// 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/Buffer.h"

#include "common/Assert.h"
#include "dawn_native/Device.h"
#include "dawn_native/DynamicUploader.h"
#include "dawn_native/ValidationUtils_autogen.h"

#include <cstdio>
#include <utility>

namespace dawn_native {

    namespace {

        class ErrorBuffer : public BufferBase {
          public:
            ErrorBuffer(DeviceBase* device) : BufferBase(device, ObjectBase::kError) {
            }

            static ErrorBuffer* MakeMapped(DeviceBase* device,
                                           uint64_t size,
                                           uint8_t** mappedPointer) {
                ASSERT(mappedPointer != nullptr);

                ErrorBuffer* buffer = new ErrorBuffer(device);
                buffer->mFakeMappedData = std::unique_ptr<uint8_t[]>(new uint8_t[size]);
                *mappedPointer = buffer->mFakeMappedData.get();

                return buffer;
            }

          private:
            MaybeError MapAtCreationImpl(uint8_t** mappedPointer) override {
                UNREACHABLE();
                return {};
            }

            MaybeError SetSubDataImpl(uint32_t start,
                                      uint32_t count,
                                      const uint8_t* data) override {
                UNREACHABLE();
                return {};
            }
            void MapReadAsyncImpl(uint32_t serial) override {
                UNREACHABLE();
            }
            void MapWriteAsyncImpl(uint32_t serial) override {
                UNREACHABLE();
            }
            void UnmapImpl() override {
                ASSERT(mFakeMappedData);
                mFakeMappedData.reset();
            }
            void DestroyImpl() override {
                UNREACHABLE();
            }

            std::unique_ptr<uint8_t[]> mFakeMappedData;
        };

    }  // anonymous namespace

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

        DAWN_TRY(ValidateBufferUsageBit(descriptor->usage));

        dawn::BufferUsageBit usage = descriptor->usage;

        const dawn::BufferUsageBit kMapWriteAllowedUsages =
            dawn::BufferUsageBit::MapWrite | dawn::BufferUsageBit::TransferSrc;
        if (usage & dawn::BufferUsageBit::MapWrite && (usage & kMapWriteAllowedUsages) != usage) {
            return DAWN_VALIDATION_ERROR("Only TransferSrc is allowed with MapWrite");
        }

        const dawn::BufferUsageBit kMapReadAllowedUsages =
            dawn::BufferUsageBit::MapRead | dawn::BufferUsageBit::TransferDst;
        if (usage & dawn::BufferUsageBit::MapRead && (usage & kMapReadAllowedUsages) != usage) {
            return DAWN_VALIDATION_ERROR("Only TransferDst is allowed with MapRead");
        }

        return {};
    }

    // Buffer

    BufferBase::BufferBase(DeviceBase* device, const BufferDescriptor* descriptor)
        : ObjectBase(device),
          mSize(descriptor->size),
          mUsage(descriptor->usage),
          mState(BufferState::Unmapped) {
    }

    BufferBase::BufferBase(DeviceBase* device, ObjectBase::ErrorTag tag)
        : ObjectBase(device, tag), mState(BufferState::Unmapped) {
    }

    BufferBase::~BufferBase() {
        if (mState == BufferState::Mapped) {
            ASSERT(!IsError());
            CallMapReadCallback(mMapSerial, DAWN_BUFFER_MAP_ASYNC_STATUS_UNKNOWN, nullptr, 0u);
            CallMapWriteCallback(mMapSerial, DAWN_BUFFER_MAP_ASYNC_STATUS_UNKNOWN, nullptr, 0u);
        }
    }

    // static
    BufferBase* BufferBase::MakeError(DeviceBase* device) {
        return new ErrorBuffer(device);
    }

    // static
    BufferBase* BufferBase::MakeErrorMapped(DeviceBase* device,
                                            uint64_t size,
                                            uint8_t** mappedPointer) {
        return ErrorBuffer::MakeMapped(device, size, mappedPointer);
    }

    uint32_t BufferBase::GetSize() const {
        ASSERT(!IsError());
        return mSize;
    }

    dawn::BufferUsageBit BufferBase::GetUsage() const {
        ASSERT(!IsError());
        return mUsage;
    }

    MaybeError BufferBase::MapAtCreation(uint8_t** mappedPointer) {
        ASSERT(!IsError());
        ASSERT(mappedPointer != nullptr);

        mState = BufferState::Mapped;
        if ((mUsage & dawn::BufferUsageBit::MapWrite) == 0) {
            // TODO(enga): Support non-mappable buffers with a staging buffer.
            return DAWN_VALIDATION_ERROR("MapWrite usage required");
        }

