// Copyright 2017 The Dawn Authors
//
// 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.

#include "dawn_native/PipelineLayout.h"

#include "common/Assert.h"
#include "common/BitSetIterator.h"
#include "common/HashUtils.h"
#include "dawn_native/BindGroupLayout.h"
#include "dawn_native/Device.h"
#include "dawn_native/ShaderModule.h"

namespace dawn_native {

    namespace {

        bool InferredBindGroupLayoutEntriesCompatible(const BindGroupLayoutEntry& lhs,
                                                      const BindGroupLayoutEntry& rhs) {
            // Minimum buffer binding size excluded because we take the maximum seen across stages
            return lhs.binding == rhs.binding && lhs.visibility == rhs.visibility &&
                   lhs.type == rhs.type && lhs.hasDynamicOffset == rhs.hasDynamicOffset &&
                   lhs.multisampled == rhs.multisampled && lhs.viewDimension == rhs.viewDimension &&
                   lhs.textureComponentType == rhs.textureComponentType;
        }

        wgpu::ShaderStage GetShaderStageVisibilityWithBindingType(wgpu::BindingType bindingType) {
            // TODO(jiawei.shao@intel.com): support read-only and read-write storage textures.
            switch (bindingType) {
                case wgpu::BindingType::StorageBuffer:
                case wgpu::BindingType::WriteonlyStorageTexture:
                    return wgpu::ShaderStage::Fragment | wgpu::ShaderStage::Compute;

                case wgpu::BindingType::StorageTexture:
                    UNREACHABLE();
                    return wgpu::ShaderStage::None;

                case wgpu::BindingType::UniformBuffer:
                case wgpu::BindingType::ReadonlyStorageBuffer:
                case wgpu::BindingType::Sampler:
                case wgpu::BindingType::ComparisonSampler:
                case wgpu::BindingType::SampledTexture:
                case wgpu::BindingType::ReadonlyStorageTexture:
                    return wgpu::ShaderStage::Vertex | wgpu::ShaderStage::Fragment |
                           wgpu::ShaderStage::Compute;
            }

            return {};
        }

    }  // anonymous namespace

    MaybeError ValidatePipelineLayoutDescriptor(DeviceBase* device,
                                                const PipelineLayoutDescriptor* descriptor) {
        if (descriptor->nextInChain != nullptr) {
            return DAWN_VALIDATION_ERROR("nextInChain must be nullptr");
        }

        if (descriptor->bindGroupLayoutCount > kMaxBindGroups) {
            return DAWN_VALIDATION_ERROR("too many bind group layouts");
        }

        uint32_t totalDynamicUniformBufferCount = 0;
        uint32_t totalDynamicStorageBufferCount = 0;
        for (uint32_t i = 0; i < descriptor->bindGroupLayoutCount; ++i) {
            DAWN_TRY(device->ValidateObject(descriptor->bindGroupLayouts[i]));
            totalDynamicUniformBufferCount +=
                descriptor->bindGroupLayouts[i]->GetDynamicUniformBufferCount();
            totalDynamicStorageBufferCount +=
                descriptor->bindGroupLayouts[i]->GetDynamicStorageBufferCount();
        }

        if (totalDynamicUniformBufferCount > kMaxDynamicUniformBufferCount) {
            return DAWN_VALIDATION_ERROR("too many dynamic uniform buffers in pipeline layout");
        }

        if (totalDynamicStorageBufferCount > kMaxDynamicStorageBufferCount) {
            return DAWN_VALIDATION_ERROR("too many dynamic storage buffers in pipeline layout");
        }

        return {};
    }

    // PipelineLayoutBase

    PipelineLayoutBase::PipelineLayoutBase(DeviceBase* device,
                                           const PipelineLayoutDescriptor* descriptor)
        : CachedObject(device) {
        ASSERT(descriptor->bindGroupLayoutCount <= kMaxBindGroups);
        for (uint32_t group = 0; group < descriptor->bindGroupLayoutCount; ++group) {
            mBindGroupLayouts[group] = descriptor->bindGroupLayouts[group];
            mMask.set(group);
        }
    }

    PipelineLayoutBase::PipelineLayoutBase(DeviceBase* device, ObjectBase::ErrorTag tag)
        : CachedObject(device, tag) {
    }

