//
// Copyright (c) 2011 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

#ifndef COMPILER_TRANSLATOR_BUILTINFUNCTIONEMULATOR_H_
#define COMPILER_TRANSLATOR_BUILTINFUNCTIONEMULATOR_H_

#include "compiler/translator/InfoSink.h"
#include "compiler/translator/IntermNode.h"
#include "compiler/translator/ParamType.h"

namespace sh
{

struct MiniFunctionId
{
    constexpr MiniFunctionId(TOperator op         = EOpNull,
                             ParamType paramType1 = ParamType::Void,
                             ParamType paramType2 = ParamType::Void,
                             ParamType paramType3 = ParamType::Void,
                             ParamType paramType4 = ParamType::Void)
        : op(op),
          paramType1(paramType1),
          paramType2(paramType2),
          paramType3(paramType3),
          paramType4(paramType4)
    {
    }

    TOperator op;
    ParamType paramType1;
    ParamType paramType2;
    ParamType paramType3;
    ParamType paramType4;
};

class FunctionId final
{
  public:
    FunctionId();
    FunctionId(TOperator op, const TType *param);
    FunctionId(TOperator op, const TType *param1, const TType *param2);
    FunctionId(TOperator op, const TType *param1, const TType *param2, const TType *param3);
    FunctionId(TOperator op,
               const TType *param1,
               const TType *param2,
               const TType *param3,
               const TType *param4);

    FunctionId(const FunctionId &) = default;
    FunctionId &operator=(const FunctionId &) = default;

    bool operator==(const FunctionId &other) const;
    bool operator<(const FunctionId &other) const;

    FunctionId getCopy() const;

  private:
    friend bool operator==(const MiniFunctionId &miniId, const FunctionId &functionId);
    TOperator mOp;

    // The memory that these TType objects use is freed by PoolAllocator. The
    // BuiltInFunctionEmulator's lifetime can extend until after the memory pool is freed, but
    // that's not an issue since this class never destructs these objects.
    const TType *mParam1;
    const TType *mParam2;
    const TType *mParam3;
    const TType *mParam4;
};

inline bool operator==(ParamType paramType, const TType *type)
{
    return SameParamType(paramType, type->getBasicType(), type->getNominalSize(),
                         type->getSecondarySize());
}

inline bool operator==(const MiniFunctionId &miniId, const FunctionId &functionId)
{
    return miniId.op == functionId.mOp && miniId.paramType1 == functionId.mParam1 &&
           miniId.paramType2 == functionId.mParam2 && miniId.paramType3 == functionId.mParam3 &&
           miniId.paramType4 == functionId.mParam4;
}

using BuiltinQueryFunc = const char *(const FunctionId &);

//
// This class decides which built-in functions need to be replaced with the emulated ones. It can be
// used to work around driver bugs or implement functions that are not natively implemented on a
// specific platform.
//
class BuiltInFunctionEmulator
{
  public:
    BuiltInFunctionEmulator();

    void markBuiltInFunctionsForEmulation(TIntermNode *root);

    void cleanup();

    // "name" gets written as "webgl_name_emu".
    static void WriteEmulatedFunctionName(TInfoSinkBase &out, const char *name);

    bool isOutputEmpty() const;

    // Output function emulation definition. This should be before any other shader source.
    void outputEmulatedFunctions(TInfoSinkBase &out) const;

    // Add functions that need to be emulated.
    FunctionId addEmulatedFunction(TOperator op,
                                   const TType *param,
                                   const char *emulatedFunctionDefinition);
    FunctionId addEmulatedFunction(TOperator op,
                                   const TType *param1,
                                   const TType *param2,
                                   const char *emulatedFunctionDefinition);
    FunctionId addEmulatedFunction(TOperator op,
                                   const TType *param1,
                                   const TType *param2,
                                   const TType *param3,
                                   const char *emulatedFunctionDefinition);
    FunctionId addEmulatedFunction(TOperator op,
                                   const TType *param1,
                                   const TType *param2,
                                   const TType *param3,
                                   const TType *param4,
                                   const char *emulatedFunctionDefinition);

    FunctionId addEmulatedFunctionWithDependency(const FunctionId &dependency,
                                                 TOperator op,
                                                 const TType *param1,
                                                 const TType *param2,
                                                 const char *emulatedFunctionDefinition);
    FunctionId addEmulatedFunctionWithDependency(const FunctionId &dependency,
                                                 TOperator op,
                                                 const TType *param1,
                                                 const TType *param2,
                                                 const TType *param3,
                                                 const TType *param4,
                                                 const char *emulatedFunctionDefinition);

    void addFunctionMap(BuiltinQueryFunc queryFunc);

  private:
    class BuiltInFunctionEmulationMarker;

    // Records that a function is called by the shader and might need to be emulated. If the
    // function is not in mEmulatedFunctions, this becomes a no-op. Returns true if the function
    // call needs to be replaced with an emulated one.
    bool setFunctionCalled(TOperator op, const TType &param);
    bool setFunctionCalled(TOperator op, const TType &param1, const TType &param2);
    bool setFunctionCalled(TOperator op,
                           const TType &param1,
                           const TType &param2,
                           const TType &param3);
    bool setFunctionCalled(TOperator op,
                           const TType &param1,
                           const TType &param2,
                           const TType &param3,
                           const TType &param4);

    bool setFunctionCalled(const FunctionId &functionId);

    const char *findEmulatedFunction(const FunctionId &functionId) const;

    // Map from function id to emulated function definition
    std::map<FunctionId, std::string> mEmulatedFunctions;

    // Map from dependent functions to their dependencies. This structure allows each function to
    // have at most one dependency.
    std::map<FunctionId, FunctionId> mFunctionDependencies;

    // Called function ids
    std::vector<FunctionId> mFunctions;

    // Constexpr function tables.
    std::vector<BuiltinQueryFunc *> mQueryFunctions;
};

}  // namespace sh

#endif  // COMPILER_TRANSLATOR_BUILTINFUNCTIONEMULATOR_H_
