(in-package :cl-tui.box)

;; ── Component Protocol ────────────────────────────────────────

(defgeneric component-layout-node (component)
  (:documentation "Return the layout-node for COMPONENT.")
  (:method ((bx box)) (box-layout-node bx))
  (:method ((tx text)) (text-layout-node tx)))

(defgeneric component-children (component)
  (:documentation "Return the children of COMPONENT, or nil.")
  (:method ((c t)) nil))

(defgeneric component-parent (component)
  (:documentation "Return the parent of COMPONENT, or nil.")
  (:method ((c t)) nil))

;; ── Rendering Pipeline ────────────────────────────────────────

(defgeneric render (component backend)
  (:documentation "Render COMPONENT at its computed position using BACKEND.")
  (:method ((c t) backend)
    (declare (ignore backend))
    (values)))

(defmethod render ((bx box) backend)
  (render-box bx backend))

(defmethod render ((tx text) backend)
  (render-text tx backend))

(defun render-screen (root backend)
  "Render the component tree ROOT using BACKEND.
  Computes layout for dirty branches, calls render on each component,
  and wraps output in synchronized updates."
  (let ((w (available-width root))
        (h (available-height root)))
    (begin-sync backend)
    (render-node root backend w h)
    (end-sync backend)))

(defun render-node (node backend w h)
  "Render a component NODE and its children."
  (compute-layout (component-layout-node node) w h)
  (render node backend)
  (dolist (child (component-children node))
    (render-node child backend w h)))

(defun available-width (component)
  "Return the available width for COMPONENT (or 80 as default)."
  (let ((ln (component-layout-node component)))
    (if ln (layout-node-width ln) 80)))

(defun available-height (component)
  "Return the available height for COMPONENT (or 24 as default)."
  (let ((ln (component-layout-node component)))
    (if ln (layout-node-height ln) 24)))

;; ── Dirty Propagation ─────────────────────────────────────────

(defun propagate-dirty (component)
  "Mark COMPONENT and all ancestors dirty."
  (mark-dirty component)
  (let ((parent (component-parent component)))
    (when parent
      (propagate-dirty parent))))