    PipelineLayoutBase::~PipelineLayoutBase() {
        // Do not uncache the actual cached object if we are a blueprint
        if (IsCachedReference()) {
            GetDevice()->UncachePipelineLayout(this);
        }
    }

    // static
    PipelineLayoutBase* PipelineLayoutBase::MakeError(DeviceBase* device) {
        return new PipelineLayoutBase(device, ObjectBase::kError);
    }

    // static
    ResultOrError<PipelineLayoutBase*> PipelineLayoutBase::CreateDefault(
        DeviceBase* device,
        const ShaderModuleBase* const* modules,
        uint32_t count) {
        ASSERT(count > 0);

        // Data which BindGroupLayoutDescriptor will point to for creation
        std::array<ityp::array<BindingIndex, BindGroupLayoutEntry, kMaxBindingsPerGroup>,
                   kMaxBindGroups>
            entryData = {};

        // A map of bindings to the index in |entryData|
        std::array<std::map<BindingNumber, BindingIndex>, kMaxBindGroups> usedBindingsMap = {};

        // A counter of how many bindings we've populated in |entryData|
        std::array<BindingIndex, kMaxBindGroups> entryCounts = {};

        uint32_t bindGroupLayoutCount = 0;
        for (uint32_t moduleIndex = 0; moduleIndex < count; ++moduleIndex) {
            const ShaderModuleBase* module = modules[moduleIndex];
            const ShaderModuleBase::ModuleBindingInfo& info = module->GetBindingInfo();

            for (uint32_t group = 0; group < info.size(); ++group) {
                for (const auto& it : info[group]) {
                    BindingNumber bindingNumber = it.first;
                    const ShaderModuleBase::ShaderBindingInfo& bindingInfo = it.second;

                    BindGroupLayoutEntry bindingSlot;
                    bindingSlot.binding = static_cast<uint32_t>(bindingNumber);

                    DAWN_TRY(ValidateBindingTypeWithShaderStageVisibility(
                        bindingInfo.type, StageBit(module->GetExecutionModel())));
                    DAWN_TRY(ValidateStorageTextureFormat(device, bindingInfo.type,
                                                          bindingInfo.storageTextureFormat));
                    DAWN_TRY(ValidateStorageTextureViewDimension(bindingInfo.type,
                                                                 bindingInfo.viewDimension));

                    if (bindingInfo.multisampled) {
                        DAWN_TRY(ValidateBindingCanBeMultisampled(bindingInfo.type,
                                                                  bindingInfo.viewDimension));
                    }

                    bindingSlot.visibility =
                        GetShaderStageVisibilityWithBindingType(bindingInfo.type);

                    bindingSlot.type = bindingInfo.type;
                    bindingSlot.hasDynamicOffset = false;
                    bindingSlot.multisampled = bindingInfo.multisampled;
                    bindingSlot.viewDimension = bindingInfo.viewDimension;
                    bindingSlot.textureComponentType =
                        Format::FormatTypeToTextureComponentType(bindingInfo.textureComponentType);
                    bindingSlot.storageTextureFormat = bindingInfo.storageTextureFormat;
                    bindingSlot.minBufferBindingSize = bindingInfo.minBufferBindingSize;

                    {
                        const auto& it = usedBindingsMap[group].find(bindingNumber);
                        if (it != usedBindingsMap[group].end()) {
                            BindGroupLayoutEntry* existingEntry = &entryData[group][it->second];

                            // Check if any properties are incompatible with existing entry
                            // If compatible, we will merge some properties
                            if (!InferredBindGroupLayoutEntriesCompatible(*existingEntry,
                                                                          bindingSlot)) {
                                return DAWN_VALIDATION_ERROR(
                                    "Duplicate binding in default pipeline layout initialization "
                                    "not compatible with previous declaration");
                            }

                            // Use the max |minBufferBindingSize| we find
                            existingEntry->minBufferBindingSize =
                                std::max(existingEntry->minBufferBindingSize,
                                         bindingSlot.minBufferBindingSize);

                            // Already used slot, continue
                            continue;
                        }
                    }

