[grilo-plugins] acoustid: add lua sources for audio identification

[Victor Toso de Carvalho <victortoso src gnome org>]

commit d8f26f2ea838415354a2726359ddc5d871a10fd8
Author: Victor Toso <me victortoso com>
Date:   Tue Feb 23 23:20:07 2016 +0100

    acoustid: add lua sources for audio identification
    
    Based on chromaprint fingerprint the AcoustID source can provice
    important metadata related to the recording.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=732879

 src/lua-factory/sources/Makefile.am      |    1 +
 src/lua-factory/sources/grl-acoustid.lua |  133 ++++++++++++++++++++++++++++++
 2 files changed, 134 insertions(+), 0 deletions(-)
---
diff --git a/src/lua-factory/sources/Makefile.am b/src/lua-factory/sources/Makefile.am
index b371162..b72b728 100644
--- a/src/lua-factory/sources/Makefile.am
+++ b/src/lua-factory/sources/Makefile.am
@@ -8,6 +8,7 @@
 include $(top_srcdir)/gtester.mk
 
 lua_sources_DATA =                                     \
+       grl-acoustid.lua                                \
        grl-thegamesdb.lua                              \
        grl-metrolyrics.lua                             \
        grl-spotify-cover.lua                           \
diff --git a/src/lua-factory/sources/grl-acoustid.lua b/src/lua-factory/sources/grl-acoustid.lua
new file mode 100644
index 0000000..bedbf39
--- /dev/null
+++ b/src/lua-factory/sources/grl-acoustid.lua
@@ -0,0 +1,133 @@
+--[[
+ * Copyright (C) 2016 Grilo Project
+ *
+ * Contact: Victor Toso <me victortoso com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ *
+--]]
+
+---------------------------
+-- Source initialization --
+---------------------------
+
+source = {
+  id = "grl-acoustid",
+  name = "Acoustid",
+  description = "a source that provides audio identification",
+  supported_keys = { "title", "album", "artist", "mb-recording-id", "mb-album-id", "mb-artist-id" },
+  supported_media = { 'audio' },
+  config_keys = {
+    required = { "api-key" },
+  },
+  resolve_keys = {
+    ["type"] = "audio",
+    required = { "duration", "chromaprint" }
+  },
+  tags = { 'music', 'net:internet' },
+}
+
+netopts = {
+  user_agent = "Grilo Source AcoustID/0.3.0",
+}
+
+------------------
+-- Source utils --
+------------------
+acoustid = {}
+
+-- https://acoustid.org/webservice#lookup
+ACOUSTID_LOOKUP = 
"https://api.acoustid.org/v2/lookup?client=%s&meta=recordings+releasegroups&duration=%d&fingerprint=%s";
+
+---------------------------------
+-- Handlers of Grilo functions --
+---------------------------------
+function grl_source_init (configs)
+    acoustid.api_key = configs.api_key
+    return true
+end
+
+function grl_source_resolve (media, options, callback)
+  local url
+  local media = grl.get_media_keys()
+
+  if not media or
+      not media.duration or
+      not media.chromaprint or
+      #media.chromaprint == 0 then
+    grl.callback ()
+    return
+  end
+
+  url = string.format (ACOUSTID_LOOKUP, acoustid.api_key, media.duration,
+                       media.acoustid_fingerprint)
+  grl.fetch (url, netopts, lookup_cb)
+end
+
+---------------
+-- Utilities --
+---------------
+
+function lookup_cb (feed)
+  if not feed then
+    grl.callback()
+    return
+  end
+
+  local json = grl.lua.json.string_to_table (feed)
+  if not json or json.status ~= "ok" then
+    grl.callback()
+  end
+
+  media = build_media (json.results)
+  grl.callback (media)
+end
+
+
+function build_media(results)
+  local media = grl.get_media_keys ()
+  local keys = grl.get_requested_keys ()
+  local record, album, artist
+
+  if results and #results > 0 and
+      results[1].recordings and
+      #results[1].recordings > 0 then
+    record = results[1].recordings[1]
+
+    media.title = keys.title and record.title or nil
+    media.mb_recording_id = keys.mb_recording_id and record.id or nil
+  end
+
+  if record and
+      record.releasegroups and
+      #record.releasegroups > 0 then
+
+    album = record.releasegroups[1]
+    media.album = keys.album and album.title or nil
+    media.mb_album_id = keys.mb_album_id and album.id or nil
+  end
+
+  -- FIXME: related-keys on lua sources are in the TODO list
+  -- https://bugzilla.gnome.org/show_bug.cgi?id=756203
+  -- and for that reason we are only returning first of all metadata
+  if album and album.artists and #album.artists > 0 then
+    artist = album.artists[1]
+    media.artist = keys.artist and artist.name or nil
+    media.mb_artist_id = keys.mb_artist_id and artist.id or nil
+  end
+
+  return media
+end