yttui/tui.cpp

// SPDX-License-Identifier: MIT
#include "tui.h"

#include <algorithm>
#include <deque>
#include <string>
#include <vector>

#include <stdarg.h>

termpaint_integration *integration;
termpaint_terminal *terminal;
termpaint_surface *surface;

AttributeSet attributes[ASetTypeCount];
std::unordered_map<std::string, std::string> key_symbols;

struct button_info {
    Button button;
    std::string string;
    size_t width;
};

std::vector<button_info> all_buttons;

std::deque<Event> eventqueue;

static void convert_tp_event(void *, termpaint_event *tp_event) {
    Event e;
    if (tp_event->type == TERMPAINT_EV_CHAR) {
        e.type = tp_event->type;
        e.modifier = tp_event->c.modifier;
        e.string = std::string(tp_event->c.string, tp_event->c.length);
        eventqueue.push_back(e);
    } else if (tp_event->type == TERMPAINT_EV_KEY) {
        e.type = tp_event->type;
        e.modifier = tp_event->key.modifier;
        e.string = std::string(tp_event->key.atom, tp_event->key.length);
        eventqueue.push_back(e);
    }
}

std::optional<Event> wait_for_event(termpaint_integration *integration, int timeout) {
    const int cols = termpaint_surface_width(surface);
    const int rows = termpaint_surface_height(surface);
    while (eventqueue.empty()) {
        bool ok = false;
        if(timeout > 0)
            ok = termpaintx_full_integration_do_iteration_with_timeout(integration, &timeout);
        else
            ok = termpaintx_full_integration_do_iteration(integration);
        if (!ok) {
            return {}; // or some other error handling
        } else if(cols != termpaint_surface_width(surface) || rows != termpaint_surface_height(surface)) {
            Event e;
            e.modifier = 0;
            e.type = EV_RESIZE;
            eventqueue.push_back(e);
        } else if(timeout == 0) {
            Event e;
            e.modifier = 0;
            e.type = EV_TIMEOUT;
            eventqueue.push_back(e);
        }
    }
    Event e = eventqueue.front();
    eventqueue.pop_front();
    return e;
}

static void tp_init_internal()
{
    all_buttons = {
        {Button::Ok, "Ok", 2},
        {Button::Cancel, "Cancel", 6},
        {Button::Yes, "Yes", 3},
        {Button::No, "No", 2},
    };
    key_symbols = {
        {"ArrowLeft", "←"},
        {"ArrowUp", "↑"},
        {"ArrowRight", "→"},
        {"ArrowDown", "↓"},
        {"Escape", "Esc"},
    };

    auto new_attr_set = [](AttributeSet &set, int color, int style = 0) {
        set.normal = termpaint_attr_new(color, TERMPAINT_DEFAULT_COLOR);
        termpaint_attr_set_style(set.normal, style);
        set.highlight = termpaint_attr_clone(set.normal);
        termpaint_attr_set_style(set.highlight, TERMPAINT_STYLE_INVERSE | style);
    };

    new_attr_set(attributes[ASNormal], TERMPAINT_DEFAULT_COLOR);
    new_attr_set(attributes[ASWatched], TERMPAINT_DEFAULT_COLOR);
    new_attr_set(attributes[ASUnwatched], TERMPAINT_DEFAULT_COLOR, TERMPAINT_STYLE_BOLD);

    surface = termpaint_terminal_get_surface(terminal);
    termpaint_terminal_set_cursor_visible(terminal, false);
}

static const char* terminal_options = "+kbdsig +kbdsigint +kbdsigtstp";

void tp_init()
{
    integration = termpaintx_full_integration_setup_terminal_fullscreen( "+kbdsig +kbdsigint +kbdsigtstp", convert_tp_event, nullptr, &terminal);
    tp_init_internal();
}

void tp_init_from_fd(int fd)
{
    integration = termpaintx_full_integration_from_fd(fd, false, terminal_options);
    if (!integration) {
        //std::string error = "Error: Terminal not available!";
        //(void)!write(fd, error.c_str(), error.size()); // already printing an error message
        return;
    }

