(ns unheard.theory
  (:require [missionary.core :as m]
            [unheard.time-object :refer
             [time-object lift phrase timeline point-query]]
            [clojure.set :refer [union]]
            [unheard.util.missionary :refer [reconcile-merge]]))

(defn note
  [>clock start duration >value]
  (lift (time-object start
                     duration
                     (m/stream
                       (m/ap
                         (let [[c v] (m/?> (m/relieve
                                             (m/latest vector >clock >value)))]
                           v))))))

;; BUG: 2d7f861
(defn read
  [>clock timeline]
  (m/relieve
   (m/reductions {} nil
                 (m/eduction (map vals)
                             (m/reductions
                              (fn [acc {:keys [id state value]}]
                                (if (= :up state)
                                  (assoc acc id value)
                                  (dissoc acc id)))
                              {}
                              (reconcile-merge (point-query timeline >clock)))))))

(comment
  (def c (atom 0))
  (def >c (m/signal (m/watch c)))
  (def v (atom 0))
  (def >v (m/signal (m/watch v)))
  (def song (phrase (note >c 4 8 >v) (note >c 6 6 >v)))
  (def t (timeline song))
  (def cancel ((m/reduce prn nil (read >c t)) prn prn))
  (cancel)
  (swap! c dec)
  (swap! c inc)
  (swap! v inc)
  (swap! v dec))

(defn poly
  [& notes]
  (m/signal (m/cp (apply union (m/?< (apply m/latest vector notes))))))

;; TODO: Group could actually wrap note, rather than using explicitly
;; WIll introduce a lot of GC churn, though
(defn group
  [clock start end content]
  (m/cp (let [content (m/signal content)]
          (if (m/?< (m/latest #(<= start % end) clock))
            (m/?< content)
            (m/amb #{})))))

;; TODO:
;; - Note literals turn into numbers
;; - Represent keyboard as byte array of shorts
;; - play a note increments, stop a note decrements
;; - Multiple instruments
;; - Mapping inputs to vars
;; - Inputs get declared at the top of a track
;; - Devices get mapped to declared inputs
;; - Notion of scenes that change mapping of inputs to vars
;; - Loops