#include "slang-ir-check-recursive-type.h"
#include "slang-ir-util.h"

namespace Slang
{
    bool checkTypeRecursionImpl(HashSet<IRInst*>& checkedTypes, HashSet<IRInst*>& stack, IRInst* type, IRInst* field, DiagnosticSink* sink)
    {
        auto visitElementType = [&](IRInst* elementType, IRInst* field) -> bool
            {
                if (!stack.add(elementType))
                {
                    sink->diagnose(field ? field : type, Diagnostics::recursiveType, type);
                    return false;
                }
                if (checkedTypes.add(elementType))
                    checkTypeRecursionImpl(checkedTypes, stack, elementType, field, sink);
                stack.remove(elementType);
                return true;
            };
        if (auto arrayType = as<IRArrayTypeBase>(type))
        {
            return visitElementType(arrayType->getElementType(), field);
        }
        else if (auto structType = as<IRStructType>(type))
        {
            for (auto sfield : structType->getFields())
                if (!visitElementType(sfield->getFieldType(), sfield))
                    return false;
        }
        return true;
    }

    void checkTypeRecursion(HashSet<IRInst*>& checkedTypes, IRInst* type, DiagnosticSink* sink)
    {
        HashSet<IRInst*> stack;
        if (checkedTypes.add(type))
        {
            stack.add(type);
            checkTypeRecursionImpl(checkedTypes, stack, type, nullptr, sink);
        }
    }

    void checkForRecursiveTypes(IRModule* module, DiagnosticSink* sink)
    {
        HashSet<IRInst*> checkedTypes;
        for (auto globalInst : module->getGlobalInsts())
        {
            switch (globalInst->getOp())
            {
            case kIROp_StructType:
                {
                    checkTypeRecursion(checkedTypes, globalInst, sink);
                }
                break;
            }
        }
    }

}