#include "fs/devices/MasterPTY.h"
#include "Pledge.h"
#include "fs/devices/DeviceRegistry.h"
#include "fs/devices/PTYMultiplexer.h"
#include "fs/devpts/FileSystem.h"
#include "memory/MemoryManager.h"
#include "thread/Scheduler.h"
#include <luna/CType.h>

Result<SharedPtr<VFS::Inode>> MasterPTY::create_pair(int index)
{
    auto master = TRY(make_shared<MasterPTY>());
    auto slave = TRY(make_shared<SlavePTY>());

    auto name = TRY(String::format("%d"_sv, index));
    for (auto& fs : g_devpts_instances) { fs->root_inode()->add_entry(slave, name.chars()); }
    slave->m_name = move(name);

    master->m_metadata.mode = 0666;
    master->m_index = index;
    master->m_slave = slave;
    master->m_metadata.devid = luna_dev_makedev(DeviceRegistry::Terminal, 0);
    master->m_settings.c_lflag = ECHO | ECHOE | ECHOCTL | ISIG | ICANON;
    master->m_settings.c_cc[VEOF] = '\4';
    master->m_settings.c_cc[VERASE] = '\b';
    master->m_settings.c_cc[VINTR] = '\3';
    master->m_settings.c_cc[VQUIT] = '\x1c';
    master->m_window.ws_col = 80;
    master->m_window.ws_row = 25;

    slave->m_master = master.ptr();
    slave->m_metadata.devid = luna_dev_makedev(DeviceRegistry::Terminal, index + 2);
    slave->m_metadata.uid = Scheduler::current()->auth.euid;
    slave->m_metadata.gid = Scheduler::current()->auth.egid;
    slave->m_metadata.mode = 0620;

    return (SharedPtr<VFS::Inode>)master;
}

Result<void> MasterPTY::handle_background_process_group(bool can_succeed, int signo) const
{
    if (!m_foreground_process_group.has_value()) return {};

    auto foreground_pgrp = m_foreground_process_group.value();

    auto* current = Scheduler::current();
    if (current->pgid == foreground_pgrp) return {};

    if ((current->signal_mask.get(signo - 1)) || (current->signal_handlers[signo - 1].sa_handler == SIG_IGN))
    {
        if (can_succeed) return {};
        return err(EIO);
    }

    current->send_signal(signo);

    if (can_succeed) return err(EINTR);
    return err(EIO);
}

bool MasterPTY::is_canonical()
{
    return m_settings.c_lflag & ICANON;
}

Result<void> MasterPTY::handle_input(u8 key)
{
    bool is_special_character { false };

    if (is_canonical())
    {
        if (key == m_settings.c_cc[VERASE])
        {
            auto maybe_char = m_current_line_buffer.try_pop();
            if (maybe_char.has_value() && maybe_char.value())
            {
                if ((m_settings.c_lflag & ECHO) && (m_settings.c_lflag & ECHOE))
                {
                    u8 backspace = (u8)'\b';
                    m_buffer.append_data(&backspace, 1);
                    if (_iscntrl(maybe_char.value())) m_buffer.append_data(&backspace, 1);
                    if (maybe_char.value() == '\t')
                    {
                        m_buffer.append_data(&backspace, 1);
                        m_buffer.append_data(&backspace, 1);
                    }
                    return {};
                }
                return {};
            }

            if ((m_settings.c_lflag & ECHOE)) return {};
            else
                is_special_character = true;
        }

        if (key == m_settings.c_cc[VEOF])
        {
            const auto size = m_current_line_buffer.size();
            auto buffer = Buffer { m_current_line_buffer.release_data(), size };
            TRY(m_lines.try_append(move(buffer)));

            is_special_character = true;
        }

        if (m_settings.c_lflag & ISIG)
        {
            if (key == m_settings.c_cc[VINTR])
            {
                if (!(m_settings.c_lflag & NOFLSH)) m_current_line_buffer.clear();

                if (m_foreground_process_group.has_value())
                    Scheduler::for_each_in_process_group(*m_foreground_process_group, [](Thread* thread) {
                        thread->send_signal(SIGINT);
                        return true;
                    });

                is_special_character = true;
            }

            if (key == m_settings.c_cc[VQUIT])
            {
                if (!(m_settings.c_lflag & NOFLSH)) m_current_line_buffer.clear();

                if (m_foreground_process_group.has_value())
                    Scheduler::for_each_in_process_group(*m_foreground_process_group, [](Thread* thread) {
                        thread->send_signal(SIGQUIT);
                        return true;
                    });

                is_special_character = true;
            }
        }
    }

    if (!is_special_character)
    {
        if (is_canonical())
        {
            const usize max_line_size = key == '\n' ? 4096 : 4095;
            if (m_current_line_buffer.size() < max_line_size) TRY(m_current_line_buffer.try_append(key));

            if (key == '\n')
            {
                const auto size = m_current_line_buffer.size();
                auto buffer = Buffer { m_current_line_buffer.release_data(), size };
                TRY(m_lines.try_append(move(buffer)));
            }
        }
        else
            TRY(m_slave->m_buffer.append_data(&key, 1));
    }

    if (!(m_settings.c_lflag & ECHO)) return {};

    if (_iscntrl(key))
    {
        if (m_settings.c_lflag & ECHOCTL)
        {
            bool should_echo = true;
            if (key == '\n' || key == '\t' || key == '\0' || key == m_settings.c_cc[VEOF]) should_echo = false;

            if (should_echo)
            {
                u8 caret_notation[2] = {
                    '^',
                    '\0',
                };
                if (key == 0x7f) caret_notation[1] = '?';
                else
                    caret_notation[1] = key + 0x40;

                m_buffer.append_data(caret_notation, 2);
            }
            else
                m_buffer.append_data(&key, 1);
        }
    }
    else
        m_buffer.append_data(&key, 1);

    return {};
}

Result<usize> MasterPTY::read(u8* buf, usize, usize length) const
{
    length = m_buffer.dequeue_data(buf, length);

    return length;
}

Result<usize> MasterPTY::write(const u8* buf, usize, usize length)
{
    for (usize i = 0; i < length; i++) { TRY(handle_input(buf[i])); }

    return length;
}

Result<u64> MasterPTY::ioctl(int request, void* arg)
{
    auto* current = Scheduler::current();
    TRY(check_pledge(current, Promise::p_tty));

    switch (request)
    {
    case TIOCGPTN: {
        if (!MemoryManager::copy_to_user_typed((int*)arg, &m_index)) return err(EFAULT);
        return 0;
    }
    default: return err(EINVAL);
    }
}

MasterPTY::~MasterPTY()
{
    m_slave->m_master = nullptr;
    for (auto& fs : g_devpts_instances) { fs->root_inode()->remove_entry(m_slave->m_name.chars()); }
    PTYMultiplexer::did_remove_pty(m_index);

    if (m_session.has_value())
    {
        auto leader = Scheduler::find_by_pid(*m_session);
        if (leader.has_value()) leader.value()->send_signal(SIGHUP);
    }
}