/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

#include <cassert>
#include <string>
#include <iostream>
#include <fstream>
#include <set>
#include "plugin.hxx"

/**
look for methods where all they do is call their superclass method
*/

namespace {

class UnnecessaryOverride:
    public RecursiveASTVisitor<UnnecessaryOverride>, public loplugin::Plugin
{
public:
    explicit UnnecessaryOverride(InstantiationData const & data): Plugin(data) {}

    virtual void run() override
    {
        // ignore some files with problematic macros
        StringRef fn( compiler.getSourceManager().getFileEntryForID(
                          compiler.getSourceManager().getMainFileID())->getName() );
        if (fn == SRCDIR "/sd/source/ui/framework/factories/ChildWindowPane.cxx")
             return;
        if (fn == SRCDIR "/forms/source/component/Date.cxx")
             return;
        if (fn == SRCDIR "/forms/source/component/Time.cxx")
            return;

        TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
    }

    bool VisitCXXMethodDecl(const CXXMethodDecl *);
};

bool UnnecessaryOverride::VisitCXXMethodDecl(const CXXMethodDecl* methodDecl)
{
    if (ignoreLocation(methodDecl->getCanonicalDecl()) || !methodDecl->doesThisDeclarationHaveABody()) {
        return true;
    }
    // if we are overriding more than one method, then this is a disambiguating override
    if (!methodDecl->isVirtual() || methodDecl->size_overridden_methods() != 1
        || (*methodDecl->begin_overridden_methods())->isPure()) {
        return true;
    }
    if (dyn_cast<CXXDestructorDecl>(methodDecl)) {
        return true;
    }
    // sometimes the disambiguation happens in a base class
    StringRef aFileName = compiler.getSourceManager().getFilename(compiler.getSourceManager().getSpellingLoc(methodDecl->getLocStart()));
    if (aFileName == SRCDIR "/comphelper/source/property/propertycontainer.cxx")
        return true;
    // not sure what is happening here
    if (aFileName == SRCDIR "/extensions/source/bibliography/datman.cxx")
        return true;

    const CXXMethodDecl* overriddenMethodDecl = *methodDecl->begin_overridden_methods();

    const CompoundStmt* compoundStmt = dyn_cast<CompoundStmt>(methodDecl->getBody());
    if (!compoundStmt || compoundStmt->size() != 1)
        return true;
    const Stmt* firstStmt = compoundStmt->body_front();
    if (const ReturnStmt* returnStmt = dyn_cast<ReturnStmt>(firstStmt)) {
        firstStmt = returnStmt->getRetValue();
    }
    if (!firstStmt)
        return true;
    const CXXMemberCallExpr* callExpr = dyn_cast<CXXMemberCallExpr>(firstStmt);
    if (!callExpr || callExpr->getMethodDecl() != overriddenMethodDecl)
        return true;
    const ImplicitCastExpr* expr1 = dyn_cast_or_null<ImplicitCastExpr>(callExpr->getImplicitObjectArgument());
    if (!expr1)
        return true;
    const CXXThisExpr* expr2 = dyn_cast_or_null<CXXThisExpr>(expr1->getSubExpr());
    if (!expr2)
        return true;
    for (unsigned i = 0; i<callExpr->getNumArgs(); ++i) {
        const DeclRefExpr * declRefExpr = dyn_cast<DeclRefExpr>(callExpr->getArg(i));
        if (!declRefExpr || declRefExpr->getDecl() != methodDecl->getParamDecl(i))
            return true;
    }

    report(
        DiagnosticsEngine::Warning, "method just calls parent method",
        methodDecl->getSourceRange().getBegin())
      << methodDecl->getSourceRange();
    if (methodDecl->getCanonicalDecl()->getLocation() != methodDecl->getLocation()) {
        const CXXMethodDecl* pOther = methodDecl->getCanonicalDecl();
        report(
            DiagnosticsEngine::Note,
            "method declaration here",
            pOther->getLocStart())
          << pOther->getSourceRange();
    }
    return true;
}


loplugin::Plugin::Registration< UnnecessaryOverride > X("unnecessaryoverride", true);

}

/* vim:set shiftwidth=4 softtabstop=4 expandtab: */