;;;; units/text.lisp

(in-package #:wheelwork)

(defclass/std text (unit interactive)
  ((font :with :ri :std (error "A font is required") :type font)
   (content :with :ri :std "")
   (color :with :std #(1.0 1.0 1.0 1.0))
   (vao elem-count newlines :r)
   (shader :with :static :r)))

(defmethod model-matrix ((text text))
  (let ((m (mat:meye 4)))
    (with-slots (font newlines x y base-width base-height scale-x scale-y rotation) text 
      (let* ((text-height
               (cl-fond:text-height (font-object font)))
             (baseline-offset
              (* newlines text-height))
             (rotation-baseline-offset
               (* 2 newlines text-height )))
        (mat:nmtranslate m (vec:vec x
                                    (+ y
                                       (*
                                        scale-y
                                        baseline-offset))
                                    0.0))

        (mat:nmtranslate m (vec:v* 0.5 (vec:vec (* scale-x base-width)
                                                (* scale-y (- base-height rotation-baseline-offset) )
                                                0.0)))
        (mat:nmrotate  m vec:+vz+ rotation)
        (mat:nmtranslate m (vec:v* -0.5 (vec:vec (* scale-x base-width )
                                                 (* scale-y (- base-height rotation-baseline-offset))
                                                 0.0))))
      
      (mat:nmscale m (vec:vec scale-x scale-y 1.0))
      m)))

(defmethod initialize-instance :after ((text text) &key)
  (with-slots (content newlines font vao elem-count shader base-width base-height scale-x scale-y) text
    (unless shader
      (setf shader
            (create-shader
             '(:vertex
               ((vert :vec2) (col :vec2))
               ((transform :mat4))
               ((values
                 (* transform (vari:vec4 vert 0.0 1.0))
                 col)))
             '(:fragment
               ((tc :vec2))
               ((tex :sampler-2d)
                (color :vec4))
               ((* color (aref (vari:texture tex tc) 0)))))))
    (multiple-value-bind (vao% count%) (cl-fond:compute-text (font-object font) content)
      (setf vao vao%
            elem-count count%))
    (setf newlines (count #\newline content))
    (let* ((extent
             (cl-fond:compute-extent (font-object font) content))
           (l
             (getf extent :l))
           (r
             (getf extent :r))) 
      (setf base-width (- r l)
            base-height (* (cl-fond:text-height (font-object font))
                           (1+ newlines))))))

(defmethod cleanup ((text text))
  (with-slots (vao shader) text
    (gl:delete-vertex-arrays (list vao))
    (when shader
      (gl:delete-program shader))
    (setf vao nil
          shader nil)))

(defmethod render ((text text))
  (with-slots (shader font vao elem-count color) text
    (gl:use-program shader)
    (gl:active-texture 0)
    (gl:bind-texture :texture-2d (cl-fond:texture (font-object font)))
    (gl:program-uniform-matrix-4fv
     shader
     (gl:get-uniform-location shader "TRANSFORM")
     (projected-matrix text))
    (gl:program-uniformi
     shader
     (gl:get-uniform-location shader "TEX")
     0)
    (gl:program-uniformfv
     shader
     (gl:get-uniform-location shader "COLOR")
     color)
    (gl:bind-vertex-array vao)
    (%gl:draw-elements :triangles elem-count :unsigned-int 0)
    (gl:bind-vertex-array 0)))