#+TITLE: Passepartout TUI — Model
#+PROPERTY: header-args:lisp :tangle ../lisp/gateway-tui-model.lisp

* Model

The TUI state is a single plist accessed via ~st~ / ~(setf st)~.
All state mutation flows through event handlers in the controller.

** Contract

1. (init-state): returns a fresh state plist with ~:msgs~ list,
   ~:input~ buffer, ~:dirty~ flag, and ~:connection~ status.
2. (add-msg type text): appends a message to the ~:msgs~ list in
   ~*state*~, tagged with a timestamp and type. Truncates at the
   message buffer limit.
3. (queue-event ev): thread-safely enqueues an event for the
   reader loop. (drain-queue) returns and clears the queue.

** Package + State
#+begin_src lisp
(defpackage :passepartout.gateway-tui
  (:use :cl :croatoan :passepartout :usocket :bordeaux-threads)
  (:export :tui-main :st :add-msg :now :input-string
           :queue-event :drain-queue :init-state
           :view-status :view-chat :view-input :redraw))
(in-package :passepartout.gateway-tui)

(defvar *state* nil)
(defvar *event-queue* nil)
(defvar *event-lock* (bt:make-lock "tui-event-lock"))

(defun st (key) (getf *state* key))
(defun (setf st) (val key) (setf (getf *state* key) val))

(defun init-state ()
  (setf *state*
        (list :running t :mode :chat :connected nil :stream nil
              :input-buffer nil :input-history nil :input-hpos 0
              :messages nil :scroll-offset 0 :dirty (list nil nil nil))))
#+end_src

** Helpers
#+begin_src lisp
(defun now ()
  (multiple-value-bind (h m) (get-decoded-time)
    (format nil "~2,'0d:~2,'0d" h m)))

(defun input-string ()
  (coerce (reverse (st :input-buffer)) 'string))

(defun add-msg (role content)
  (push (list :role role :content content :time (now)) (st :messages))
  (setf (st :dirty) (list t t nil)))
#+end_src

** Event Queue
#+begin_src lisp
(defun queue-event (ev)
  (bt:with-lock-held (*event-lock*) (push ev *event-queue*)))

(defun drain-queue ()
  (bt:with-lock-held (*event-lock*)
    (let ((evs (nreverse *event-queue*)))
      (setf *event-queue* nil) evs)))
#+end_src