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/tracklist.rb | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

(limited to 'lib/dtas/tracklist.rb')

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
-- 
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