    terminal = termpaint_terminal_new(integration);
    termpaintx_full_integration_set_terminal(integration, terminal);
    termpaint_terminal_set_event_cb(terminal, convert_tp_event, nullptr);
    termpaint_terminal_auto_detect(terminal);
    termpaintx_full_integration_wait_for_ready_with_message(integration, 10000,
                                           "Terminal auto detection is taking unusually long, press space to abort.");
    termpaintx_full_integration_apply_input_quirks(integration);
    int width, height;
    termpaintx_full_integration_terminal_size(integration, &width, &height);
    termpaint_terminal_setup_fullscreen(terminal, width, height, terminal_options);
    termpaintx_full_integration_ttyrescue_start(integration);

    tp_init_internal();
}

void tp_shutdown()
{
    auto free_attr_set = [](AttributeSet &set) {
        termpaint_attr_free(set.normal);
        termpaint_attr_free(set.highlight);
    };

    free_attr_set(attributes[ASNormal]);
    free_attr_set(attributes[ASWatched]);
    free_attr_set(attributes[ASUnwatched]);

    termpaint_terminal_free_with_restore(terminal);
}

void tp_flush(const bool force)
{
    termpaint_terminal_flush(terminal, force);
}

std::optional<Event> tp_wait_for_event(int timeout)
{
    return wait_for_event(integration, timeout);
}

static std::string repeated(const int n, const std::string &what)
{
    std::string out;
    for(int i=0; i<n; i++)
        out.append(what);
    return out;
}

size_t string_width(const std::string &str)
{
    termpaint_text_measurement *m = termpaint_text_measurement_new(surface);
    termpaint_text_measurement_feed_utf8(m, str.c_str(), str.length(), true);
    const int width = termpaint_text_measurement_last_width(m);
    termpaint_text_measurement_free(m);
    return width;
}

static void resolve_align(const Align align, const int width, const int height, const int xmin, const int xmax, const int ymin, const int ymax, int &x, int &y)
{
    int available_width = xmax-xmin;
    x = xmin;
    if(((int)align & 0x0f) == (int)Align::HCenter)
        x = (available_width - width) / 2;
    else if(((int)align & 0x0f) == (int)Align::Right)
        x = xmax - width;

    int available_rows = ymax - ymin;
    y = ymin;
    if(((int)align & 0xf0) == (int)Align::VCenter)
        y = (available_rows - height) / 2;
    else if(((int)align & 0xf0) == (int)Align::Bottom)
        y = ymax - height;
}

class surface_backup
{
    int x, y;
    int w, h;
    termpaint_surface *backup;
public:
    surface_backup(int x, int y, int w, int h): x(x), y(y), w(w), h(h), backup(termpaint_surface_new_surface(surface, w, h))
    {
        termpaint_surface_copy_rect(surface, x, y, w, h, backup, 0, 0, TERMPAINT_COPY_NO_TILE, TERMPAINT_COPY_NO_TILE);
    }
    ~surface_backup()
    {
        termpaint_surface_copy_rect(backup, 0, 0, w, h, surface, x, y, TERMPAINT_COPY_NO_TILE, TERMPAINT_COPY_NO_TILE);
        termpaint_surface_free(backup);
    }

};

void draw_box_with_caption(int x, int y, int w, int h, const std::string &caption)
{
    termpaint_surface_clear_rect(surface, x, y, w, h, TERMPAINT_DEFAULT_COLOR, TERMPAINT_DEFAULT_COLOR);
    const int fill = w - 2;
    const int endy = y+h;

    for(int yy = y; yy<endy; yy++)
    {
        std::string s;
        if(yy == y) {
            s = "┌" + repeated(fill, "─") + "┐";
        } else if(yy + 1 == endy) {
            s = "└" + repeated(fill, "─") + "┘";
        } else {
            s = "│" + repeated(fill, " ") + "│";
        }
        termpaint_surface_write_with_attr(surface, x, yy, s.c_str(), attributes[ASNormal].normal);
    }
    if(!caption.empty())
        termpaint_surface_write_with_attr(surface, x+2, y, caption.c_str(), attributes[ASNormal].normal);
}

