guise/input/

pin.rs

//! `PinInput` — segmented one-character code boxes (gpui entity).
//!
//! Owns its slots, cursor, and focus; renders N single-character boxes and
//! emits [`PinInputEvent`] as the code changes or completes. Typing advances,
//! backspace clears and retreats, arrows move, and Cmd+V fills the boxes from
//! the clipboard.
//!
//! ```ignore
//! let pin = cx.new(|cx| PinInput::new(cx).length(6).mask(true));
//! cx.subscribe(&pin, |_this, _pin, event: &PinInputEvent, _cx| {
//!     if let PinInputEvent::Complete(code) = event { /* verify */ }
//! })
//! .detach();
//! ```

use gpui::prelude::*;
use gpui::{
  div, px, App, Context, Entity, EventEmitter, FocusHandle, IntoElement, KeyDownEvent, MouseButton,
  SharedString, Window,
};

use super::control_metrics;
use crate::devtools::Probed;
use crate::reactive::Signal;
use crate::theme::{theme, Size};

/// Emitted as the user edits the code.
#[derive(Debug, Clone)]
pub enum PinInputEvent {
  /// The code changed. Carries the filled characters in order.
  Change(String),
  /// Every box is filled. Carries the full code (a `Change` fires first).
  Complete(String),
}

/// The pure editing model: N single-character slots plus an active-slot cursor.
#[derive(Debug, Clone, PartialEq, Eq)]
struct PinModel {
  slots: Vec<Option<char>>,
  cursor: usize,
}

impl PinModel {
  fn new(length: usize) -> Self {
    PinModel {
      slots: vec![None; length.max(1)],
      cursor: 0,
    }
  }

  fn len(&self) -> usize {
    self.slots.len()
  }

  /// The filled characters, in slot order.
  fn value(&self) -> String {
    self.slots.iter().flatten().collect()
  }

  fn is_complete(&self) -> bool {
    self.slots.iter().all(|slot| slot.is_some())
  }

  /// Type one character into the active slot and advance. Whitespace and
  /// control characters are rejected. Returns whether the code changed —
  /// re-typing the character a slot already holds only moves the cursor, so
  /// a full pin never re-emits `Complete` on a no-op keystroke.
  fn insert(&mut self, ch: char) -> bool {
    if ch.is_whitespace() || ch.is_control() {
      return false;
    }
    let changed = self.slots[self.cursor] != Some(ch);
    self.slots[self.cursor] = Some(ch);
    if self.cursor + 1 < self.len() {
      self.cursor += 1;
    }
    changed
  }

  /// Clear the active slot; if it was already empty, retreat and clear that
  /// one instead. Returns whether anything changed.
  fn backspace(&mut self) -> bool {
    if self.slots[self.cursor].is_some() {
      self.slots[self.cursor] = None;
      true
    } else if self.cursor > 0 {
      self.cursor -= 1;
      self.slots[self.cursor] = None;
      true
    } else {
      false
    }
  }

  fn left(&mut self) {
    self.cursor = self.cursor.saturating_sub(1);
  }

  fn right(&mut self) {
    if self.cursor + 1 < self.len() {
      self.cursor += 1;
    }
  }

  /// Replace the code with pasted text: non-whitespace characters fill the
  /// slots from the start. Returns whether the code changed — re-pasting
  /// the identical text is a no-op and must not re-emit `Complete`.
  fn paste(&mut self, text: &str) -> bool {
    let len = self.len();
    let chars: Vec<char> = text
      .chars()
      .filter(|c| !c.is_whitespace() && !c.is_control())
      .take(len)
      .collect();
    if chars.is_empty() {
      return false;
    }
    let before = self.slots.clone();
    self.slots.fill(None);
    for (i, ch) in chars.iter().enumerate() {
      self.slots[i] = Some(*ch);
    }
    self.cursor = chars.len().min(len - 1);
    self.slots != before
  }

