//
// Created by Kirill Zhukov on 20.04.2025.
//

#include "SharedMemoryManager.h"

#include <iostream>

namespace usub::core
{
    SharedMemoryManager::SharedMemoryManager(const std::string& name, size_t size, bool create_new) :
        shm_name("/" + name), shm_size(size), shm_fd(-1), shm_ptr(nullptr)
    {
        if (create_new)
        {
            create();
        }
        else
        {
            open();
        }
    }

    SharedMemoryManager::~SharedMemoryManager()
    {
        if (this->shm_ptr != nullptr)
        {
            munmap(this->shm_ptr, shm_size);
        }
        if (this->shm_fd != -1)
        {
            close(this->shm_fd);
        }
    }

    void* SharedMemoryManager::base_ptr() const noexcept
    {
        return this->shm_ptr;
    }

    size_t SharedMemoryManager::size() const noexcept
    {
        return this->shm_size;
    }

    const std::string& SharedMemoryManager::name() const noexcept
    {
        return this->shm_name;
    }

    void SharedMemoryManager::destroy()
    {
        munmap(this->shm_ptr, this->shm_size);
        close(this->shm_fd);
        shm_unlink(this->shm_name.c_str());
        this->shm_ptr = nullptr;
        this->shm_fd = -1;
    }

    bool SharedMemoryManager::exists(const std::string& name)
    {
        int fd = shm_open(("/" + name).c_str(), O_RDWR, 0600);
        if (fd == -1)
            return false;
        close(fd);
        return true;
    }

    void SharedMemoryManager::create()
    {
        ::shm_unlink((this->shm_name).c_str());
        this->shm_fd = ::shm_open(this->shm_name.c_str(), O_CREAT | O_RDWR | O_EXCL, 0600);
        if (this->shm_fd == -1)
        {
            throw std::runtime_error("Failed to create shared memory: " + shm_name);
        }
        if (::ftruncate(this->shm_fd, this->shm_size) == -1)
        {
            ::close(this->shm_fd);
            ::shm_unlink(this->shm_name.c_str());
            throw std::runtime_error("Failed to set size for shared memory: " + this->shm_name);
        }
        this->shm_ptr = ::mmap(nullptr, this->shm_size, PROT_READ | PROT_WRITE, MAP_SHARED, this->shm_fd, 0);
        if (this->shm_ptr == MAP_FAILED)
        {
            ::close(this->shm_fd);
            ::shm_unlink(this->shm_name.c_str());
            throw std::runtime_error("Failed to mmap shared memory: " + this->shm_name);
        }
        std::memset(this->shm_ptr, 0, this->shm_size);
    }

    void SharedMemoryManager::open()
    {
        this->shm_fd = ::shm_open(this->shm_name.c_str(), O_RDWR, 0600);
        if (this->shm_fd == -1)
        {
            throw std::runtime_error("Failed to open shared memory: " + this->shm_name);
        }
        else
        {
            std::cout << "[shm_open] name: " << this->shm_name << ", fd: " << this->shm_fd << '\n';
        }
        this->shm_ptr = ::mmap(nullptr, shm_size, PROT_READ | PROT_WRITE, MAP_SHARED, this->shm_fd, 0);
        if (this->shm_ptr == MAP_FAILED)
        {
            ::close(this->shm_fd);
            throw std::runtime_error("Failed to mmap shared memory: " + this->shm_name);
        }
    }
}