/*
 *  Copyright 2019-2021 Diligent Graphics LLC
 *  Copyright 2015-2019 Egor Yusov
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  In no event and under no legal theory, whether in tort (including negligence), 
 *  contract, or otherwise, unless required by applicable law (such as deliberate 
 *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
 *  liable for any damages, including any direct, indirect, special, incidental, 
 *  or consequential damages of any character arising as a result of this License or 
 *  out of the use or inability to use the software (including but not limited to damages 
 *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
 *  all other commercial damages or losses), even if such Contributor has been advised 
 *  of the possibility of such damages.
 */

#include "PipelineResourceSignatureBase.hpp"

#include <unordered_map>

#include "HashUtils.hpp"
#include "StringTools.hpp"

namespace Diligent
{

#define LOG_PRS_ERROR_AND_THROW(...) LOG_ERROR_AND_THROW("Description of a pipeline resource signature '", (Desc.Name ? Desc.Name : ""), "' is invalid: ", ##__VA_ARGS__)

void ValidatePipelineResourceSignatureDesc(const PipelineResourceSignatureDesc& Desc,
                                           const DeviceFeatures&                Features) noexcept(false)
{
    if (Desc.BindingIndex >= MAX_RESOURCE_SIGNATURES)
        LOG_PRS_ERROR_AND_THROW("Desc.BindingIndex (", Uint32{Desc.BindingIndex}, ") exceeds the maximum allowed value (", MAX_RESOURCE_SIGNATURES - 1, ").");

    if (Desc.NumResources > MAX_RESOURCES_IN_SIGNATURE)
        LOG_PRS_ERROR_AND_THROW("Desc.NumResources (", Uint32{Desc.NumResources}, ") exceeds the maximum allowed value (", MAX_RESOURCES_IN_SIGNATURE, ").");

    if (Desc.NumResources != 0 && Desc.Resources == nullptr)
        LOG_PRS_ERROR_AND_THROW("Desc.NumResources (", Uint32{Desc.NumResources}, ") is not zero, but Desc.Resources is null.");

    if (Desc.NumImmutableSamplers != 0 && Desc.ImmutableSamplers == nullptr)
        LOG_PRS_ERROR_AND_THROW("Desc.NumImmutableSamplers (", Uint32{Desc.NumImmutableSamplers}, ") is not zero, but Desc.ImmutableSamplers is null.");

    if (Desc.UseCombinedTextureSamplers && (Desc.CombinedSamplerSuffix == nullptr || Desc.CombinedSamplerSuffix[0] == '\0'))
        LOG_PRS_ERROR_AND_THROW("Desc.UseCombinedTextureSamplers is true, but Desc.CombinedSamplerSuffix is null or empty");


    // Hash map of all resources by name
    std::unordered_multimap<HashMapStringKey, const PipelineResourceDesc&, HashMapStringKey::Hasher> Resources;
    for (Uint32 i = 0; i < Desc.NumResources; ++i)
    {
        const auto& Res = Desc.Resources[i];

        if (Res.Name == nullptr)
            LOG_PRS_ERROR_AND_THROW("Desc.Resources[", i, "].Name must not be null.");

        if (Res.Name[0] == '\0')
            LOG_PRS_ERROR_AND_THROW("Desc.Resources[", i, "].Name must not be empty.");

        if (Res.ShaderStages == SHADER_TYPE_UNKNOWN)
            LOG_PRS_ERROR_AND_THROW("Desc.Resources[", i, "].ShaderStages must not be SHADER_TYPE_UNKNOWN.");

        if (Res.ArraySize == 0)
            LOG_PRS_ERROR_AND_THROW("Desc.Resources[", i, "].ArraySize must not be 0.");

        const auto res_range = Resources.equal_range(Res.Name);
        for (auto res_it = res_range.first; res_it != res_range.second; ++res_it)
        {
            if ((res_it->second.ShaderStages & Res.ShaderStages) != 0)
            {
                LOG_PRS_ERROR_AND_THROW("Multiple resources with name '", Res.Name,
                                        "' specify overlapping shader stages. There may be multiple resources with the same name in different shader stages, "
                                        "but the stages must not overlap.");
            }

            if (Features.SeparablePrograms == DEVICE_FEATURE_STATE_DISABLED)
            {
                VERIFY_EXPR(res_it->second.ShaderStages != SHADER_TYPE_UNKNOWN);
                LOG_PRS_ERROR_AND_THROW("This device does not support separable programs, but there are separate resources with the name '",
                                        Res.Name, "' in shader stages ",
                                        GetShaderStagesString(Res.ShaderStages), " and ",
                                        GetShaderStagesString(res_it->second.ShaderStages),
                                        ". When separable programs are not supported, every resource is always shared between all stages. "
                                        "Use distinct resource names for each stage or define a single resource for all stages.");
            }
        }

