/*
   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 <syscalls.hpp>
#include <memory.hpp>
#include <lock.hpp>
#include <exec.hpp>

#include <debug.h>

#include "../syscalls.h"
#include "../kernel.h"

#include "../ipc.h"

using InterProcessCommunication::IPC;
using InterProcessCommunication::IPCID;
using Tasking::Token;
using Tasking::TTL;
using Tasking::TTL::Trusted;
using Tasking::TTL::TrustedByKernel;
using Tasking::TTL::UnknownTrustLevel;
using Tasking::TTL::Untrusted;

static inline bool CheckTrust(int TrustLevel)
{
    // SmartTimeoutLock(SyscallsLock, 10000); - This is already done in the caller
    Token token = TaskManager->GetCurrentThread()->Security.UniqueToken;
    if (TaskManager->GetSecurityManager()->IsTokenTrusted(token, TrustLevel))
        return true;

    warn("Thread %s(%lld) tried to access a system call \"%s\" with insufficient trust level",
         TaskManager->GetCurrentThread()->Name, TaskManager->GetCurrentThread()->ID,
         KernelSymbolTable->GetSymbolFromAddress((uintptr_t)__builtin_extract_return_addr(__builtin_return_address(0))));
    debug("Token: token=%#lx, trust=%d", token, TaskManager->GetSecurityManager()->GetTokenTrustLevel(token));
    return false;
}

static int sys_exit(SyscallsFrame *Frame, int code)
{
    /* Allow everyone to exit */
    if (!CheckTrust(TrustedByKernel | Trusted | Untrusted | UnknownTrustLevel))
        return SYSCALL_ACCESS_DENIED;

    trace("Userspace thread %s(%lld) exited with code %#llx", TaskManager->GetCurrentThread()->Name, TaskManager->GetCurrentThread()->ID, code);
    TaskManager->GetCurrentThread()->ExitCode = code;
    TaskManager->GetCurrentThread()->Status = Tasking::TaskStatus::Terminated;
    UNUSED(Frame);
    return SYSCALL_OK;
}

static int sys_print(SyscallsFrame *Frame, char Char, int Index)
{
    /* Only trusted threads can write to the kernel console */
    if (!CheckTrust(TrustedByKernel | Trusted))
        return SYSCALL_ACCESS_DENIED;

    char ret = Display->Print(Char, Index, true);
    if (!Config.BootAnimation && Index == 0)
#ifdef DEBUG
        Display->SetBuffer(Index);
#else
        if (Char == '\n')
            Display->SetBuffer(Index);
#endif
    UNUSED(Frame);
    return ret;
}

static uintptr_t sys_request_pages(SyscallsFrame *Frame, size_t Count)
{
    /* Allow everyone to request pages */
    if (!CheckTrust(TrustedByKernel | Trusted | Untrusted))
        return SYSCALL_ACCESS_DENIED;
    UNUSED(Frame);
    return (uintptr_t)TaskManager->GetCurrentThread()->Memory->RequestPages(Count + 1, true);
}

static int sys_free_pages(SyscallsFrame *Frame, uintptr_t Address, size_t Count)
{
    /* Allow everyone to free pages */
    if (!CheckTrust(TrustedByKernel | Trusted | Untrusted))
        return SYSCALL_ACCESS_DENIED;
    TaskManager->GetCurrentThread()->Memory->FreePages((void *)Address, Count + 1);
    UNUSED(Frame);
    return SYSCALL_OK;
}

static int sys_detach_address(SyscallsFrame *Frame, uintptr_t Address)
{
    /* Only trusted threads can detach allocated addresses */
    if (!CheckTrust(TrustedByKernel | Trusted))
        return SYSCALL_ACCESS_DENIED;
    TaskManager->GetCurrentThread()->Memory->DetachAddress((void *)Address);
    UNUSED(Frame);
    return SYSCALL_OK;
}

static uintptr_t sys_kernelctl(SyscallsFrame *Frame, uint64_t Command, uint64_t Arg1, uint64_t Arg2, uint64_t Arg3, uint64_t Arg4)
{
    if (!CheckTrust(TrustedByKernel | Trusted | Untrusted))
        return SYSCALL_ACCESS_DENIED;

    return SYSCALL_NOT_IMPLEMENTED;

