refactoring
This commit is contained in:
@@ -0,0 +1,524 @@
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#lang racket/base
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(require json
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net/url
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racket-audio
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racket/contract
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racket/file
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racket/path
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racket/port
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racket/string
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simple-log
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"player-agent-translate.rkt")
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(provide (struct-out player-agent-runtime)
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make-player-agent-runtime)
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(sl-def-log player-agent)
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(struct exn:fail:agent-denied exn:fail () #:transparent)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; goal : Expose the small procedure-based interface of a running agent.
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; pre : Constructor fields are lifecycle/query procedures and a stable ID.
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; post : Creating or recognizing a value changes no external state.
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; result : player-agent-runtime? recognizes values returned by the factory.
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; internals: make-player-agent-runtime stores its local start!, reconnect!,
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; shutdown!, snapshot and current-track procedures in this struct.
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; Those procedures retain access to the factory closure, keeping the
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; shared polling and audio state private without introducing a class.
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(struct player-agent-runtime
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(start! reconnect! shutdown! snapshot current-track running? app-id)
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#:transparent)
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;;; Normalizes a configured server address and converts it to a URL value.
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(define (base-url value)
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(string->url
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(regexp-replace #px"/+$" (string-trim value) "")))
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;;; Resolves an agent API path relative to a normalized server URL.
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(define (endpoint-url base path)
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(combine-url/relative (base-url base) path))
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;;; Posts JSON to an agent API endpoint and reads its JSON response.
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;;; Authorization failures receive a distinct exception for poll-loop.
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(define (post-json base path data)
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(let ((input
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(post-pure-port
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(endpoint-url base path)
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(jsexpr->bytes data)
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(list "Content-Type: application/json"
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"Cache-Control: no-store"))))
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(dynamic-wind
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void
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(λ ()
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(let ((response (read-json input)))
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(when (and (hash? response)
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(string? (hash-ref response 'error #f)))
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(if (equal? (hash-ref response 'code #f)
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"agent-not-authorized")
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(raise
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(exn:fail:agent-denied
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(hash-ref response 'error)
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(current-continuation-marks)))
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(error 'player-agent (hash-ref response 'error))))
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response))
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(λ () (close-input-port input)))))
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;;; Converts racket-audio states to the state names sent to the web player.
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(define (normal-state state)
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(cond
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((memq state '(initialized no-media)) "stopped")
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((eq? state 'transitioning) "starting")
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(else (symbol->string state))))
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;;; Deletes a temporary media file and logs recoverable deletion failures.
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(define (safe-delete-file file)
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(when (and file (file-exists? file))
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(with-handlers ((exn:fail?
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(λ (exception)
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(warn-player-agent
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"Could not remove temporary media file ~a: ~a"
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file
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(exn-message exception)))))
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(delete-file file))))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Provided functions
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; goal : Create the headless polling and audio runtime for one agent.
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; pre : Server URL, display name and application ID are strings; callbacks
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; accept the status/denial messages supplied to them.
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; post : Mutable state is initialized but no worker thread or audio backend
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; is started until the returned start! procedure is called.
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; result : A player-agent-runtime containing its lifecycle/query procedures.
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; internals: start! launches poll-loop, which registers through post-json and
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; sends snapshots until it receives a command. A command worker runs
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; execute-command! and acknowledges it only after completion.
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; ensure-audio! connects racket-audio callbacks to update-from-audio!
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; and advance-at-decoder-eof!. with-agent-state protects their shared
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; state; stop! and shutdown! stop threads, audio and cached files.
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(define/contract (make-player-agent-runtime initial-server-url
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initial-name
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app-id
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#:status-callback
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[status-callback void]
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#:denied-callback
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[denied-callback void])
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(->* (string? string? string?)
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(#:status-callback (-> string? any/c)
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#:denied-callback (-> string? any/c))
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player-agent-runtime?)
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(let* ((server-url initial-server-url)
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(assigned-name initial-name)
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(state-lock (make-semaphore 1))
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(worker #f)
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(command-worker #f)
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(executing-command-id 0)
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(running #f)
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(authorization-notified? #f)
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(audio #f)
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(current-media-key #f)
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(cached-media (make-hash))
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(prefetched-track #f)
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(auto-started-key #f)
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(pending-auto-music-id #f)
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(music-tracks (make-hash))
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(current-track-value #f)
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(acknowledged-command 0)
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(ended-counter 0)
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(logical-volume 50)
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(agent-state
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(hasheq 'state "stopped"
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'position 0
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'duration 'null
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'rate 'null
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'channels 'null
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'bits 'null
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'format ""
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'volume logical-volume
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'error 'null)))
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;;; Runs a procedure while holding the semaphore for shared agent state.
