From 6c1aa4b33b14be7ab9069e01619b48052d0d0e02 Mon Sep 17 00:00:00 2001
From: Krzysztof Wende <wende@hey.com>
Date: Tue, 29 Aug 2023 17:36:19 +0200
Subject: [PATCH] Directive order

---
 lib/recode/task/directive_order.ex    | 96 +++++++++++++++++++++++++++
 test/recode/task/alias_order_test.exs |  2 +
 test/recode/task/directive_order.exs  | 48 ++++++++++++++
 3 files changed, 146 insertions(+)
 create mode 100644 lib/recode/task/directive_order.ex
 create mode 100644 test/recode/task/directive_order.exs

diff --git a/lib/recode/task/directive_order.ex b/lib/recode/task/directive_order.ex
new file mode 100644
index 0000000..b9d1ce0
--- /dev/null
+++ b/lib/recode/task/directive_order.ex
@@ -0,0 +1,96 @@
+defmodule Recode.Task.DirectiveOrder do
+  @shortdoc "Checks if directives (use/import/alias/require) are sorted ."
+
+  @moduledoc """
+  Alphabetically sorted lists are easier to read.
+
+      # preferred
+
+      alias Alpha
+      alias Bravo
+      alias Delta.{Echo, Foxtrot}
+
+      # not preferred
+
+      alias Delta.{Foxtrot, Echo}
+      alias Alpha
+      alias Bravo
+  """
+
+  use Recode.Task, corrector: true, category: :readability
+
+  alias Recode.AST
+  alias Recode.Task.AliasOrder
+  alias Rewrite.Source
+  alias Sourceror.Zipper
+
+  @nodes [:use, :import, :alias, :require]
+
+  @impl Recode.Task
+  def run(source, opts) do
+    source
+    |> Source.get(:quoted)
+    |> Zipper.zip()
+    |> do_run(source, opts[:autocorrect])
+  end
+
+  defp do_run(_zipper, _source, false) do
+    throw("Not implemented yet")
+  end
+
+  defp do_run(zipper, source, true) do
+    new_zipper =
+      zipper
+      |> Zipper.traverse_while([[]], &alias_order/2)
+      |> update()
+
+    Source.update(source, AliasOrder, :quoted, Zipper.root(new_zipper))
+  end
+
+  defp alias_order(%Zipper{node: {node, _meta, _args} = ast} = zipper, [group | groups])
+       when node in @nodes do
+    last_node = if group == [], do: node, else: elem(hd(group), 0)
+
+    if last_node == node do
+      {:skip, zipper, [[ast | group] | groups]}
+    else
+      {:skip, zipper, [[ast], group | groups]}
+    end
+  end
+
+  defp alias_order(zipper, acc) do
+    {:cont, zipper, acc}
+  end
+
+  defp update({zipper, []}), do: zipper
+
+  defp update({zipper, acc}) do
+    groups = Enum.map(acc, &Enum.reverse/1) |> Enum.reverse()
+
+    [[first | _] | _] = groups
+    sorted = sorted(groups)
+
+    rewound = Zipper.find(zipper, :next, fn item -> item == first end)
+
+    Enum.reduce(sorted, rewound, fn group, zipper ->
+      group
+      |> Enum.reduce(zipper, fn ast, z ->
+        Zipper.update(z, fn _ast -> AST.put_newlines(ast, 1) end) |> skip()
+      end)
+      |> prev()
+      |> Zipper.update(fn ast -> AST.put_newlines(ast, 2) end)
+      |> skip()
+    end)
+  end
+
+  defp sorted(groups) do
+    Enum.sort(groups, fn
+      [ast1 | _], [ast2 | _] ->
+        Enum.find_index(@nodes, fn node -> node == elem(ast1, 0) end) <=
+          Enum.find_index(@nodes, fn node -> node == elem(ast2, 0) end)
+    end)
+  end
+
+  defp skip(zipper), do: Zipper.right(zipper) || Zipper.next(zipper)
+  defp prev(zipper), do: Zipper.left(zipper) || Zipper.prev(zipper)
+end
diff --git a/test/recode/task/alias_order_test.exs b/test/recode/task/alias_order_test.exs
index c34b142..427d604 100644
--- a/test/recode/task/alias_order_test.exs
+++ b/test/recode/task/alias_order_test.exs
@@ -1,7 +1,9 @@
 defmodule Recode.Task.AliasOrderTest do
   use RecodeCase
 
+  alias Rewrite.Source
   alias Recode.Task.AliasOrder
+  alias Recode.Task.DirectiveOrder
 
   test "keeps a single alias" do
     """
diff --git a/test/recode/task/directive_order.exs b/test/recode/task/directive_order.exs
new file mode 100644
index 0000000..19a995e
--- /dev/null
+++ b/test/recode/task/directive_order.exs
@@ -0,0 +1,48 @@
+defmodule Recode.Task.DirectiveOrderTest do
+  use RecodeCase
+
+  alias Recode.Task.DirectiveOrder
+
+  test "sorts Use/Import/Alias/Require" do
+    code = """
+    defmodule MyModule do
+
+      require Alpha
+      alias Delta
+      alias Alpha.{Bravo, Charlie}
+      use Epsilon
+      alias Alpha
+      use Alpha
+
+
+      import Bravo
+
+
+      defp test(), do: 1
+    end
+    """
+
+    expected = """
+    defmodule MyModule do
+      use Epsilon
+
+      use Alpha
+
+      import Bravo
+
+      alias Delta
+      alias Alpha.{Bravo, Charlie}
+
+      alias Alpha
+
+      require Alpha
+
+      defp test(), do: 1
+    end
+    """
+
+    code
+    |> run_task(DirectiveOrder, autocorrect: true)
+    |> assert_code(expected)
+  end
+end