/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/
**
** This file is part of the QtQml module of the Qt Toolkit.
**
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** GNU Lesser General Public License Usage
** This file may be used under the terms of the GNU Lesser General Public
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** appearing in the file LICENSE.LGPL included in the packaging of this
** file. Please review the following information to ensure the GNU Lesser
** General Public License version 2.1 requirements will be met:
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** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of this
** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
** http://www.gnu.org/copyleft/gpl.html.
**
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** conditions contained in a signed written agreement between you and Nokia.
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** $QT_END_LICENSE$
**
****************************************************************************/

#include "qqmlrewrite_p.h"

#include <private/qqmlglobal_p.h>

#include <QtCore/qdebug.h>

QT_BEGIN_NAMESPACE

DEFINE_BOOL_CONFIG_OPTION(rewriteDump, QML_REWRITE_DUMP);

namespace QQmlRewrite {

static void rewriteStringLiteral(AST::StringLiteral *ast, const QString *code, int startPosition, TextWriter *writer)
{
    const unsigned position = ast->firstSourceLocation().begin() - startPosition + 1;
    const unsigned length = ast->literalToken.length - 2;
    const QStringRef spell = code->midRef(position, length);
    const int end = spell.size();
    int index = 0;

    while (index < end) {
        const QChar ch = spell.at(index++);

        if (index < end && ch == QLatin1Char('\\')) {
            int pos = index;

            // skip a possibly empty sequence of \r characters
            while (pos < end && spell.at(pos) == QLatin1Char('\r'))
                ++pos;

            if (pos < end && spell.at(pos) == QLatin1Char('\n')) {
                // This is a `\' followed by a newline terminator.
                // In this case there's nothing to replace. We keep the code
                // as it is and we resume the searching.
                index = pos + 1; // refresh the index
            }
        } else if (ch == QLatin1Char('\r') || ch == QLatin1Char('\n')) {
            const QString sep = ch == QLatin1Char('\r') ? QLatin1String("\\r") : QLatin1String("\\n");
            const int pos = index - 1;
            QString s = sep;

            while (index < end && spell.at(index) == ch) {
                s += sep;
                ++index;
            }

            writer->replace(position + pos, index - pos, s);
        }
    }
}

bool SharedBindingTester::isSharable(const QString &code)
{
    Engine engine;
    Lexer lexer(&engine);
    Parser parser(&engine);
    lexer.setCode(code, 0);
    parser.parseStatement();
    if (!parser.statement()) 
        return false;

    return isSharable(parser.statement());
}

bool SharedBindingTester::isSharable(AST::Node *node)
{
    _sharable = true;
    AST::Node::acceptChild(node, this);
    return _sharable;
}

QString RewriteBinding::operator()(const QString &code, bool *ok, bool *sharable)
{
    Engine engine;
    Lexer lexer(&engine);
    Parser parser(&engine);
    lexer.setCode(code, 0);
    parser.parseStatement();
    if (!parser.statement()) {
        if (ok) *ok = false;
        return QString();
    } else {
        if (ok) *ok = true;
        if (sharable) {
            SharedBindingTester tester;
            *sharable = tester.isSharable(parser.statement());
        }
    }
    return rewrite(code, 0, parser.statement());
}

QString RewriteBinding::operator()(QQmlJS::AST::Node *node, const QString &code, bool *sharable)
{
    if (!node)
        return code;

    if (sharable) {
        SharedBindingTester tester;
        *sharable = tester.isSharable(node);
    }

    QQmlJS::AST::ExpressionNode *expression = node->expressionCast();
    QQmlJS::AST::Statement *statement = node->statementCast();
    if(!expression && !statement)
        return code;

    TextWriter w;
    _writer = &w;
    _position = expression ? expression->firstSourceLocation().begin() : statement->firstSourceLocation().begin();
    _inLoop = 0;
    _code = &code;

    accept(node);

    unsigned startOfStatement = 0;
    unsigned endOfStatement = (expression ? expression->lastSourceLocation().end() : statement->lastSourceLocation().end()) - _position;

    QString startString = QLatin1String("(function ") + _name + QLatin1String("() { ");
    if (expression)
        startString += QLatin1String("return ");
    _writer->replace(startOfStatement, 0, startString);
    _writer->replace(endOfStatement, 0, QLatin1String(" })"));

    if (rewriteDump()) {
        qWarning() << "=============================================================";
        qWarning() << "Rewrote:";
        qWarning() << qPrintable(code);
    }

    QString codeCopy = code;
    w.write(&codeCopy);

    if (rewriteDump()) {
        qWarning() << "To:";
        qWarning() << qPrintable(codeCopy);
        qWarning() << "=============================================================";
    }

    return codeCopy;
}

void RewriteBinding::accept(AST::Node *node)
{
    AST::Node::acceptChild(node, this);
}

QString RewriteBinding::rewrite(QString code, unsigned position,
                                AST::Statement *node)
{
    TextWriter w;
    _writer = &w;
    _position = position;
    _inLoop = 0;
    _code = &code;

    accept(node);

    unsigned startOfStatement = node->firstSourceLocation().begin() - _position;
    unsigned endOfStatement = node->lastSourceLocation().end() - _position;