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(define (with-agent-state proc)
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(call-with-semaphore state-lock proc))
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;;; Replaces an unavailable state value with its JSON fallback.
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(define (state-value value fallback)
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(if (eq? value #f) fallback value))
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;;; Returns the latest audio state while holding the state semaphore.
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(define (snapshot)
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(with-agent-state (λ () agent-state)))
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;;; Returns the currently audible track while holding the state semaphore.
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(define (current-track)
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(with-agent-state (λ () current-track-value)))
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;;; Stores an error in the state reported by the next poll.
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(define (set-agent-error! message)
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(with-agent-state
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(λ ()
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(set! agent-state (hash-set agent-state 'error message)))))
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;;; Removes an earlier error from the state reported by the next poll.
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(define (clear-agent-error!)
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(with-agent-state
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(λ ()
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(set! agent-state (hash-set agent-state 'error 'null)))))
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;;; Copies racket-audio state into the agent snapshot.
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;;; It also confirms when a prefetched track has become audible.
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(define (update-from-audio! state full-state)
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(with-agent-state
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(λ ()
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(let ((audible-music-id (hash-ref full-state 'at-music-id #f)))
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(set! agent-state
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(hasheq
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'state (normal-state state)
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'position (state-value (hash-ref full-state 'at-second #f) 0)
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'duration (state-value (hash-ref full-state 'duration #f) 'null)
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'rate (state-value (hash-ref full-state 'rate #f) 'null)
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'channels (state-value (hash-ref full-state 'channels #f) 'null)
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'bits (state-value (hash-ref full-state 'bits #f) 'null)
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'format (let ((decoder (hash-ref full-state 'decoder #f)))
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(if decoder (format "~a" decoder) ""))
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'volume logical-volume
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'error 'null))
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(when (and pending-auto-music-id
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(number? audible-music-id)
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(= pending-auto-music-id audible-music-id))
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(let ((audible-track
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(hash-ref music-tracks audible-music-id #f)))
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(when audible-track
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(set! current-track-value audible-track)
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(hash-clear! music-tracks)
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(hash-set! music-tracks audible-music-id audible-track)))
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(set! pending-auto-music-id #f)
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(set! ended-counter (+ ended-counter 1)))))))
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;;; Creates and configures the audio player on first use.
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;;; Its callbacks update reported state and continue prefetched playback.
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(define (ensure-audio!)
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(unless audio
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(set! audio
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(make-audio-player
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(λ (_handle state full-state)
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(update-from-audio! state full-state))
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(λ (handle)
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(advance-at-decoder-eof! handle))))
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(audio-ao-buf-ms! audio 500)
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(audio-buf-seconds! audio 4 10)
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(let ((scaled (/ logical-volume 100.0)))
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(audio-volume! audio (* 100.0 scaled scaled))))
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audio)
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;;; Downloads one protected media resource to a temporary local file.
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;;; A failed download closes its port and removes its partial file.
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(define (download-media! token filename)
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(let* ((extension
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(or (path-get-extension (string->path filename)) #""))
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(target
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(make-temporary-file
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(string-append "rkt-player-agent-~a"
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(bytes->string/utf-8 extension))))
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(path (format "/api/agent/media/~a/~a" app-id token))
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(input (get-pure-port (endpoint-url server-url path))))
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(with-handlers ((exn:fail?
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(λ (exception)
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(close-input-port input)
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(safe-delete-file target)
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(raise exception))))
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(call-with-output-file
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target
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(λ (output) (copy-port input output))
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#:exists 'truncate/replace)
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(close-input-port input)
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target)))
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;;; Selects the stable cache key carried by a playback command.
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(define (command-cache-key data)
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(hash-ref data 'cacheKey (hash-ref data 'mediaToken)))
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;;; Returns cached media or downloads and records it when absent.
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(define (ensure-media-cached! data)
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(let* ((key (command-cache-key data))
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(found (hash-ref cached-media key #f)))
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(if (and found (file-exists? found))
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found
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(let ((downloaded
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(download-media!
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(hash-ref data 'mediaToken)
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(hash-ref data 'filename "track"))))
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(hash-set! cached-media key downloaded)
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downloaded))))
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;;; Removes every cached media file except the entry identified by keep-key.
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(define (discard-unused-media! keep-key)
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(let loop ((remaining (hash->list cached-media)))
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(unless (null? remaining)
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(let ((entry (car remaining)))
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(unless (equal? (car entry) keep-key)
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(safe-delete-file (cdr entry))
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(hash-remove! cached-media (car entry))))
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(loop (cdr remaining)))))
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;;; Continues with prefetched media when the current decoder reaches EOF.
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;;; Decoder EOF precedes audible EOF, so audio-play! queues behind the buffer.
