/*
    This file is part of Fennix Kernel.

    Fennix Kernel is free software: you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation, either version 3 of
    the License, or (at your option) any later version.

    Fennix Kernel is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Fennix Kernel. If not, see <https://www.gnu.org/licenses/>.
*/

#include <ipc.hpp>

#include <task.hpp>

#include "../kernel.h"
#include "../ipc.h"

namespace InterProcessCommunication
{
    void IPC::Fork(IPC *Parent)
    {
        std::vector<IPCHandle *> ParentHandles = Parent->GetHandles();

        foreach (auto Hnd in ParentHandles)
        {
            debug("Forking IPC with ID %d", Hnd->ID);
            IPCHandle *NewHnd = (IPCHandle *)vma->RequestPages(TO_PAGES(sizeof(IPCHandle) + 1));
            memcpy(NewHnd, Hnd, sizeof(IPCHandle));
            NewHnd->Node = fs->Create(Hnd->Node->Name, vfs::NodeType::FILE, IPCNode);
            Handles.push_back(NewHnd);
        }
    }

    IPCHandle *IPC::Create(IPCType Type, char UniqueToken[16])
    {
        UNUSED(Type);
        SmartLock(this->IPCLock);
        IPCHandle *Hnd = (IPCHandle *)vma->RequestPages(TO_PAGES(sizeof(IPCHandle) + 1));

        Hnd->ID = NextID++;
        Hnd->Node = fs->Create(UniqueToken, vfs::NodeType::FILE, IPCNode);
        Hnd->Buffer = nullptr;
        Hnd->Length = 0;
        Hnd->Listening = false;

        Handles.push_back(Hnd);
        debug("Created IPC with ID %d", Hnd->ID);
        return Hnd;
    }

    IPCErrorCode IPC::Destroy(IPCID ID)
    {
        SmartLock(this->IPCLock);
        forItr(itr, Handles)
        {
            if ((*itr)->ID == ID)
            {
                fs->Delete((*itr)->Node);
                vma->FreePages((*itr), TO_PAGES(sizeof(IPCHandle) + 1));
                Handles.erase(itr);
                debug("Destroyed IPC with ID %d", ID);
                return IPCSuccess;
            }
        }

        debug("Failed to destroy IPC with ID %d", ID);
        return IPCIDNotFound;
    }

    IPCErrorCode IPC::Allocate(IPCID ID, long Size)
    {
        SmartLock(this->IPCLock);
        if (Size < 0)
            return IPCError;

        foreach (auto Hnd in Handles)
        {
            if (Hnd->ID == ID)
            {
                if (Hnd->Buffer != nullptr || Hnd->Length != 0)
                    return IPCAlreadyAllocated;

                Hnd->Buffer = (uint8_t *)vma->RequestPages(TO_PAGES(Size + 1));
                Hnd->Length = Size;
                return IPCSuccess;
            }
        }
        return IPCIDNotFound;
    }

    IPCErrorCode IPC::Deallocate(IPCID ID)
    {
        SmartLock(this->IPCLock);
        foreach (auto Hnd in Handles)
        {
            if (Hnd->ID == ID)
            {
                if (Hnd->Buffer == nullptr || Hnd->Length == 0)
                    return IPCNotAllocated;

                vma->FreePages(Hnd->Buffer, TO_PAGES(Hnd->Length + 1));
                Hnd->Buffer = nullptr;
                Hnd->Length = 0;
                return IPCSuccess;
            }
        }
        return IPCIDNotFound;
    }

    IPCErrorCode IPC::Read(IPCID ID, void *Buffer, long Size)
    {
        SmartLock(this->IPCLock);
        if (Size < 0)
            return IPCError;

        foreach (auto Hnd in Handles)
        {
            if (Hnd->ID == ID)
            {
                if (Hnd->Listening)
                {
                    debug("IPC %d is listening", ID);
                    return IPCNotListening;
                }
                if (Hnd->Length < Size)
                {
                    debug("IPC %d is too small", ID);
                    return IPCError;
                }
                debug("IPC %d reading %d bytes", ID, Size);
                memcpy(Buffer, Hnd->Buffer, Size);
                debug("IPC read %d bytes", Size);
                return IPCSuccess;
            }
        }
        debug("IPC %d not found", ID);
        return IPCIDNotFound;
    }

