// Copyright 2018 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <cstring>
#include <memory>

#include "common/alignment.h"
#include "core/core.h"
#include "video_core/renderer_opengl/gl_buffer_cache.h"
#include "video_core/renderer_opengl/gl_rasterizer.h"

namespace OpenGL {

CachedBufferEntry::CachedBufferEntry(VAddr cpu_addr, std::size_t size, GLintptr offset,
                                     std::size_t alignment, u8* host_ptr)
    : RasterizerCacheObject{host_ptr}, cpu_addr{cpu_addr}, size{size}, offset{offset},
      alignment{alignment} {}

OGLBufferCache::OGLBufferCache(RasterizerOpenGL& rasterizer, std::size_t size)
    : RasterizerCache{rasterizer}, stream_buffer(size, true) {}

GLintptr OGLBufferCache::UploadMemory(GPUVAddr gpu_addr, std::size_t size, std::size_t alignment,
                                      bool cache) {
    auto& memory_manager = Core::System::GetInstance().GPU().MemoryManager();

    // Cache management is a big overhead, so only cache entries with a given size.
    // TODO: Figure out which size is the best for given games.
    cache &= size >= 2048;

    const auto& host_ptr{memory_manager.GetPointer(gpu_addr)};
    if (cache) {
        auto entry = TryGet(host_ptr);
        if (entry) {
            if (entry->GetSize() >= size && entry->GetAlignment() == alignment) {
                return entry->GetOffset();
            }
            Unregister(entry);
        }
    }

    AlignBuffer(alignment);
    const GLintptr uploaded_offset = buffer_offset;

    if (!host_ptr) {
        return uploaded_offset;
    }

    std::memcpy(buffer_ptr, host_ptr, size);
    buffer_ptr += size;
    buffer_offset += size;

    if (cache) {
        auto entry = std::make_shared<CachedBufferEntry>(
            *memory_manager.GpuToCpuAddress(gpu_addr), size, uploaded_offset, alignment, host_ptr);
        Register(entry);
    }

    return uploaded_offset;
}

GLintptr OGLBufferCache::UploadHostMemory(const void* raw_pointer, std::size_t size,
                                          std::size_t alignment) {
    AlignBuffer(alignment);
    std::memcpy(buffer_ptr, raw_pointer, size);
    const GLintptr uploaded_offset = buffer_offset;

    buffer_ptr += size;
    buffer_offset += size;
    return uploaded_offset;
}

std::tuple<u8*, GLintptr> OGLBufferCache::ReserveMemory(std::size_t size, std::size_t alignment) {
    AlignBuffer(alignment);
    u8* const uploaded_ptr = buffer_ptr;
    const GLintptr uploaded_offset = buffer_offset;

    buffer_ptr += size;
    buffer_offset += size;
    return std::make_tuple(uploaded_ptr, uploaded_offset);
}

bool OGLBufferCache::Map(std::size_t max_size) {
    bool invalidate;
    std::tie(buffer_ptr, buffer_offset_base, invalidate) =
        stream_buffer.Map(static_cast<GLsizeiptr>(max_size), 4);
    buffer_offset = buffer_offset_base;

    if (invalidate) {
        InvalidateAll();
    }
    return invalidate;
}

void OGLBufferCache::Unmap() {
    stream_buffer.Unmap(buffer_offset - buffer_offset_base);
}

GLuint OGLBufferCache::GetHandle() const {
    return stream_buffer.GetHandle();
}

void OGLBufferCache::AlignBuffer(std::size_t alignment) {
    // Align the offset, not the mapped pointer
    const GLintptr offset_aligned =
        static_cast<GLintptr>(Common::AlignUp(static_cast<std::size_t>(buffer_offset), alignment));
    buffer_ptr += offset_aligned - buffer_offset;
    buffer_offset = offset_aligned;
}

} // namespace OpenGL
