From 4b29f098adfaa900dc7c293163eb914f6725d800 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Mon, 9 Sep 2013 04:12:28 +0000
Subject: tracklist: preliminary tracklist class

This should allow us to eventually implement a MPRIS 2.0-compliant
tracklist.
---
 lib/dtas/tracklist.rb  | 108 +++++++++++++++++++++++++++++++++++++++++++++++++
 test/test_tracklist.rb |  75 ++++++++++++++++++++++++++++++++++
 2 files changed, 183 insertions(+)
 create mode 100644 lib/dtas/tracklist.rb
 create mode 100644 test/test_tracklist.rb

diff --git a/lib/dtas/tracklist.rb b/lib/dtas/tracklist.rb
new file mode 100644
index 0000000..2c4ad03
--- /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
diff --git a/test/test_tracklist.rb b/test/test_tracklist.rb
new file mode 100644
index 0000000..cc462c5
--- /dev/null
+++ b/test/test_tracklist.rb
@@ -0,0 +1,75 @@
+# 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 'helper'
+require 'dtas/tracklist'
+class TestTracklist < Testcase
+  def test_tl_add_tracks
+    tl = DTAS::Tracklist.new
+    tl.add_track("/foo.flac")
+    assert_equal(%w(/foo.flac), tl.instance_variable_get(:@list))
+
+    oids = tl.tracks
+    assert_kind_of Array, oids
+    assert_equal 1, oids.size
+    assert_equal [ [ oids[0], "/foo.flac" ] ], tl.get_tracks(oids)
+
+    tl.add_track("/bar.flac")
+    assert_equal(%w(/bar.flac /foo.flac), tl.instance_variable_get(:@list))
+
+    tl.add_track("/after.flac", oids[0])
+    assert_equal(%w(/bar.flac /foo.flac /after.flac),
+                 tl.instance_variable_get(:@list))
+  end
+
+  def test_add_current
+    tl = DTAS::Tracklist.new
+    tl.instance_variable_get(:@list).replace(%w(a b c d e f g))
+    tl.add_track('/foo.flac', nil, true)
+    assert_equal '/foo.flac', tl.cur_track
+  end
+
+  def test_next_track
+    tl = DTAS::Tracklist.new
+    tl.instance_variable_get(:@list).replace(%w(a b c d e f g))
+    %w(a b c d e f g).each do |t|
+      assert_equal t, tl.next_track
+    end
+    assert_nil tl.next_track
+    tl.repeat = true
+    assert_equal 'a', tl.next_track
+  end
+
+  def _build_mapping(tl)
+    tracks = tl.get_tracks(tl.tracks)
+    Hash[tracks.map { |(oid,name)| [ name, oid ] }]
+  end
+
+  def test_goto
+    tl = DTAS::Tracklist.new
+    tl.instance_variable_get(:@list).replace(%w(a b c d e f g))
+    mapping = _build_mapping(tl)
+    assert_equal 'f', tl.go_to(mapping['f'])
+    assert_nil tl.go_to(1 << 128)
+    assert_equal 'g', tl.next_track
+  end
+
+  def test_remove_track
+    tl = DTAS::Tracklist.new
+    tl.instance_variable_get(:@list).replace(%w(a b c d e f g))
+    mapping = _build_mapping(tl)
+    %w(a b c d e f g).each { |t| assert_kind_of Integer, mapping[t] }
+
+    tl.remove_track(mapping['a'])
+    assert_equal %w(b c d e f g), tl.instance_variable_get(:@list)
+
+    tl.remove_track(mapping['d'])
+    assert_equal %w(b c e f g), tl.instance_variable_get(:@list)
+
+    tl.remove_track(mapping['g'])
+    assert_equal %w(b c e f), tl.instance_variable_get(:@list)
+
+    # it'll be a while before OIDs require >128 bits, right?
+    tl.remove_track(1 << 128)
+    assert_equal %w(b c e f), tl.instance_variable_get(:@list), "no change"
+  end
+end
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