(defpackage :cl-tui-layout-test
  (:use :cl :fiveam :cl-tui.layout)
  (:export #:run-tests))
(in-package :cl-tui-layout-test)

(def-suite layout-suite :description "Layout engine tests")
(in-suite layout-suite)

(defun run-tests ()
  (let ((result (run 'layout-suite)))
    (fiveam:explain! result)
    (uiop:quit 0)))

(test make-layout-node-defaults
  (let ((n (make-layout-node)))
    (is (typep n 'layout-node))
    (is (eql (layout-node-direction n) :column))))

(test make-layout-node-row
  (let ((n (make-layout-node :direction :row)))
    (is (eql (layout-node-direction n) :row))))

(test add-child-sets-parent
  (let ((parent (make-layout-node)) (child (make-layout-node)))
    (layout-node-add-child parent child)
    (is (eql (layout-node-parent child) parent))
    (is (= (length (layout-node-children parent)) 1))))

(test remove-child-clears-parent
  (let ((parent (make-layout-node)) (child (make-layout-node)))
    (layout-node-add-child parent child)
    (layout-node-remove-child parent child)
    (is (null (layout-node-parent child)))
    (is (= (length (layout-node-children parent)) 0))))

(test column-two-children-vertical
  (let* ((root (make-layout-node :direction :column))
         (c1 (make-layout-node :height 3))
         (c2 (make-layout-node :height 5)))
    (layout-node-add-child root c1) (layout-node-add-child root c2)
    (compute-layout root 20 20)
    (is (= (layout-node-y c1) 0)) (is (= (layout-node-height c1) 3))
    (is (= (layout-node-y c2) 3)) (is (= (layout-node-height c2) 5))))

(test row-two-children-horizontal
  (let* ((root (make-layout-node :direction :row))
         (c1 (make-layout-node :width 10))
         (c2 (make-layout-node :width 5)))
    (layout-node-add-child root c1) (layout-node-add-child root c2)
    (compute-layout root 20 10)
    (is (= (layout-node-x c1) 0)) (is (= (layout-node-width c1) 10))
    (is (= (layout-node-x c2) 10)) (is (= (layout-node-width c2) 5))))

(test flex-grow-distributes-space
  (let* ((root (make-layout-node :direction :row :width 20))
         (c1 (make-layout-node :width 4 :grow 1))
         (c2 (make-layout-node :width 4 :grow 2)))
    (layout-node-add-child root c1) (layout-node-add-child root c2)
    (compute-layout root 20 10)
    (is (= (layout-node-width c1) 8)) (is (= (layout-node-width c2) 12))))

(test flex-grow-single-child
  (let* ((root (make-layout-node :direction :row :width 20))
         (c (make-layout-node :width 5 :grow 1)))
    (layout-node-add-child root c)
    (compute-layout root 20 10)
    (is (= (layout-node-width c) 20))))

(test flex-shrink-reduces-overflow
  (let* ((root (make-layout-node :direction :row :width 10))
         (c1 (make-layout-node :width 8 :shrink 1))
         (c2 (make-layout-node :width 8 :shrink 1)))
    (layout-node-add-child root c1) (layout-node-add-child root c2)
    (compute-layout root 10 10)
    (is (= (layout-node-width c1) 5)) (is (= (layout-node-width c2) 5))))

(test padding-reduces-content-area
  (let* ((root (make-layout-node :direction :column :padding '(:top 1 :left 1 :bottom 1 :right 1)))
         (c (make-layout-node :height 3)))
    (layout-node-add-child root c)
    (compute-layout root 20 10)
    (is (= (layout-node-x c) 1)) (is (= (layout-node-y c) 1))
    (is (= (layout-node-height c) 3))))

(test gap-between-children
  (let* ((root (make-layout-node :direction :column :gap 2))
         (c1 (make-layout-node :height 3))
         (c2 (make-layout-node :height 3)))
    (layout-node-add-child root c1) (layout-node-add-child root c2)
    (compute-layout root 20 20)
    (is (= (layout-node-y c1) 0)) (is (= (layout-node-y c2) 5))))

