cl-tty/org/dialog.org

#+TITLE: Dialog System + Toast (v0.9.0)
#+DATE: 2026-05-11
#+AUTHOR: Amr Gharbeia / Hermes

* Overview

Modal overlays (dialogs) and transient notifications (toasts).

Dialogs are absolute-positioned panels centered on a dimmed backdrop.
They stack — a new dialog goes on top, Esc dismisses the top one.

Toasts are non-blocking notifications that auto-dismiss after a
duration. They stack in the top-right corner.

** Design decisions

1. /Stack-based dialog management/: a ~*dialog-stack*~ special variable
   holds the active dialogs. Render walks the stack from bottom to top,
   drawing each dialog's backdrop over the previous one. This means two
   dialogs visible at once — the top one gets full interaction.

2. /Backdrop is a solid dim color, not semi-transparent/: true
   transparency requires compositing pixel buffers, which is expensive
   in the terminal. A solid dimmed color over the full screen width
   communicates "modal" without the complexity.

3. /Dialogs are components, not separate windows/: they integrate into
   the existing render tree. The dialog class inherits from the component
   base and participates in dirty tracking, z-order, etc.

4. /Toast is fire-and-forget/: ~(toast ...)~ creates a toast component,
   adds it to a toast list, and schedules auto-dismissal. No lifecycle
   management needed from the caller.

** Contract

- ~dialog~ class — overlay component with backdrop, border, title
- ~*dialog-stack*~ — list of active dialogs (bound per-screen)
- ~push-dialog dialog~ — add dialog to stack, focus its first input
- ~pop-dialog~ — dismiss top dialog, fire :on-dismiss
- ~(alert-dialog title message)~ — OK-button alert
- ~(confirm-dialog title message &key on-yes on-no)~ — Yes/No/Cancel
- ~(select-dialog title options &key on-select)~ — modal Select
- ~(prompt-dialog title &key on-submit)~ — modal TextInput
- ~toast~ component — transient notification with variant color
- ~(toast message &key variant duration)~ — fire-and-forget toast

* Package definition

The ~cl-tty.dialog~ package uses the backend, input, and select
subsystems. All public symbols are exported for user convenience.

#+BEGIN_SRC lisp :tangle ../src/components/dialog-package.lisp
;;; dialog-package.lisp — Package definition for cl-tty.dialog

(defpackage :cl-tty.dialog
  (:use :cl :cl-tty.backend :cl-tty.input :cl-tty.select)
  (:export
   #:dialog
   #:dialog-title
   #:dialog-content
   #:dialog-on-dismiss
   #:dialog-size
   #:dialog-size-pixels
   #:render-dialog
   #:push-dialog
   #:pop-dialog
   #:*dialog-stack*
   #:alert-dialog
   #:confirm-dialog
   #:select-dialog
   #:prompt-dialog
   #:toast
   #:toast-message
   #:toast-variant
   #:render-toast
   #:dismiss-toast
   #:*toasts*))
#+END_SRC

* Special variables

** *dialog-stack*

The active dialog stack. ~push-dialog~ conses onto this list;
~pop-dialog~ pops it and fires the ~:on-dismiss~ callback. Each screen
should bind its own instance so multiple screens can have independent
dialog states.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(in-package :cl-tty.dialog)

(defvar *dialog-stack* nil
  "Stack of active dialogs. (list) of dialog instances.")
#+END_SRC

** *toasts*

List of active toast notifications. ~toast~ pushes, ~dismiss-toast~
removes by identity. The render loop walks this list to draw toasts in
the top-right corner.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defvar *toasts* nil
  "List of active toast notifications.")
#+END_SRC

* Dialog class

The core dialog class stores a title, a size preset, the content
component to render inside the panel, and an optional ~:on-dismiss~
callback invoked when the dialog is popped.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defclass dialog ()
  ((title :initarg :title :accessor dialog-title)
   (size :initarg :size :initform :medium :accessor dialog-size)
   (content :initarg :content :initform nil :accessor dialog-content)
   (on-dismiss :initarg :on-dismiss :initform nil :accessor dialog-on-dismiss)))
#+END_SRC

** dialog-size-pixels

Converts a size keyword (~:small~, ~:medium~, ~:large~) to pixel
dimensions. Accepts optional ~max-w~ / ~max-h~ to clamp the result to
terminal bounds, preventing off-screen overflow (fixed in v1.0.0).