                    BindingIndex currentBindingCount = entryCounts[group];
                    entryData[group][currentBindingCount] = bindingSlot;

                    usedBindingsMap[group][bindingNumber] = currentBindingCount;

                    entryCounts[group]++;

                    bindGroupLayoutCount = std::max(bindGroupLayoutCount, group + 1);
                }
            }
        }

        std::array<BindGroupLayoutBase*, kMaxBindGroups> bindGroupLayouts = {};
        for (uint32_t group = 0; group < bindGroupLayoutCount; ++group) {
            BindGroupLayoutDescriptor desc = {};
            desc.entries = entryData[group].data();
            desc.entryCount = static_cast<uint32_t>(entryCounts[group]);

            // We should never produce a bad descriptor.
            ASSERT(!ValidateBindGroupLayoutDescriptor(device, &desc).IsError());
            DAWN_TRY_ASSIGN(bindGroupLayouts[group], device->GetOrCreateBindGroupLayout(&desc));
        }

        PipelineLayoutDescriptor desc = {};
        desc.bindGroupLayouts = bindGroupLayouts.data();
        desc.bindGroupLayoutCount = bindGroupLayoutCount;
        PipelineLayoutBase* pipelineLayout = device->CreatePipelineLayout(&desc);
        ASSERT(!pipelineLayout->IsError());

        // These bind group layouts are created internally and referenced by the pipeline layout.
        // Release the external refcount.
        for (uint32_t group = 0; group < bindGroupLayoutCount; ++group) {
            if (bindGroupLayouts[group] != nullptr) {
                bindGroupLayouts[group]->Release();
            }
        }

        for (uint32_t moduleIndex = 0; moduleIndex < count; ++moduleIndex) {
            ASSERT(modules[moduleIndex]
                       ->ValidateCompatibilityWithPipelineLayout(pipelineLayout)
                       .IsSuccess());
        }

        return pipelineLayout;
    }

    const BindGroupLayoutBase* PipelineLayoutBase::GetBindGroupLayout(uint32_t group) const {
        ASSERT(!IsError());
        ASSERT(group < kMaxBindGroups);
        ASSERT(mMask[group]);
        const BindGroupLayoutBase* bgl = mBindGroupLayouts[group].Get();
        ASSERT(bgl != nullptr);
        return bgl;
    }

    BindGroupLayoutBase* PipelineLayoutBase::GetBindGroupLayout(uint32_t group) {
        ASSERT(!IsError());
        ASSERT(group < kMaxBindGroups);
        ASSERT(mMask[group]);
        BindGroupLayoutBase* bgl = mBindGroupLayouts[group].Get();
        ASSERT(bgl != nullptr);
        return bgl;
    }

    const std::bitset<kMaxBindGroups> PipelineLayoutBase::GetBindGroupLayoutsMask() const {
        ASSERT(!IsError());
        return mMask;
    }

    std::bitset<kMaxBindGroups> PipelineLayoutBase::InheritedGroupsMask(
        const PipelineLayoutBase* other) const {
        ASSERT(!IsError());
        return {(1 << GroupsInheritUpTo(other)) - 1u};
    }

    uint32_t PipelineLayoutBase::GroupsInheritUpTo(const PipelineLayoutBase* other) const {
        ASSERT(!IsError());

        for (uint32_t i = 0; i < kMaxBindGroups; ++i) {
            if (!mMask[i] || mBindGroupLayouts[i].Get() != other->mBindGroupLayouts[i].Get()) {
                return i;
            }
        }
        return kMaxBindGroups;
    }

    size_t PipelineLayoutBase::HashFunc::operator()(const PipelineLayoutBase* pl) const {
        size_t hash = Hash(pl->mMask);

        for (uint32_t group : IterateBitSet(pl->mMask)) {
            HashCombine(&hash, pl->GetBindGroupLayout(group));
        }

        return hash;
    }

    bool PipelineLayoutBase::EqualityFunc::operator()(const PipelineLayoutBase* a,
                                                      const PipelineLayoutBase* b) const {
        if (a->mMask != b->mMask) {
            return false;
        }

        for (uint32_t group : IterateBitSet(a->mMask)) {
            if (a->GetBindGroupLayout(group) != b->GetBindGroupLayout(group)) {
                return false;
            }
        }

        return true;
    }

}  // namespace dawn_native