(in-package :cl-tty.backend)

(defclass simple-backend (backend)
  ((output-stream :initform *standard-output*
                  :initarg :output-stream
                  :accessor backend-output-stream)))

(defun make-simple-backend (&key output-stream)
  (make-instance 'simple-backend
    :output-stream (or output-stream *standard-output*)))

(defmethod initialize-backend ((b simple-backend))
  (backend-write b (format nil "~C[2J~C[H" #\Esc #\Esc))  ; clear + home
  (backend-write b (format nil "~C[?25l" #\Esc))  ; hide cursor
  b)

(defmethod shutdown-backend ((b simple-backend))
  (backend-write b (format nil "~C[?25h" #\Esc))  ; show cursor
  (values))

(defmethod suspend-backend ((b simple-backend))
  (backend-write b (format nil "~C[?25h" #\Esc))
  (values))

(defmethod resume-backend ((b simple-backend))
  (backend-write b (format nil "~C[?25l" #\Esc))
  (values))

(defmethod backend-size ((b simple-backend))
  (flet ((ioctl-size (fd)
           (let* ((+tiocgwinsz+ 21523)
                  (winsize (sb-alien:make-alien sb-alien:unsigned-short 4)))
             (unwind-protect
                  (progn
                    (sb-unix:unix-ioctl fd +tiocgwinsz+
                                        (sb-alien:alien-sap winsize))
                    (values (sb-alien:deref winsize 1)
                            (sb-alien:deref winsize 0)))
               (sb-alien:free-alien winsize)))))
    (or (ignore-errors (ioctl-size 0))
        (ignore-errors
          (ioctl-size (sb-sys:fd-stream-fd (backend-output-stream b))))
        (ignore-errors
          (let* ((cstr (sb-ext:posix-getenv "COLUMNS"))
                 (rstr (sb-ext:posix-getenv "LINES"))
                 (cols (when cstr (parse-integer cstr :junk-allowed t)))
                 (rows (when rstr (parse-integer rstr :junk-allowed t))))
            (when (and cols rows (> cols 0) (> rows 0))
              (values cols rows))))
        (values 80 24))))

(defmethod backend-write ((b simple-backend) string)
  (let ((stream (backend-output-stream b)))
    (write-string string stream)
    (finish-output stream)
    (length string)))

(defmethod capable-p ((b simple-backend) feature)
  (declare (ignore feature))
  nil)

(defun %cursor-move (x y)
  (format nil "~C[~d;~dH" #\Esc (1+ y) (1+ x)))

(defmethod cursor-hide ((b simple-backend))
  (backend-write b (format nil "~C[?25l" #\Esc)))

(defmethod cursor-show ((b simple-backend))
  (backend-write b (format nil "~C[?25h" #\Esc)))

(defmethod cursor-move ((b simple-backend) x y)
  (backend-write b (%cursor-move x y)))

(defmethod draw-text ((b simple-backend) x y string fg bg
                      &key bold italic underline reverse dim blink
                      &allow-other-keys)
  (declare (ignore fg bg bold italic underline reverse dim blink))
  (backend-write b (concatenate 'string (%cursor-move x y) string)))

(defun %simple-border-char (pos)
  (case pos
    ((:top-left :top-right :bottom-left :bottom-right) #\+)
    (:horizontal #\-)
    (:vertical #\|)))

(defmethod draw-border ((b simple-backend) x y width height
                        &key style fg bg title title-align)
  (declare (ignore style fg bg))
  (let ((h (%simple-border-char :horizontal))
        (v (%simple-border-char :vertical))
        (tl (%simple-border-char :top-left))
        (tr (%simple-border-char :top-right))
        (bl (%simple-border-char :bottom-left))
        (br (%simple-border-char :bottom-right)))
    ;; Top edge
    (backend-write b (%cursor-move x y))
    (backend-write b (string tl))
    (if (and title (plusp (length title)))
        (let* ((align (or title-align :left))
               (inner-width (- width 2))
               (max-tlen (- inner-width 2))
               (tlen (min (length title) max-tlen))
               (trunc-title (subseq title 0 tlen)))
          (ecase align
            (:left
             (backend-write b (string #\Space))
             (backend-write b trunc-title)
             (backend-write b (string #\Space))
             (backend-write b (make-string (- inner-width tlen 2) :initial-element h)))
            (:center
             (let* ((total-pad (- inner-width tlen))
                    (left-pad (floor total-pad 2))
                    (right-pad (- total-pad left-pad)))
               (backend-write b (make-string left-pad :initial-element h))
               (backend-write b trunc-title)
               (backend-write b (make-string right-pad :initial-element h))))))
        (backend-write b (make-string (- width 2) :initial-element h)))
    (backend-write b (string tr))
    ;; Sides
    (loop for i from 1 below (1- height)
          do (backend-write b (%cursor-move x (+ y i)))
             (backend-write b (string v))
             (backend-write b (make-string (- width 2) :initial-element #\space))
             (backend-write b (string v)))
    ;; Bottom edge
    (backend-write b (%cursor-move x (+ y height -1)))
    (backend-write b (string bl))
    (backend-write b (make-string (- width 2) :initial-element h))
    (backend-write b (string br))))

(defmethod draw-rect ((b simple-backend) x y width height
                      &key bg)
  (declare (ignore bg))
  (let ((line (make-string width :initial-element #\space)))
    (loop for row from 0 below height
          do (backend-write b (%cursor-move x (+ y row)))
             (backend-write b line))))

(defmethod draw-link ((b simple-backend) x y string url
                      &key fg bg)
  (declare (ignore url fg bg))
  (draw-text b x y string nil nil))

(defmethod draw-ellipsis ((b simple-backend) x y width
                          &key fg bg)
  (declare (ignore width fg bg))
  (draw-text b x y "..." nil nil))