#pragma once

#include "arch/MMU.h"
#include "fs/VFS.h"
#include "memory/UserVM.h"
#include <luna/LinkedList.h>
#include <luna/OwnedPtr.h>
#include <luna/Result.h>
#include <luna/Stack.h>

#ifdef ARCH_X86_64
#include "arch/x86_64/CPU.h"
#else
#error "Unknown architecture."
#endif

enum class ThreadState
{
    Idle,
    Runnable,
    Sleeping,
    Dying
};

struct FileDescriptor
{
    SharedPtr<VFS::Inode> inode;
    usize offset { 0 };
    int flags { 0 };
};

static constexpr int FD_MAX = 64;

struct FileDescriptorTable
{
    Option<FileDescriptor> fds[FD_MAX] = {};
};

struct Thread : public LinkedListNode<Thread>
{
    Registers regs;

    u64 id;

    u64 ticks = 0;
    u64 ticks_in_user = 0;
    u64 ticks_in_kernel = 0;

    u64 ticks_left;
    u64 sleep_ticks_left;

    Stack stack;
    Stack kernel_stack;

    OwnedPtr<UserVM> vm_allocator;
    Option<FileDescriptorTable> fd_table;

    Result<int> allocate_fd(int min);

    FPData fp_data;

    ThreadState state = ThreadState::Runnable;

    bool is_kernel { true };

    PageDirectory* directory;

    bool is_idle()
    {
        return state == ThreadState::Idle;
    }

    void init_regs_kernel();
    void init_regs_user();

    void set_arguments(u64 arg1, u64 arg2, u64 arg3, u64 arg4);

    void set_ip(u64 ip);
    u64 ip();

    void set_sp(u64 sp);
    u64 sp();

    static void init();
};

void switch_context(Thread* old_thread, Thread* new_thread, Registers* regs);

bool is_in_kernel(Registers* regs);

Result<Thread*> new_thread();

extern LinkedList<Thread> g_threads;