int get_selection(const std::string &caption, const std::vector<std::string> &entries, size_t selected, const Align align)
{
    selected = std::max(size_t(0), std::min(entries.size(), selected));

    size_t cols_needed = string_width(caption);
    for(const auto &e: entries)
        cols_needed = std::max(cols_needed, string_width(e));

    cols_needed += 4; // Border and left/right padding

    const int rows_needed = entries.size()+2; // Number of entries and top/bottom border

    bool done = false;
    bool force_repaint = false;
    std::vector<action> actions = {
        {TERMPAINT_EV_KEY, "ArrowUp", 0, [&](){ if(selected > 0) selected--; }, "Previous option"},
        {TERMPAINT_EV_KEY, "ArrowDown", 0, [&](){ if(selected < entries.size() - 1) selected++; }, "Next option"},
        {TERMPAINT_EV_KEY, "Escape", 0, [&](){ selected = -1; done = true; }, "Abort selection"},
        {TERMPAINT_EV_KEY, "Enter", 0, [&](){ done = true; }, "Confirm selection"},
        {EV_IGNORE, "1..9", 0, nullptr, "Select option 1..9"},
        {TERMPAINT_EV_CHAR, "l", TERMPAINT_MOD_CTRL, [&](){ force_repaint = true; }, "Force redraw"},
    };

    while (!done) {
        const int cols = termpaint_surface_width(surface);
        const int rows = termpaint_surface_height(surface);

        int x, y;
        resolve_align(align, cols_needed, rows_needed, 0, cols, 0, rows, x, y);
        surface_backup backup(x, y, cols_needed, rows_needed);

        draw_box_with_caption(x, y, cols_needed, rows_needed, caption);
        int yy = y+1;

        size_t cur_entry = 0;
        for(const auto &e: entries) {
            termpaint_attr *attr = cur_entry == selected ? attributes[ASNormal].highlight : attributes[ASNormal].normal;
            termpaint_surface_write_with_attr(surface, x+2, yy++, e.c_str(), attr);
            cur_entry++;
        }
        termpaint_terminal_flush(terminal, force_repaint);
        force_repaint = false;

        auto event = wait_for_event(integration, 0);
        if(!event)
            abort();

        if(!tui_handle_action(*event, actions)) {
            if(event->type == TERMPAINT_EV_CHAR && event->string.length() == 1) {
                char c = event->string[0];
                if(c>'0' && c<='9') {
                    size_t idx = c - '0';
                    if(idx > entries.size())
                        continue;
                    selected = idx - 1;
                    done = true;
                }
            }
        }
    }

    return selected;
}

Align operator|(const Align &a, const Align &b)
{
    return Align((int)a | (int)b);
}

Button operator|(const Button &a, const Button &b)
{
    return Button((int)a | (int)b);
}

Button operator&(const Button &a, const Button &b)
{
    return Button((int)a & (int)b);
}

std::string get_string(const std::string &caption, const std::string &text, const Align align)
{
    const int cols = termpaint_surface_width(surface);
    const int rows = termpaint_surface_height(surface);

    const size_t rows_needed = 3 + !text.empty();
    const size_t cols_needed = cols/2;

    int x, y;
    resolve_align(align, cols_needed, rows_needed, 0, cols, 0, rows, x, y);
    surface_backup backup(x, y, cols_needed, rows_needed);

    const int input_row = y + 1 + !text.empty();

    std::string input;
    size_t input_pos = 0;
    termpaint_terminal_set_cursor_visible(terminal, true);
    termpaint_terminal_set_cursor_style(terminal, TERMPAINT_CURSOR_STYLE_BAR, true);

