/*
 * Copyright 2021 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "experimental/graphite/src/mtl/MtlBuffer.h"

#include "experimental/graphite/src/mtl/MtlGpu.h"

namespace skgpu::mtl {

#ifdef SK_ENABLE_MTL_DEBUG_INFO
NSString* kBufferTypeNames[kBufferTypeCount] = {
    @"Vertex",
    @"Index",
    @"Xfer CPU to GPU",
    @"Xfer GPU to CPU",
    @"Uniform",
};
#endif

sk_sp<Buffer> Buffer::Make(const Gpu* gpu,
                           size_t size,
                           BufferType type,
                           PrioritizeGpuReads prioritizeGpuReads) {
    if (size <= 0) {
        return nullptr;
    }

    const Caps& mtlCaps = gpu->mtlCaps();

    NSUInteger options = 0;
    if (@available(macOS 10.11, iOS 9.0, *)) {
        if (prioritizeGpuReads == PrioritizeGpuReads::kNo) {
#ifdef SK_BUILD_FOR_MAC
            if (mtlCaps.isMac()) {
                options |= MTLResourceStorageModeManaged;
            } else {
                SkASSERT(mtlCaps.isApple());
                options |= MTLResourceStorageModeShared;
            }
#else
            options |= MTLResourceStorageModeShared;
#endif
        } else {
            options |= MTLResourceStorageModePrivate;
        }
    }

    size = SkAlignTo(size, mtlCaps.getMinBufferAlignment());
    sk_cfp<id<MTLBuffer>> buffer([gpu->device() newBufferWithLength: size options: options]);
#ifdef SK_ENABLE_MTL_DEBUG_INFO
    (*buffer).label = kBufferTypeNames[(int)type];
#endif

    return sk_sp<Buffer>(new Buffer(gpu, size, type, prioritizeGpuReads, std::move(buffer)));
}

Buffer::Buffer(const Gpu* gpu,
               size_t size,
               BufferType type,
               PrioritizeGpuReads prioritizeGpuReads,
               sk_cfp<id<MTLBuffer>> buffer)
        : skgpu::Buffer(gpu, size, type, prioritizeGpuReads)
        , fBuffer(std::move(buffer)) {}

void Buffer::onMap() {
    SkASSERT(fBuffer);
    SkASSERT(!this->isMapped());

    if ((*fBuffer).storageMode == MTLStorageModePrivate) {
        return;
    }

    fMapPtr = static_cast<char*>((*fBuffer).contents);
}

void Buffer::onUnmap() {
    SkASSERT(fBuffer);
    SkASSERT(this->isMapped());
#ifdef SK_BUILD_FOR_MAC
    if ((*fBuffer).storageMode == MTLStorageModeManaged) {
        [*fBuffer didModifyRange: NSMakeRange(0, this->size())];
    }
#endif
    fMapPtr = nullptr;
}

void Buffer::onFreeGpuData() {
    fBuffer.reset();
}

} // namespace skgpu::mtl