    // switch (Command)
    // {
    // case KCTL_GET_PID:
    //     return TaskManager->GetCurrentThread()->Parent->ID;
    // case KCTL_GET_TID:
    //     return TaskManager->GetCurrentThread()->ID;
    // case KCTL_GET_PAGE_SIZE:
    //     return PAGE_SIZE;
    // case KCTL_IS_CRITICAL:
    //     return TaskManager->GetCurrentThread()->Security.IsCritical;
    // case KCTL_REGISTER_ELF_LIB:
    // {
    //     if (!CheckTrust(TrustedByKernel | Trusted))
    //         return SYSCALL_ACCESS_DENIED;
    //     char *Identifier = (char *)Arg1;
    //     const char *Path = (const char *)Arg2;

    //     if (!Identifier || !Path)
    //         return SYSCALL_INVALID_ARGUMENT;

    //     std::string FullPath = Path;
    //     int retries = 0;
    // RetryReadPath:
    //     debug("KCTL_REGISTER_ELF_LIB: Trying to open %s", FullPath.c_str());
    //     VirtualFileSystem::File f = vfs->Open(FullPath.c_str());

    //     if (!f.IsOK())
    //     {
    //         FullPath.clear();
    //         switch (retries)
    //         {
    //         case 0:
    //             FullPath = "/system/lib/";
    //             break;
    //         case 1:
    //             FullPath = "/system/lib64/";
    //             break;
    //         case 2:
    //             FullPath = "/system/";
    //             break;
    //         case 3:
    //         {
    //             // TODO: Check process binary path
    //             break;
    //         }
    //         default:
    //         {
    //             vfs->Close(f);
    //             return SYSCALL_INVALID_ARGUMENT;
    //         }
    //         }
    //         FullPath += Path;
    //         vfs->Close(f);
    //         retries++;
    //         goto RetryReadPath;
    //     }

    //     vfs->Close(f);
    //     if (Execute::AddLibrary(Identifier, (void *)f.node->Address, f.node->Length))
    //         return SYSCALL_OK;
    //     else
    //         return SYSCALL_INTERNAL_ERROR;
    // }
    // case KCTL_GET_ELF_LIB_FILE:
    // {
    //     if (!CheckTrust(TrustedByKernel | Trusted))
    //         return SYSCALL_ACCESS_DENIED;
    //     char *Identifier = (char *)Arg1;
    //     if (!Identifier)
    //         return 0;

    //     Execute::SharedLibraries lib = Execute::GetLibrary(Identifier);
    //     if (!lib.Address)
    //     {
    //         debug("Failed to get library address %#lx", (uintptr_t)lib.Address);
    //     }

    //     debug("Returning library address %#lx (%s)", (uintptr_t)lib.Address, Identifier);
    //     return (uintptr_t)lib.Address;
    // }
    // case KCTL_GET_ELF_LIB_MEMORY_IMAGE:
    // {
    //     if (!CheckTrust(TrustedByKernel | Trusted))
    //         return SYSCALL_ACCESS_DENIED;
    //     char *Identifier = (char *)Arg1;
    //     if (!Identifier)
    //         return 0;

    //     Execute::SharedLibraries lib = Execute::GetLibrary(Identifier);

    //     if (!lib.MemoryImage)
    //     {
    //         debug("Failed to get library memory image %#lx", (uintptr_t)lib.MemoryImage);
    //     }

    //     debug("Returning memory image %#lx (%s)", (uintptr_t)lib.MemoryImage, Identifier);
    //     return (uintptr_t)lib.MemoryImage;
    // }
    // case KCTL_GET_FRAMEBUFFER_BUFFER:
    //     return r_cst(uint64_t, Display->GetBuffer(0)->Buffer);
    // case KCTL_GET_FRAMEBUFFER_WIDTH:
    //     return Display->GetBuffer(0)->Width;
    // case KCTL_GET_FRAMEBUFFER_HEIGHT:
    //     return Display->GetBuffer(0)->Height;
    // case KCTL_GET_FRAMEBUFFER_SIZE:
    //     return Display->GetBuffer(0)->Size;
    // default:
    // {
    //     warn("KernelCTL: Unknown command: %lld", Command);
    //     return SYSCALL_INVALID_ARGUMENT;
    // }
    // }