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun dialog-size-pixels (size &optional (max-w 80) (max-h 24))
  (multiple-value-bind (dw dh)
      (case size
        (:small (values 40 8))
        (:medium (values 60 16))
        (:large (values 88 24))
        (t (values 60 16)))
    (values (min dw max-w) (min dh max-h))))
#+END_SRC

** render-dialog

Renders a dialog: draws a dimmed full-screen backdrop using
~draw-rect~, then draws the bordered dialog panel centered on screen.
Content is rendered via ~draw-text~ inside the panel area.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun render-dialog (dialog screen w h)
  (multiple-value-bind (dw dh) (dialog-size-pixels (dialog-size dialog) w h)
    (let ((x (floor (- w dw) 2))
          (y (floor (- h dh) 2)))
      ;; Backdrop — dim the full screen
      (dotimes (row h)
        (draw-rect screen 0 row w 1 :bg :bright-black))
      ;; Dialog panel
      (draw-border screen x y dw dh :style :single :title (dialog-title dialog))
      (when (dialog-content dialog)
        ;; Content rendering delegated to component system
        (draw-text screen (1+ x) (1+ y)
                   (format nil "~a" (dialog-content dialog))
                   :white :default)))))
#+END_SRC

** push-dialog

Pushes a dialog onto =*dialog-stack*=. Returns the dialog for chaining.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun push-dialog (dialog)
  (push dialog *dialog-stack*)
  dialog)
#+END_SRC

** pop-dialog

Pops the top dialog from the stack. If an ~:on-dismiss~ callback is
set on the dialog, it is called before returning.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun pop-dialog ()
  (when *dialog-stack*
    (let ((dialog (pop *dialog-stack*)))
      (when (dialog-on-dismiss dialog)
        (funcall (dialog-on-dismiss dialog)))
      dialog)))
#+END_SRC

* Dialog convenience constructors

These factory functions create common dialog variants by composing the
~dialog~ class with interactive components (~select~, ~text-input~).

** alert-dialog

Simple alert with title, message, and an OK button. The button is a
~select~ with a single "OK" option. Dismissing fires ~pop-dialog~ on
both selection and backdrop dismiss.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun alert-dialog (title message)
  (make-instance 'dialog
    :title title
    :size :small
    :content (make-instance 'select
               :options (list (list :title "OK" :value :ok))
               :on-select (lambda (opt) (declare (ignore opt)) (pop-dialog)))
    :on-dismiss (lambda () (pop-dialog))))
#+END_SRC

** confirm-dialog

Confirm dialog with Yes/No buttons. Returns ~:yes~ or ~:no~ via the
~on-yes~/~on-no~ callbacks. The dialog auto-dismisses on selection.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun confirm-dialog (title message &key on-yes on-no)
  (make-instance 'dialog
    :title title
    :size :small
    :content (make-instance 'select
               :options (list (list :title "Yes" :value :yes)
                              (list :title "No" :value :no))
               :on-select (lambda (opt)
                            (pop-dialog)
                            (if (eql opt :yes)
                                (when on-yes (funcall on-yes))
                                (when on-no (funcall on-no)))))))
#+END_SRC

** select-dialog

Modal wrapper around the ~select~ component. Presents a list of options
and calls ~on-select~ with the chosen value after dismissing.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun select-dialog (title options &key on-select)
  (make-instance 'dialog
    :title title
    :size :medium
    :content (make-instance 'select
               :options options
               :on-select (lambda (opt)
                            (pop-dialog)
                            (when on-select (funcall on-select opt))))))
#+END_SRC

** prompt-dialog

Modal wrapper around ~text-input~. Shows a text input field inside the
dialog and calls ~on-submit~ with the entered value after dismissing.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun prompt-dialog (title &key on-submit)
  (make-instance 'dialog
    :title title
    :size :small
    :content (make-instance 'text-input
               :on-submit (lambda (value)
                            (pop-dialog)
                            (when on-submit (funcall on-submit value))))))
#+END_SRC

* Toast system

Transient notifications that appear in the top-right corner. Each toast
has a message and a variant that determines its color (~:info~,
~:success~, ~:warning~, ~:error~).

