From 56d0f674850c59c26a9466f927316be541844a94 Mon Sep 17 00:00:00 2001
From: Colin Okay <colin@cicadas.surf>
Date: Mon, 24 Oct 2022 15:30:33 -0500
Subject: Add: downloader.lisp

---
 downloader.lisp | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 downloader.lisp

diff --git a/downloader.lisp b/downloader.lisp
new file mode 100644
index 0000000..5f7077a
--- /dev/null
+++ b/downloader.lisp
@@ -0,0 +1,62 @@
+;;;; downloader.lisp
+
+(in-package #:vampire)
+
+(defvar *dl-cluster*
+  nil)
+
+(defun start-downloader-service (&key (count 5))
+  (setf *dl-cluster* (or *dl-cluster* (legion:make-cluster count 'run-job)))
+  (legion:start *dl-cluster*))
+
+(defun run-job (thunk)
+  (funcall thunk))
+
+(defun add-fetch-track-job (url ok err)
+  (legion:add-job
+   *dl-cluster*
+   (lambda ()
+     (if-let (track (download-media url))
+       (funcall ok track)
+       (funcall err url)))))
+
+(defun info-file-with-name (dir name)
+  (merge-pathnames
+   (format nil "~a.info.json" name)
+   dir))
+
+(defun trackinfo (path)
+  "Returns a trackinfo object - a list whose first member is a path to
+   a file and whose CDR is a PLIST of attributes to pass
+   to (make-instance 'track ...)"
+  (with-plist ((title :|title|)
+               (album :|album|)
+               (codec :|acodec|)
+               (artist :|artist|)
+               (dur :|duration|)
+               (file :|filename|)
+               (thumbs :|thumbnails|)
+               (source :|webpage_url|))
+      (jonathan:parse (alexandria:read-file-into-string path))
+    (with-plist ((url :|url|)) (first thumbs)
+      (cons file 
+            (list
+             :source source
+             :title title
+             :album album
+             :codec codec
+             :artist artist
+             :duration dur
+             :thumb-url url)))))
+
+(defun download-media (url)
+  (with-temp-dir (tmpdir)
+    (let* ((tmpname
+             (default-name "media"))
+           (trackinfo-file
+             (info-file-with-name tmpdir tmpname)))
+      (uiop:run-program 
+       (format nil "youtube-dl --write-info-json -x -o \"~a/~a.%(ext)s\" ~a"
+               tmpdir tmpname url))
+      (when (uiop:file-exists-p trackinfo-file)
+        (new-track (trackinfo trackinfo-file))))))
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