    UNUSED(Arg1);
    UNUSED(Arg2);
    UNUSED(Arg3);
    UNUSED(Arg4);
    UNUSED(Frame);
}

static int sys_ipc(SyscallsFrame *Frame, enum IPCCommand Command, enum IPCType Type, int ID, int Flags, void *Buffer, size_t Size)
{
    /* Allow everyone to use IPC */
    if (!CheckTrust(TrustedByKernel | Trusted | Untrusted))
        return SYSCALL_ACCESS_DENIED;
    UNUSED(Frame);
    return TaskManager->GetCurrentProcess()->IPC->HandleSyscall(Command, Type, ID, Flags, Buffer, Size);
}

static uint64_t sys_file_open(SyscallsFrame *Frame, const char *Path, uint64_t Flags)
{
    debug("(Path: %s, Flags: %#lx)", Path, Flags);
    VirtualFileSystem::File KPObj = vfs->Open(Path);
    if (!KPObj.IsOK())
    {
        debug("Failed to open file %s (%d)", Path, KPObj.Status);
        vfs->Close(KPObj);
        return SYSCALL_INTERNAL_ERROR;
    }

    VirtualFileSystem::File *KernelPrivate = (VirtualFileSystem::File *)TaskManager->GetCurrentThread()->Memory->RequestPages(TO_PAGES(sizeof(VirtualFileSystem::File)));
    *KernelPrivate = KPObj;
    debug("Opened file %s (%d)", KPObj.Name, KPObj.Status);
    return (uint64_t)KernelPrivate;
    UNUSED(Frame);
    UNUSED(Flags);
}

static int sys_file_close(SyscallsFrame *Frame, void *KernelPrivate)
{
    debug("(KernelPrivate: %#lx)", KernelPrivate);
    if (KernelPrivate)
    {
        VirtualFileSystem::File KPObj = *(VirtualFileSystem::File *)KernelPrivate;
        debug("Closed file %s (%d)", KPObj.Name, KPObj.Status);
        vfs->Close(KPObj);
        TaskManager->GetCurrentThread()->Memory->FreePages(KernelPrivate, TO_PAGES(sizeof(VirtualFileSystem::File)));
        return SYSCALL_OK;
    }
    return SYSCALL_INVALID_ARGUMENT;
    UNUSED(Frame);
}

static uint64_t sys_file_read(SyscallsFrame *Frame, void *KernelPrivate, uint64_t Offset, uint8_t *Buffer, uint64_t Size)
{
    debug("(KernelPrivate: %#lx, Offset: %#lx, Buffer: %#lx, Size: %#lx)", KernelPrivate, Offset, Buffer, Size);
    return vfs->Read(*(VirtualFileSystem::File *)KernelPrivate, Offset, Buffer, Size);
    UNUSED(Frame);
}

static uint64_t sys_file_write(SyscallsFrame *Frame, void *KernelPrivate, uint64_t Offset, uint8_t *Buffer, uint64_t Size)
{
    debug("(KernelPrivate: %#lx, Offset: %#lx, Buffer: %#lx, Size: %#lx)", KernelPrivate, Offset, Buffer, Size);
    return vfs->Write(*(VirtualFileSystem::File *)KernelPrivate, Offset, Buffer, Size);
    UNUSED(Frame);
}

static int sys_file_seek(SyscallsFrame *Frame)
{
    fixme("sys_file_seek: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_file_status(SyscallsFrame *Frame)
{
    fixme("sys_file_status: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_sleep(SyscallsFrame *Frame, uint64_t Milliseconds)
{
    UNUSED(Frame);
    if (!CheckTrust(TrustedByKernel | Trusted | Untrusted))
        return SYSCALL_ACCESS_DENIED;
    TaskManager->Sleep(Milliseconds);
    return 0;
}