  /// Programmatic replace (used by `set_text`/`bind`).
  fn set_value(&mut self, value: &str) {
    let len = self.len();
    self.slots.fill(None);
    for (i, ch) in value.chars().take(len).enumerate() {
      self.slots[i] = Some(ch);
    }
    self.cursor = self
      .slots
      .iter()
      .position(|slot| slot.is_none())
      .unwrap_or(len - 1);
  }

  fn resize(&mut self, length: usize) {
    self.slots.resize(length.max(1), None);
    self.cursor = self.cursor.min(self.slots.len() - 1);
  }
}

/// A one-time-code field. Create with `cx.new(|cx| PinInput::new(cx))`.
pub struct PinInput {
  model: PinModel,
  focus: FocusHandle,
  mask: bool,
  size: Size,
  disabled: bool,
}

impl EventEmitter<PinInputEvent> for PinInput {}

impl PinInput {
  pub fn new(cx: &mut Context<Self>) -> Self {
    PinInput {
      model: PinModel::new(4),
      focus: cx.focus_handle(),
      mask: false,
      size: Size::Sm,
      disabled: false,
    }
  }

  /// Number of boxes (default 4).
  pub fn length(mut self, length: usize) -> Self {
    self.model.resize(length);
    self
  }

  /// Render filled boxes as bullets instead of the typed characters.
  pub fn mask(mut self, mask: bool) -> Self {
    self.mask = mask;
    self
  }

  pub fn size(mut self, size: Size) -> Self {
    self.size = size;
    self
  }

  pub fn disabled(mut self, disabled: bool) -> Self {
    self.disabled = disabled;
    self
  }

  /// Initial code (builder). Extra characters beyond `length` are dropped.
  pub fn value(mut self, value: &str) -> Self {
    self.model.set_value(value);
    self
  }

  /// The field's focus handle, so a host can focus it on open.
  pub fn focus_handle(&self) -> FocusHandle {
    self.focus.clone()
  }

  /// The current code — the filled characters in order.
  pub fn text(&self) -> String {
    self.model.value()
  }

  /// Replace the code programmatically.
  pub fn set_text(&mut self, value: &str, cx: &mut Context<Self>) {
    self.model.set_value(value);
    cx.notify();
  }

  /// Two-way bind this field's code to a `Signal<String>`. The signal is
  /// the source of truth: the field adopts its value now, edits write back
  /// through [`Signal::set_if_changed`], and signal writes replace the code.
  /// Equality guards on both directions prevent update loops.
  pub fn bind(entity: &Entity<PinInput>, signal: &Signal<String>, cx: &mut App) {
    let initial = signal.get(cx);
    entity.update(cx, |this, cx| {
      if this.text() != initial {
        this.set_text(&initial, cx);
      }
    });
    let sink = signal.clone();
    cx.subscribe(entity, move |_pin, event: &PinInputEvent, cx| {
      if let PinInputEvent::Change(text) = event {
        sink.set_if_changed(cx, text.clone());
      }
    })
    .detach();
    let pin = entity.downgrade();
    cx.observe(signal.entity(), move |observed, cx| {
      let value = observed.read(cx).clone();
      pin
        .update(cx, |this, cx| {
          if this.text() != value {
            this.set_text(&value, cx);
          }
        })
        .ok();
    })
    .detach();
  }

  /// Emit `Change` (and `Complete` when full), repaint, and consume the key.
  fn emit_edit(&mut self, cx: &mut Context<Self>) {
    let value = self.model.value();
    cx.emit(PinInputEvent::Change(value.clone()));
    if self.model.is_complete() {
      cx.emit(PinInputEvent::Complete(value));
    }
    cx.notify();
    cx.stop_propagation();
  }

