rewrite pipechains ending in blocks with one or two pipes

lib/style/pipes.ex

@@ -43,7 +43,15 @@ defmodule Styler.Style.Pipes do
     case fix_pipe_start(zipper) do
       {{:|>, _, _}, _} = zipper ->
         case Zipper.traverse(zipper, fn {node, meta} -> {fix_pipe(node), meta} end) do
-          {{:|>, _, [{:|>, _, _}, _]}, _} = chain_zipper ->
+          # a |> f(...args) |> block(do ... end)
+          # =>
+          # block f(a, ...args) do ... end
+          {{:|>, _, [{:|>, _, [a, {f, fm, args}]}, {b, bm, [[{{:__block__, dm, [:do]}, _} | _]] = ba}]}, _} = blockz ->
+            {:cont, Zipper.replace(blockz, {b, bm, [Style.set_line({f, fm, [a | args]}, dm[:line]) | ba]}), ctx}
+
+          {{:|>, _, [{:|>,_, x}, _]}, _} = chain_zipper ->
+            IO.puts "chaining it up"
+            dbg(x)
             {:cont, find_pipe_start(chain_zipper), ctx}
 
           # don't un-pipe into unquotes, as some expressions are only valid as pipes

test/style/pipes_test.exs

@@ -168,6 +168,72 @@
       )
     end
 
+    test "block extraction: optimize the pipe!" do
+      assert_style("""
+      foo
+      |> case do
+        nil -> nil
+      end
+      """,
+      """
+      case foo do
+        nil -> nil
+      end
+      """)
+
+      assert_style("""
+      foo
+      |> bar(baz)
+      |> case do
+        nil -> nil
+      end
+      """,
+      """
+      case bar(foo, baz) do
+        nil -> nil
+      end
+      """)
+
+      assert_style("""
+      foo
+      |> bar(baz)
+      |> if do
+        :horay
+      else
+        :boo
+      end
+      """,
+      """
+      if bar(foo, baz) do
+        :horay
+      else
+        :boo
+      end
+      """)
+    end
+
+    test "do block in the middle of a chain" do
+      assert_style("""
+      foo
+      |> bar(baz)
+      |> case(do
+        nil -> nil
+      end)
+      |> bop()
+      |> nooo()
+      """,
+      """
+      case_result =
+        case bar(foo, baz) do
+          nil -> nil
+        end
+
+      case_result
+      |> bop()
+      |> nooo()
+      """)
+    end
+
     test "macro with arg and do block" do
       assert_style("""
       "baz"