/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: IPCMemory.Unix.cpp
    Date: 2022-4-14
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "IPC.hpp"
#include "IPCHandle.hpp"
#include "IPCMemory.Unix.hpp"

#include <Source/IO/IPC/IPC.hpp>
#include <Source/IO/IPC/IPCHandle.hpp>

#include <sys/mman.h>
#include <sys/stat.h>        /* For mode constants */
#include <fcntl.h>           /* For O_* constants */

namespace Aurora::IO::IPC
{
    //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    // Shared memory
    //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    
    struct IPCSharedMemoryImpl : IPCSharedMemory
    {
        IPCSharedMemoryImpl(int fd, void *ptr, const IPC::IPCHandle &handle, bool owns);
        ~IPCSharedMemoryImpl();

        virtual Memory::MemoryViewWrite GetMemory() override;
        virtual AuUInt GetLength() override;

        virtual AuString ExportToString() override;

    private:
        IPC::IPCHandle handle_;
        bool owns_;
        int fd_{};
        void *base_{};
        AuUInt len_ {};
    };

    static AuString GetServerPath(const IPC::IPCHandle &handle)
    {
        AuString path;
        path += "/AURORA_";
        path += AuToString(AuUInt32(handle.cookie));
        path += "_";
        path += AuToString(AuUInt32(handle.pid));
        return path;
    }

    IPCSharedMemoryImpl::IPCSharedMemoryImpl(int fd, void *ptr, const IPC::IPCHandle &handle, bool owns) : 
        fd_(fd), base_(ptr), len_(handle.word), owns_(owns), handle_(handle)
    {

    }

    IPCSharedMemoryImpl::~IPCSharedMemoryImpl()
    {
        if (this->base_)
        {
            ::munmap(this->base_, this->len_);
        }

        int fd {-1};
        if ((fd = AuExchange(this->fd_, -1)) != -1)
        {
            ::close(fd);
        }
    }

    Memory::MemoryViewWrite IPCSharedMemoryImpl::GetMemory()
    {
        return AuMemoryViewWrite(this->base_, this->len_);
    }

    AuUInt IPCSharedMemoryImpl::GetLength()
    {
        return this->len_;
    }

    AuString IPCSharedMemoryImpl::ExportToString()
    {
        return this->handle_.ToString();
    }

    AUKN_SYM AuSPtr<IPCSharedMemory>      NewSharedMemory(AuUInt length)
    {
        IPC::IPCHandle handle;
        handle.NewId(length);

        auto path = GetServerPath(handle);
        int fd = ::shm_open(path.c_str(), O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
        if (fd == -1)
        {
            SysPushErrorIO();
            return {};
        }

        if (::ftruncate(fd, length) == -1)
        {
            SysPushErrorMem();
            ::close(fd);
            return {};
        }

        auto map = ::mmap(nullptr, length, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
        if (map == MAP_FAILED)
        {
            SysPushErrorIO();
            ::close(fd);
            return {};
        }

        auto object = AuMakeShared<IPCSharedMemoryImpl>(fd, map, handle, true);
        if (!object)
        {
            SysPushErrorMem();
            ::munmap(map, length);
            ::close(fd);
            return {};
        }

        return object;
    }

    AUKN_SYM AuSPtr<IPCSharedMemory>      ImportSharedMemory(const AuString &handleString)
    {
        IPC::IPCHandle handle;

        if (!handle.FromString(handleString))
        {
            SysPushErrorParseError();
            return {};
        }

        auto path = GetServerPath(handle);
        int fd = ::shm_open(path.c_str(), O_RDWR, S_IRUSR | S_IWUSR);
        if (fd == -1)
        {
            SysPushErrorIO();
            return {};
        }

        auto map = ::mmap(nullptr, handle.word, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
        if (map == MAP_FAILED)
        {
            SysPushErrorIO();
            ::close(fd);
            return {};
        }

        auto object = AuMakeShared<IPCSharedMemoryImpl>(fd, map, handle, false);
        if (!object)
        {
            SysPushErrorMem();
            ::munmap(map, handle.word);
            ::close(fd);
            return {};
        }

        return object;
    }
}