(lastParenTokenIndex, m_workingCursor);


        bool isInsideDeclarator =
                m_initialChangeSelectionCursor.anchor() >= firstSquareBracketPosStart &&
                m_initialChangeSelectionCursor.position() <= lastParenPosEnd;

        if (currentASTStep() == 1 && isInsideDeclarator) {
            if (debug)
                qDebug() << "Selecting lambda capture group and arguments.";
            positions.astPosStart = firstSquareBracketPosStart;
            positions.astPosEnd = lastParenPosEnd;
        }
        if (currentASTStep() == 2 && isInsideDeclarator && trailingReturnTypeAST) {
            if (debug)
                qDebug() << "Selecting lambda prototype.";

            unsigned lastReturnTypeTokenIndex = trailingReturnTypeAST->lastToken();
            Token lastReturnTypeToken = m_unit->tokenAt(lastReturnTypeTokenIndex);
            if (debug)
                qDebug() << "lastReturnTypeToken:" << lastReturnTypeToken.spell();
            int lastReturnTypePosEnd = getTokenEndCursorPosition(lastReturnTypeTokenIndex,
                                                                 m_workingCursor);

            positions.astPosStart = firstSquareBracketPosStart;
            positions.astPosEnd = lastReturnTypePosEnd - 2;
        }
    }
}

bool CppSelectionChanger::performSelectionChange(QTextCursor &cursorToModify)
{
    forever {
        if (ASTNodePositions positions = findNextASTStepPositions(m_workingCursor)) {
            if (!shouldSkipASTNodeBasedOnPosition(positions, m_workingCursor)) {
                updateCursorSelection(cursorToModify, positions);
                return true;
            } else {
                if (debug)
                    qDebug() << "Skipping node.";
            }
        } else if (m_direction == ShrinkSelection) {
            // The last possible action to do, if there was no step with a smaller selection, is
            // to set the cursor to the initial change selection cursor, without an anchor.
            QTextCursor finalCursor(m_initialChangeSelectionCursor);
            finalCursor.setPosition(finalCursor.position(), QTextCursor::MoveAnchor);
            cursorToModify = finalCursor;
            setNodeIndexAndStep(NodeIndexAndStepNotSet);
            if (debug)
                qDebug() << "Final shrink selection case.";
            return true;
        } else if (m_direction == ExpandSelection) {
            // The last possible action to do, if there was no step with a bigger selection, is
            // to set the cursor to the whole document including header inclusions.
            QTextCursor finalCursor = getWholeDocumentCursor(m_initialChangeSelectionCursor);
            cursorToModify = finalCursor;
            setNodeIndexAndStep(NodeIndexAndStepWholeDocument);
            if (debug)
                qDebug() << "Final expand selection case.";
            return true;
        }
        // Break out of the loop, because no further modification of the selection can be done.
        else break;
    }

    // No next step found for given direction, return early without modifying the cursor.
    return false;
}

void CppSelectionChanger::setNodeIndexAndStep(NodeIndexAndStepState state)
{
    switch (state) {
        case NodeIndexAndStepWholeDocument:
            m_changeSelectionNodeIndex = kChangeSelectionNodeIndexWholeDocoument;
            m_nodeCurrentStep = kChangeSelectionNodeIndexWholeDocoument;
            break;
        case NodeIndexAndStepNotSet:
        default:
            m_changeSelectionNodeIndex = kChangeSelectionNodeIndexNotSet;
            m_nodeCurrentStep = kChangeSelectionNodeIndexNotSet;
            break;
    }
}

bool CppSelectionChanger::changeSelection(
        Direction direction,
        QTextCursor &cursorToModify,
        const CPlusPlus::Document::Ptr doc)
{
    m_workingCursor = cursorToModify;

    if (hasNoSelectionAndShrinking(direction, m_workingCursor))
        return false;

    if (isWholeDocumentSelectedAndExpanding(direction, m_workingCursor))
        return false;

    if (!isDocumentAvailable(doc)) {
        return false;
    }

    ensureCursorSelectionIsNotFlipped(m_workingCursor);

    m_doc = doc;
    m_unit = m_doc->translationUnit();
    m_direction = direction;

    return performSelectionChange(cursorToModify);
}

void CppSelectionChanger::startChangeSelection()
{
    // Stop cursorPositionChanged signal handler from setting the initial
    // change selection cursor, when the cursor is being changed as a result of the change
    // selection operation.
    m_inChangeSelection = true;
}

void CppSelectionChanger::stopChangeSelection()
{
    m_inChangeSelection = false;
}

int CppSelectionChanger::possibleASTStepCount(CPlusPlus::AST *ast) const
{
    // Different AST nodes, have a different number of steps though which they can go.
    // For example in a string literal, we first want to select the literal contents on the first
    // step, and then the quotes + the literal content in the second step.
    if (!ast)
        return 1;
    if (ast->asCompoundStatement())
        return 2;
    if (ast->asCall())
        return 3;
    if (ast->asStringLiteral())
        return 2;
    if (NumericLiteralAST* numericLiteralAST = ast->asNumericLiteral()) {
        Token firstToken = m_unit->tokenAt(numericLiteralAST->firstToken());
        if (firstToken.isCharLiteral())
            return 2;
        return 1;
    }
    if (ast->asForStatement())
        return 3;
    if (ast->asRangeBasedForStatement())
        return 3;
    if (ast->asClassSpecifier())
        return 3;
    if (ast->asNamespace())
        return 3;
    if (ast->asExpressionListParen())
        return 2;
    if (ast->asFunctionDeclarator())
        return 1;
    if (ast->asFunctionDefinition())
        return 2;
    if (ast->asTemplateId())
        return 2;
    if (ast->asDeclarator())
        return 2;
    if (ast->asTemplateDeclaration())
        return 3;
    if (ast->asLambdaExpression())
        return 3;

    return 1;
}

int CppSelectionChanger::currentASTStep() const
{
    return m_nodeCurrentStep;
}

} // namespace CppEditor
