/* -*- 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 "plugin.hxx"
#include "check.hxx"
#include "compat.hxx"
#include "functionaddress.hxx"

#include <algorithm>
#include <cassert>
#include <set>
#include <utility>
#include <vector>

// The SAL_CALL function annotation is only necessary on our outward
// facing C++ ABI, anywhere else it is just cargo-cult.
//

//TODO: To find inconsistencies like
//
//  template<typename> struct S { void f(); }; // #1
//  template<typename T> void S<T>::f() {} // #2
//  template void SAL_CALL S<void>::f();
//
// VisitFunctionDecl would need to also visit explicit instantiations, by letting
// shouldVisitTemplateInstantiations return true and returning from VisitFunctionDecl early iff
// decl->getTemplateSpecializationKind() == TSK_ImplicitInstantiation.  However, an instantiated
// FunctionDecl is created in TemplateDeclInstantiator::VisitCXXMethodDecl by copying information
// (including source locations) from the declaration at #1, and later modified in
// Sema::InstantiateFunctionDefinition with some source location information from the definition at
// #2.  That means that the source scanning in isSalCallFunction below would be thoroughly confused
// and break.  (This happens for both explicit and implicit template instantiations, which is the
// reason why calls to isSalCallFunction make sure to not call it with any FunctionDecls
// representing such template instantiations.)

namespace
{
//static bool startswith(const std::string& rStr, const char* pSubStr)
//{
//    return rStr.compare(0, strlen(pSubStr), pSubStr) == 0;
//}

CXXMethodDecl const* getTemplateInstantiationPattern(CXXMethodDecl const* decl)
{
    auto const p = decl->getTemplateInstantiationPattern();
    return p == nullptr ? decl : cast<CXXMethodDecl>(p);
}

class SalCall final : public loplugin::FunctionAddress<loplugin::FilteringRewritePlugin<SalCall>>
{
public:
    explicit SalCall(loplugin::InstantiationData const& data)
        : FunctionAddress(data)
    {
    }

    virtual void run() override
    {
        if (TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()))
        {
            auto const& addressOfSet = getFunctionsWithAddressTaken();
            for (auto const decl : m_decls)
            {
                if (addressOfSet.find(decl->getCanonicalDecl()) == addressOfSet.end())
                {
                    handleFunctionDecl(decl);
                }
            }
        }
    }

    bool VisitFunctionDecl(FunctionDecl const*);

private:
    void handleFunctionDecl(FunctionDecl const* decl);
    bool rewrite(SourceLocation);
    bool isSalCallFunction(FunctionDecl const* functionDecl, SourceLocation* pLoc = nullptr);

    std::set<FunctionDecl const*> m_decls;
};

bool SalCall::VisitFunctionDecl(FunctionDecl const* decl)
{
    if (ignoreLocation(decl))
        return true;

    // ignore template stuff
    if (decl->getTemplatedKind() != clang::FunctionDecl::TK_NonTemplate)
        return true;
    auto recordDecl = dyn_cast<CXXRecordDecl>(decl->getDeclContext());
    if (recordDecl
        && (recordDecl->getTemplateSpecializationKind() != TSK_Undeclared
            || recordDecl->isDependentContext()))
    {
        return true;
    }

    auto canonicalDecl = decl->getCanonicalDecl();

    // ignore UNO implementations
    if (isInUnoIncludeFile(
            compiler.getSourceManager().getSpellingLoc(canonicalDecl->getLocation())))
        return true;

    SourceLocation rewriteLoc;
    SourceLocation rewriteCanonicalLoc;
    bool bDeclIsSalCall = isSalCallFunction(decl, &rewriteLoc);
    bool bCanonicalDeclIsSalCall = isSalCallFunction(canonicalDecl, &rewriteCanonicalLoc);