        if ((Res.Flags & PIPELINE_RESOURCE_FLAG_RUNTIME_ARRAY) != 0 && !Features.ShaderResourceRuntimeArray)
        {
            LOG_PRS_ERROR_AND_THROW("Incorrect Desc.Resources[", i, "].Flags (RUNTIME_ARRAY) can only be used if ShaderResourceRuntimeArray device feature is enabled.");
        }

        if (Res.ResourceType == SHADER_RESOURCE_TYPE_ACCEL_STRUCT && !Features.RayTracing)
        {
            LOG_PRS_ERROR_AND_THROW("Incorrect Desc.Resources[", i, "].ResourceType (ACCEL_STRUCT): ray tracing is not supported by device.");
        }

        auto AllowedResourceFlags = GetValidPipelineResourceFlags(Res.ResourceType);
        if ((Res.Flags & ~AllowedResourceFlags) != 0)
        {
            LOG_PRS_ERROR_AND_THROW("Incorrect Desc.Resources[", i, "].Flags (", GetPipelineResourceFlagsString(Res.Flags),
                                    "). Only the following flags are valid for a ", GetShaderResourceTypeLiteralName(Res.ResourceType),
                                    ": ", GetPipelineResourceFlagsString(AllowedResourceFlags, false, ", "), ".");
        }

        Resources.emplace(Res.Name, Res);

        // NB: when creating immutable sampler array, we have to define the sampler as both resource and
        //     immutable sampler. The sampler will not be exposed as a shader variable though.
        //if (Res.ResourceType == SHADER_RESOURCE_TYPE_SAMPLER)
        //{
        //    if (FindImmutableSampler(Desc.ImmutableSamplers, Desc.NumImmutableSamplers, Res.ShaderStages, Res.Name,
        //                             Desc.UseCombinedTextureSamplers ? Desc.CombinedSamplerSuffix : nullptr) >= 0)
        //    {
        //        LOG_PRS_ERROR_AND_THROW("Sampler '", Res.Name, "' is defined as both shader resource and immutable sampler.");
        //    }
        //}
    }

    // Hash map of all immutable samplers by name
    std::unordered_multimap<HashMapStringKey, const ImmutableSamplerDesc&, HashMapStringKey::Hasher> ImtblSamplers;
    for (Uint32 i = 0; i < Desc.NumImmutableSamplers; ++i)
    {
        const auto& SamDesc = Desc.ImmutableSamplers[i];
        if (SamDesc.SamplerOrTextureName == nullptr)
            LOG_PRS_ERROR_AND_THROW("Desc.ImmutableSamplers[", i, "].SamplerOrTextureName must not be null.");

        if (SamDesc.SamplerOrTextureName[0] == '\0')
            LOG_PRS_ERROR_AND_THROW("Desc.ImmutableSamplers[", i, "].SamplerOrTextureName must not be empty.");

        if (SamDesc.ShaderStages == SHADER_TYPE_UNKNOWN)
            LOG_PRS_ERROR_AND_THROW("Desc.ImmutableSamplers[", i, "].ShaderStages must not be SHADER_TYPE_UNKNOWN.");

        const auto sam_range = ImtblSamplers.equal_range(SamDesc.SamplerOrTextureName);
        for (auto sam_it = sam_range.first; sam_it != sam_range.second; ++sam_it)
        {
            if ((sam_it->second.ShaderStages & SamDesc.ShaderStages) != 0)
            {
                LOG_PRS_ERROR_AND_THROW("Multiple immutable samplers with name '", SamDesc.SamplerOrTextureName,
                                        "' specify overlapping shader stages. There may be multiple immutable samplers with the same name in different shader stages, "
                                        "but the stages must not overlap.");
            }
            if (Features.SeparablePrograms == DEVICE_FEATURE_STATE_DISABLED)
            {
                VERIFY_EXPR(sam_it->second.ShaderStages != SHADER_TYPE_UNKNOWN);
                LOG_PRS_ERROR_AND_THROW("This device does not support separable programs, but there are separate immutable samplers with the name '",
                                        SamDesc.SamplerOrTextureName, "' in shader stages ",
                                        GetShaderStagesString(SamDesc.ShaderStages), " and ",
                                        GetShaderStagesString(sam_it->second.ShaderStages),
                                        ". When separable programs are not supported, every resource is always shared between all stages. "
                                        "Use distinct immutable sampler names for each stage or define a single sampler for all stages.");
            }
        }

