From 6c8504238ddbd96deea577df58c043b95cb1068d Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Mon, 7 Dec 2015 02:34:28 +0000
Subject: tracklist: swap functionality

This (from the point of the client) will atomically swap
two tracks.  This should allow easily implementing of a
tracklist editor.
---
 lib/dtas/player/client_handler.rb |  8 ++++++++
 lib/dtas/tracklist.rb             | 21 +++++++++++++++++++++
 test/test_tracklist.rb            | 11 +++++++++++
 3 files changed, 40 insertions(+)

diff --git a/lib/dtas/player/client_handler.rb b/lib/dtas/player/client_handler.rb
index e0af295..17cd6c3 100644
--- a/lib/dtas/player/client_handler.rb
+++ b/lib/dtas/player/client_handler.rb
@@ -696,6 +696,14 @@ module DTAS::Player::ClientHandler # :nodoc:
     io.emit('OK')
   end
 
+  def _dpc_tl_swap(io, msg)
+    usage = 'ERR usage: "tl swap TRACK_ID_A TRACK_ID_B"'
+    a_id = msg.shift or return io.emit(usage)
+    b_id = msg.shift or return io.emit(usage)
+    @tl.swap(a_id.to_i, b_id.to_i) or return io.emit('MISSING')
+    io.emit('OK')
+  end
+
   def __bp_prev_next(io, msg, cur, bp)
     case type = msg[1]
     when nil, "track"
diff --git a/lib/dtas/tracklist.rb b/lib/dtas/tracklist.rb
index b9abe55..7366799 100644
--- a/lib/dtas/tracklist.rb
+++ b/lib/dtas/tracklist.rb
@@ -220,4 +220,25 @@ class DTAS::Tracklist # :nodoc:
     end
     @goto_pos = prev_idx
   end
+
+  def swap(a_id, b_id)
+    ok = { a_id => a_idx = [], b_id => b_idx = [] }
+    @list.each_with_index do |t,i|
+      ary = ok.delete(t.track_id) or next
+      ary[0] = i
+      break if ok.empty?
+    end
+    a_idx = a_idx[0] or return
+    b_idx = b_idx[0] or return
+    @list[a_idx], @list[b_idx] = @list[b_idx], @list[a_idx]
+    unless @shuffle
+      [ :@goto_pos, :@pos ].each do |v|
+        case instance_variable_get(v)
+        when a_idx then instance_variable_set(v, b_idx)
+        when b_idx then instance_variable_set(v, a_idx)
+        end
+      end
+    end
+    true
+  end
 end
diff --git a/test/test_tracklist.rb b/test/test_tracklist.rb
index c918ff7..c05090c 100644
--- a/test/test_tracklist.rb
+++ b/test/test_tracklist.rb
@@ -120,4 +120,15 @@ class TestTracklist < Testcase
     assert_kind_of Integer, tl.add_track('y')
     assert_equal 2, tl.instance_variable_get(:@list).size
   end
+
+  def test_swap
+    tl = DTAS::Tracklist.new
+    list_add(tl, %w(a b c d e f g))
+    mapping = _build_mapping(tl)
+    assert tl.swap(mapping['a'], mapping['g'])
+    assert_equal %w(g b c d e f a), list_to_path(tl)
+
+    assert_nil tl.swap(-2, -3), 'no swap on invalid'
+    assert_equal %w(g b c d e f a), list_to_path(tl)
+  end
 end
-- 
cgit v1.2.3-24-ge0c7