    bool done = false;
    bool force_repaint = false;
    std::vector<action> actions = {
        {TERMPAINT_EV_KEY, "Home", 0, [&](){ input_pos = 0; }, "Go to beginning of input"},
        {TERMPAINT_EV_CHAR, "a", TERMPAINT_MOD_CTRL, [&](){ input_pos = 0; }, "Go to beginning of input"},
        {TERMPAINT_EV_KEY, "End", 0, [&](){ input_pos = input.size(); }, "Go to end of input"},
        {TERMPAINT_EV_CHAR, "e", TERMPAINT_MOD_CTRL, [&](){ input_pos = input.size(); }, "Go to end of input"},
        {TERMPAINT_EV_KEY, "ArrowLeft", 0, [&](){ if(input_pos > 0) input_pos--; }, "Move left"},
        {TERMPAINT_EV_KEY, "ArrowRight", 0, [&](){ if(input_pos < input.size()) input_pos++; }, "Move right"},

        // FIXME: Correctly handle deletion of clusters with more than one codepoint e.g. ° or ä
        {TERMPAINT_EV_KEY, "Delete", 0, [&](){ if(input_pos < input.size()) { input.erase(input_pos, 1); } }, "Delete input forward"},
        {TERMPAINT_EV_KEY, "Backspace", 0, [&](){ if(input_pos > 0) { input.erase(input_pos - 1, 1); input_pos--; }}, "Delete input backward"},

        {TERMPAINT_EV_KEY, "Escape", 0, [&](){ input.clear(); done = true; }, "Abort input"},
        {TERMPAINT_EV_KEY, "Enter", 0, [&](){ done = true; }, "Confirm input"},
        {TERMPAINT_EV_CHAR, "l", TERMPAINT_MOD_CTRL, [&](){ force_repaint = true; }, "Force redraw"},
    };

    while(!done) {
        draw_box_with_caption(x, y, cols_needed, rows_needed, caption);
        if(!text.empty())
            termpaint_surface_write_with_attr(surface, x + 1, y + 1, text.c_str(), attributes[ASNormal].normal);
        termpaint_surface_write_with_attr(surface, x + 1, input_row, input.c_str(), attributes[ASNormal].normal);
        termpaint_terminal_set_cursor_position(terminal, x + 1 + input_pos, input_row);

        termpaint_terminal_flush(terminal, force_repaint);
        force_repaint = false;

        auto event = wait_for_event(integration, 0);
        if(!event)
            abort();

        if(!tui_handle_action(*event, actions) && event->type != EV_TIMEOUT)
        {
            if(input_pos + 1 == cols_needed - 1)
                continue;
            if(event->type == TERMPAINT_EV_KEY) {
                if(event->string == "Space")
                    event->string = " ";
                else
                    continue;
            }
            input.insert(input_pos, event->string);
            input_pos++;
        }
    }

    termpaint_terminal_set_cursor_visible(terminal, false);
    termpaint_terminal_set_cursor_style(terminal, TERMPAINT_CURSOR_STYLE_TERM_DEFAULT, false);
    return input;
}

std::vector<std::string> split(const std::string &str, const char delim, const unsigned int max_splits=0)
{
    std::vector<std::string> parts;

    std::string::const_iterator prev = str.cbegin();
    std::string::const_iterator cur = str.cbegin();
    unsigned int splits_done = 0;

    do {
        cur = std::find(prev, str.cend(), delim);
        if(max_splits!=0 && splits_done>=max_splits) {
            parts.emplace_back(prev, str.cend());
            break;
        }
        parts.emplace_back(prev, cur);
        splits_done++;
        if(cur!=str.cend())
            cur++;
        prev = cur;
    } while(cur!=str.cend());

    return parts;
}

static const char *button_gfx_left[] = {"[", " "};
static const char *button_gfx_right[] = {"]", " "};