    IPCErrorCode IPC::Write(IPCID ID, void *Buffer, long Size)
    {
        SmartLock(this->IPCLock);
        if (Size < 0)
        {
            debug("IPC %d is too small", ID);
            return IPCError;
        }

        foreach (auto Hnd in Handles)
        {
            if (Hnd->ID == ID)
            {
                if (!Hnd->Listening)
                {
                    debug("IPC %d is NOT listening", ID);
                    return IPCNotListening;
                }
                if (Hnd->Length < Size)
                {
                    debug("IPC %d is too small", ID);
                    return IPCError;
                }
                debug("IPC %d writing %d bytes", ID, Size);
                memcpy(Hnd->Buffer, Buffer, Size);
                Hnd->Listening = false;
                debug("IPC %d wrote %d bytes and now is %s", ID, Size, Hnd->Listening ? "listening" : "ready");
                return IPCSuccess;
            }
        }
        debug("IPC %d not found", ID);
        return IPCIDNotFound;
    }

    IPCErrorCode IPC::Listen(IPCID ID, bool Listen)
    {
        foreach (auto Hnd in Handles)
        {
            if (Hnd->ID == ID)
            {
                Hnd->Listening = Listen;
                debug("IPC %d is now set to %s", ID, Listen ? "listening" : "ready");
                return IPCSuccess;
            }
        }
        debug("IPC %d not found", ID);
        return IPCIDNotFound;
    }

    IPCErrorCode IPC::Wait(IPCID ID)
    {
        foreach (auto Hnd in Handles)
        {
            if (Hnd->ID == ID)
            {
                if (!CPU::Interrupts())
                    warn("Interrupts are disabled. This may cause a kernel hang.");
                debug("Waiting for IPC %d (now %s)", ID, Hnd->Listening ? "listening" : "ready");
                while (Hnd->Listening)
                    TaskManager->Yield();
                debug("IPC %d is ready", ID);
                return IPCSuccess;
            }
        }
        debug("IPC %d not found", ID);
        return IPCIDNotFound;
    }

    IPCHandle *IPC::SearchByToken(char UniqueToken[16])
    {
        foreach (auto Hnd in Handles)
        {
            if (strcmp(Hnd->Node->Name, UniqueToken) == 0)
            {
                debug("Found IPC with token %s", UniqueToken);
                return Hnd;
            }
        }
        debug("Failed to find IPC with token %s", UniqueToken);
        return nullptr;
    }

    int IPC::HandleSyscall(long Command, long Type, int ID, int Flags, void *Buffer, size_t Size)
    {
        switch (Command)
        {
        case IPC_CREATE:
        {
            char UniqueToken[16];
            if (Buffer != nullptr)
                strcpy(UniqueToken, (char *)Buffer);
            else
                snprintf(UniqueToken, 16, "IPC_%d", ID);
            IPCHandle *Hnd = this->Create((IPCType)Type, UniqueToken);
            this->Allocate(Hnd->ID, Size ? Size : PAGE_SIZE);
            return Hnd->ID;
        }
        case IPC_READ:
            return this->Read(ID, Buffer, Size);
        case IPC_WRITE:
            return TaskManager->GetProcessByID(Flags)->IPC->Write(ID, Buffer, Size);
        case IPC_DELETE:
        {
            this->Deallocate(ID);
            return this->Destroy(ID);
        }
        case IPC_WAIT:
            return this->Wait(ID);
        case IPC_LISTEN:
            return this->Listen(ID, Flags);
        default:
            return IPCInvalidCommand;
        }
        return IPCError;
    }

    IPC::IPC(void *Process)
    {
        Tasking::PCB *pcb = (Tasking::PCB *)Process;
        this->Process = Process;
        this->vma = new Memory::VirtualMemoryArea(pcb->PageTable);
        IPCNode = fs->Create("ipc", vfs::NodeType::DIRECTORY,
                              pcb->ProcessDirectory);
    }

    IPC::~IPC()
    {
        fs->Delete(IPCNode, true);
        delete this->vma, this->vma = nullptr;
    }
}