(use srfi-1)

(add-load-path "/home/hip/src/lisp/x11")
(use x11)

(define (rounded-number->string x . digits-of-precision)
  (if (null? digits-of-precision)
      (number->string (inexact->exact (round x)))
      (let* ((digits (car digits-of-precision))
             (factor (expt 10.0 digits))
             (n (abs (inexact->exact (round (* x factor)))))
             (s (number->string n))
             (l (string-length s))
             (rs (if (< n factor)
                     (string-append "0."
                                    (make-string (- digits l) #\0)
                                    s)
                     (string-append (substring s 0 (- l digits))
                                    "."
                                    (substring s (- l digits) l)))))
        (if (< x 0) (string-append "-" rs) rs))))

(define (read-log)
  (call-with-input-file "/home/hip/lib/smart/hddtemp.log"
    (lambda (p)
      (port->string-list p))))

(define (get-temperature-from-logline line)
  "Fri Dec 19 18:40:03 CET 2003 /dev/hda: WDC WD800BB-00DKA0: 29 C"
  (string->number
   (car
    (list-tail (string-split line " ") 9))))

(define (temperatures)
  (filter number?
          (map get-temperature-from-logline
               (read-log))))

;; todo: statistical analysis, averages, std deviations
;; monitoring of actual temperatures to stay within 2x stddev

(define (average ls)
  (let loop ((l ls) (total 0))
    (cond ((null? l)
           (/ total (length ls)))
          (else
           (loop (cdr l) (+ (car l) total))))))

(define screen-width 512)
(define screen-height 512)

(define (transform-y y)
  (- screen-height                      ; put origin a bottom-left
     (* 5 y)))                          ; scale up 5 times

(define (transform-to-screen temperatures)
  (let ((samples-per-pixel (round (/ (length temperatures) screen-width))))
    (let loop ((ts temperatures) (result ()))
      'xxx)))

(define (expose)
  (let* ((ts (temperatures))
         (ts-len (length ts))
         (ts-avg (rounded-number->string (average ts) 2)))
    (draw-string 10 20 #`",ts-len samples, average ,ts-avg C")
    (for-each
     (lambda (coord)
       (draw-point (car coord)
                   (transform-y (cadr coord))))
     (zip (iota screen-width)
          (take-right ts screen-width)))))

(make-window expose)