    _writer->replace(startOfStatement, 0, QLatin1String("(function ") + _name + QLatin1String("() { "));
    _writer->replace(endOfStatement, 0, QLatin1String(" })"));

    if (rewriteDump()) {
        qWarning() << "=============================================================";
        qWarning() << "Rewrote:";
        qWarning() << qPrintable(code);
    }

    w.write(&code);

    if (rewriteDump()) {
        qWarning() << "To:";
        qWarning() << qPrintable(code);
        qWarning() << "=============================================================";
    }

    return code;
}

bool RewriteBinding::visit(AST::Block *ast)
{
    for (AST::StatementList *it = ast->statements; it; it = it->next) {
        if (! it->next) {
            // we need to rewrite only the last statement of a block.
            accept(it->statement);
        }
    }

    return false;
}

bool RewriteBinding::visit(AST::ExpressionStatement *ast)
{
    if (! _inLoop) {
        unsigned startOfExpressionStatement = ast->firstSourceLocation().begin() - _position;
        _writer->replace(startOfExpressionStatement, 0, QLatin1String("return "));
    }

    return false;
}

bool RewriteBinding::visit(AST::StringLiteral *ast)
{
    rewriteStringLiteral(ast, _code, _position, _writer);
    return false;
}

bool RewriteBinding::visit(AST::DoWhileStatement *)
{
    ++_inLoop;
    return true;
}

void RewriteBinding::endVisit(AST::DoWhileStatement *)
{
    --_inLoop;
}

bool RewriteBinding::visit(AST::WhileStatement *)
{
    ++_inLoop;
    return true;
}

void RewriteBinding::endVisit(AST::WhileStatement *)
{
    --_inLoop;
}

bool RewriteBinding::visit(AST::ForStatement *)
{
    ++_inLoop;
    return true;
}

void RewriteBinding::endVisit(AST::ForStatement *)
{
    --_inLoop;
}

bool RewriteBinding::visit(AST::LocalForStatement *)
{
    ++_inLoop;
    return true;
}

void RewriteBinding::endVisit(AST::LocalForStatement *)
{
    --_inLoop;
}

bool RewriteBinding::visit(AST::ForEachStatement *)
{
    ++_inLoop;
    return true;
}

void RewriteBinding::endVisit(AST::ForEachStatement *)
{
    --_inLoop;
}

bool RewriteBinding::visit(AST::LocalForEachStatement *)
{
    ++_inLoop;
    return true;
}

void RewriteBinding::endVisit(AST::LocalForEachStatement *)
{
    --_inLoop;
}

bool RewriteBinding::visit(AST::CaseBlock *ast)
{
    // Process the initial sequence of the case clauses.
    for (AST::CaseClauses *it = ast->clauses; it; it = it->next) {
        // Return the value of the last statement in the block, if this is the last `case clause'
        // of the switch statement.
        bool returnTheValueOfLastStatement = (it->next == 0) && (ast->defaultClause == 0) && (ast->moreClauses == 0);

        if (AST::CaseClause *clause = it->clause) {
            accept(clause->expression);
            rewriteCaseStatements(clause->statements, returnTheValueOfLastStatement);
        }
    }

    // Process the default case clause
    if (ast->defaultClause) {
        // Return the value of the last statement in the block, if this is the last `case clause'
        // of the switch statement.
        bool rewriteTheLastStatement = (ast->moreClauses == 0);

        rewriteCaseStatements(ast->defaultClause->statements, rewriteTheLastStatement);
    }

    // Process trailing `case clauses'
    for (AST::CaseClauses *it = ast->moreClauses; it; it = it->next) {
        // Return the value of the last statement in the block, if this is the last `case clause'
        // of the switch statement.
        bool returnTheValueOfLastStatement = (it->next == 0);

        if (AST::CaseClause *clause = it->clause) {
            accept(clause->expression);
            rewriteCaseStatements(clause->statements, returnTheValueOfLastStatement);
        }
    }

    return false;
}

void RewriteBinding::rewriteCaseStatements(AST::StatementList *statements, bool rewriteTheLastStatement)
{
    for (AST::StatementList *it = statements; it; it = it->next) {
        if (it->next && AST::cast<AST::BreakStatement *>(it->next->statement) != 0) {
            // The value of the first statement followed by a `break'.
            accept(it->statement);
            break;
        } else if (!it->next) {
            if (rewriteTheLastStatement)
                accept(it->statement);
            else if (AST::Block *block = AST::cast<AST::Block *>(it->statement))
                rewriteCaseStatements(block->statements, rewriteTheLastStatement);
        }
    }
}

RewriteSignalHandler::RewriteSignalHandler()
    : _writer(0)
    , _code(0)
    , _position(0)
{
}

void RewriteSignalHandler::accept(AST::Node *node)
{
    AST::Node::acceptChild(node, this);
}

bool RewriteSignalHandler::visit(AST::StringLiteral *ast)
{
    rewriteStringLiteral(ast, _code, _position, _writer);
    return false;
}

QString RewriteSignalHandler::operator()(QQmlJS::AST::Node *node, const QString &code, const QString &name)
{
    if (rewriteDump()) {
        qWarning() << "=============================================================";
        qWarning() << "Rewrote:";
        qWarning() << qPrintable(code);
    }

    QQmlJS::AST::ExpressionNode *expression = node->expressionCast();
    QQmlJS::AST::Statement *statement = node->statementCast();
    if (!expression && !statement)
        return code;

    TextWriter w;
    _writer = &w;
    _code = &code;

    _position = expression ? expression->firstSourceLocation().begin() : statement->firstSourceLocation().begin();
    accept(node);

    QString rewritten = code;
    w.write(&rewritten);

    rewritten = QStringLiteral("(function ") + name + QStringLiteral("() { ") + rewritten + QStringLiteral(" })");

    if (rewriteDump()) {
        qWarning() << "To:";
        qWarning() << qPrintable(rewritten);
        qWarning() << "=============================================================";
    }

    return rewritten;
}

} // namespace QQmlRewrite

QT_END_NAMESPACE