// SPDX-FileCopyrightText: Copyright 2019 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#pragma once

#include <memory>
#include "common/common_funcs.h"
#include "common/common_types.h"
#include "common/virtual_buffer.h"

namespace Common {

enum class MemoryPermission : u32 {
    Read = 1 << 0,
    Write = 1 << 1,
    ReadWrite = Read | Write,
    Execute = 1 << 2,
};
DECLARE_ENUM_FLAG_OPERATORS(MemoryPermission)

/**
 * A low level linear memory buffer, which supports multiple mappings
 * Its purpose is to rebuild a given sparse memory layout, including mirrors.
 */
class HostMemory {
public:
    explicit HostMemory(size_t backing_size_, size_t virtual_size_);
    ~HostMemory();

    /**
     * Copy constructors. They shall return a copy of the buffer without the mappings.
     * TODO: Implement them with COW if needed.
     */
    HostMemory(const HostMemory& other) = delete;
    HostMemory& operator=(const HostMemory& other) = delete;

    /**
     * Move constructors. They will move the buffer and the mappings to the new object.
     */
    HostMemory(HostMemory&& other) noexcept;
    HostMemory& operator=(HostMemory&& other) noexcept;

    void Map(size_t virtual_offset, size_t host_offset, size_t length, MemoryPermission perms);

    void Unmap(size_t virtual_offset, size_t length);

    void Protect(size_t virtual_offset, size_t length, bool read, bool write, bool execute = false);

    void EnableDirectMappedAddress();

    void ClearBackingRegion(size_t physical_offset, size_t length, u32 fill_value);

    [[nodiscard]] u8* BackingBasePointer() noexcept {
        return backing_base;
    }
    [[nodiscard]] const u8* BackingBasePointer() const noexcept {
        return backing_base;
    }

    [[nodiscard]] u8* VirtualBasePointer() noexcept {
        return virtual_base;
    }
    [[nodiscard]] const u8* VirtualBasePointer() const noexcept {
        return virtual_base;
    }

private:
    size_t backing_size{};
    size_t virtual_size{};

    // Low level handler for the platform dependent memory routines
    class Impl;
    std::unique_ptr<Impl> impl;
    u8* backing_base{};
    u8* virtual_base{};
    size_t virtual_base_offset{};

    // Fallback if fastmem is not supported on this platform
    std::unique_ptr<Common::VirtualBuffer<u8>> fallback_buffer;
};

} // namespace Common