Button message_box(const std::string &caption, const std::string &text, const Button buttons, const Button default_button, const Align align)
{
    std::vector<button_info> active_buttons;

    size_t buttons_width = 0;
    for(const button_info &info: all_buttons) {
        if((buttons & info.button) == info.button) {
            active_buttons.push_back(info);
            buttons_width += info.width + 2 + 1;
        }
    }
    if(buttons_width)
        buttons_width -= 1;
    size_t selected_button = std::distance(active_buttons.begin(),
                                           std::find_if(active_buttons.begin(), active_buttons.end(),
                                                        [default_button](const button_info &info){ return info.button == default_button; }));

    size_t width = std::max(string_width(caption), buttons_width);

    const std::vector<std::string> lines = split(text, '\n');
    for(const std::string &line: lines) {
        width = std::max(width, string_width(line));
    }

    const size_t rows_needed = 4 + lines.size();
    const size_t cols_needed = width + 4;

    bool done = false;
    bool force_repaint = false;
    std::vector<action> actions;
    if(active_buttons.size() > 1) {
        actions = {
            {TERMPAINT_EV_KEY, "Enter", 0, [&](){ done = true; }, "Confirm Selection"},
            {TERMPAINT_EV_KEY, "ArrowLeft", 0, [&](){ if(selected_button > 0) selected_button--;}, "Previous option"},
            {TERMPAINT_EV_KEY, "ArrowRight", 0, [&](){ if(selected_button < active_buttons.size() - 1) selected_button++; }, "Next option"},
            {TERMPAINT_EV_CHAR, "l", TERMPAINT_MOD_CTRL, [&](){ force_repaint = true; }, "Force redraw"},
        };
    } else {
        actions = {
            {TERMPAINT_EV_KEY, "Enter", 0, [&](){ done = true; }, "Close dialog"},
            {TERMPAINT_EV_CHAR, "l", TERMPAINT_MOD_CTRL, [&](){ force_repaint = true; }, "Force redraw"},
        };
    }

    while(!done) {
        const size_t cols = termpaint_surface_width(surface);
        const size_t rows = termpaint_surface_height(surface);
        int x, y;
        resolve_align(align, cols_needed, rows_needed, 0, cols, 0, rows, x, y);
        surface_backup backup(x, y, cols_needed, rows_needed);

        draw_box_with_caption(x, y, cols_needed, rows_needed, caption);

        for(size_t i=0; i<lines.size(); i++) {
            termpaint_surface_write_with_attr(surface, x + 2, y + 1 + i, lines[i].c_str(), attributes[ASNormal].normal);
        }

        int button_x = x + 2;
        for(size_t btn=0; btn<active_buttons.size(); btn++) {
            const bool button_selected = selected_button == btn;
            termpaint_attr *attr = button_selected ? attributes[ASNormal].highlight : attributes[ASNormal].normal;

            termpaint_surface_write_with_attr(surface, button_x, y + rows_needed - 2, button_gfx_left[button_selected], attr);
            termpaint_surface_write_with_attr(surface, button_x + 1, y + rows_needed - 2, active_buttons[btn].string.c_str(), attr);
            termpaint_surface_write_with_attr(surface, button_x + active_buttons[btn].width + 1, y + rows_needed - 2, button_gfx_right[button_selected], attr);

            button_x += active_buttons[btn].width + 2 + 1;
        }

        termpaint_terminal_flush(terminal, force_repaint);
        force_repaint = false;

        auto event = wait_for_event(integration, 0);
        if(!event)
            abort();

        tui_handle_action(*event, actions);
    }

    return active_buttons[selected_button].button;
}

void tp_pause()
{
    termpaint_terminal_pause(terminal);
}

void tp_unpause()
{
    termpaint_terminal_unpause(terminal);
}

struct progress_info
{
    Align align;
    size_t width, height;
    std::string caption;
    int value, maxvalue;
};

static void draw_progress(progress_info *info)
{
    const size_t cols = termpaint_surface_width(surface);
    const size_t rows = termpaint_surface_height(surface);

    int x, y;
    resolve_align(info->align, info->width, info->height, 0, cols, 0, rows, x, y);

    draw_box_with_caption(x, y, info->width, info->height, info->caption);

