#pragma once

#include <AK/Types.h>
#include <AK/InlineLinkedList.h>
#include <AK/AKString.h>
#include <AK/Vector.h>
#include <AK/WeakPtr.h>
#include <AK/Weakable.h>
#include <Kernel/FileSystem/VirtualFileSystem.h>
#include <Kernel/VM/RangeAllocator.h>
#include <Kernel/TTY/TTY.h>
#include <Kernel/Syscall.h>
#include <Kernel/UnixTypes.h>
#include <Kernel/Thread.h>
#include <Kernel/Lock.h>
#include <LibC/signal_numbers.h>

class ELFLoader;
class FileDescriptor;
class PageDirectory;
class Region;
class VMObject;
class ProcessTracer;

void kgettimeofday(timeval&);

class Process : public InlineLinkedListNode<Process>, public Weakable<Process> {
    friend class InlineLinkedListNode<Process>;
    friend class Thread;
public:
    static Process* create_kernel_process(String&& name, void (*entry)());
    static Process* create_user_process(const String& path, uid_t, gid_t, pid_t ppid, int& error, Vector<String>&& arguments = Vector<String>(), Vector<String>&& environment = Vector<String>(), TTY* = nullptr);
    ~Process();

    static Vector<pid_t> all_pids();
    static Vector<Process*> all_processes();

    enum Priority {
        IdlePriority,
        LowPriority,
        NormalPriority,
        HighPriority,
    };

    enum RingLevel {
        Ring0 = 0,
        Ring3 = 3,
    };

    bool is_dead() const { return m_dead; }

    Thread::State state() const { return main_thread().state(); }

    Thread& main_thread() { return *m_main_thread; }
    const Thread& main_thread() const { return *m_main_thread; }

    bool is_ring0() const { return m_ring == Ring0; }
    bool is_ring3() const { return m_ring == Ring3; }

    PageDirectory& page_directory() { return *m_page_directory; }
    const PageDirectory& page_directory() const { return *m_page_directory; }

    static Process* from_pid(pid_t);

    void set_priority(Priority p) { m_priority = p; }
    Priority priority() const { return m_priority; }

    const String& name() const { return m_name; }
    pid_t pid() const { return m_pid; }
    pid_t sid() const { return m_sid; }
    pid_t pgid() const { return m_pgid; }
    uid_t uid() const { return m_uid; }
    gid_t gid() const { return m_gid; }
    const HashTable<gid_t>& gids() const { return m_gids; }
    uid_t euid() const { return m_euid; }
    gid_t egid() const { return m_egid; }
    pid_t ppid() const { return m_ppid; }

    mode_t umask() const { return m_umask; }

    bool in_group(gid_t) const;

    FileDescriptor* file_descriptor(int fd);
    const FileDescriptor* file_descriptor(int fd) const;

    template<typename Callback> static void for_each(Callback);
    template<typename Callback> static void for_each_in_pgrp(pid_t, Callback);
    template<typename Callback> void for_each_child(Callback);
    template<typename Callback> void for_each_thread(Callback) const;

    void die();
    void finalize();

