/* -*- 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 <string>
#include <iostream>

#include "plugin.hxx"
#include "compat.hxx"
#include "clang/AST/CXXInheritance.h"

// Final goal: Checker for VCL widget references. Makes sure that VCL Window subclasses are properly referenced counted and dispose()'ed.
//
// But at the moment it just finds subclasses of Window which are not heap-allocated
//
// TODO do I need to check for local and static variables, too ?
// TODO when we have a dispose() method, verify that the dispose() methods releases all of the Window references
// TODO when we have a dispose() method, verify that it calls the super-class dispose() method at some point.

namespace {

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

    virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }

    bool VisitVarDecl(const VarDecl *);

    bool VisitFieldDecl(const FieldDecl *);

    bool VisitParmVarDecl(const ParmVarDecl *);

    bool VisitFunctionDecl(const FunctionDecl *);

    bool VisitCXXDestructorDecl(const CXXDestructorDecl *);

    bool VisitCXXDeleteExpr(const CXXDeleteExpr *);

private:
    bool isDisposeCallingSuperclassDispose(const CXXMethodDecl* pMethodDecl);
};

static bool startsWith(const std::string& s, const char* other)
{
    return s.compare(0, strlen(other), other) == 0;
}

bool BaseCheckNotWindowSubclass(const CXXRecordDecl *BaseDefinition, void *) {
    if (BaseDefinition && BaseDefinition->getQualifiedNameAsString().compare("vcl::Window") == 0) {
        return false;
    }
    return true;
}

bool isDerivedFromWindow(const CXXRecordDecl *decl) {
    if (!decl)
        return false;
    if (decl->getQualifiedNameAsString() == "vcl::Window")
        return true;
    if (!decl->hasDefinition()) {
        return false;
    }
    if (// not sure what hasAnyDependentBases() does,
        // but it avoids classes we don't want, e.g. WeakAggComponentImplHelper1
        !decl->hasAnyDependentBases() &&
        !decl->forallBases(BaseCheckNotWindowSubclass, nullptr, true)) {
        return true;
    }
    return false;
}

bool containsWindowSubclass(const Type* pType0);

bool containsWindowSubclass(const QualType& qType) {
    if (startsWith(qType.getAsString(), "VclPtr"))
        return false;
    if (startsWith(qType.getAsString(), "class VclPtr"))
        return false;
    if (startsWith(qType.getAsString(), "const class VclPtr"))
        return false;
    return containsWindowSubclass(qType.getTypePtr());
}

bool containsWindowSubclass(const Type* pType0) {
    if (!pType0)
        return false;
    const Type* pType = pType0->getUnqualifiedDesugaredType();
    if (!pType)
        return false;
    const CXXRecordDecl* pRecordDecl = pType->getAsCXXRecordDecl();
    if (pRecordDecl) {
        const ClassTemplateSpecializationDecl* pTemplate = dyn_cast<ClassTemplateSpecializationDecl>(pRecordDecl);
        if (pTemplate) {
            for(unsigned i=0; i<pTemplate->getTemplateArgs().size(); ++i) {
                const TemplateArgument& rArg = pTemplate->getTemplateArgs()[i];
                if (rArg.getKind() == TemplateArgument::ArgKind::Type &&
                    containsWindowSubclass(rArg.getAsType()))
                {
                    return true;
                }
            }
        }
    }
    if (pType->isPointerType()) {
        QualType pointeeType = pType->getPointeeType();
        return containsWindowSubclass(pointeeType);
    } else if (pType->isArrayType()) {
        const ArrayType* pArrayType = dyn_cast<ArrayType>(pType);
        QualType elementType = pArrayType->getElementType();
        return containsWindowSubclass(elementType);
    } else {
        return isDerivedFromWindow(pRecordDecl);
    }
}