    size_t progress_w = info->width - 4;
    float progress = info->value / (float)info->maxvalue;
    int full_blocks = progress_w * progress;
    int partial_block = ((progress_w * progress) - full_blocks) * 8;

    std::string draw = repeated(full_blocks, "█");

    switch(partial_block) {
    case 1:
        draw.append("▏"); break;
    case 2:
        draw.append("▎"); break;
    case 3:
        draw.append("▍"); break;
    case 4:
        draw.append("▌"); break;
    case 5:
        draw.append("▋"); break;
    case 6:
        draw.append("▊"); break;
    case 7:
        draw.append("▉"); break;
    default:
        break;
    }

    termpaint_surface_write_with_attr(surface, x + 2, y + 1, draw.c_str(), attributes[ASNormal].normal);
    termpaint_terminal_flush(terminal, false);
}

progress_info* begin_progress(const std::string &caption, const int width, const Align align)
{
    progress_info *info = new progress_info;

    info->align = align;
    info->width = width + 4;
    info->height = 3;
    info->caption = caption;
    info->value = 0;
    info->maxvalue = 100;

    draw_progress(info);

    return info;
}

void update_progress(progress_info *info, int value, int maxvalue)
{
    info->value = value;
    info->maxvalue = maxvalue;
    draw_progress(info);
}

void end_progress(progress_info *info)
{
    delete info;
}

std::pair<size_t, size_t> string_size(const std::string &str)
{
    size_t width = 0;
    const std::vector<std::string> lines = split(str, '\n');
    for(const std::string &line: lines) {
        width = std::max(width, string_width(line));
    }
    return {width, lines.size()};
}

void write_multiline_string(const int x, const int y, const std::string &str, termpaint_attr *attr)
{
    const std::vector<std::string> lines = split(str, '\n');
    for(size_t i=0; i<lines.size(); i++) {
        termpaint_surface_write_with_attr(surface, x, y + i, lines[i].c_str(), attr);
    }
}

std::string text_wrap(const std::string &text, const size_t desired_width)
{
    std::string out;
    termpaint_text_measurement *m = termpaint_text_measurement_new(surface);
    size_t cur = 0;
    size_t next = 0;
    do {
        next = text.find('\n', cur);
        const std::string part = text.substr(cur, next - cur);
        termpaint_text_measurement_reset(m);
        termpaint_text_measurement_set_limit_width(m, desired_width);
        if(termpaint_text_measurement_feed_utf8(m, part.data(), part.size(), true)) {
            // Line doesn't fit as a whole
            size_t partpos = 0;
            do {
                size_t fitting_bytes = termpaint_text_measurement_last_ref(m);
                bool adjust = part[partpos + fitting_bytes - 1] != ' ';
                if(adjust && partpos + fitting_bytes < part.size()) { // If we're inside the part only adjust if the last fitting char isn't the word boundary
                    adjust = part[partpos + fitting_bytes] != ' ' && part[partpos + fitting_bytes] != '\n';
                } else { // Don't adjust at the end of the part
                    adjust = false;
                }
                while(adjust && part[partpos + fitting_bytes - 1] != ' ' && fitting_bytes > 0) { // If necessary scan backwards for a space.
                    fitting_bytes--;
                }
                if(fitting_bytes == 0) { // Can't be soft broken.
                    fitting_bytes = termpaint_text_measurement_last_ref(m); // Just get the last fitting character and hard break
                    adjust = false;
                }
                const std::string fragment = part.substr(partpos, fitting_bytes - adjust);
                out.append(fragment).append("\n");
                partpos += fitting_bytes;
                termpaint_text_measurement_reset(m);
                termpaint_text_measurement_set_limit_width(m, desired_width);
                termpaint_text_measurement_feed_utf8(m, part.data() + partpos, part.size() - partpos + 1, partpos == part.size() - 1);
            } while(partpos != part.size());
        } else {
            // Line fits as-is.
            out.append(part).append("\n");
        }
        cur = next + 1;
    } while(next != std::string::npos);
    termpaint_text_measurement_free(m);
    if(out.back() == '\n' && text.back() != '\n')
        out.pop_back();
    return out;
}