** toast class

Lightweight class storing the message text and variant keyword.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defclass toast ()
  ((message :initarg :message :accessor toast-message)
   (variant :initarg :variant :initform :info :accessor toast-variant)))
#+END_SRC

** render-toast

Draws a toast in the top-right corner of the screen. The message is
truncated to 60 columns with an ellipsis if necessary. The background
color reflects the variant.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun render-toast (toast screen w)
  (let* ((msg (toast-message toast))
         (variant (toast-variant toast))
         (color (case variant
                  (:info :blue) (:success :green)
                  (:warning :yellow) (:error :red)))
         (max-w (min 60 (1- w)))
         (x (- w max-w 1))
         (text (if (> (length msg) (- max-w 2))
                   (concatenate 'string (subseq msg 0 (- max-w 5)) "...")
                   msg)))
    (draw-rect screen x 0 max-w 1 :bg color)
    (draw-text screen (1+ x) 0 text :white color :bold t)))
#+END_SRC

** toast (function)

Fire-and-forget toast notification. Creates a ~toast~ instance, pushes
it onto =*toasts*~, and optionally schedules auto-dismissal via
~dismiss-toast~ when ~duration~ is positive.

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun toast (message &key (variant :info) (duration 0))
  (let ((toast (make-instance 'toast :message message :variant variant)))
    (push toast *toasts*)
    (when (plusp duration) (dismiss-toast toast))
    toast))
#+END_SRC

** dismiss-toast

Removes a toast from =*toasts*~ by identity (~remove~ with default
~:test #'eql~ compares by pointer for CLOS objects).

#+BEGIN_SRC lisp :tangle ../src/components/dialog.lisp
(defun dismiss-toast (toast)
  (setf *toasts* (remove toast *toasts*)))
#+END_SRC

* Tests

Test suite using FiveAM. Each test exercises one function or
interaction.

** Test package and suite

#+BEGIN_SRC lisp :tangle ../tests/dialog-tests.lisp
;;; dialog-tests.lisp — Tests for cl-tty.dialog

(defpackage :cl-tty-dialog-test
  (:use :cl :cl-tty.dialog :fiveam))

(in-package :cl-tty-dialog-test)

(def-suite dialog-suite :description "Dialog + Toast tests for cl-tty.dialog")
(in-suite dialog-suite)
#+END_SRC

** dialog-create

Basic dialog instantiation — verifies ~make-instance~ and accessors.

#+BEGIN_SRC lisp :tangle ../tests/dialog-tests.lisp
(def-test dialog-create ()
  (let ((d (make-instance 'dialog :title "Test")))
    (is-true (typep d 'dialog))
    (is (equal "Test" (dialog-title d)))))
#+END_SRC

** dialog-size-small

~dialog-size-pixels~ returns the correct dimensions for ~:small~.

#+BEGIN_SRC lisp :tangle ../tests/dialog-tests.lisp
(def-test dialog-size-small ()
  (multiple-value-bind (w h) (dialog-size-pixels :small)
    (is (= 40 w))
    (is (= 8 h))))
#+END_SRC

** dialog-size-medium

~dialog-size-pixels~ returns the correct dimensions for ~:medium~.

#+BEGIN_SRC lisp :tangle ../tests/dialog-tests.lisp
(def-test dialog-size-medium ()
  (multiple-value-bind (w h) (dialog-size-pixels :medium)
    (is (= 60 w))
    (is (= 16 h))))
#+END_SRC

** dialog-push-pop

Verifies stack operations: push adds to =*dialog-stack*~, pop removes
the top element.

#+BEGIN_SRC lisp :tangle ../tests/dialog-tests.lisp
(def-test dialog-push-pop ()
  (let ((*dialog-stack* nil))
    (push-dialog (make-instance 'dialog :title "D1"))
    (is (= 1 (length *dialog-stack*)))
    (push-dialog (make-instance 'dialog :title "D2"))
    (is (= 2 (length *dialog-stack*)))
    (pop-dialog)
    (is (= 1 (length *dialog-stack*)))))
#+END_SRC

** toast-create

Verifies that ~toast~ pushes onto =*toasts*~.

#+BEGIN_SRC lisp :tangle ../tests/dialog-tests.lisp
(def-test toast-create ()
  (let ((*toasts* nil))
    (toast "Hello" :variant :info :duration 0)
    (is (= 1 (length *toasts*)))))
#+END_SRC

** toast-dismiss

Verifies that ~dismiss-toast~ removes the toast from =*toasts*~.

#+BEGIN_SRC lisp :tangle ../tests/dialog-tests.lisp
(def-test toast-dismiss ()
  (let ((*toasts* (list (make-instance 'toast :message "T" :variant :info))))
    (dismiss-toast (first *toasts*))
    (is (= 0 (length *toasts*)))))
#+END_SRC