bool VCLWidgets::VisitCXXDestructorDecl(const CXXDestructorDecl* pCXXDestructorDecl)
{
    if (ignoreLocation(pCXXDestructorDecl)) {
        return true;
    }
    if (!pCXXDestructorDecl->isThisDeclarationADefinition()) {
        return true;
    }
    const CXXRecordDecl * pRecordDecl = pCXXDestructorDecl->getParent();
    // ignore vcl::Window class
    if (pRecordDecl->getQualifiedNameAsString().compare("vcl::Window") == 0) {
        return true;
    }
    // check if this class is derived from Window
    if (!isDerivedFromWindow(pRecordDecl)) {
        return true;
    }
    bool foundVclPtrField = false;
    for(auto fieldDecl : pRecordDecl->fields()) {
        const RecordType *pFieldRecordType = fieldDecl->getType()->getAs<RecordType>();
        if (pFieldRecordType) {
            const CXXRecordDecl *pFieldRecordTypeDecl = dyn_cast<CXXRecordDecl>(pFieldRecordType->getDecl());
            if (startsWith(pFieldRecordTypeDecl->getQualifiedNameAsString(), "VclPtr")) {
               foundVclPtrField = true;
               break;
            }
       }
    }
    bool foundDispose = false;
    for(auto methodDecl : pRecordDecl->methods()) {
        if (methodDecl->isInstance() && methodDecl->param_size()==0 && methodDecl->getNameAsString() == "dispose") {
           foundDispose = true;
           break;
        }
    }
    const CompoundStmt *pCompoundStatement = dyn_cast<CompoundStmt>(pCXXDestructorDecl->getBody());
    // having an empty body and no dispose() method is fine
    if (!foundVclPtrField && !foundDispose && pCompoundStatement && pCompoundStatement->size() == 0) {
        return true;
    }
    if (foundVclPtrField && pCompoundStatement && pCompoundStatement->size() == 0) {
        report(
            DiagnosticsEngine::Warning,
            "vcl::Window subclass with VclPtr field must call dispose() from it's destructor.",
            pCXXDestructorDecl->getLocStart())
          << pCXXDestructorDecl->getSourceRange();
        return true;
    }
    // check that the destructor for a vcl::Window subclass does nothing except call into the dispose() method
    bool ok = false;
    if (pCompoundStatement && pCompoundStatement->size() == 1) {
        const CXXMemberCallExpr *pCallExpr = dyn_cast<CXXMemberCallExpr>(*pCompoundStatement->body_begin());
        if (pCallExpr) {
            if( const FunctionDecl* func = pCallExpr->getDirectCallee()) {
                if( func->getNumParams() == 0 && func->getIdentifier() != NULL
                    && ( func->getName() == "disposeOnce" )) {
                    ok = true;
                }
            }
        }
    }
    if (!ok) {
        report(
            DiagnosticsEngine::Warning,
            "vcl::Window subclass should have nothing in it's destructor but a call to disposeOnce().",
            pCXXDestructorDecl->getLocStart())
          << pCXXDestructorDecl->getSourceRange();
        return true;
    }
    return true;
}


bool VCLWidgets::VisitVarDecl(const VarDecl * pVarDecl) {
    if (ignoreLocation(pVarDecl)) {
        return true;
    }
    const RecordType *recordType = pVarDecl->getType()->getAs<RecordType>();
    if (recordType == nullptr) {
        return true;
    }
    const CXXRecordDecl *recordDecl = dyn_cast<CXXRecordDecl>(recordType->getDecl());
    if (recordDecl == nullptr) {
        return true;
    }

    // check if this field is derived from Window
    if (isDerivedFromWindow(recordDecl)) {
        report(
            DiagnosticsEngine::Warning,
            "vcl::Window subclass allocated on stack, should be allocated via VclPtr or via *.",
            pVarDecl->getLocation())
          << pVarDecl->getSourceRange();
    }
    return true;
}

bool VCLWidgets::VisitFieldDecl(const FieldDecl * fieldDecl) {
    if (ignoreLocation(fieldDecl)) {
        return true;
    }
    if (fieldDecl->isBitField()) {
        return true;
    }
    if (containsWindowSubclass(fieldDecl->getType())) {
        report(
            DiagnosticsEngine::Warning,
            "vcl::Window subclass declared as a pointer field, should be wrapped in VclPtr." + fieldDecl->getType().getAsString(),
            fieldDecl->getLocation())
          << fieldDecl->getSourceRange();
        return true;
    }
    const RecordType *recordType = fieldDecl->getType()->getAs<RecordType>();
    if (recordType == nullptr) {
        return true;
    }
    const CXXRecordDecl *recordDecl = dyn_cast<CXXRecordDecl>(recordType->getDecl());
    if (recordDecl == nullptr) {
        return true;
    }