        ImtblSamplers.emplace(SamDesc.SamplerOrTextureName, SamDesc);
    }

    if (Desc.UseCombinedTextureSamplers)
    {
        VERIFY_EXPR(Desc.CombinedSamplerSuffix != nullptr);

        // List of samplers assigned to some texture
        std::unordered_multimap<HashMapStringKey, SHADER_TYPE, HashMapStringKey::Hasher> AssignedSamplers;
        // List of immutable samplers assigned to some texture
        std::unordered_multimap<HashMapStringKey, SHADER_TYPE, HashMapStringKey::Hasher> AssignedImtblSamplers;
        for (Uint32 i = 0; i < Desc.NumResources; ++i)
        {
            const auto& Res = Desc.Resources[i];
            if (Res.ResourceType != SHADER_RESOURCE_TYPE_TEXTURE_SRV)
            {
                // Only texture SRVs can be combined with samplers
                continue;
            }

            {
                const auto AssignedSamplerName = String{Res.Name} + Desc.CombinedSamplerSuffix;

                const auto sam_range = Resources.equal_range(AssignedSamplerName.c_str());
                for (auto sam_it = sam_range.first; sam_it != sam_range.second; ++sam_it)
                {
                    const auto& Sam = sam_it->second;
                    VERIFY_EXPR(AssignedSamplerName == Sam.Name);

                    if ((Sam.ShaderStages & Res.ShaderStages) != 0)
                    {
                        if (Sam.ResourceType != SHADER_RESOURCE_TYPE_SAMPLER)
                        {
                            LOG_PRS_ERROR_AND_THROW("Resource '", Sam.Name, "' combined with texture '", Res.Name, "' is not a sampler.");
                        }

                        if ((Sam.ShaderStages & Res.ShaderStages) != Res.ShaderStages)
                        {
                            LOG_PRS_ERROR_AND_THROW("Texture '", Res.Name, "' is defined for the following shader stages: ", GetShaderStagesString(Res.ShaderStages),
                                                    ", but sampler '", Sam.Name, "' assigned to it uses only some of these stages: ", GetShaderStagesString(Sam.ShaderStages),
                                                    ". A resource that is present in multiple shader stages can't be combined with different samplers in different stages. "
                                                    "Either use separate resources for different stages, or define the sampler for all stages that the resource uses.");
                        }

                        if (Sam.VarType != Res.VarType)
                        {
                            LOG_PRS_ERROR_AND_THROW("The type (", GetShaderVariableTypeLiteralName(Res.VarType), ") of texture resource '", Res.Name,
                                                    "' does not match the type (", GetShaderVariableTypeLiteralName(Sam.VarType),
                                                    ") of sampler '", Sam.Name, "' that is assigned to it.");
                        }

                        AssignedSamplers.emplace(Sam.Name, Sam.ShaderStages);

                        break;
                    }
                }
            }

            {
                const auto imtbl_sam_range = ImtblSamplers.equal_range(Res.Name);
                for (auto sam_it = imtbl_sam_range.first; sam_it != imtbl_sam_range.second; ++sam_it)
                {
                    const auto& Sam = sam_it->second;
                    VERIFY_EXPR(strcmp(Sam.SamplerOrTextureName, Res.Name) == 0);

                    if ((Sam.ShaderStages & Res.ShaderStages) != 0)
                    {
                        if ((Sam.ShaderStages & Res.ShaderStages) != Res.ShaderStages)
                        {
                            LOG_PRS_ERROR_AND_THROW("Texture '", Res.Name, "' is defined for the following shader stages: ", GetShaderStagesString(Res.ShaderStages),
                                                    ", but immutable sampler that is assigned to it uses only some of these stages: ", GetShaderStagesString(Sam.ShaderStages),
                                                    ". A resource that is present in multiple shader stages can't be combined with different immutable samples in different stages. "
                                                    "Either use separate resources for different stages, or define the immutable sampler for all stages that the resource uses.");
                        }

                        AssignedImtblSamplers.emplace(Sam.SamplerOrTextureName, Sam.ShaderStages);

