Basic functionality to merge and insert metadata

src/functions.liq

@@ -22,6 +22,71 @@
 # METADATA
 #
 
+# Merge with previous metadata, avoid duplicates
+def merge_meta(last_meta, meta) =
+    log(level=5, label="metadata", "Merge | last metadata: #{last_meta}")
+    log(level=5, label="metadata", "Merge | current metadata: #{meta}")
+    merged = ref(last_meta)
+
+    def add_meta_entry(entry) =
+        let (k, _) = entry
+        if list.assoc.mem(k, !merged) then
+            log(level=5, label="metadata", "Remove existing entry #{entry}")
+            merged := list.assoc.remove(k, !merged)
+        end
+        merged := list.add(entry, !merged)
+    end
+
+    list.iter(add_meta_entry, (meta))
+    log(level=5, label="metadata", "Merge | resulting metadata: #{!merged}")
+    !merged
+end
+
+# Checks for the existence of show-specific metadata
+def has_show_meta(meta) =
+    list.assoc.mem(engine_meta_key_show_id, meta) ? true : false
+end
+
+# Checks if the show ID in two metadata objects matches
+def is_same_show(last_meta, current_meta) =
+    last_meta[engine_meta_key_show_id] == current_meta[engine_meta_key_show_id] ? true : false
+end
+
+# Checks if the current show metadata is same as the previous one
+def is_same_show(last_meta, current_meta) =
+    if has_show_meta(last_meta) then
+        if not has_show_meta(current_meta) then
+            # No current show meta: handle as same show
+            true
+        elsif is_same_show(last_meta, current_meta) then
+            true
+        else
+            # A new show has started
+            false
+        end
+    else
+        # Last show has no show meta
+        if not has_show_meta(current_meta) then
+            # And the current one either: handle as same show
+            true
+        else
+            # Treat missing last show info as the same show
+            true
+        end
+    end
+end
+
+# Handles either insert or merge & insert of metadata, depending on the show ID
+def do_meta_insert(last_meta_callback, insert_meta_callback, meta) =
+    lm = (last_meta_callback() ?? [])
+    if is_same_show(lm, meta) then
+        lm = (last_meta_callback() ?? [])
+        merged = merge_meta(lm, meta)
+        insert_meta_callback(merged)
+    else
+        insert_meta_callback(meta)
+    end
+end
 
 # Builds a metadata object from data passed as JSON
 def build_metadata(json_string) =

src/settings.liq

@@ -156,6 +156,7 @@ print("Station Fallback Playlist: '#{fallback_station_playlist_path}'")
 print("Station Fallback Directory: '#{fallback_station_dir}'")
 
 # Metadata Configuration
+engine_meta_key_show_id = list.assoc(default="show_id", "meta_key_show_id", ini)
 engine_default_track_type = list.assoc(default="0", "default_track_type", ini)
 engine_fallback_show_name = ref(list.assoc(default="Station Fallback", "fallback_show_name", ini))
 engine_fallback_show_id = ref(list.assoc(default="-1", "fallback_show_id", ini))