Initial commit

1 files changed, 38 insertions, 0 deletions

diff --git a/lib/pather.rb b/lib/pather.rb
new file mode 100644
index 0000000..5ce7d02
--- /dev/null
+++ b/lib/pather.rb
@@ -0,0 +1,38 @@
+class Pather
+  def initialize
+    @assets = {}
+    @current_path = []
+  end
+
+  def add asset_id, path
+    @assets[asset_id] = @current_path + path.split('/')
+  end
+
+  def path_to asset_id
+    other_path = @assets[asset_id]
+    find_path_between @current_path, other_path
+  end
+
+  def find_path_between from, to
+    from, to = drop_common_prefix from, to
+    path = ('../' * from.length) + to.join('/')
+  end
+
+  def drop_common_prefix path1, path2
+    common_prefix_length = path1.zip(path2).take_while do |(segment1, segment2)|
+      segment1 == segment2
+    end.length
+
+    return path1[common_prefix_length..], path2[common_prefix_length..]
+  end
+
+  def cd path
+    path.split('/').each do |segment|
+      if segment == '..'
+        @current_path.pop
+      else
+        @current_path.push segment
+      end
+    end
+  end
+end