static int sys_wait(SyscallsFrame *Frame)
{
    fixme("sys_wait: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_kill(SyscallsFrame *Frame)
{
    fixme("sys_kill: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_spawn(SyscallsFrame *Frame)
{
    fixme("sys_spawn: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_spawn_thread(SyscallsFrame *Frame)
{
    fixme("sys_spawn_thread: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_get_thread_list_of_process(SyscallsFrame *Frame)
{
    fixme("sys_get_thread_list_of_process: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_get_current_process(SyscallsFrame *Frame)
{
    fixme("sys_get_current_process: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_get_current_thread(SyscallsFrame *Frame)
{
    fixme("sys_get_current_thread: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_get_process_by_pid(SyscallsFrame *Frame)
{
    fixme("sys_get_process_by_pid: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_get_thread_by_tid(SyscallsFrame *Frame)
{
    fixme("sys_get_thread_by_tid: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_kill_process(SyscallsFrame *Frame)
{
    fixme("sys_kill_process: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_kill_thread(SyscallsFrame *Frame)
{
    fixme("sys_kill_thread: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_sys_reserved_create_process(SyscallsFrame *Frame)
{
    fixme("sys_sys_reserved_create_process: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static int sys_sys_reserved_create_thread(SyscallsFrame *Frame)
{
    fixme("sys_sys_reserved_create_thread: %#lx", Frame);
    return SYSCALL_NOT_IMPLEMENTED;
}

static void *NativeSyscallsTable[] = {
    [_Exit] = (void *)sys_exit,
    [_Print] = (void *)sys_print,

    [_RequestPages] = (void *)sys_request_pages,
    [_FreePages] = (void *)sys_free_pages,
    [_DetachAddress] = (void *)sys_detach_address,

    [_KernelCTL] = (void *)sys_kernelctl,
    [_IPC] = (void *)sys_ipc,

    [_FileOpen] = (void *)sys_file_open,
    [_FileClose] = (void *)sys_file_close,
    [_FileRead] = (void *)sys_file_read,
    [_FileWrite] = (void *)sys_file_write,
    [_FileSeek] = (void *)sys_file_seek,
    [_FileStatus] = (void *)sys_file_status,

    [_Sleep] = (void *)sys_sleep,
    [_Wait] = (void *)sys_wait,
    [_Kill] = (void *)sys_kill,
    [_Spawn] = (void *)sys_spawn,
    [_SpawnThread] = (void *)sys_spawn_thread,
    [_GetThreadListOfProcess] = (void *)sys_get_thread_list_of_process,
    [_GetCurrentProcess] = (void *)sys_get_current_process,
    [_GetCurrentThread] = (void *)sys_get_current_thread,
    [_GetProcessByPID] = (void *)sys_get_process_by_pid,
    [_GetThreadByTID] = (void *)sys_get_thread_by_tid,
    [_KillProcess] = (void *)sys_kill_process,
    [_KillThread] = (void *)sys_kill_thread,
    [_SysReservedCreateProcess] = (void *)sys_sys_reserved_create_process,
    [_SysReservedCreateThread] = (void *)sys_sys_reserved_create_thread,
};

uintptr_t HandleNativeSyscalls(SyscallsFrame *Frame)
{
#if defined(a64)
    if (Frame->rax > sizeof(NativeSyscallsTable))
    {
        fixme("Syscall %ld not implemented", Frame->rax);
        return SYSCALL_NOT_IMPLEMENTED;
    }

    uintptr_t (*call)(uintptr_t, ...) = reinterpret_cast<uintptr_t (*)(uintptr_t, ...)>(NativeSyscallsTable[Frame->rax]);
    if (!call)
    {
        error("Syscall %#lx failed.", Frame->rax);
        return SYSCALL_INTERNAL_ERROR;
    }

    // debug("[%#lx]->( %#lx  %#lx  %#lx  %#lx  %#lx  %#lx )",
    //       Frame->rax,
    //       Frame->rdi, Frame->rsi, Frame->rdx, Frame->rcx, Frame->r8, Frame->r9);

    uintptr_t ret = call((uintptr_t)Frame, Frame->rdi, Frame->rsi, Frame->rdx, Frame->r10, Frame->r8, Frame->r9);
    Frame->rax = ret;
    return ret;
#elif defined(a32)
    if (Frame->eax > sizeof(NativeSyscallsTable))
    {
        fixme("Syscall %ld not implemented", Frame->eax);
        return SYSCALL_NOT_IMPLEMENTED;
    }

    /* ... */

    return SYSCALL_INTERNAL_ERROR;
#elif defined(aa64)
    return SYSCALL_INTERNAL_ERROR;
#endif
}