#pragma once
#include "arch/MMU.h"
#include "fs/OpenFileDescription.h"
#include "fs/VFS.h"
#include "lib/Mutex.h"
#include "memory/AddressSpace.h"
#include <bits/signal.h>
#include <luna/Bitset.h>
#include <luna/LinkedList.h>
#include <luna/OwnedPtr.h>
#include <luna/Result.h>
#include <luna/Stack.h>
#include <luna/StaticString.h>
#include <luna/String.h>

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

constexpr int MAX_POSIX_TIMERS = 64;
constexpr i64 PROCESS_SHOULD_REAP = -1;

class Timer;

enum class ThreadState
{
    None,
    Idle,
    Runnable,
    Sleeping,
    Waiting,
    Stopped,
    Exited,
    Dying
};

static constexpr int FD_MAX = 64;

struct Credentials
{
    u32 uid { 0 };
    u32 euid { 0 };
    u32 suid { 0 };
    u32 gid { 0 };
    u32 egid { 0 };
    u32 sgid { 0 };
};

struct Process : public LinkedListNode<Process>
{
    Atomic<i64> thread_count;

    pid_t id;
    Atomic<pid_t> pgid { 0 };
    Atomic<pid_t> sid { 0 };

    bool has_called_exec { false };

    mode_t umask { 0 };

    int promises { -1 };
    int execpromises { -1 };

    Process* parent { nullptr };

    MutexLocked<Credentials> auth { Credentials { 0, 0, 0, 0, 0, 0 } };

    MutexLocked<Vector<gid_t>> extra_groups { {} };

    Credentials credentials();
    Result<Vector<gid_t>> copy_groups();

    MutexLocked<OwnedPtr<AddressSpace>> address_space;

    MutexLocked<Option<FileDescriptor>[FD_MAX]> fd_table = {};

    Timer real_timer;
    Timer virtual_timer;
    Timer profiling_timer;

    Clock virtual_clock;
    Clock profiling_clock;

    bool is_kernel { false };

    Option<Timer> posix_timers[MAX_POSIX_TIMERS];
    Mutex posix_timer_mutex;

    StaticString<128> cmdline;

    Atomic<u64> user_ticks_self = 0;
    Atomic<u64> kernel_ticks_self = 0;
    Atomic<u64> user_ticks_children = 0;
    Atomic<u64> kernel_ticks_children = 0;

    Result<int> allocate_timerid();
    Result<Timer*> resolve_timerid(int id);

    Result<int> allocate_fd(int min, FileDescriptor& descriptor);
    Result<FileDescriptor*> resolve_fd(int fd);
    Result<SharedPtr<VFS::Inode>> resolve_atfile(int dirfd, const String& path, bool allow_empty_path,
                                                 bool follow_last_symlink,
                                                 SharedPtr<VFS::Inode>* parent_inode = nullptr);

    String current_directory_path = {};
    SharedPtr<VFS::Inode> current_directory = {};

    SharedPtr<VFS::Inode> controlling_terminal;

    int status { 0 };

    void send_signal(int signo);

    bool is_session_leader()
    {
        return id == sid;
    }

    bool alive()
    {
        return thread_count > 0;
    }

    bool dead()
    {
        return thread_count == 0;
    }

    static Process* current();

    [[noreturn]] void exit(int status);
};

struct Thread : public LinkedListNode<Thread>
{
    Process* process;

    pid_t tid;

    Registers regs;

    Atomic<u64> ticks_left;
    Atomic<u64> sleep_ticks_left;

    Atomic<u64> user_ticks_self = 0;
    Atomic<u64> kernel_ticks_self = 0;

    Stack stack;
    Stack kernel_stack;

    struct sigaction signal_handlers[NSIG];
    Bitset<sigset_t> signal_mask { 0 };
    Bitset<sigset_t> pending_signals { 0 };
    bool interrupted { false };

    Atomic<pid_t> child_being_waited_for = -2;

    bool unrestricted_task { false };

    FPData fp_data;

    ThreadState state = ThreadState::Runnable;

    bool is_kernel { false };

    StaticString<128> cmdline;

    PageDirectory* self_directory() const
    {
        PageDirectory* result;
        auto lambda = Function<OwnedPtr<AddressSpace>&>::wrap([&](OwnedPtr<AddressSpace>& space) {
                          result = space->page_directory();
                      }).release_value();
        process->address_space.with_lock(move(lambda));
        return result;
    }

    PageDirectory* active_directory { nullptr };

    void quit();
    void exit(bool yield = true);

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

    void wake_up()
    {
        state = ThreadState::Runnable;
    }

    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() const;

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

    void set_return(u64 ret);
    u64 return_register();

    void process_pending_signals(Registers* current_regs);

    int pending_signal_count();
    int pending_signal();
    bool will_ignore_pending_signal();

    bool deliver_signal(int signo, Registers* current_regs);
    void sigreturn(Registers* current_regs);

    Result<u64> push_mem_on_stack(const u8* mem, usize size);
    Result<u64> pop_mem_from_stack(u8* mem, usize size);

    bool check_stack_on_exception(u64 stack_pointer);

    void stop();
    void resume();

    void send_signal(int signo);

    static void init();
};

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

bool is_in_kernel(Registers* regs);

Result<Thread*> new_thread();

pid_t next_thread_id();

extern LinkedList<Thread> g_threads;
extern LinkedList<Process> g_processes;