feat(liquidsoap): emit cover_path + up_next in now-playing json

also fix path.extension -> file.extension (path module has no .extension in 2.3.3)

config/liquidsoap.liq

@@ -17,7 +17,7 @@ def make_deck(dir) =
     all = file.ls(dir, recursive=true, absolute=true)
     audio_exts = ["flac", "mp3", "opus", "m4a", "wav", "ogg"]
     audio = list.filter(
-      fun(f) -> list.mem(string.case(lower=true, path.extension(leading_dot=false, f)), audio_exts),
+      fun(f) -> list.mem(string.case(lower=true, file.extension(leading_dot=false, f)), audio_exts),
       all
     )
     files := list.shuffle(audio)
@@ -56,20 +56,55 @@ def make_deck(dir) =
   { source = request.dynamic(next_request), peek = peek }
 end
 
-def emit_now_playing(station, m) =
+# walk up from the audio file to find cover.{jpg,png,webp}.
+# falls back to <station>/cover.* (one level above tracks/).
+def cover_for(filename) =
+  def find_in(dir) =
+    candidates = ["#{dir}/cover.jpg", "#{dir}/cover.png", "#{dir}/cover.webp"]
+    list.fold(
+      fun(found, c) -> if found == "" and file.exists(c) then c else found end,
+      "",
+      candidates
+    )
+  end
+  album_dir = path.dirname(filename)
+  c1 = find_in(album_dir)
+  if c1 != "" then c1 else
+    tracks_dir = path.dirname(album_dir)
+    station_root = path.dirname(tracks_dir)
+    find_in(station_root)
+  end
+end
+
+# build a json object for one upcoming track from its filename.
+# reads tags via request.metadata; uses request.duration for length.
+def track_meta_json(filename) =
+  r = request.create(filename)
+  ignore(request.resolve(r))
+  m = request.metadata(r)
+  request.destroy(r)
+  d = null.get(default=-1., request.duration(filename))
+  obj = json()
+  obj.add("title", m["title"])
+  obj.add("artist", m["artist"])
+  obj.add("album", m["album"])
+  obj.add("duration", if d > 0. then string(int_of_float(d)) else "" end)
+  obj.add("cover_path", cover_for(filename))
+  obj
+end
+
+def emit_now_playing(station, m, upcoming) =
   filename = m["filename"]
   if filename != "" then
-    # decoder-reported metadata may be empty; fall back to request.duration which
-    # reads it directly from the file. -1.0 means unknown.
     meta_dur = m["duration"]
     dur_str =
       if meta_dur != "" then
         meta_dur
       else
-        # request.duration returns float? in liquidsoap 2.3 — unwrap with default -1.
         d = null.get(default=-1., request.duration(filename))
         if d > 0. then string(int_of_float(d)) else "" end
       end
+
     payload = json()
     payload.add("station", station)
     payload.add("artist", m["artist"])
@@ -78,7 +113,17 @@ def emit_now_playing(station, m) =
     payload.add("filename", filename)
     payload.add("duration", dur_str)
     payload.add("started_at", string(int_of_float(time())))
-    file.write(data=payload.stringify(), atomic=true, temp_dir="/now-playing", "/now-playing/#{station}.json")
+    payload.add("cover_path", cover_for(filename))
+
+    up_arr = list.map(track_meta_json, upcoming)
+    payload.add("up_next", up_arr)
+
+    file.write(
+      data=payload.stringify(),
+      atomic=true,
+      temp_dir="/now-playing",
+      "/now-playing/#{station}.json"
+    )
   end
 end