    int sys$gettid();
    int sys$donate(int tid);
    int sys$shm_open(const char* name, int flags, mode_t);
    int sys$shm_unlink(const char* name);
    int sys$ftruncate(int fd, off_t);
    pid_t sys$setsid();
    pid_t sys$getsid(pid_t);
    int sys$setpgid(pid_t pid, pid_t pgid);
    pid_t sys$getpgrp();
    pid_t sys$getpgid(pid_t);
    uid_t sys$getuid();
    gid_t sys$getgid();
    uid_t sys$geteuid();
    gid_t sys$getegid();
    pid_t sys$getpid();
    pid_t sys$getppid();
    mode_t sys$umask(mode_t);
    int sys$open(const char* path, int options, mode_t mode = 0);
    int sys$close(int fd);
    ssize_t sys$read(int fd, byte*, ssize_t);
    ssize_t sys$write(int fd, const byte*, ssize_t);
    ssize_t sys$writev(int fd, const struct iovec* iov, int iov_count);
    int sys$fstat(int fd, stat*);
    int sys$lstat(const char*, stat*);
    int sys$stat(const char*, stat*);
    int sys$lseek(int fd, off_t, int whence);
    int sys$kill(pid_t pid, int sig);
    [[noreturn]] void sys$exit(int status);
    [[noreturn]] void sys$sigreturn();
    pid_t sys$waitpid(pid_t, int* wstatus, int options);
    void* sys$mmap(const Syscall::SC_mmap_params*);
    int sys$munmap(void*, size_t size);
    int sys$set_mmap_name(void*, size_t, const char*);
    int sys$select(const Syscall::SC_select_params*);
    int sys$poll(pollfd*, int nfds, int timeout);
    ssize_t sys$get_dir_entries(int fd, void*, ssize_t);
    int sys$getcwd(char*, ssize_t);
    int sys$chdir(const char*);
    int sys$sleep(unsigned seconds);
    int sys$usleep(useconds_t usec);
    int sys$gettimeofday(timeval*);
    int sys$gethostname(char*, ssize_t);
    int sys$uname(utsname*);
    int sys$readlink(const char*, char*, ssize_t);
    int sys$ttyname_r(int fd, char*, ssize_t);
    int sys$ptsname_r(int fd, char*, ssize_t);
    pid_t sys$fork(RegisterDump&);
    int sys$execve(const char* filename, const char** argv, const char** envp);
    int sys$isatty(int fd);
    int sys$getdtablesize();
    int sys$dup(int oldfd);
    int sys$dup2(int oldfd, int newfd);
    int sys$sigaction(int signum, const sigaction* act, sigaction* old_act);
    int sys$sigprocmask(int how, const sigset_t* set, sigset_t* old_set);
    int sys$sigpending(sigset_t*);
    int sys$getgroups(ssize_t, gid_t*);
    int sys$setgroups(ssize_t, const gid_t*);
    int sys$pipe(int* pipefd);
    int sys$killpg(int pgrp, int sig);
    int sys$setgid(gid_t);
    int sys$setuid(uid_t);
    unsigned sys$alarm(unsigned seconds);
    int sys$access(const char* pathname, int mode);
    int sys$fcntl(int fd, int cmd, dword extra_arg);
    int sys$ioctl(int fd, unsigned request, unsigned arg);
    int sys$mkdir(const char* pathname, mode_t mode);
    clock_t sys$times(tms*);
    int sys$utime(const char* pathname, const struct utimbuf*);
    int sys$link(const char* old_path, const char* new_path);
    int sys$unlink(const char* pathname);
    int sys$symlink(const char* target, const char* linkpath);
    int sys$rmdir(const char* pathname);
    int sys$read_tsc(dword* lsw, dword* msw);
    int sys$chmod(const char* pathname, mode_t);
    int sys$fchmod(int fd, mode_t);
    int sys$chown(const char* pathname, uid_t, gid_t);
    int sys$socket(int domain, int type, int protocol);
    int sys$bind(int sockfd, const sockaddr* addr, socklen_t);
    int sys$listen(int sockfd, int backlog);
    int sys$accept(int sockfd, sockaddr*, socklen_t*);
    int sys$connect(int sockfd, const sockaddr*, socklen_t);
    ssize_t sys$sendto(const Syscall::SC_sendto_params*);
    ssize_t sys$recvfrom(const Syscall::SC_recvfrom_params*);
    int sys$getsockopt(const Syscall::SC_getsockopt_params*);
    int sys$setsockopt(const Syscall::SC_setsockopt_params*);
    int sys$getsockname(int sockfd, sockaddr* addr, socklen_t* addrlen);
    int sys$getpeername(int sockfd, sockaddr* addr, socklen_t* addrlen);
    int sys$restore_signal_mask(dword mask);
    int sys$create_thread(int(*)(void*), void*);
    void sys$exit_thread(int code);
    int sys$rename(const char* oldpath, const char* newpath);
    int sys$systrace(pid_t);
    int sys$mknod(const char* pathname, mode_t, dev_t);
    int sys$create_shared_buffer(pid_t peer_pid, int, void** buffer);
    void* sys$get_shared_buffer(int shared_buffer_id);
    int sys$release_shared_buffer(int shared_buffer_id);
    int sys$seal_shared_buffer(int shared_buffer_id);
    int sys$get_shared_buffer_size(int shared_buffer_id);

    static void initialize();

