; ****************************************************************
; | OM-SRR, 2023                                                 |
; |                                                              |
; | Library for spectral rhythm model via integer time ratios    |
; | (partials) as phase-alilgned amplitude modulations.          |
; | See https://steffenkrebber.de/research/sinusoidal-run-rhythm/|
; ****************************************************************
;
;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 2
;of the License, or (at your option) any later version.
;
;See file LICENSE for further informations on licensing terms.
;
;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, write to the Free Software
;Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,10 USA.
;
;Authors: M. Schumacher

(in-package :om)

; main function

; gen-wave

(defmethod! gen-partial (subdivision &key (precision 0.01) (decimals 5))

            ;:icon 141  
            ;:initvals '(0 0.1 5)
            ;:indoc '("subdivision" "precision" "decimals")
            :numouts 2

  (let* ((sampled-function (multiple-value-list   
                            (om-sample #'cos (* subdivision precision) 0 (* subdivision (* 2 pi)) decimals)))
         (x-points (second sampled-function))
         (y-points (third sampled-function)))
  

    (values (om/ x-points subdivision) y-points)
    )
  )

; example 

; (gen-partial 8)


; GEN-SRR 
    
(defmethod! gen-srr (&rest subdivisions)

            :icon 988  
            :initvals '(nil)
            :indoc '("subdivisions")
            :numouts 2
            (let ((valuelist (mat-trans
                   (loop for sub in subdivisions 
                         collect (multiple-value-list (gen-partial sub))))))

              
              (values (caar valuelist) 
                      (om* (expt 0.5 (length subdivisions)) 
                           (om+ (length subdivisions) ;(apply 'om+ (second valuelist)))))
                                (loop for i from 0 to (1- (length (car (second valuelist)))) 
                                      collect (reduce '+  (loop for list in (second valuelist) collect (nth i list)))
                                      ))  
                           )
                      )
              )
            )

; legacy method

(defmethod! gen-srr_2 (subdivision1 subdivision2 &key (precision 0.01) (decimals 5))

            ;:icon 141  
            ;:initvals '(0 0.1 5)
            ;:indoc '("subdivision" "sampling-factor" "decimals")
            :numouts 2

  (let* ((pointlist1 (multiple-value-list (gen-partial subdivision1 :precision precision :decimals decimals)))
         (pointlist2 (multiple-value-list (gen-partial subdivision2 :precision precision :decimals decimals)))
         )
    (values (first pointlist1)
            (om* 0.25 (om+ 2 (om+ (second pointlist1) (second pointlist2))))
            )
    )
  )


; polar-plot

(defmethod! polar-plot ((srr bpf))
  (let* ((xpoints (x-points srr))
         (ypoints (y-points srr))
         (x-factor (/ 360.0 (* 2 pi)))
         (polar-values (multiple-value-list (ad->xy (om* x-factor xpoints) ypoints))))
    (simple-bpf-from-list (first polar-values) (second polar-values) 'bpc (decimals srr))
    )
  )
    
       

; output the object or the point lists
; optionally output cartesian or polar representation


; Computation of Farey-Sequence
; A Farey sequence of order n is the sequence of irreducible fractions between 0 and 1 that have denominators less than or equal to n, arranged in increasing order.

(defun farey-sequence (n)
  "Compute the Farey sequence of order n."
  (let ((fractions '()))
    (loop for denominator from 1 to n
          do (loop for numerator from 0 to denominator
                   when (and (>= numerator 0) (<= numerator denominator)
                             (= 1 (gcd numerator denominator)))
                   do (push (cons numerator denominator) fractions)))
    (sort fractions (lambda (a b)
                      (let ((num-a (car a)) (den-a (cdr a))
                            (num-b (car b)) (den-b (cdr b)))
                        (< (* num-a (float den-b)) (* num-b (float den-a))))))

    (loop for (a . b) in fractions collect
          (/ a b)
          )
    ))

(defparameter *farey-seq* '(0 1/5 1/4 1/3 2/5 1/2 3/5 2/3 3/4 4/5 1))

(loop for item in *farey-seq* 
        collect (unless (zerop item)
                  (/ 1 item)))

;; Example usage
(print (farey-sequence 5))
(farey-sequence 5)

(let ((conspair '(1 . 5)))
 (/ (car conspair)
    (cdr conspair))
)