/*
 * Copyright (c) 2021, Sahan Fernando <sahan.h.fernando@gmail.com>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/DistinctNumeric.h>
#include <AK/IntrusiveList.h>
#include <Kernel/Devices/CharacterDevice.h>
#include <Kernel/Devices/Device.h>
#include <Kernel/Devices/GPU/VirtIO/Protocol.h>
#include <Kernel/Locking/SpinlockProtected.h>

namespace Kernel::Graphics::VirtIOGPU {

enum class VirGLCommand : u32 {
    NOP = 0,
    CREATE_OBJECT = 1,
    BIND_OBJECT,
    DESTROY_OBJECT,
    SET_VIEWPORT_STATE,
    SET_FRAMEBUFFER_STATE,
    SET_VERTEX_BUFFERS,
    CLEAR,
    DRAW_VBO,
    RESOURCE_INLINE_WRITE,
    SET_SAMPLER_VIEWS,
    SET_INDEX_BUFFER,
    SET_CONSTANT_BUFFER,
    SET_STENCIL_REF,
    SET_BLEND_COLOR,
    SET_SCISSOR_STATE,
    BLIT,
    RESOURCE_COPY_REGION,
    BIND_SAMPLER_STATES,
    BEGIN_QUERY,
    END_QUERY,
    GET_QUERY_RESULT,
    SET_POLYGON_STIPPLE,
    SET_CLIP_STATE,
    SET_SAMPLE_MASK,
    SET_STREAMOUT_TARGETS,
    SET_RENDER_CONDITION,
    SET_UNIFORM_BUFFER,

    SET_SUB_CTX,
    CREATE_SUB_CTX,
    DESTROY_SUB_CTX,
    BIND_SHADER,
    SET_TESS_STATE,
    SET_MIN_SAMPLES,
    SET_SHADER_BUFFERS,
    SET_SHADER_IMAGES,
    MEMORY_BARRIER,
    LAUNCH_GRID,
    SET_FRAMEBUFFER_STATE_NO_ATTACH,
    TEXTURE_BARRIER,
    SET_ATOMIC_BUFFERS,
    SET_DBG_FLAGS,
    GET_QUERY_RESULT_QBO,
    TRANSFER3D,
    END_TRANSFERS,
    COPY_TRANSFER3D,
    SET_TWEAKS,
    CLEAR_TEXTURE,
    PIPE_RESOURCE_CREATE,
    PIPE_RESOURCE_SET_TYPE,
    GET_MEMORY_INFO,
    SEND_STRING_MARKER,
    MAX_COMMANDS
};

union ClearType {
    struct {
        u32 depth : 1;
        u32 stencil : 1;
        u32 color0 : 1;
        u32 color1 : 1;
        u32 color2 : 1;
        u32 color3 : 1;
        u32 color4 : 1;
        u32 color5 : 1;
        u32 color6 : 1;
        u32 color7 : 1;
    } flags;
    u32 value;
};

}

namespace Kernel {

class VirtIOGraphicsAdapter;
class VirtIOGPU3DDevice : public CharacterDevice {
    friend class Device;

public:
    static ErrorOr<NonnullRefPtr<VirtIOGPU3DDevice>> create(VirtIOGraphicsAdapter&);

private:
    VirtIOGPU3DDevice(VirtIOGraphicsAdapter const& graphics_adapter, NonnullOwnPtr<Memory::Region> transfer_buffer_region, Graphics::VirtIOGPU::ContextID kernel_context_id);

    class PerContextState final : public AtomicRefCounted<PerContextState> {
        friend class VirtIOGPU3DDevice;

    public:
        static ErrorOr<NonnullRefPtr<PerContextState>> try_create(OpenFileDescription& description, Graphics::VirtIOGPU::ContextID context_id)
        {
            auto region_result = TRY(MM.allocate_kernel_region(
                NUM_TRANSFER_REGION_PAGES * PAGE_SIZE,
                "VIRGL3D userspace upload buffer"sv,
                Memory::Region::Access::ReadWrite,
                AllocationStrategy::AllocateNow));
            return TRY(adopt_nonnull_ref_or_enomem(new (nothrow) PerContextState(description, context_id, move(region_result))));
        }
        Graphics::VirtIOGPU::ContextID context_id() { return m_context_id; }
        Memory::Region& transfer_buffer_region() { return *m_transfer_buffer_region; }

        OpenFileDescription& description() { return m_attached_file_description; }

    private:
        PerContextState() = delete;
        PerContextState(OpenFileDescription&, Graphics::VirtIOGPU::ContextID context_id, OwnPtr<Memory::Region> transfer_buffer_region);
        Graphics::VirtIOGPU::ContextID m_context_id;
        OwnPtr<Memory::Region> m_transfer_buffer_region;

        // NOTE: We clean this whole object when the file description is closed, therefore we need to hold
        // a raw reference here instead of a strong reference pointer (e.g. RefPtr, which will make it
        // possible to leak the attached OpenFileDescription for a context in this device).
        OpenFileDescription& m_attached_file_description;

        IntrusiveListNode<PerContextState, NonnullRefPtr<PerContextState>> m_list_node;
    };

    virtual bool can_read(OpenFileDescription const&, u64) const override { return true; }
    virtual bool can_write(OpenFileDescription const&, u64) const override { return true; }
    virtual ErrorOr<size_t> read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t) override { return ENOTSUP; }
    virtual ErrorOr<size_t> write(OpenFileDescription&, u64, UserOrKernelBuffer const&, size_t) override { return ENOTSUP; }
    virtual StringView class_name() const override { return "virgl3d"sv; }

    virtual ErrorOr<void> ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg) override;
    virtual void detach(OpenFileDescription&) override;

    using ContextList = IntrusiveListRelaxedConst<&PerContextState::m_list_node>;

private:
    NonnullLockRefPtr<VirtIOGraphicsAdapter> m_graphics_adapter;
    // Context used for kernel operations (e.g. flushing resources to scanout)
    Graphics::VirtIOGPU::ContextID m_kernel_context_id;
    SpinlockProtected<ContextList, LockRank::None> m_context_state_list;
    // Memory management for backing buffers
    NonnullOwnPtr<Memory::Region> m_transfer_buffer_region;
    constexpr static size_t NUM_TRANSFER_REGION_PAGES = 1024;
};

}