    // first, check for consistency, so we don't trip ourselves up on Linux, where we normally run the plugin
    if (canonicalDecl != decl)
    {
        if (bCanonicalDeclIsSalCall)
            ; // this is fine, the actual definition have or not have SAL_CALL, and MSVC is fine with it
        else if (bDeclIsSalCall)
        {
            // not fine
            report(DiagnosticsEngine::Warning, "SAL_CALL inconsistency", decl->getLocation())
                << decl->getSourceRange();
            report(DiagnosticsEngine::Note, "SAL_CALL inconsistency", canonicalDecl->getLocation())
                << canonicalDecl->getSourceRange();
            return true;
        }
    }
    auto methodDecl = dyn_cast<CXXMethodDecl>(canonicalDecl);
    if (methodDecl)
    {
        for (auto iter = methodDecl->begin_overridden_methods();
             iter != methodDecl->end_overridden_methods(); ++iter)
        {
            const CXXMethodDecl* overriddenMethod
                = getTemplateInstantiationPattern(*iter)->getCanonicalDecl();
            if (bCanonicalDeclIsSalCall != isSalCallFunction(overriddenMethod))
            {
                report(DiagnosticsEngine::Warning, "SAL_CALL inconsistency",
                       methodDecl->getLocation())
                    << methodDecl->getSourceRange();
                report(DiagnosticsEngine::Note, "SAL_CALL inconsistency",
                       overriddenMethod->getLocation())
                    << overriddenMethod->getSourceRange();
                return true;
            }
        }
    }

    if (!bCanonicalDeclIsSalCall)
        return true;

    if (!decl->isThisDeclarationADefinition() && !(methodDecl && compat::isPureVirtual(methodDecl)))
        return true;

    m_decls.insert(decl);
    return true;
}

void SalCall::handleFunctionDecl(FunctionDecl const* decl)
{
    // some base classes are overridden by sub-classes which override both the base-class and a UNO class
    if (auto recordDecl = dyn_cast<CXXRecordDecl>(decl->getDeclContext()))
    {
        auto dc = loplugin::DeclCheck(recordDecl);
        if (dc.Class("OProxyAggregation").Namespace("comphelper").GlobalNamespace()
            || dc.Class("OComponentProxyAggregationHelper")
                   .Namespace("comphelper")
                   .GlobalNamespace()
            || dc.Class("SvxShapeMaster").GlobalNamespace()
            || dc.Class("ListBoxAccessibleBase").Namespace("accessibility").GlobalNamespace()
            || dc.Class("AsyncEventNotifierBase").Namespace("comphelper").GlobalNamespace()
            || dc.Class("ODescriptor")
                   .Namespace("sdbcx")
                   .Namespace("connectivity")
                   .GlobalNamespace()
            || dc.Class("IController").Namespace("dbaui").GlobalNamespace()
            || dc.Class("ORowSetBase").Namespace("dbaccess").GlobalNamespace()
            || dc.Class("OComponentAdapterBase").Namespace("bib").GlobalNamespace()
            || dc.Class("IEventProcessor").Namespace("comphelper").GlobalNamespace()
            || dc.Class("SvxUnoTextBase").GlobalNamespace()
            || dc.Class("OInterfaceContainer").Namespace("frm").GlobalNamespace()
            || dc.Class("AccessibleComponentBase").Namespace("accessibility").GlobalNamespace()
            || dc.Class("ContextHandler2Helper")
                   .Namespace("core")
                   .Namespace("oox")
                   .GlobalNamespace()
            || dc.Class("AccessibleStaticTextBase").Namespace("accessibility").GlobalNamespace()
            || dc.Class("OCommonPicker").Namespace("svt").GlobalNamespace()
            || dc.Class("VbaDocumentBase").GlobalNamespace()
            || dc.Class("VbaPageSetupBase").GlobalNamespace()
            || dc.Class("ScVbaControl").GlobalNamespace()

        )
            return;
    }

    auto canonicalDecl = decl->getCanonicalDecl();

    // if any of the overridden methods are SAL_CALL, we should be too
    if (auto methodDecl = dyn_cast<CXXMethodDecl>(canonicalDecl))
    {
        for (auto iter = methodDecl->begin_overridden_methods();
             iter != methodDecl->end_overridden_methods(); ++iter)
        {
            const CXXMethodDecl* overriddenMethod
                = getTemplateInstantiationPattern(*iter)->getCanonicalDecl();
            if (isSalCallFunction(overriddenMethod))
                return;
        }
    }