    // check if this field is derived from Window
    if (isDerivedFromWindow(recordDecl)) {
        report(
            DiagnosticsEngine::Warning,
            "vcl::Window subclass allocated as a class member, should be allocated via VclPtr.",
            fieldDecl->getLocation())
          << fieldDecl->getSourceRange();
    }

    // If this field is a VclPtr field, then the class MUST have a dispose method
    const CXXRecordDecl *pParentRecordDecl = dyn_cast<CXXRecordDecl>(fieldDecl->getParent());
    if (pParentRecordDecl && isDerivedFromWindow(pParentRecordDecl)
        && startsWith(recordDecl->getQualifiedNameAsString(), "VclPtr"))
    {
        bool foundDispose = false;
        for(auto methodDecl : pParentRecordDecl->methods()) {
            if (methodDecl->isInstance() && methodDecl->param_size()==0 && methodDecl->getNameAsString() == "dispose") {
               foundDispose = true;
               break;
            }
        }
        if (!foundDispose) {
            report(
                DiagnosticsEngine::Warning,
                "vcl::Window subclass with a VclPtr field MUST have a dispose() method.",
                fieldDecl->getLocation())
              << fieldDecl->getSourceRange();
        }
    }

    return true;
}

bool VCLWidgets::VisitParmVarDecl(ParmVarDecl const * pvDecl)
{
    if (ignoreLocation(pvDecl)) {
        return true;
    }
    // ignore the stuff in the VclPtr template class
    const CXXMethodDecl *pMethodDecl = dyn_cast<CXXMethodDecl>(pvDecl->getDeclContext());
    if (pMethodDecl
        && pMethodDecl->getParent()->getQualifiedNameAsString().find("VclPtr") != std::string::npos) {
        return true;
    }
    // we exclude this method in VclBuilder because it's so useful to have it like this
    if (pMethodDecl
        && pMethodDecl->getNameAsString() == "get"
        && (pMethodDecl->getParent()->getQualifiedNameAsString() == "VclBuilder"
            || pMethodDecl->getParent()->getQualifiedNameAsString() == "VclBuilderContainer"))
    {
        return true;
    }
    if (!pvDecl->getType()->isReferenceType() && pvDecl->getType().getAsString().find("VclPtr") != std::string::npos) {
        report(
            DiagnosticsEngine::Warning,
            "vcl::Window subclass passed as a VclPtr parameter, should be passed as a raw pointer.",
            pvDecl->getCanonicalDecl()->getLocation())
          << pvDecl->getCanonicalDecl()->getSourceRange();
    }
    return true;
}

static void findDisposeAndClearStatements2(std::vector<std::string>& aVclPtrFields, const Stmt *pStmt);

static void findDisposeAndClearStatements(std::vector<std::string>& aVclPtrFields, const CompoundStmt *pCompoundStatement)
{
    for(const Stmt* pStmt : pCompoundStatement->body()) {
        findDisposeAndClearStatements2(aVclPtrFields, pStmt);
    }
}

static void findDisposeAndClearStatements2(std::vector<std::string>& aVclPtrFields, const Stmt *pStmt)
{
    if (isa<CompoundStmt>(pStmt)) {
        findDisposeAndClearStatements(aVclPtrFields, dyn_cast<CompoundStmt>(pStmt));
        return;
    }
    if (isa<ForStmt>(pStmt)) {
        const CompoundStmt *pBody = dyn_cast<CompoundStmt>(dyn_cast<ForStmt>(pStmt)->getBody());
        if (pBody)
            findDisposeAndClearStatements(aVclPtrFields, pBody);
        return;
    }
    if (!isa<CallExpr>(pStmt)) return;
    const CallExpr *pCallExpr = dyn_cast<CallExpr>(pStmt);