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(define (advance-at-decoder-eof! handle)
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(let ((prepared
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(with-agent-state
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(λ ()
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(let ((value prefetched-track))
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(set! prefetched-track #f)
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value)))))
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(cond
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(prepared
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(let* ((data (car prepared))
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(path (cdr prepared))
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(key (command-cache-key data)))
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(with-handlers
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((exn:fail?
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(λ (exception)
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(warn-player-agent "Could not start prefetched track: ~a"
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(exn-message exception))
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(set-agent-error! (exn-message exception))
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(with-agent-state
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(λ () (set! ended-counter (+ ended-counter 1)))))))
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(let ((music-id (audio-play! handle path)))
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(info-player-agent "Queued prefetched track ~a as music id ~a"
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(hash-ref data 'filename "track")
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music-id)
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(set! current-media-key key)
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(discard-unused-media! key)
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(with-agent-state
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(λ ()
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(hash-set! music-tracks music-id data)
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(set! auto-started-key key)
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(set! pending-auto-music-id music-id)))))))
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(else
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(warn-player-agent
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"Decoder reached EOF before the next track was prefetched")
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(with-agent-state
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(λ () (set! ended-counter (+ ended-counter 1))))))))
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;;; Applies one server command to audio, cache and reported agent state.
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;;; Play and prefetch commands also maintain gapless track bookkeeping.
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(define (execute-command! command)
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(let ((action (hash-ref command 'action ""))
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(data (hash-ref command 'data (hasheq))))
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(info-player-agent "Executing command ~a" action)
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(cond
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((string=? action "play")
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(let* ((next-key (command-cache-key data))
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(already-started?
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(with-agent-state
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(λ ()
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(let ((matches?
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(and auto-started-key
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(equal? auto-started-key next-key))))
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(when matches?
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(set! auto-started-key #f))
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matches?)))))
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(with-agent-state
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(λ () (set! current-track-value data)))
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(unless already-started?
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(with-agent-state
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(λ ()
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(set! prefetched-track #f)
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(set! auto-started-key #f)
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(set! pending-auto-music-id #f)
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(set! agent-state
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(hash-set
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(hash-set agent-state 'state "starting")
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'error 'null))))
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(let* ((next-media (ensure-media-cached! data))
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;; audio-play! interrupts and closes the previous decoder.
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(music-id (audio-play! (ensure-audio!) next-media)))
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(with-agent-state
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(λ ()
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(hash-clear! music-tracks)
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(hash-set! music-tracks music-id data)))
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(set! current-media-key next-key)
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(discard-unused-media! next-key)))))
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((string=? action "prefetch")
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(let ((key (command-cache-key data))
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(path (ensure-media-cached! data)))
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(with-agent-state
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(λ () (set! prefetched-track (cons data path))))
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(info-player-agent "Prefetched ~a"
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(hash-ref data 'filename "track"))
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(let loop ((remaining (hash->list cached-media)))
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(unless (null? remaining)
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(let ((entry (car remaining)))
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(unless (or (equal? (car entry) current-media-key)
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(equal? (car entry) key))
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(safe-delete-file (cdr entry))
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(hash-remove! cached-media (car entry))))
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(loop (cdr remaining))))))
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((string=? action "pause")
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(audio-pause! (ensure-audio!) #t))
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((string=? action "resume")
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(audio-pause! (ensure-audio!) #f))
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((string=? action "stop")
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(with-agent-state
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(λ ()
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(set! prefetched-track #f)
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(set! auto-started-key #f)
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(set! pending-auto-music-id #f)))
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(when audio
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(audio-stop! audio)))
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((string=? action "seek")
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(audio-seek! (ensure-audio!) (hash-ref data 'percentage 0)))
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((string=? action "volume")
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(set! logical-volume (min 100 (max 0 (hash-ref data 'value 50))))
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(let ((scaled (/ logical-volume 100.0)))
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(audio-volume! (ensure-audio!) (* 100.0 scaled scaled)))
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(with-agent-state
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(λ ()
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(set! agent-state
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(hash-set agent-state 'volume logical-volume)))))
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(else
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(error 'player-agent "unknown command: ~a" action)))))
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;;; Registers the agent and repeatedly exchanges state for server commands.
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;;; Connection and authorization failures are reported before a delayed retry.
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(define (poll-loop)
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(with-handlers
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((exn:fail:agent-denied?
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(λ (exception)
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(let ((message (format (tr 'denied-message) app-id)))
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(warn-player-agent "Agent authorization refused: ~a"
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(exn-message exception))
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(set-agent-error! message)
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(status-callback
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(tr 'unauthorized-status))
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(unless authorization-notified?
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(set! authorization-notified? #t)
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(denied-callback message))
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(when running
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(sleep 3)
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(poll-loop)))))
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(exn:fail?