    SourceLocation rewriteLoc;
    SourceLocation rewriteCanonicalLoc;
    bool bDeclIsSalCall = isSalCallFunction(decl, &rewriteLoc);
    isSalCallFunction(canonicalDecl, &rewriteCanonicalLoc);

    bool bOK = rewrite(rewriteLoc);
    if (bOK && canonicalDecl != decl)
    {
        bOK = rewrite(rewriteCanonicalLoc);
    }
    if (bOK)
        return;

    if (bDeclIsSalCall)
    {
        report(DiagnosticsEngine::Warning, "SAL_CALL unnecessary here",
               rewriteLoc.isValid() ? rewriteLoc : decl->getLocation())
            << decl->getSourceRange();
    }
    if (canonicalDecl != decl)
    {
        report(DiagnosticsEngine::Warning, "SAL_CALL unnecessary here", rewriteCanonicalLoc)
            << canonicalDecl->getSourceRange();
        if (!bDeclIsSalCall)
        {
            report(DiagnosticsEngine::Note, "defined here (without SAL_CALL decoration)",
                   decl->getLocation())
                << decl->getSourceRange();
        }
    }
}

//TODO: This doesn't handle all possible cases of macro usage (and possibly never will be able to),
// just what is encountered in practice:
bool SalCall::isSalCallFunction(FunctionDecl const* functionDecl, SourceLocation* pLoc)
{
    assert(!functionDecl->isTemplateInstantiation());

    //TODO:  It appears that FunctionDecls representing explicit template specializations have the
    // same issue as those representing (implicit or explicit) instantiations, namely that their
    // data (including relevant source locations) is an incoherent combination of data from the
    // original template declaration and the later specialization definition.  For example, for the
    // OValueLimitedType<double>::registerProperties specialization at
    // forms/source/xforms/datatyperepository.cxx:241, the FunctionDecl (which is even considered
    // canonic) representing the base-class function overridden by ODecimalType::registerProperties
    // (forms/source/xforms/datatypes.hxx:299) is dumped as
    //
    //  CXXMethodDecl <forms/source/xforms/datatypes.hxx:217:9, col:54>
    //   forms/source/xforms/datatyperepository.cxx:242:37 registerProperties 'void (void)' virtual
    //
    // mixing the source range ("datatypes.hxx:217:9, col:54") from the original declaration with
    // the name location ("datatyperepository.cxx:242:37") from the explicit specialization.  Just
    // give up for now and assume no "SAL_CALL" is present:
    if (functionDecl->getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
    {
        return false;
    }

    SourceManager& SM = compiler.getSourceManager();
    std::vector<SourceRange> ranges;

    SourceLocation startLoc;
    SourceLocation endLoc;
    bool noReturnType = isa<CXXConstructorDecl>(functionDecl)
                        || isa<CXXDestructorDecl>(functionDecl)
                        || isa<CXXConversionDecl>(functionDecl);
    bool startAfterReturnType = !noReturnType;
    if (startAfterReturnType)
    {
        // For functions that do have a return type, start searching for "SAL_CALL" after the return
        // type (which for SAL_CALL functions on Windows will be an AttributedTypeLoc, which the
        // implementation of FunctionDecl::getReturnTypeSourceRange does not take into account, so
        // do that here explicitly):
        auto const TSI = functionDecl->getTypeSourceInfo();
        if (TSI == nullptr)
        {
            if (isDebugMode())
            {
                report(DiagnosticsEngine::Fatal, "TODO: unexpected failure #1, needs investigation",
                       functionDecl->getLocation())
                    << functionDecl->getSourceRange();
            }
            return false;
        }
        auto TL = TSI->getTypeLoc().IgnoreParens();
        if (auto ATL = TL.getAs<AttributedTypeLoc>())
        {
            TL = ATL.getModifiedLoc();
        }
        auto const FTL = TL.getAs<FunctionTypeLoc>();
        if (!FTL)
        {
            // Happens when a function declaration uses a typedef for the function type, as in
            //
            //  SAL_JNI_EXPORT javaunohelper::detail::Func_bootstrap
            //  Java_com_sun_star_comp_helper_Bootstrap_cppuhelper_1bootstrap;
            //
            // in javaunohelper/source/juhx-export-functions.hxx.
            //TODO: check the typedef for mention of "SAL_CALL" (and also check for usage of such
            // typedefs in the !startAfterReturnType case below)
            return false;
        }
        startLoc = FTL.getReturnLoc().getEndLoc();
        while (SM.isMacroArgExpansion(startLoc, &startLoc))
        {
        }