    [[noreturn]] void crash(int signal = SIGSEGV);
    [[nodiscard]] static int reap(Process&);

    const TTY* tty() const { return m_tty; }
    void set_tty(TTY* tty) { m_tty = tty; }

    size_t region_count() const { return m_regions.size(); }
    const Vector<Retained<Region>>& regions() const { return m_regions; }
    void dump_regions();

    ProcessTracer* tracer() { return m_tracer.ptr(); }
    ProcessTracer& ensure_tracer();

    dword m_ticks_in_user { 0 };
    dword m_ticks_in_kernel { 0 };

    dword m_ticks_in_user_for_dead_children { 0 };
    dword m_ticks_in_kernel_for_dead_children { 0 };

    bool validate_read_from_kernel(LinearAddress) const;

    bool validate_read(const void*, ssize_t) const;
    bool validate_write(void*, ssize_t) const;
    bool validate_read_str(const char* str);
    template<typename T> bool validate_read_typed(T* value, size_t count = 1) { return validate_read(value, sizeof(T) * count); }
    template<typename T> bool validate_write_typed(T* value, size_t count = 1) { return validate_write(value, sizeof(T) * count); }

    Inode& cwd_inode();
    Inode* executable_inode() { return m_executable.ptr(); }

    int number_of_open_file_descriptors() const;
    int max_open_file_descriptors() const { return m_max_open_file_descriptors; }

    size_t amount_virtual() const;
    size_t amount_resident() const;
    size_t amount_shared() const;

    Process* fork(RegisterDump&);
    int exec(String path, Vector<String> arguments, Vector<String> environment);

    bool is_superuser() const { return m_euid == 0; }

    Region* allocate_region_with_vmo(LinearAddress, size_t, Retained<VMObject>&&, size_t offset_in_vmo, String&& name, bool is_readable, bool is_writable);
    Region* allocate_file_backed_region(LinearAddress, size_t, RetainPtr<Inode>&&, String&& name, bool is_readable, bool is_writable);
    Region* allocate_region(LinearAddress, size_t, String&& name, bool is_readable = true, bool is_writable = true, bool commit = true);
    bool deallocate_region(Region& region);

    void set_being_inspected(bool b) { m_being_inspected = b; }
    bool is_being_inspected() const { return m_being_inspected; }

    void terminate_due_to_signal(byte signal);
    void send_signal(byte, Process* sender);

    int thread_count() const;

    Lock& big_lock() { return m_big_lock; }

    unsigned syscall_count() const { return m_syscall_count; }
    void did_syscall() { ++m_syscall_count; }

    const ELFLoader* elf_loader() const { return m_elf_loader.ptr(); }

private:
    friend class MemoryManager;
    friend class Scheduler;
    friend class Region;

    Process(String&& name, uid_t, gid_t, pid_t ppid, RingLevel, RetainPtr<Inode>&& cwd = nullptr, RetainPtr<Inode>&& executable = nullptr, TTY* = nullptr, Process* fork_parent = nullptr);

    Range allocate_range(LinearAddress, size_t);

    int do_exec(String path, Vector<String> arguments, Vector<String> environment);
    ssize_t do_write(FileDescriptor&, const byte*, int data_size);

    int alloc_fd(int first_candidate_fd = 0);
    void disown_all_shared_buffers();

    void create_signal_trampolines_if_needed();

    Thread* m_main_thread { nullptr };

    RetainPtr<PageDirectory> m_page_directory;

    Process* m_prev { nullptr };
    Process* m_next { nullptr };

    String m_name;

    pid_t m_pid { 0 };
    uid_t m_uid { 0 };
    gid_t m_gid { 0 };
    uid_t m_euid { 0 };
    gid_t m_egid { 0 };
    pid_t m_sid { 0 };
    pid_t m_pgid { 0 };