    if (!pCallExpr->getDirectCallee()) return;
    if (!isa<CXXMethodDecl>(pCallExpr->getDirectCallee())) return;
    const CXXMethodDecl *pCalleeMethodDecl = dyn_cast<CXXMethodDecl>(pCallExpr->getDirectCallee());
    if (pCalleeMethodDecl->getNameAsString() != "disposeAndClear") return;

    if (!pCallExpr->getCallee()) return;

    if (!isa<MemberExpr>(pCallExpr->getCallee())) return;
    const MemberExpr *pCalleeMemberExpr = dyn_cast<MemberExpr>(pCallExpr->getCallee());

    if (!pCalleeMemberExpr->getBase()) return;
    if (!isa<MemberExpr>(pCalleeMemberExpr->getBase())) return;
    const MemberExpr *pCalleeMemberExprBase = dyn_cast<MemberExpr>(pCalleeMemberExpr->getBase());

    std::string xxx = pCalleeMemberExprBase->getMemberDecl()->getNameAsString();
    aVclPtrFields.erase(std::remove(aVclPtrFields.begin(), aVclPtrFields.end(), xxx), aVclPtrFields.end());
}


bool VCLWidgets::VisitFunctionDecl( const FunctionDecl* functionDecl )
{
    if (ignoreLocation(functionDecl)) {
        return true;
    }
    // ignore the stuff in the VclPtr template class
    const CXXMethodDecl *pMethodDecl = dyn_cast<CXXMethodDecl>(functionDecl);
    if (pMethodDecl
        && pMethodDecl->getParent()->getQualifiedNameAsString() == "VclPtr") {
        return true;
    }
    // ignore the vcl::Window::dispose() method
    if (pMethodDecl
        && pMethodDecl->getParent()->getQualifiedNameAsString() == "vcl::Window") {
        return true;
    }
    QualType t1 { compat::getReturnType(*functionDecl) };
    if (t1.getAsString().find("VclPtr") == 0) {
        report(
            DiagnosticsEngine::Warning,
            "VclPtr declared as a return type from a method/function, should be passed as a raw pointer.",
            functionDecl->getLocation())
          << functionDecl->getSourceRange();
    }
    if (functionDecl->hasBody() && pMethodDecl && isDerivedFromWindow(pMethodDecl->getParent())) {
        // check the last thing that the dispose() method does, is to call into the superclass dispose method
        if (pMethodDecl->getNameAsString() == "dispose") {
            if (!isDisposeCallingSuperclassDispose(pMethodDecl)) {
                report(
                    DiagnosticsEngine::Warning,
                    "vcl::Window subclass dispose() method MUST call it's superclass dispose() as the last thing it does",
                    functionDecl->getLocStart())
                  << functionDecl->getSourceRange();
           }
        }
    }
    // check dispose method to make sure we are actually disposing all of the VclPtr fields
    if (pMethodDecl && pMethodDecl->isInstance() && pMethodDecl->getBody()
        && pMethodDecl->param_size()==0
        && pMethodDecl->getNameAsString() == "dispose"
        && isDerivedFromWindow(pMethodDecl->getParent()) )
    {
        // exclude a couple of methods with hard-to-parse code
        if (pMethodDecl->getQualifiedNameAsString() == "SvxRubyDialog::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "SvxPersonalizationTabPage::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "SelectPersonaDialog::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "MappingDialog_Impl::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "BibGeneralPage::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "SwCreateAuthEntryDlg_Impl::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "SwTableColumnPage::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "SwAssignFieldsControl::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "ScOptSolverDlg::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "ScPivotFilterDlg::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "SmToolBoxWindow::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "dbaui::DlgOrderCrit::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "SvxStyleBox_Impl::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "dbaui::OAppDetailPageHelper::dispose")
            return true;
        if (pMethodDecl->getQualifiedNameAsString() == "sd::CustomAnimationCreateDialog::dispose")
            return true;