        // Stop searching for "SAL_CALL" at the start of the function declaration's name (for
        // qualified names this will point after the qualifiers, but needlessly including those in
        // the search should be harmless---modulo issues with using "SAL_CALL" as the name of a
        // function-like macro parameter as discussed below):
        endLoc = functionDecl->getNameInfo().getBeginLoc();
        while (SM.isMacroArgExpansion(endLoc, &endLoc))
        {
        }
        while (endLoc.isMacroID() && SM.isAtStartOfImmediateMacroExpansion(endLoc, &endLoc))
        {
        }
        endLoc = SM.getSpellingLoc(endLoc);

        auto const slEnd = Lexer::getLocForEndOfToken(startLoc, 0, SM, compiler.getLangOpts());
        if (slEnd.isValid())
        {
            // startLoc is either non-macro, or at end of macro; one source range from startLoc to
            // endLoc:
            startLoc = slEnd;
            while (startLoc.isMacroID() && SM.isAtEndOfImmediateMacroExpansion(startLoc, &startLoc))
            {
            }
            startLoc = SM.getSpellingLoc(startLoc);

            if (startLoc.isValid() && endLoc.isValid() && startLoc != endLoc
                && !SM.isBeforeInTranslationUnit(startLoc, endLoc))
            {
                // Happens for uses of trailing return type (in which case starting instead at the
                // start of the function declaration should be fine), but also for cases like
                //
                //  void (*f())();
                //
                // where the function name is within the function type (TODO: in which case starting
                // at the start can erroneously pick up the "SAL_CALL" from the returned pointer-to-
                // function type in cases like
                //
                //  void SAL_CALL (*f())();
                //
                // that are hopefully rare):
                startAfterReturnType = false;
            }
        }
        else
        {
            // startLoc is within a macro body; two source ranges, first is the remainder of the
            // corresponding macro definition's replacement text, second is from after the macro
            // invocation to endLoc, unless endLoc is already in the first range:
            //TODO: If the macro is a function-like macro with a parameter named "SAL_CALL", uses of
            // that parameter in the remainder of the replacement text will be false positives.
            assert(SM.isMacroBodyExpansion(startLoc));
            auto const startLoc2 = compat::getImmediateExpansionRange(SM, startLoc).second;
            auto name = Lexer::getImmediateMacroName(startLoc, SM, compiler.getLangOpts());
            while (compat::starts_with(name, "\\\n"))
            {
                name = name.drop_front(2);
                while (!name.empty()
                       && (name.front() == ' ' || name.front() == '\t' || name.front() == '\n'
                           || name.front() == '\v' || name.front() == '\f'))
                {
                    name = name.drop_front(1);
                }
            }
            auto const MI = compiler.getPreprocessor()
                                .getMacroDefinitionAtLoc(&compiler.getASTContext().Idents.get(name),
                                                         SM.getSpellingLoc(startLoc))
                                .getMacroInfo();
            assert(MI != nullptr);
            auto endLoc1 = MI->getDefinitionEndLoc();
            assert(endLoc1.isFileID());
            endLoc1 = Lexer::getLocForEndOfToken(endLoc1, 0, SM, compiler.getLangOpts());
            startLoc = Lexer::getLocForEndOfToken(SM.getSpellingLoc(startLoc), 0, SM,
                                                  compiler.getLangOpts());
            if (!SM.isPointWithin(endLoc, startLoc, endLoc1))
            {
                ranges.emplace_back(startLoc, endLoc1);
                startLoc = Lexer::getLocForEndOfToken(SM.getSpellingLoc(startLoc2), 0, SM,
                                                      compiler.getLangOpts());
            }
        }
    }
    if (!startAfterReturnType)
    {
        // Stop searching for "SAL_CALL" at the start of the function declaration's name (for
        // qualified names this will point after the qualifiers, but needlessly including those in
        // the search should be harmless):
        endLoc = functionDecl->getNameInfo().getBeginLoc();
        while (endLoc.isMacroID() && SM.isAtStartOfImmediateMacroExpansion(endLoc, &endLoc))
        {
        }