    Priority m_priority { NormalPriority };

    struct FileDescriptorAndFlags {
        operator bool() const { return !!descriptor; }
        void clear();
        void set(Retained<FileDescriptor>&& d, dword f = 0);
        RetainPtr<FileDescriptor> descriptor;
        dword flags { 0 };
    };
    Vector<FileDescriptorAndFlags> m_fds;
    RingLevel m_ring { Ring0 };

    int m_max_open_file_descriptors { 128 };

    byte m_termination_status { 0 };
    byte m_termination_signal { 0 };

    RetainPtr<Inode> m_cwd;
    RetainPtr<Inode> m_executable;

    TTY* m_tty { nullptr };

    Region* region_from_range(LinearAddress, size_t);

    Vector<Retained<Region>> m_regions;

    LinearAddress m_return_to_ring3_from_signal_trampoline;
    LinearAddress m_return_to_ring0_from_signal_trampoline;

    pid_t m_ppid { 0 };
    mode_t m_umask { 022 };

    static void notify_waiters(pid_t waitee, int exit_status, int signal);

    HashTable<gid_t> m_gids;

    bool m_being_inspected { false };
    bool m_dead { false };

    int m_next_tid { 0 };

    unsigned m_syscall_count { 0 };

    RetainPtr<ProcessTracer> m_tracer;
    OwnPtr<ELFLoader> m_elf_loader;

    Lock m_big_lock { "Process" };
};

class ProcessInspectionHandle {
public:
    ProcessInspectionHandle(Process& process)
        : m_process(process)
    {
        if (&process != &current->process()) {
            ASSERT(!m_process.is_being_inspected());
            m_process.set_being_inspected(true);
        }
    }
    ~ProcessInspectionHandle()
    {
        m_process.set_being_inspected(false);
    }

    Process& process() { return m_process; }

    static OwnPtr<ProcessInspectionHandle> from_pid(pid_t pid)
    {
        InterruptDisabler disabler;
        auto* process = Process::from_pid(pid);
        if (process)
            return make<ProcessInspectionHandle>(*process);
        return nullptr;
    }

    Process* operator->() { return &m_process; }
    Process& operator*() { return m_process; }
private:
    Process& m_process;
};

extern const char* to_string(Process::Priority);

extern InlineLinkedList<Process>* g_processes;

template<typename Callback>
inline void Process::for_each(Callback callback)
{
    ASSERT_INTERRUPTS_DISABLED();
    for (auto* process = g_processes->head(); process;) {
        auto* next_process = process->next();
        if (!callback(*process))
            break;
        process = next_process;
    }
}

template<typename Callback>
inline void Process::for_each_child(Callback callback)
{
    ASSERT_INTERRUPTS_DISABLED();
    pid_t my_pid = pid();
    for (auto* process = g_processes->head(); process;) {
        auto* next_process = process->next();
        if (process->ppid() == my_pid) {
            if (!callback(*process))
                break;
        }
        process = next_process;
    }
}

template<typename Callback>
inline void Process::for_each_thread(Callback callback) const
{
    InterruptDisabler disabler;
    pid_t my_pid = pid();
    for (auto* thread = g_runnable_threads->head(); thread;) {
        auto* next_thread = thread->next();
        if (thread->pid() == my_pid) {
            if (callback(*thread) == IterationDecision::Abort)
                break;
        }
        thread = next_thread;
    }
    for (auto* thread = g_nonrunnable_threads->head(); thread;) {
        auto* next_thread = thread->next();
        if (thread->pid() == my_pid) {
            if (callback(*thread) == IterationDecision::Abort)
                break;
        }
        thread = next_thread;
    }
}

template<typename Callback>
inline void Process::for_each_in_pgrp(pid_t pgid, Callback callback)
{
    ASSERT_INTERRUPTS_DISABLED();
    for (auto* process = g_processes->head(); process;) {
        auto* next_process = process->next();
        if (process->pgid() == pgid) {
            if (!callback(*process))
                break;
        }
        process = next_process;
    }
}

inline bool InodeMetadata::may_read(Process& process) const
{
    return may_read(process.euid(), process.gids());
}

inline bool InodeMetadata::may_write(Process& process) const
{
    return may_write(process.euid(), process.gids());
}

inline bool InodeMetadata::may_execute(Process& process) const
{
    return may_execute(process.euid(), process.gids());
}

inline int Thread::pid() const
{
    return m_process.pid();
}