void tui_abort(const std::string &message)
{
    const size_t cols = termpaint_surface_width(surface);

    message_box("Error", text_wrap(message, cols/2));
    exit(1);
}

static void pad_to_width(std::string &str, const size_t width)
{
    const size_t current = string_width(str);
    str.append(width-current, ' ');
}

struct helpitem {
    std::string key;
    std::string text;
};

static void draw_help(const std::vector<helpitem> &items)
{
    const size_t rows = termpaint_surface_height(surface);

    const size_t rows_per_column = rows / 3 * 2;

    std::vector<std::vector<std::string>> column_texts;

    const size_t text_columns = 1 + items.size() / rows_per_column;

    size_t item = 0;
    for(size_t column=0; column<text_columns; column++) {
        const size_t items_this_column = std::min(items.size() - item, rows_per_column);
        std::vector<std::string> texts;
        size_t key_width = 0;
        size_t text_width = 0;
        for(size_t i=0; i<items_this_column; i++) {
            key_width = std::max(string_width(items[item + i].key), key_width);
            text_width = std::max(string_width(items[item + i].text), text_width);
        }
        for(size_t i=0; i<items_this_column; i++) {
            std::string s = items[item].key;
            pad_to_width(s, key_width);
            s.append(" ");
            s.append(items[item].text);
            pad_to_width(s, key_width + 1 + text_width);
            texts.push_back(s);

            item++;
        }
        column_texts.push_back(texts);
    }

    std::string to_show;
    for(size_t i=0; i<rows_per_column; i++) {
        for(size_t column=0; column<text_columns; column++) {
            if(i >= column_texts[column].size())
                continue;
            to_show.append(column_texts[column][i]);
            if(column+1 < text_columns)
                to_show.append(" ");
        }
        to_show.append("\n");
    }

    message_box("Help", to_show);
}

static std::string format_key(const action &action) {
    std::string str;
    if(action.modifier & TERMPAINT_MOD_CTRL)
        str.append("C-");
    if(action.modifier & TERMPAINT_MOD_ALT)
        str.append("M-");
    if(action.type == TERMPAINT_EV_KEY) {
        auto it = key_symbols.find(action.string);
        if(it == key_symbols.end())
            str.append(action.string);
        else
            str.append(it->second);
    } else {
        str.append(action.string);
    }
    return str;
}

bool tui_handle_action(const Event &event, const std::vector<action> &actions)
{
    if(event.type == EV_TIMEOUT)
        return false;

    const auto it = std::find_if(actions.cbegin(), actions.cend(), [&](const action &a) {
        return a.type == event.type
                && a.string == event.string
                && event.modifier == a.modifier;
    });
    if(it == actions.cend()) {
        if(event.type == TERMPAINT_EV_KEY && event.string == "F1") {
            std::vector<helpitem> items = {{"F1", "Display this help"}};
            for(const action &action: actions) {
                if(action.help.empty())
                    continue;
                items.push_back({format_key(action), action.help});
            }
            draw_help(items);
            return true;
        }
        return false;
    }
    if(it->func)
        it->func();
    return true;
}

void tui_abort(const char *fmt, ...)
{
    va_list ap, ap2;
    va_start(ap, fmt);
    va_copy(ap2, ap);
    int required = vsnprintf(nullptr, 0, fmt, ap);
    va_end(ap);
    if(required < 0) {
        va_end(ap2);
        abort();
    }
    std::vector<char> buffer(required + 1, 0);
    int written = vsnprintf(buffer.data(), required + 1, fmt, ap2);
    if(written != required) {
        va_end(ap2);
        abort();
    }
    const std::string message(buffer.data());
    const size_t cols = termpaint_surface_width(surface);

    message_box("Error", text_wrap(message, cols*0.75f));
    exit(1);
}