(in-package :cl-tty.backend)

(defclass backend () ())

(defgeneric initialize-backend (backend)
  (:method ((b backend)) b))

(defgeneric shutdown-backend (backend)
  (:method ((b backend)) (values)))

(defgeneric backend-size (backend)
  (:method ((b backend))
    (values 80 24)))

(defgeneric backend-write (backend string))

(defgeneric backend-clear (backend)
  (:method ((b backend))
    (backend-write b (format nil "~C[2J~C[H" #\Esc #\Esc))))

(defgeneric draw-text (backend x y string fg bg &key
                       bold italic underline reverse dim blink
                       &allow-other-keys))

(defgeneric draw-border (backend x y width height
                         &key style fg bg title title-align))

(defgeneric draw-rect (backend x y width height &key bg))

(defgeneric draw-link (backend x y string url &key fg bg))

(defgeneric draw-ellipsis (backend x y width &key fg bg))

(defgeneric cursor-move (backend x y)
  (:method ((b backend) x y) (declare (ignore x y)) (values)))

(defgeneric cursor-hide (backend)
  (:method ((b backend)) (values)))

(defgeneric cursor-show (backend)
  (:method ((b backend)) (values)))

(defgeneric cursor-style (backend shape &key blink)
  (:method ((b backend) shape &key blink) (values)))

(defgeneric begin-sync (backend)
  (:method ((b backend)) (values)))

(defgeneric end-sync (backend)
  (:method ((b backend)) (values)))

(defgeneric read-event (backend &key timeout)
  (:method ((b backend) &key timeout) (values nil nil)))

(defgeneric enable-mouse (backend)
  (:method ((b backend)) (values)))

(defgeneric enable-bracketed-paste (backend)
  (:method ((b backend)) (values)))

(defgeneric capable-p (backend feature)
  (:method ((b backend) feature)
    (declare (ignore feature))
    nil))

(in-package :cl-tty.backend)

(defgeneric suspend-backend (backend)
  (:documentation "Temporarily suspend the backend, restoring terminal to normal state.
Called before SIGTSTP or similar suspension. Application should redraw after resume.")
  (:method ((b backend)) (values)))

(defgeneric resume-backend (backend)
  (:documentation "Re-initialize the backend after suspension.
Called after SIGCONT or similar resume. Re-enables raw mode and backend features.")
  (:method ((b backend)) (values)))

(in-package :cl-tty.backend)

(defmacro with-terminal ((backend-var &optional cols-var rows-var)
                         &body body)
  "Execute BODY with a fully initialized terminal backend.

DETECT-BACKEND, INITIALIZE-BACKEND, and SHUTDOWN-BACKEND are called
automatically.  The backend instance is bound to BACKEND-VAR.  If
COLS-VAR and ROWS-VAR are provided, they are bound to the terminal
dimensions at startup.

The caller should wrap this in SB-POSIX:WITH-RAW-TERMINAL (or
equivalent) if raw-mode input handling is needed.

Example:
  (with-terminal (be cols rows)
    (loop for ev = (read-event be :timeout 0.1)
          while ev
          do (format t \"~A~%\" ev))))"
  (let ((be-sym (gensym "BE"))
        (c-sym (gensym "COLS"))
        (r-sym (gensym "ROWS")))
    `(let* ((,be-sym (detect-backend))
            ,@(when cols-var `((,c-sym (nth-value 0 (backend-size ,be-sym)))))
            ,@(when rows-var `((,r-sym (nth-value 1 (backend-size ,be-sym))))))
       (initialize-backend ,be-sym)
       (unwind-protect
            (let ((,backend-var ,be-sym)
                  ,@(when cols-var `((,cols-var ,c-sym)))
                  ,@(when rows-var `((,rows-var ,r-sym))))
              ,@body)
         (shutdown-backend ,be-sym)))))