        SourceRange macroRange;
        if (SM.isMacroBodyExpansion(endLoc))
        {
            auto name = Lexer::getImmediateMacroName(endLoc, SM, compiler.getLangOpts());
            while (compat::starts_with(name, "\\\n"))
            {
                name = name.drop_front(2);
                while (!name.empty()
                       && (name.front() == ' ' || name.front() == '\t' || name.front() == '\n'
                           || name.front() == '\v' || name.front() == '\f'))
                {
                    name = name.drop_front(1);
                }
            }
            auto const MI = compiler.getPreprocessor()
                                .getMacroDefinitionAtLoc(&compiler.getASTContext().Idents.get(name),
                                                         SM.getSpellingLoc(endLoc))
                                .getMacroInfo();
            assert(MI != nullptr);
            macroRange = SourceRange(MI->getDefinitionLoc(), MI->getDefinitionEndLoc());
            if (isDebugMode() && macroRange.isInvalid())
            {
                report(DiagnosticsEngine::Fatal, "TODO: unexpected failure #4, needs investigation",
                       functionDecl->getLocation())
                    << functionDecl->getSourceRange();
            }
        }

#if defined _WIN32
        auto const macroExpansion = SM.getExpansionLoc(endLoc);
#endif
        endLoc = SM.getSpellingLoc(endLoc);

        // Ctors/dtors/conversion functions don't have a return type, start searching for "SAL_CALL"
        // at the start of the function declaration:
        startLoc = functionDecl->getSourceRange().getBegin();
        while (startLoc.isMacroID()
               && !(macroRange.isValid()
                    && SM.isPointWithin(SM.getSpellingLoc(startLoc), macroRange.getBegin(),
                                        macroRange.getEnd()))
               && SM.isAtStartOfImmediateMacroExpansion(startLoc, &startLoc))
        {
        }
#if !defined _WIN32
        auto const macroStartLoc = startLoc;
#endif
        startLoc = SM.getSpellingLoc(startLoc);