        std::vector<std::string> aVclPtrFields;
        for(auto fieldDecl : pMethodDecl->getParent()->fields()) {
            if (startsWith(fieldDecl->getType().getAsString(), "VclPtr")) {
                aVclPtrFields.push_back(fieldDecl->getNameAsString());
            }
        }
        if (!aVclPtrFields.empty()) {
            if (pMethodDecl->getBody() && isa<CompoundStmt>(pMethodDecl->getBody()))
                findDisposeAndClearStatements( aVclPtrFields, dyn_cast<CompoundStmt>(pMethodDecl->getBody()) );
            if (!aVclPtrFields.empty()) {
                //pMethodDecl->dump();
                std::string aMessage = "vcl::Window subclass dispose() method does not call disposeAndClear() on the following field(s) ";
                for(auto s : aVclPtrFields)
                    aMessage += "\n    " + s + ".clear();";
                report(
                    DiagnosticsEngine::Warning,
                    aMessage,
                    functionDecl->getLocStart())
                  << functionDecl->getSourceRange();
           }
       }
    }
    return true;
}

bool VCLWidgets::VisitCXXDeleteExpr(const CXXDeleteExpr *pCXXDeleteExpr)
{
    if (ignoreLocation(pCXXDeleteExpr)) {
        return true;
    }
    const ImplicitCastExpr* pImplicitCastExpr = dyn_cast<ImplicitCastExpr>(pCXXDeleteExpr->getArgument());
    if (!pImplicitCastExpr) {
        return true;
    }
    if (pImplicitCastExpr->getCastKind() != CK_UserDefinedConversion) {
        return true;
    }
    report(
        DiagnosticsEngine::Warning,
        "calling delete on instance of VclPtr, must rather call disposeAndClear()",
        pCXXDeleteExpr->getLocStart())
     << pCXXDeleteExpr->getSourceRange();
    return true;
}


/**
The AST looks like:
`-CXXMemberCallExpr 0xb06d8b0 'void'
  `-MemberExpr 0xb06d868 '<bound member function type>' ->dispose 0x9d34880
    `-ImplicitCastExpr 0xb06d8d8 'class SfxTabPage *' <UncheckedDerivedToBase (SfxTabPage)>
      `-CXXThisExpr 0xb06d850 'class SfxAcceleratorConfigPage *' this

*/
bool VCLWidgets::isDisposeCallingSuperclassDispose(const CXXMethodDecl* pMethodDecl)
{
    const CompoundStmt *pCompoundStatement = dyn_cast<CompoundStmt>(pMethodDecl->getBody());
    if (!pCompoundStatement) return false;
    if (pCompoundStatement->size() == 0) return false;
    // find the last statement
    const CXXMemberCallExpr *pCallExpr = dyn_cast<CXXMemberCallExpr>(*pCompoundStatement->body_rbegin());
    if (!pCallExpr) return false;
    const MemberExpr *pMemberExpr = dyn_cast<MemberExpr>(pCallExpr->getCallee());
    if (!pMemberExpr) return false;
    if (pMemberExpr->getMemberDecl()->getNameAsString() != "dispose") return false;
    const CXXMethodDecl *pDirectCallee = dyn_cast<CXXMethodDecl>(pCallExpr->getDirectCallee());
    if (!pDirectCallee) return false;
/* Not working yet. Partially because sometimes the superclass does not a dispose() method, so it gets passed up the chain.
   Need complex checking for that case.
    if (pDirectCallee->getParent()->getTypeForDecl() != (*pMethodDecl->getParent()->bases_begin()).getType().getTypePtr()) {
        report(
            DiagnosticsEngine::Warning,
            "dispose() method calling wrong baseclass, calling " + pDirectCallee->getParent()->getQualifiedNameAsString() +
            " should be calling " + (*pMethodDecl->getParent()->bases_begin()).getType().getAsString(),
            pCallExpr->getLocStart())
          << pCallExpr->getSourceRange();
        return false;
    }*/
    return true;
}



loplugin::Plugin::Registration< VCLWidgets > X("vclwidgets");

}

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