elna/shell/interactive.cpp

#include "elna/interactive.hpp"

#include <boost/algorithm/string/predicate.hpp>
#include <boost/process.hpp>
#include <termios.h>
#include <filesystem>

namespace elna
{
    static termios original_termios;

    interactive_exception::interactive_exception()
        : runtime_error("read")
    {
    }

    template<typename T>
    static std::pair<T, unsigned char> read_number()
    {
        T position{ 0 };
        unsigned char c{ 0 };

        while (read(STDIN_FILENO, &c, 1) == 1 && std::isdigit(c))
        {
            position = position * 10 + (c - '0');
        }
        return std::make_pair(position, c);
    }

    void loop()
    {
        editor_history history;
        do
        {
            auto line = read_line(history);

            if (!line.has_value())
            {
                write(STDOUT_FILENO, "\r\n", 2);
                break;
            }
            history.push(line.value().command_line());

            if (!execute(line.value().command_line()))
            {
                break;
            }
        }
        while (true);
    }

    std::optional<editor_state> read_line(editor_history& history)
    {
        editor_state state;
        std::string buffer;
        std::string saved;

        state.draw(std::back_inserter(buffer));
        write(STDOUT_FILENO, buffer.data(), buffer.size());

        while (true)
        {
            buffer.clear();
            auto pressed_key = read_key();

            if (pressed_key.empty())
            {
                continue;
            }
            switch (state.process_keypress(pressed_key))
            {
                case action::finalize:
                    if (pressed_key == key('d', modifier::ctrl))
                    {
                        return std::optional<editor_state>();
                    }
                    else if (pressed_key == '\r')
                    {
                        write(STDOUT_FILENO, "\r\n", 2);
                        return std::make_optional(state);
                    }
                    break;
                case action::complete:
                    write(STDOUT_FILENO, "\x1b[1E\x1b[2K", 8);
                    state.insert(complete(state.command_line(), state.relative_position()));
                    write(STDOUT_FILENO, "\x1b[1A", 4);
                    state.draw(std::back_inserter(buffer));
                    write(STDOUT_FILENO, buffer.data(), buffer.size());
                    break;
                case action::redraw:
                    state.draw(std::back_inserter(buffer));
                    write(STDOUT_FILENO, buffer.data(), buffer.size());
                    break;
                case action::write:
                    write(STDOUT_FILENO, &pressed_key, 1);
                    break;
                case action::move:
                    buffer = cursor_to_column(state.absolute_position());
                    write(STDOUT_FILENO, buffer.data(), buffer.size());
                    break;
                case action::ignore:
                    break;
                case action::history:
                    editor_history::const_iterator history_iterator = history.cend();

                    if (pressed_key == key(special_key::arrow_up, modifier::ctrl))
                    {
                        if (history.current() == history.cend())
                        {
                            saved = state.command_line();
                        }
                        history_iterator = history.prev();
                    }
                    else if (pressed_key == key(special_key::arrow_down, modifier::ctrl))
                    {
                        history_iterator = history.next();
                        if (history_iterator == history.cend())
                        {
                            state.load(saved);
                        }
                    }
                    if (history_iterator != history.cend())
                    {
                        state.load(*history_iterator);
                    }
                    state.draw(std::back_inserter(buffer));
                    write(STDOUT_FILENO, buffer.data(), buffer.size());
                    break;
            }
        }
    }

    key read_key()
    {
        char c{ 0 };

        if (read(STDIN_FILENO, &c, 1) == -1 && errno != EAGAIN)
        {
            throw interactive_exception();
        }
        if (c != '\x1b')
        {
            return key(c);
        }
        if (read(STDIN_FILENO, &c, 1) != 1 || c != '[')
        {
            return key();
        }
        auto [number, last_char] = read_number<key::char_t>();
        std::uint8_t modifiers{ 0 };

        if (last_char == ';')
        {
            auto modifier_response = read_number<std::uint8_t>();
            modifiers = modifier_response.first;
            last_char = modifier_response.second;
        }
        if (number == 0 || number == 1)
        {
            switch (last_char)
            {
                case 'A':
                    return key(special_key::arrow_up, modifiers);
                case 'B':
                    return key(special_key::arrow_down, modifiers);
                case 'C':
                    return key(special_key::arrow_right, modifiers);
                case 'D':
                    return key(special_key::arrow_left, modifiers);
                case 'H':
                    return key(special_key::home_key, modifiers);
                case 'F':
                    return key(special_key::end_key, modifiers);
            }
        }
        else if (last_char == '~')
        {
            switch (number)
            {
                case 5:
                    return key(special_key::page_up, modifiers);
                case 6:
                    return key(special_key::page_up, modifiers);
                case 7:
                    return key(special_key::home_key, modifiers);
                case 8:
                    return key(special_key::end_key, modifiers);
            }
        }
        else if (last_char == 'u')
        {
            return key(number, modifiers);
        }
        return key();
    }

    void print_exception(const std::exception& exception)
    {
        std::string message{ exception.what()  };
        message += "\r\n";
        write(STDERR_FILENO, message.data(), message.size());
    }

    bool execute(const std::string& line)
    {
        if (line.empty())
        {
            return true;
        }
        if (line == "exit")
        {
            return false;
        }
        else if (boost::starts_with(line, "cd "))
        {
            try
            {
                std::filesystem::current_path(line.substr(strlen("cd ")));
            }
            catch (const std::filesystem::filesystem_error& exception)
            {
                print_exception(exception);
            }

            return true;
        }
        launch(line);
        return true;
    }

    void launch(const std::string& program)
    {
        try
        {
            boost::process::system(program);
        }
        catch (const boost::process::process_error& exception)
        {
            print_exception(exception);
        }
        enable_raw_mode();
    }

    bool enable_raw_mode()
    {
        if (tcgetattr(STDIN_FILENO, &original_termios) == -1)
        {
            return false;
        }
        termios raw = original_termios;

        raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
        raw.c_oflag &= ~(OPOST);
        raw.c_cflag |= CS8;
        raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);

        write(STDOUT_FILENO, start_kitty_keybaord, strlen(start_kitty_keybaord));

        return tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) != -1;
    }

    void disable_raw_mode()
    {
        write(STDOUT_FILENO, end_kitty_keybaord, strlen(end_kitty_keybaord));
        tcsetattr(STDIN_FILENO, TCSAFLUSH, &original_termios);
    }

    std::string complete(const std::string& input, const std::size_t position)
    {
        std::filesystem::path program = boost::process::search_path("fzf");

        if (program.empty())
        {
            return "";
        }
        boost::process::ipstream output;
        boost::process::system(program,
                "--height=10", "--layout=reverse", "-1", "--no-multi",
                boost::process::std_out > output);

        std::string selections;
        std::getline(output, selections, '\n');

        return selections;
    }
}