  fn on_key(&mut self, event: &KeyDownEvent, _window: &mut Window, cx: &mut Context<Self>) {
    if self.disabled {
      return;
    }
    let ks = &event.keystroke;
    let m = &ks.modifiers;
    match ks.key.as_str() {
      "left" => {
        self.model.left();
        cx.notify();
        cx.stop_propagation();
      }
      "right" => {
        self.model.right();
        cx.notify();
        cx.stop_propagation();
      }
      "backspace" => {
        if self.model.backspace() {
          self.emit_edit(cx);
        } else {
          cx.stop_propagation();
        }
      }
      "v" if m.platform => {
        if let Some(text) = cx.read_from_clipboard().and_then(|item| item.text()) {
          if self.model.paste(&text) {
            self.emit_edit(cx);
          }
        }
        cx.stop_propagation();
      }
      _ => {
        // Printable input: never on Cmd/Ctrl chords; Option+key is
        // allowed so composed glyphs land (same rule as TextInput).
        if !m.platform && !m.control {
          if let Some(typed) = ks.key_char.as_deref().filter(|t| !t.is_empty()) {
            let cursor_before = self.model.cursor;
            let mut changed = false;
            for ch in typed.chars() {
              changed |= self.model.insert(ch);
            }
            if changed {
              self.emit_edit(cx);
            } else if self.model.cursor != cursor_before {
              // Same character over a filled slot: the cursor
              // advanced but the code is untouched — repaint,
              // no Change/Complete.
              cx.notify();
              cx.stop_propagation();
            }
          }
        }
      }
    }
  }
}

impl Render for PinInput {
  fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
    let t = theme(cx);
    let (height, _pad_x, font) = control_metrics(self.size);
    let radius = t.radius(t.default_radius);
    let focused = self.focus.is_focused(window) && !self.disabled;

    let border = t.border().hsla();
    let active_border = t.primary().hsla();
    let surface = t.surface().hsla();
    let text_color = t.text().hsla();

    let cursor = self.model.cursor;
    let mask = self.mask;

    let mut row = div()
      .id("guise-pininput")
      .track_focus(&self.focus)
      .on_key_down(cx.listener(Self::on_key))
      .flex()
      .items_center()
      .gap(px(8.0));

    for (i, slot) in self.model.slots.iter().enumerate() {
      let ch = slot.map(|c| if mask { '\u{2022}' } else { c });
      let active = focused && i == cursor;
      let mut cell = div()
        .id(("guise-pin-box", i))
        .flex()
        .items_center()
        .justify_center()
        .w(px(height))
        .h(px(height))
        .rounded(px(radius))
        .border_1()
        .border_color(if active { active_border } else { border })
        .bg(surface)
        .text_size(px(font))
        .text_color(text_color)
        .on_mouse_down(
          MouseButton::Left,
          cx.listener(move |this, _ev, window, cx| {
            window.focus(&this.focus);
            this.model.cursor = i.min(this.model.len() - 1);
            cx.notify();
          }),
        );
      if let Some(ch) = ch {
        cell = cell.child(SharedString::from(ch.to_string()));
      }
      row = row.child(cell);
    }

    let element = if self.disabled { row.opacity(0.6) } else { row };

    element.probe("PinInput")
  }
}

#[cfg(test)]
mod tests {
  use super::PinModel;

  #[test]
  fn typing_advances_and_stops_at_the_last_box() {
    let mut pin = PinModel::new(4);
    assert!(pin.insert('1'));
    assert!(pin.insert('2'));
    assert_eq!(pin.value(), "12");
    assert_eq!(pin.cursor, 2);

    pin.insert('3');
    pin.insert('4');
    assert_eq!(pin.cursor, 3, "cursor parks on the last box");
    assert!(pin.is_complete());

    // Typing again overwrites the last box in place.
    assert!(pin.insert('9'));
    assert_eq!(pin.value(), "1239");
    assert_eq!(pin.cursor, 3);
  }

  #[test]
  fn retyping_the_same_char_reports_no_change() {
    let mut pin = PinModel::new(4);
    pin.paste("1234");
    // Double-pressing the final digit: complete pin, parked cursor.
    assert!(!pin.insert('4'));
    assert_eq!(pin.value(), "1234");
    // Mid-pin, the cursor still advances but the code is unchanged.
    pin.left();
    assert!(!pin.insert('3'));
    assert_eq!(pin.cursor, 3);
    assert_eq!(pin.value(), "1234");
  }

