#!/gnu/store/rg44gfcbwb59z7m33baybxi83k2q0nwv-guile-2.0.13/bin/guile \
--debug -e main
!#

;;; uptop.scm -- Uppercase top.

;; Copyright (C) 2016 Artyom V. Poptsov <poptsov.artyom@gmail.com>
;;
;; This program is free software: you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation, either version 3 of the
;; License, or (at your option) any later version.
;;
;; This program is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;; General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see <http://www.gnu.org/licenses/>.


;;; Commentary:

;; Connect to a remote host, execute 'top' command on it and print the output
;; in uppercase letters.


;;; Code:

(use-modules (srfi srfi-41)             ; streams
             (ssh session)
             (ssh auth)
             (ssh popen)                ; remote pipes
             (ssh channel))             ; channel-set-pty-size!

(define (pipe->stream p)
  "Convert a pipe P to a SRFI-41 stream."
  (stream-let loop ((c (read-char p)))
    (if (eof-object? c)
        (begin
          (close-input-port p)
          stream-null)
        (stream-cons c (loop (read-char p))))))

(define (open-remote-input-pipe/pty* session command . args)
  "Open remote input pipe with PTY, run a COMMAND with ARGS."
  (define OPEN_PTY_READ (string-append OPEN_PTY OPEN_READ))
  (let ((p (apply open-remote-pipe* session OPEN_PTY_READ command args)))
    (channel-set-pty-size! p 80 40)
    p))

(define char-upcase/skip-esc
  (let ((state 'regular-char))
    (lambda (chr)
      "Return the uppercase character version of a CHR, skip therminal escape
sequences."
      (cond
       ((char=? chr (integer->char 27))
        (set! state 'escape-sequence)
        chr)
       ((char=? chr #\m)
        (if (equal? state 'escape-sequence)
            (begin
              (set! state 'regular-char)
              chr)
            (char-upcase chr)))
       (else
        (char-upcase chr))))))


;;;

(define (main args)
  "Entry point."
  (let ((s (make-session #:host (cadr args))))
    (connect! s)
    (userauth-agent! s)
    (let ((rs (pipe->stream (open-remote-input-pipe/pty* s "top" "-u $USER"))))
      (stream-for-each display (stream-map char-upcase/skip-esc rs)))))

;;; uptop.scm ends here.