#if defined _WIN32
        if (macroRange.isValid()
            && !SM.isPointWithin(startLoc, macroRange.getBegin(), macroRange.getEnd()))
        {
            // endLoc is within a macro body but startLoc is not; two source ranges, first is from
            // startLoc to the macro invocation, second is the leading part of the corresponding
            // macro definition's replacement text:
            ranges.emplace_back(startLoc, macroExpansion);
            startLoc = macroRange.getBegin();
        }
#else
        // When the SAL_CALL macro expands to nothing, it may even precede the function
        // declaration's source range, so go back one token (unless the declaration is known to
        // start with a token that must precede a possible "SAL_CALL", like "virtual" or
        // "explicit"):
        //TODO: this will produce false positives if the declaration is immediately preceded by a
        // macro definition whose replacement text ends in "SAL_CALL"
        if (noReturnType
            && !(functionDecl->isVirtualAsWritten()
                 || (isa<CXXConstructorDecl>(functionDecl)
                     && cast<CXXConstructorDecl>(functionDecl)->getExplicitSpecifier().isExplicit())
                 || (isa<CXXConversionDecl>(functionDecl)
                     && cast<CXXConversionDecl>(functionDecl)
                            ->getExplicitSpecifier()
                            .isExplicit())))
        {
            SourceLocation endLoc1;
            if (macroStartLoc.isMacroID()
                && SM.isAtStartOfImmediateMacroExpansion(macroStartLoc, &endLoc1))
            {
                // startLoc is at the start of a macro body; two source ranges, first one is looking
                // backwards one token from the call site of the macro:
                auto startLoc1 = endLoc1;
                for (;;)
                {
                    startLoc1 = Lexer::GetBeginningOfToken(startLoc1.getLocWithOffset(-1), SM,
                                                           compiler.getLangOpts());
                    auto const s = StringRef(
                        SM.getCharacterData(startLoc1),
                        Lexer::MeasureTokenLength(startLoc1, SM, compiler.getLangOpts()));
                    // When looking backward at least through a function-like macro replacement like
                    //
                    // | foo\         |
                    // |    barbaz##X    |
                    //
                    // starting at "barbaz" in the second line, the next token reported will start at "\"
                    // in the first line and include the intervening spaces and (part of? looks like an
                    // error in Clang) "barbaz", so just skip any tokens starting with backslash-newline
                    // when looking backwards here, without even trying to look at their content:
                    if (!(s.empty() || compat::starts_with(s, "/*") || compat::starts_with(s, "//")
                          || compat::starts_with(s, "\\\n")))
                    {
                        break;
                    }
                }
                ranges.emplace_back(startLoc1, endLoc1);
            }
            else
            {
                for (;;)
                {
                    startLoc = Lexer::GetBeginningOfToken(startLoc.getLocWithOffset(-1), SM,
                                                          compiler.getLangOpts());
                    auto const s = StringRef(
                        SM.getCharacterData(startLoc),
                        Lexer::MeasureTokenLength(startLoc, SM, compiler.getLangOpts()));
                    // When looking backward at least through a function-like macro replacement like
                    //
                    // | foo\         |
                    // |    barbaz##X    |
                    //
                    // starting at "barbaz" in the second line, the next token reported will start at "\"
                    // in the first line and include the intervening spaces and (part of? looks like an
                    // error in Clang) "barbaz", so just skip any tokens starting with backslash-newline
                    // when looking backwards here, without even trying to look at their content:
                    if (!(s.empty() || compat::starts_with(s, "/*") || compat::starts_with(s, "//")
                          || compat::starts_with(s, "\\\n")))
                    {
                        break;
                    }
                }
            }
        }
#endif
    }
    ranges.emplace_back(startLoc, endLoc);

    for (auto const& range : ranges)
    {
        if (range.isInvalid())
        {
            if (isDebugMode())
            {
                report(DiagnosticsEngine::Fatal, "TODO: unexpected failure #2, needs investigation",
                       functionDecl->getLocation())
                    << functionDecl->getSourceRange();
            }
            return false;
        }
        if (isDebugMode() && range.getBegin() != range.getEnd()
            && !SM.isBeforeInTranslationUnit(range.getBegin(), range.getEnd()))
        {
            report(DiagnosticsEngine::Fatal, "TODO: unexpected failure #3, needs investigation",
                   functionDecl->getLocation())
                << functionDecl->getSourceRange();
        }

        for (auto loc = range.getBegin(); SM.isBeforeInTranslationUnit(loc, range.getEnd());)
        {
            unsigned n = Lexer::MeasureTokenLength(loc, SM, compiler.getLangOpts());
            auto s = StringRef(compiler.getSourceManager().getCharacterData(loc), n);
            while (compat::starts_with(s, "\\\n"))
            {
                s = s.drop_front(2);
                while (!s.empty()
                       && (s.front() == ' ' || s.front() == '\t' || s.front() == '\n'
                           || s.front() == '\v' || s.front() == '\f'))
                {
                    s = s.drop_front(1);
                }
            }
            if (s == "SAL_CALL")
            {
                if (pLoc)
                    *pLoc = loc;
                return true;
            }
            loc = loc.getLocWithOffset(std::max<unsigned>(n, 1));
        }
    }
    return false;
}

bool SalCall::rewrite(SourceLocation locBegin)
{
    if (!rewriter)
        return false;
    if (!locBegin.isValid())
        return false;

    auto locEnd = locBegin.getLocWithOffset(8);
    if (!locEnd.isValid())
        return false;

    SourceRange range(locBegin, locEnd);

    if (!replaceText(locBegin, 9, ""))
        return false;

    return true;
}

static loplugin::Plugin::Registration<SalCall> reg("salcall", true);
}

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