feat: code action for refactoring UnlessWithElse

lib/credo_language_server/check.ex

@@ -37,6 +37,27 @@ defmodule CredoLanguageServer.Check do
       ]
     end
 
+    def fetch(%{
+          check: Credo.Check.Refactor.UnlessWithElse = check,
+          diagnostic: diagnostic,
+          uri: uri,
+          document: document
+        }) do
+      [
+        CodeAction.DisableCheck.new(
+          uri: uri,
+          diagnostic: diagnostic,
+          text: document,
+          check: Macro.to_string(check)
+        ),
+        CodeAction.UnlessWithElse.new(
+          uri: uri,
+          diagnostic: diagnostic,
+          text: document
+        )
+      ]
+    end
+
     def fetch(%{
           check: check,
           diagnostic: diagnostic,

lib/credo_language_server/code_action/unless_with_else.ex

@@ -0,0 +1,60 @@
+defmodule CredoLanguageServer.CodeAction.UnlessWithElse do
+  @moduledoc false
+
+  alias GenLSP.Structures.{
+    CodeAction,
+    WorkspaceEdit
+  }
+
+  def new(opts) do
+    %CodeAction{
+      title: "Refactor to use if",
+      diagnostics: [opts.diagnostic],
+      edit: %WorkspaceEdit{}
+    }
+  end
+
+  def refactor(text) do
+    {:ok, ast, comments} =
+      Code.string_to_quoted_with_comments(text,
+        literal_encoder: &{:ok, {:__block__, &2, [&1]}},
+        token_metadata: true,
+        unescape: false
+      )
+
+    IO.inspect(comments)
+
+    ast
+    |> IO.inspect()
+    |> transform_ast()
+    |> Code.quoted_to_algebra(comments: comments)
+    |> Inspect.Algebra.format(:infinity)
+    |> IO.iodata_to_binary()
+  end
+
+  defp transform_ast({:unless, line, [condition, [block1, block2]]}) do
+    {:if, line,
+     [condition, [change_block(block2, :do), change_block(block1, :else)]]}
+  end
+
+  defp change_block({{:__block__, line, _}, rest}, new) do
+    {{:__block__, line, [new]}, rest}
+  end
+
+  defp adjust_comment_lines(comments, block_line1, block_line2) do
+    comments
+    |> Enum.map(&adjust_comment_line(&1, block_line1, block_line2))
+  end
+
+  defp adjust_comment_line(%{line: line} = comment, a, b) when line > b do
+    diff = b - a
+    Map.put(comment, :line, line - diff)
+  end
+
+  defp adjust_comment_line(%{line: line} = comment, a, b) when line < b do
+    diff = b - a
+    Map.put(comment, :line, line + diff)
+  end
+
+  defp adjust_comment_line(comment, _a, _b), do: comment
+end

test/credo_language_server/code_action/unless_with_else_test.exs

@@ -0,0 +1,63 @@
+defmodule CredoLanguageServer.CodeAction.UnlessWithElseTest do
+  use ExUnit.Case, async: true
+
+  alias CredoLanguageServer.CodeAction.UnlessWithElse
+
+  describe "refactor" do
+    test "replaces unless with if and swaps code blocks" do
+      source = """
+      unless allowed? do
+        raise "Not allowed!"
+      else
+        proceed_as_planned()
+      end
+      """
+
+      expected_result =
+        """
+        if allowed? do
+          proceed_as_planned()
+        else
+          raise "Not allowed!"
+        end
+        """
+        |> String.trim_trailing()
+
+      result = UnlessWithElse.refactor(source)
+
+      assert result == expected_result
+    end
+
+    test "preserves comments" do
+      source = """
+      unless allowed? do
+        # one
+        raise "Not allowed!" # two
+        # three
+      else
+        # four
+        proceed_as_planned() # five
+        # six
+      end
+      """
+
+      expected_result =
+        """
+        if allowed? do
+          # four
+          proceed_as_planned() # five
+          # six
+        else
+          # one
+          raise "Not allowed!" # two
+          # three
+        end
+        """
+        |> String.trim_trailing()
+
+      result = UnlessWithElse.refactor(source)
+
+      assert result == expected_result
+    end
+  end
+end