        DAWN_TRY(MapAtCreationImpl(mappedPointer));
        ASSERT(*mappedPointer != nullptr);

        return {};
    }

    MaybeError BufferBase::ValidateCanUseInSubmitNow() const {
        ASSERT(!IsError());

        switch (mState) {
            case BufferState::Destroyed:
                return DAWN_VALIDATION_ERROR("Destroyed buffer used in a submit");
            case BufferState::Mapped:
                return DAWN_VALIDATION_ERROR("Buffer used in a submit while mapped");
            case BufferState::Unmapped:
                return {};
        }
    }

    void BufferBase::CallMapReadCallback(uint32_t serial,
                                         DawnBufferMapAsyncStatus status,
                                         const void* pointer,
                                         uint32_t dataLength) {
        ASSERT(!IsError());
        if (mMapReadCallback != nullptr && serial == mMapSerial) {
            ASSERT(mMapWriteCallback == nullptr);
            // Tag the callback as fired before firing it, otherwise it could fire a second time if
            // for example buffer.Unmap() is called inside the application-provided callback.
            DawnBufferMapReadCallback callback = mMapReadCallback;
            mMapReadCallback = nullptr;
            callback(status, pointer, dataLength, mMapUserdata);
        }
    }

    void BufferBase::CallMapWriteCallback(uint32_t serial,
                                          DawnBufferMapAsyncStatus status,
                                          void* pointer,
                                          uint32_t dataLength) {
        ASSERT(!IsError());
        if (mMapWriteCallback != nullptr && serial == mMapSerial) {
            ASSERT(mMapReadCallback == nullptr);
            // Tag the callback as fired before firing it, otherwise it could fire a second time if
            // for example buffer.Unmap() is called inside the application-provided callback.
            DawnBufferMapWriteCallback callback = mMapWriteCallback;
            mMapWriteCallback = nullptr;
            callback(status, pointer, dataLength, mMapUserdata);
        }
    }

    void BufferBase::SetSubData(uint32_t start, uint32_t count, const uint8_t* data) {
        if (GetDevice()->ConsumedError(ValidateSetSubData(start, count))) {
            return;
        }
        ASSERT(!IsError());

        if (GetDevice()->ConsumedError(SetSubDataImpl(start, count, data))) {
            return;
        }
    }

    void BufferBase::MapReadAsync(DawnBufferMapReadCallback callback,
                                  DawnCallbackUserdata userdata) {
        if (GetDevice()->ConsumedError(ValidateMap(dawn::BufferUsageBit::MapRead))) {
            callback(DAWN_BUFFER_MAP_ASYNC_STATUS_ERROR, nullptr, 0, userdata);
            return;
        }
        ASSERT(!IsError());

        ASSERT(mMapWriteCallback == nullptr);

        // TODO(cwallez@chromium.org): what to do on wraparound? Could cause crashes.
        mMapSerial++;
        mMapReadCallback = callback;
        mMapUserdata = userdata;
        mState = BufferState::Mapped;

        MapReadAsyncImpl(mMapSerial);
    }

    MaybeError BufferBase::SetSubDataImpl(uint32_t start, uint32_t count, const uint8_t* data) {
        DynamicUploader* uploader = nullptr;
        DAWN_TRY_ASSIGN(uploader, GetDevice()->GetDynamicUploader());

        // TODO(bryan.bernhart@intel.com): Remove once alignment constraint is added to validation
        // (dawn:73). D3D12 does not specify so we assume 4-byte alignment to be safe.
        static constexpr size_t kDefaultAlignment = 4;

        UploadHandle uploadHandle;
        DAWN_TRY_ASSIGN(uploadHandle, uploader->Allocate(count, kDefaultAlignment));
        ASSERT(uploadHandle.mappedBuffer != nullptr);

        memcpy(uploadHandle.mappedBuffer, data, count);

        DAWN_TRY(GetDevice()->CopyFromStagingToBuffer(
            uploadHandle.stagingBuffer, uploadHandle.startOffset, this, start, count));

        return {};
    }

    void BufferBase::MapWriteAsync(DawnBufferMapWriteCallback callback,
                                   DawnCallbackUserdata userdata) {
        if (GetDevice()->ConsumedError(ValidateMap(dawn::BufferUsageBit::MapWrite))) {
            callback(DAWN_BUFFER_MAP_ASYNC_STATUS_ERROR, nullptr, 0, userdata);
            return;
        }
        ASSERT(!IsError());