  #[test]
  fn identical_paste_reports_no_change() {
    let mut pin = PinModel::new(4);
    assert!(pin.paste("1234"));
    assert!(!pin.paste("1234"));
    assert!(pin.paste("129"), "different content still reports a change");
    assert_eq!(pin.value(), "129");
  }

  #[test]
  fn whitespace_and_control_chars_are_rejected() {
    let mut pin = PinModel::new(4);
    assert!(!pin.insert(' '));
    assert!(!pin.insert('\t'));
    assert!(!pin.insert('\u{7}'));
    assert_eq!(pin.value(), "");
    assert_eq!(pin.cursor, 0);
  }

  #[test]
  fn backspace_clears_current_then_retreats() {
    let mut pin = PinModel::new(4);
    pin.insert('1');
    pin.insert('2');
    // cursor sits on the empty third box: retreat and clear box 2.
    assert!(pin.backspace());
    assert_eq!(pin.value(), "1");
    assert_eq!(pin.cursor, 1);
    // Now box 1 (empty after the clear)... clear box 0 next.
    assert!(pin.backspace());
    assert_eq!(pin.value(), "");
    assert_eq!(pin.cursor, 0);
    // Empty at the first box: nothing to do.
    assert!(!pin.backspace());
  }

  #[test]
  fn backspace_clears_a_filled_box_in_place() {
    let mut pin = PinModel::new(4);
    pin.paste("1234");
    assert_eq!(pin.cursor, 3);
    assert!(pin.backspace());
    assert_eq!(pin.value(), "123");
    assert_eq!(pin.cursor, 3, "clears the filled box without retreating");
  }

  #[test]
  fn arrows_clamp_to_the_boxes() {
    let mut pin = PinModel::new(3);
    pin.left();
    assert_eq!(pin.cursor, 0);
    pin.right();
    pin.right();
    pin.right();
    assert_eq!(pin.cursor, 2);
    pin.left();
    assert_eq!(pin.cursor, 1);
  }

  #[test]
  fn paste_fills_from_the_start_and_skips_whitespace() {
    let mut pin = PinModel::new(4);
    pin.insert('9');
    assert!(pin.paste(" 12 34 56 "));
    assert_eq!(pin.value(), "1234", "replaces old content, truncates");
    assert!(pin.is_complete());
    assert_eq!(pin.cursor, 3);
  }

  #[test]
  fn short_paste_leaves_the_cursor_on_the_next_empty_box() {
    let mut pin = PinModel::new(6);
    assert!(pin.paste("12"));
    assert_eq!(pin.value(), "12");
    assert_eq!(pin.cursor, 2);
    assert!(!pin.paste("   "), "whitespace-only paste is a no-op");
  }

  #[test]
  fn set_value_places_the_cursor_at_the_first_empty_box() {
    let mut pin = PinModel::new(4);
    pin.set_value("12");
    assert_eq!(pin.cursor, 2);
    pin.set_value("123456");
    assert_eq!(pin.value(), "1234", "extra characters are dropped");
    assert_eq!(pin.cursor, 3);
    pin.set_value("");
    assert_eq!(pin.value(), "");
    assert_eq!(pin.cursor, 0);
  }

  #[test]
  fn resize_preserves_slots_and_clamps_the_cursor() {
    let mut pin = PinModel::new(6);
    pin.paste("123456");
    pin.resize(3);
    assert_eq!(pin.value(), "123");
    assert_eq!(pin.cursor, 2);
    pin.resize(5);
    assert_eq!(pin.value(), "123");
    assert_eq!(pin.len(), 5);
    // Zero-length requests are clamped to one box.
    pin.resize(0);
    assert_eq!(pin.len(), 1);
    assert_eq!(pin.cursor, 0);
  }
}