// 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.

#ifndef SRC_DAWN_NATIVE_BINDGROUPLAYOUT_H_
#define SRC_DAWN_NATIVE_BINDGROUPLAYOUT_H_

#include <algorithm>
#include <bitset>
#include <map>
#include <string>

#include "dawn/common/Constants.h"
#include "dawn/common/Math.h"
#include "dawn/common/SlabAllocator.h"
#include "dawn/common/ityp_span.h"
#include "dawn/common/ityp_vector.h"
#include "dawn/native/BindingInfo.h"
#include "dawn/native/CachedObject.h"
#include "dawn/native/Error.h"
#include "dawn/native/Forward.h"
#include "dawn/native/ObjectBase.h"

#include "dawn/native/dawn_platform.h"

namespace dawn::native {
// TODO(dawn:1082): Minor optimization to use BindingIndex instead of BindingNumber
struct ExternalTextureBindingExpansion {
    BindingNumber plane0;
    BindingNumber plane1;
    BindingNumber params;
};

using ExternalTextureBindingExpansionMap = std::map<BindingNumber, ExternalTextureBindingExpansion>;

MaybeError ValidateBindGroupLayoutDescriptor(DeviceBase* device,
                                             const BindGroupLayoutDescriptor* descriptor,
                                             bool allowInternalBinding = false);

// Bindings are specified as a |BindingNumber| in the BindGroupLayoutDescriptor.
// These numbers may be arbitrary and sparse. Internally, Dawn packs these numbers
// into a packed range of |BindingIndex| integers.
class BindGroupLayoutBase : public ApiObjectBase, public CachedObject {
  public:
    BindGroupLayoutBase(DeviceBase* device,
                        const BindGroupLayoutDescriptor* descriptor,
                        PipelineCompatibilityToken pipelineCompatibilityToken,
                        ApiObjectBase::UntrackedByDeviceTag tag);
    BindGroupLayoutBase(DeviceBase* device,
                        const BindGroupLayoutDescriptor* descriptor,
                        PipelineCompatibilityToken pipelineCompatibilityToken);
    ~BindGroupLayoutBase() override;

    static BindGroupLayoutBase* MakeError(DeviceBase* device);

    ObjectType GetType() const override;

    // A map from the BindingNumber to its packed BindingIndex.
    using BindingMap = std::map<BindingNumber, BindingIndex>;

    const BindingInfo& GetBindingInfo(BindingIndex bindingIndex) const {
        ASSERT(!IsError());
        ASSERT(bindingIndex < mBindingInfo.size());
        return mBindingInfo[bindingIndex];
    }
    const BindingMap& GetBindingMap() const;
    bool HasBinding(BindingNumber bindingNumber) const;
    BindingIndex GetBindingIndex(BindingNumber bindingNumber) const;

    // Functions necessary for the unordered_set<BGLBase*>-based cache.
    size_t ComputeContentHash() override;

    struct EqualityFunc {
        bool operator()(const BindGroupLayoutBase* a, const BindGroupLayoutBase* b) const;
    };

    BindingIndex GetBindingCount() const;
    // Returns |BindingIndex| because buffers are packed at the front.
    BindingIndex GetBufferCount() const;
    // Returns |BindingIndex| because dynamic buffers are packed at the front.
    BindingIndex GetDynamicBufferCount() const;
    uint32_t GetUnverifiedBufferCount() const;

    // Used to get counts and validate them in pipeline layout creation. Other getters
    // should be used to get typed integer counts.
    const BindingCounts& GetBindingCountInfo() const;

    uint32_t GetExternalTextureBindingCount() const;

    // Used to specify unpacked external texture binding slots when transforming shader modules.
    const ExternalTextureBindingExpansionMap& GetExternalTextureBindingExpansionMap() const;

    uint32_t GetUnexpandedBindingCount() const;

    // Tests that the BindingInfo of two bind groups are equal,
    // ignoring their compatibility groups.
    bool IsLayoutEqual(const BindGroupLayoutBase* other,
                       bool excludePipelineCompatibiltyToken = false) const;
    PipelineCompatibilityToken GetPipelineCompatibilityToken() const;

    struct BufferBindingData {
        uint64_t offset;
        uint64_t size;
    };

    struct BindingDataPointers {
        ityp::span<BindingIndex, BufferBindingData> const bufferData = {};
        ityp::span<BindingIndex, Ref<ObjectBase>> const bindings = {};
        ityp::span<uint32_t, uint64_t> const unverifiedBufferSizes = {};
    };

    // Compute the amount of space / alignment required to store bindings for a bind group of
    // this layout.
    size_t GetBindingDataSize() const;
    static constexpr size_t GetBindingDataAlignment() {
        static_assert(alignof(Ref<ObjectBase>) <= alignof(BufferBindingData));
        return alignof(BufferBindingData);
    }

    BindingDataPointers ComputeBindingDataPointers(void* dataStart) const;

    bool IsStorageBufferBinding(BindingIndex bindingIndex) const;

    // Returns a detailed string representation of the layout entries for use in error messages.
    std::string EntriesToString() const;

  protected:
    // Constructor used only for mocking and testing.
    explicit BindGroupLayoutBase(DeviceBase* device);
    void DestroyImpl() override;

    template <typename BindGroup>
    SlabAllocator<BindGroup> MakeFrontendBindGroupAllocator(size_t size) {
        return SlabAllocator<BindGroup>(
            size,                                                                        // bytes
            Align(sizeof(BindGroup), GetBindingDataAlignment()) + GetBindingDataSize(),  // size
            std::max(alignof(BindGroup), GetBindingDataAlignment())  // alignment
        );
    }

  private:
    BindGroupLayoutBase(DeviceBase* device, ObjectBase::ErrorTag tag);

    BindingCounts mBindingCounts = {};
    ityp::vector<BindingIndex, BindingInfo> mBindingInfo;

    // Map from BindGroupLayoutEntry.binding to packed indices.
    BindingMap mBindingMap;

    ExternalTextureBindingExpansionMap mExternalTextureBindingExpansionMap;

    // Non-0 if this BindGroupLayout was created as part of a default PipelineLayout.
    const PipelineCompatibilityToken mPipelineCompatibilityToken = PipelineCompatibilityToken(0);

    uint32_t mUnexpandedBindingCount;
};

}  // namespace dawn::native

#endif  // SRC_DAWN_NATIVE_BINDGROUPLAYOUT_H_