Peristency and mtime support.

src/libs/medialib.liq

@@ -1,17 +1,60 @@
-def medialib(directories=[])
+def medialib(~persistency=null(), directories=[])
   db = ref([])
 
-  def scan()
-    for d = list.iterator(directories) do
-      for f = list.iterator(file.ls(absolute=true, recursive=true, d)) do
-        log.debug("adding file: #{f}")
+  # Add a file to the database.
+  def add(f)
+    # If file doesn't exist remove it
+    if not (file.exists(f)) then
+      db := list.assoc.remove(f, db())
+    else
+      # Not recent enough metadata
+      if not list.assoc.mem(f, db()) or (string.to_float(list.assoc("scan-time",list.assoc(f, db()))) > file.mtime(f)) then
         m = file.metadata(f)
+        m = metadata.cover.remove(m)
         m = ("filename",f) :: m
-        db := (f,m) :: db()
+        m = ("scan-time",string.float(time())) :: m
+        db := (f,m) :: list.assoc.remove(f, db())
+      end
+    end
+  end
+
+  # Update database by renewing metadata and removing removed files.
+  def update()
+    for fm = list.iterator(db()) do
+      let (f,_) = fm
+      add(f)
+    end
+  end
+
+  # Make sure that new files from directories are registered.
+  def scan()
+    for d = list.iterator(directories) do
+      list.iter(add, file.ls(absolute=true, recursive=true, d))
+    end
+  end
+
+  # Load from the persistent file.
+  def load()
+    db := []
+    if null.defined(persistency) then
+      f = null.get(persistency)
+      if file.exists(f) then
+        let json.parse ( parsed : [(string * [(string * string)])]? ) = file.contents(f)
+        if null.defined(parsed) then
+          db := null.get(parsed)
+        end
       end
     end
   end
 
+  # Store the file in a persistent file.
+  def store()
+    if null.defined(persistency) then
+      data = json.stringify(db())
+      file.write(data=data, null.get(persistency))
+    end
+  end
+
   def find(~artist=null(), ~artist_contains=null())
     def p(m)
       (null.defined(artist) ? m["artist"] == null.get(artist) : true)
@@ -23,6 +66,9 @@ def medialib(directories=[])
     l
   end
 
+  load()
   scan()
+  store()
+
   {find = find}
 end