1 files changed, 108 insertions, 0 deletions
diff --git a/lib/dtas/tracklist.rb b/lib/dtas/tracklist.rb
new file mode 100644
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--- /dev/null
+++ b/lib/dtas/tracklist.rb
@@ -0,0 +1,108 @@
+# Copyright (C) 2013, Eric Wong <normalperson@yhbt.net> and all contributors
+# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
+require_relative '../dtas'
+require_relative 'serialize'
+
+# this is inspired by the MPRIS 2.0 TrackList spec
+class DTAS::Tracklist
+  include DTAS::Serialize
+  attr_accessor :repeat
+
+  SIVS = %w(list pos repeat)
+  TL_DEFAULTS = {
+    "list" => [],
+    "pos" => -1,
+    "repeat" => false,
+  }
+
+  def self.load(hash)
+    obj = new
+    obj.instance_eval do
+      list = hash["list"] and @list.replace(list)
+      @pos = hash["pos"] || -1
+      @repeat = hash["repeat"] || false
+    end
+    obj
+  end
+
+  def to_hsh
+    ivars_to_hash(SIVS).delete_if { |k,v| TL_DEFAULTS[k] == v }
+  end
+
+  def initialize
+    TL_DEFAULTS.each { |k,v| instance_variable_set("@#{k}", v) }
+    @list = []
+  end
+
+  def size
+    @list.size
+  end
+
+  # caching this probably isn't worth it.  a tracklist is usually
+  # a few tens of tracks, maybe a hundred at most.
+  def _track_id_map
+    by_track_id = {}
+    @list.each_with_index { |t,i| by_track_id[t.object_id] = i }
+    by_track_id
+  end
+
+  def get_tracks(track_ids)
+    by_track_id = _track_id_map
+    track_ids.map do |track_id|
+      idx = by_track_id[track_id]
+      # dtas-mpris fills in the metadata, we just return a path
+      [ track_id, idx ? @list[idx] : nil ]
+    end
+  end
+
+  def tracks
+    @list.map { |t| t.object_id }
+  end
+
+  def next_track(repeat_ok = true)
+    return if @list.empty?
+    next_pos = @pos + 1
+    if @list[next_pos]
+      @pos = next_pos
+    elsif @repeat && repeat_ok
+      next_pos = @pos = 0
+    else
+      return
+    end
+    @list[next_pos]
+  end
+
+  def cur_track
+    @pos >= 0 ? @list[@pos] : nil
+  end
+
+  def add_track(track, after_track_id = nil, set_as_current = false)
+    if after_track_id
+      by_track_id = _track_id_map
+      idx = by_track_id[after_track_id] or
+        raise ArgumentError, "after_track_id invalid"
+      @list[idx, 1] = [ @list[idx], track ]
+      @pos = idx + 1 if set_as_current
+    else # nil = first_track
+      @list.unshift(track)
+      @pos = 0 if set_as_current
+    end
+  end
+
+  def remove_track(track_id)
+    by_track_id = _track_id_map
+    if idx = by_track_id.delete(track_id)
+      @list[idx] = nil
+      @list.compact!
+      # TODO: what do we do with @pos (and the currently-playing track)
+    end
+  end
+
+  def go_to(track_id)
+    by_track_id = _track_id_map
+    if idx = by_track_id[track_id]
+      return @list[@pos = idx]
+    end
+    # noop if track_id is invalid
+  end
+end