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(λ (exception)
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(warn-player-agent "Connection cycle failed: ~a"
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(exn-message exception))
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(set-agent-error! (exn-message exception))
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(status-callback
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(format (tr 'disconnected) (exn-message exception)))
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(when running
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(sleep 3)
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(poll-loop)))))
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(post-json server-url
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"/api/agent/register"
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(hasheq 'appId app-id 'name assigned-name))
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(clear-agent-error!)
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(status-callback (tr 'connected))
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(info-player-agent "Registered at ~a as ~a" server-url assigned-name)
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(let loop ()
|
||||
(when running
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||||
(let* ((response
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||||
(post-json
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server-url
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"/api/agent/poll"
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||||
(hasheq 'appId app-id
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'name assigned-name
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'ack acknowledged-command
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'endedCounter ended-counter
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'state (snapshot))))
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(command (hash-ref response 'command 'null)))
|
||||
(when (and (hash? command)
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(> (hash-ref command 'id 0) acknowledged-command)
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||||
(not (= (hash-ref command 'id 0)
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||||
executing-command-id)))
|
||||
(set! executing-command-id (hash-ref command 'id))
|
||||
(set! command-worker
|
||||
(thread
|
||||
(λ ()
|
||||
(with-handlers
|
||||
((exn:fail?
|
||||
(λ (exception)
|
||||
(warn-player-agent "Command failed: ~a"
|
||||
(exn-message exception))
|
||||
(set-agent-error! (exn-message exception)))))
|
||||
(clear-agent-error!)
|
||||
(execute-command! command))
|
||||
(set! acknowledged-command (hash-ref command 'id))
|
||||
(set! executing-command-id 0)
|
||||
(set! command-worker #f))))))
|
||||
(sleep 1)
|
||||
(loop)))))
|
||||
|
||||
;;; Starts the polling worker once and reports the connecting state.
|
||||
(define (start!)
|
||||
(unless running
|
||||
(set! running #t)
|
||||
(status-callback (tr 'connecting))
|
||||
(set! worker (thread poll-loop))))
|
||||
|
||||
;;; Stops polling and command workers and clears their lifecycle state.
|
||||
(define (stop!)
|
||||
(set! running #f)
|
||||
(when (and worker (not (thread-dead? worker)))
|
||||
(kill-thread worker))
|
||||
(when (and command-worker (not (thread-dead? command-worker)))
|
||||
(kill-thread command-worker))
|
||||
(set! worker #f)
|
||||
(set! command-worker #f)
|
||||
(set! executing-command-id 0))
|
||||
|
||||
;;; Restarts the runtime with a new normalized server address and name.
|
||||
(define (reconnect! new-server-url new-name)
|
||||
(stop!)
|
||||
(set! authorization-notified? #f)
|
||||
(set! server-url (string-trim new-server-url))
|
||||
(set! assigned-name (string-trim new-name))
|
||||
(start!))
|
||||
|
||||
;;; Stops the runtime, closes audio and removes all cached media files.
|
||||
(define (shutdown!)
|
||||
(stop!)
|
||||
(when audio
|
||||
(with-handlers ((exn:fail? void))
|
||||
(audio-quit! audio))
|
||||
(set! audio #f))
|
||||
(let loop ((paths (hash-values cached-media)))
|
||||
(unless (null? paths)
|
||||
(safe-delete-file (car paths))
|
||||
(loop (cdr paths))))
|
||||
(hash-clear! cached-media))
|
||||
|
||||
(player-agent-runtime start!
|
||||
reconnect!
|
||||
shutdown!
|
||||
snapshot
|
||||
current-track
|
||||
(λ () running)
|
||||
app-id)))
|
||||
|
||||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||||
;; Tests for module player-agent-core.rkt
|
||||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||||
|
||||
(module+ test
|
||||
(require rackunit)
|
||||
|
||||
(check-equal? (normal-state 'initialized) "stopped")
|
||||
(check-equal? (normal-state 'transitioning) "starting")
|
||||
(check-equal? (normal-state 'playing) "playing")
|
||||
|
||||
(let* ((app-id (make-string 64 #\a))
|
||||
(runtime
|
||||
(make-player-agent-runtime "http://127.0.0.1:1234"
|
||||
"Test agent"
|
||||
app-id)))
|
||||
(check-false ((player-agent-runtime-running? runtime)))
|
||||
(check-false ((player-agent-runtime-current-track runtime)))
|
||||
(check-equal?
|
||||
(hash-ref ((player-agent-runtime-snapshot runtime)) 'state)
|
||||
"stopped")
|
||||
(check-equal? (player-agent-runtime-app-id runtime) app-id)))
|
||||
Reference in New Issue
Block a user