        ASSERT(mMapReadCallback == nullptr);

        // TODO(cwallez@chromium.org): what to do on wraparound? Could cause crashes.
        mMapSerial++;
        mMapWriteCallback = callback;
        mMapUserdata = userdata;
        mState = BufferState::Mapped;

        MapWriteAsyncImpl(mMapSerial);
    }

    void BufferBase::Destroy() {
        if (GetDevice()->ConsumedError(ValidateDestroy())) {
            return;
        }
        ASSERT(!IsError());

        if (mState == BufferState::Mapped) {
            Unmap();
        }
        DestroyInternal();
    }

    void BufferBase::Unmap() {
        if (IsError()) {
            // It is an error to call Unmap() on an ErrorBuffer, but we still need to reclaim the
            // fake mapped staging data.
            UnmapImpl();
        }
        if (GetDevice()->ConsumedError(ValidateUnmap())) {
            return;
        }
        ASSERT(!IsError());

        // A map request can only be called once, so this will fire only if the request wasn't
        // completed before the Unmap
        CallMapReadCallback(mMapSerial, DAWN_BUFFER_MAP_ASYNC_STATUS_UNKNOWN, nullptr, 0u);
        CallMapWriteCallback(mMapSerial, DAWN_BUFFER_MAP_ASYNC_STATUS_UNKNOWN, nullptr, 0u);
        UnmapImpl();
        mState = BufferState::Unmapped;
        mMapReadCallback = nullptr;
        mMapWriteCallback = nullptr;
        mMapUserdata = 0;
    }

    MaybeError BufferBase::ValidateSetSubData(uint32_t start, uint32_t count) const {
        DAWN_TRY(GetDevice()->ValidateObject(this));

        if (mState == BufferState::Destroyed) {
            return DAWN_VALIDATION_ERROR("Buffer is destroyed");
        }

        if (mState == BufferState::Mapped) {
            return DAWN_VALIDATION_ERROR("Buffer is mapped");
        }

        if (count > GetSize()) {
            return DAWN_VALIDATION_ERROR("Buffer subdata with too much data");
        }

        // Metal requests buffer to buffer copy size must be a multiple of 4 bytes on macOS
        if (count % 4 != 0) {
            return DAWN_VALIDATION_ERROR("Buffer subdata size must be a multiple of 4 bytes");
        }

        // Metal requests offset of buffer to buffer copy must be a multiple of 4 bytes on macOS
        if (start % 4 != 0) {
            return DAWN_VALIDATION_ERROR("Start position must be a multiple of 4 bytes");
        }

        // Note that no overflow can happen because we already checked for GetSize() >= count
        if (start > GetSize() - count) {
            return DAWN_VALIDATION_ERROR("Buffer subdata out of range");
        }

        if (!(mUsage & dawn::BufferUsageBit::TransferDst)) {
            return DAWN_VALIDATION_ERROR("Buffer needs the transfer dst usage bit");
        }

        return {};
    }

    MaybeError BufferBase::ValidateMap(dawn::BufferUsageBit requiredUsage) const {
        DAWN_TRY(GetDevice()->ValidateObject(this));

        if (mState == BufferState::Destroyed) {
            return DAWN_VALIDATION_ERROR("Buffer is destroyed");
        }

        if (mState == BufferState::Mapped) {
            return DAWN_VALIDATION_ERROR("Buffer already mapped");
        }

        if (!(mUsage & requiredUsage)) {
            return DAWN_VALIDATION_ERROR("Buffer needs the correct map usage bit");
        }

        return {};
    }

    MaybeError BufferBase::ValidateUnmap() const {
        DAWN_TRY(GetDevice()->ValidateObject(this));

        if ((mUsage & (dawn::BufferUsageBit::MapRead | dawn::BufferUsageBit::MapWrite)) == 0) {
            return DAWN_VALIDATION_ERROR("Buffer does not have map usage");
        }
        switch (mState) {
            case BufferState::Unmapped:
            case BufferState::Mapped:
                return {};
            case BufferState::Destroyed:
                return DAWN_VALIDATION_ERROR("Buffer is destroyed");
        }
    }

    MaybeError BufferBase::ValidateDestroy() const {
        DAWN_TRY(GetDevice()->ValidateObject(this));
        return {};
    }

    void BufferBase::DestroyInternal() {
        if (mState != BufferState::Destroyed) {
            DestroyImpl();
        }
        mState = BufferState::Destroyed;
    }

}  // namespace dawn_native