(test vbox-macro
  (let ((r (vbox () (make-layout-node :height 3) (make-layout-node :height 5))))
    (compute-layout r 20 20)
    (is (= (length (layout-node-children r)) 2))
    (is (= (layout-node-y (elt (layout-node-children r) 1)) 3))))

(test hbox-macro
  (let ((r (hbox () (make-layout-node :width 5) (make-layout-node :width 3))))
    (compute-layout r 20 10)
    (is (= (length (layout-node-children r)) 2))
    (is (= (layout-node-x (elt (layout-node-children r) 1)) 5))))

(test spacer-takes-grow
  (let ((r (hbox (:width 20) (make-layout-node :width 5) (spacer :grow 1) (make-layout-node :width 5))))
    (compute-layout r 20 10)
    (let ((c (layout-node-children r)))
      (is (= (layout-node-x (elt c 2)) 15)) (is (= (layout-node-width (elt c 1)) 10)))))

(test nested-vbox-in-hbox
  (let* ((sidebar (vbox (:width 5 :height 10) (make-layout-node :height 3) (make-layout-node :height 7)))
         (main (vbox (:grow 1 :height 10) (make-layout-node :height 2) (make-layout-node :grow 1)))
         (r (hbox (:width 30 :height 10) sidebar main)))
    (compute-layout r 30 10)
    (is (= (layout-node-width sidebar) 5))
    (is (>= (layout-node-width main) 20))
    (let ((sc (layout-node-children sidebar)))
      (is (= (layout-node-y (elt sc 0)) 0))
      (is (= (layout-node-y (elt sc 1)) 3)))))

;; ── Edge Cases ────────────────────────────────────────────────

(test empty-container-does-not-crash
  "compute-layout on a node with no children should not error"
  (let ((r (make-layout-node)))
    (compute-layout r 20 20)
    (is (integerp (layout-node-width r)))
    (is (integerp (layout-node-height r)))))

(test single-child-in-column
  "A column with one child places it correctly"
  (let* ((r (make-layout-node :direction :column :width 10 :height 20))
         (c (make-layout-node :height 5)))
    (layout-node-add-child r c)
    (compute-layout r 10 20)
    (is (= (layout-node-y c) 0))
    (is (= (layout-node-height c) 5))))

(test zero-size-container
  "compute-layout with zero available space should not error"
  (let* ((r (make-layout-node :direction :column))
         (c (make-layout-node :height 5)))
    (layout-node-add-child r c)
    (compute-layout r 0 0)
    (is (integerp (layout-node-x c)))
    (is (integerp (layout-node-y c)))))

(test deep-nesting-three-levels
  "Three-level deep nesting produces correct leaf positions"
  (let* ((out (vbox ()                                    ; outer box
                (vbox (:grow 1)                           ; middle box
                  (make-layout-node :height 2))))         ; leaf
         (leaf (elt (layout-node-children
                      (elt (layout-node-children out) 0)) 0)))
    (compute-layout out 20 20)
    (is (= (layout-node-y leaf) 0))))

(test large-padding-leaves-room
  "Large padding reduces content area but doesn't crash"
  (let* ((r (make-layout-node :direction :column
                              :padding '(:top 5 :left 5 :bottom 5 :right 5)))
         (c (make-layout-node :height 3)))
    (layout-node-add-child r c)
    (compute-layout r 20 20)
    (is (= (layout-node-x c) 5))
    (is (= (layout-node-y c) 5))))

(test negative-grow-is-clamped
  "Grow values are adjusted but still compute"
  (let* ((r (make-layout-node :direction :row :width 10))
         (c (make-layout-node :width 5 :grow -1)))
    (layout-node-add-child r c)
    (compute-layout r 10 10)
    (is (integerp (layout-node-width c)))))