                        break;
                    }
                }
            }
        }

        for (Uint32 i = 0; i < Desc.NumResources; ++i)
        {
            const auto& Res = Desc.Resources[i];
            if (Res.ResourceType != SHADER_RESOURCE_TYPE_SAMPLER)
                continue;

            auto assigned_sam_range = AssignedSamplers.equal_range(Res.Name);

            auto it = assigned_sam_range.first;
            while (it != assigned_sam_range.second)
            {
                if (it->second == Res.ShaderStages)
                    break;
                ++it;
            }
            if (it == assigned_sam_range.second)
            {
                LOG_WARNING_MESSAGE("Sampler '", Res.Name, "' (", GetShaderStagesString(Res.ShaderStages), ")' is not assigned to any texture. All samplers should be assigned to textures when combined texture samplers are used.");
            }
        }

        for (Uint32 i = 0; i < Desc.NumImmutableSamplers; ++i)
        {
            const auto& SamDesc = Desc.ImmutableSamplers[i];

            auto assigned_sam_range = AssignedImtblSamplers.equal_range(SamDesc.SamplerOrTextureName);

            auto it = assigned_sam_range.first;
            while (it != assigned_sam_range.second)
            {
                if (it->second == SamDesc.ShaderStages)
                    break;
                ++it;
            }
            if (it == assigned_sam_range.second)
            {
                LOG_WARNING_MESSAGE("Immutable sampler '", SamDesc.SamplerOrTextureName, "' (", GetShaderStagesString(SamDesc.ShaderStages), ") is not assigned to any texture or sampler. All immutable samplers should be assigned to textures or samplers when combined texture samplers are used.");
            }
        }
    }
}

#undef LOG_PRS_ERROR_AND_THROW


Uint32 FindImmutableSampler(const ImmutableSamplerDesc* ImtblSamplers,
                            Uint32                      NumImtblSamplers,
                            SHADER_TYPE                 ShaderStages,
                            const char*                 ResourceName,
                            const char*                 SamplerSuffix)
{
    for (Uint32 s = 0; s < NumImtblSamplers; ++s)
    {
        const auto& Sam = ImtblSamplers[s];
        if (((Sam.ShaderStages & ShaderStages) != 0) && StreqSuff(ResourceName, Sam.SamplerOrTextureName, SamplerSuffix))
        {
            VERIFY((Sam.ShaderStages & ShaderStages) == ShaderStages,
                   "Immutable sampler uses only some of the stages that resource '", ResourceName,
                   "' is defined for. This error should've been caught by ValidatePipelineResourceSignatureDesc().");
            return s;
        }
    }

    return InvalidImmutableSamplerIndex;
}

/// Returns true if two pipeline resources are compatible
inline bool PipelineResourcesCompatible(const PipelineResourceDesc& lhs, const PipelineResourceDesc& rhs)
{
    // Ignore resource names.
    // clang-format off
    return lhs.ShaderStages == rhs.ShaderStages &&
           lhs.ArraySize    == rhs.ArraySize    &&
           lhs.ResourceType == rhs.ResourceType &&
           lhs.VarType      == rhs.VarType      &&
           lhs.Flags        == rhs.Flags;
    // clang-format on
}

bool PipelineResourceSignaturesCompatible(const PipelineResourceSignatureDesc& Desc0,
                                          const PipelineResourceSignatureDesc& Desc1) noexcept
{
    if (Desc0.BindingIndex != Desc1.BindingIndex)
        return false;

    if (Desc0.NumResources != Desc1.NumResources)
        return false;

    for (Uint32 r = 0; r < Desc0.NumResources; ++r)
    {
        if (!PipelineResourcesCompatible(Desc0.Resources[r], Desc1.Resources[r]))
            return false;
    }

    if (Desc0.NumImmutableSamplers != Desc1.NumImmutableSamplers)
        return false;

    for (Uint32 s = 0; s < Desc0.NumImmutableSamplers; ++s)
    {
        const auto& Samp0 = Desc0.ImmutableSamplers[s];
        const auto& Samp1 = Desc1.ImmutableSamplers[s];

        if (Samp0.ShaderStages != Samp1.ShaderStages ||
            !(Samp0.Desc == Samp1.Desc))
            return false;
    }

    return true;
}

size_t CalculatePipelineResourceSignatureDescHash(const PipelineResourceSignatureDesc& Desc) noexcept
{
    if (Desc.NumResources == 0 && Desc.NumImmutableSamplers == 0)
        return 0;

    size_t Hash = ComputeHash(Desc.NumResources, Desc.NumImmutableSamplers, Desc.BindingIndex);

    for (Uint32 i = 0; i < Desc.NumResources; ++i)
    {
        const auto& Res = Desc.Resources[i];
        HashCombine(Hash, Uint32{Res.ShaderStages}, Res.ArraySize, Uint32{Res.ResourceType}, Uint32{Res.VarType}, Uint32{Res.Flags});
    }

    for (Uint32 i = 0; i < Desc.NumImmutableSamplers; ++i)
    {
        HashCombine(Hash, Uint32{Desc.ImmutableSamplers[i].ShaderStages}, Desc.ImmutableSamplers[i].Desc);
    }

    return Hash;
}

} // namespace Diligent