From ab42f01db57390e6c60fa7659010902605134773 Mon Sep 17 00:00:00 2001
From: edgurgel <eduardo@gurgel.me>
Date: Tue, 27 Aug 2024 21:59:34 +1200
Subject: [PATCH] WIP

---
 lib/ham/type_engine.ex         | 13 ++++++++++++-
 lib/ham/type_match_error.ex    | 30 ++----------------------------
 lib/ham/utils.ex               | 34 ++++++++++++++++++++++++++++++++++
 src/test.erl                   |  6 ++++++
 test/ham/type_checker_test.exs |  9 +++++++--
 test/ham/utils_test.exs        | 17 +++++++++++++++++
 test/support/module.ex         | 12 +++++++++++-
 7 files changed, 89 insertions(+), 32 deletions(-)
 create mode 100644 src/test.erl
 create mode 100644 test/ham/utils_test.exs

diff --git a/lib/ham/type_engine.ex b/lib/ham/type_engine.ex
index 6761703..17f5cb8 100644
--- a/lib/ham/type_engine.ex
+++ b/lib/ham/type_engine.ex
@@ -5,7 +5,18 @@ defmodule Ham.TypeEngine do
   alias Ham.Utils
 
   @type_kinds [:type, :typep, :opaque]
-
+  @typep entry_type :: tuple
+  @typep value :: term
+
+  @type reason ::
+          {:protocol_type_mismatch, value, module}
+          | {:remote_type_fetch_failure, {module, atom, arity}}
+          | {:module_fetch_failure, module}
+          | {:struct_name_type_mismatch, module | nil, module}
+          | {:required_field_unfulfilled_map_type_mismatch, entry_type}
+          | {:type_mismatch, value, entry_type}
+
+  @spec match_type(term, entry_type) :: :ok | {:error, [reason]}
   def match_type(value, {:type, _, :union, union_types} = union) when is_list(union_types) do
     results =
       Enum.reduce_while(union_types, [], fn type, reason_stacks ->
diff --git a/lib/ham/type_match_error.ex b/lib/ham/type_match_error.ex
index 0ab2bd6..8b5faff 100644
--- a/lib/ham/type_match_error.ex
+++ b/lib/ham/type_match_error.ex
@@ -4,9 +4,11 @@ defmodule Ham.TypeMatchError do
   match types defined in typespecs.
   """
   defexception [:reasons]
+
   @type t :: %__MODULE__{}
 
   alias Ham.Utils
+  import Ham.Utils, only: [type_to_string: 1]
 
   @impl Exception
   def exception({:error, reasons}), do: %__MODULE__{reasons: reasons}
@@ -123,32 +125,4 @@ defmodule Ham.TypeMatchError do
 
     padding <> string
   end
-
-  defp type_to_string({:type, _, :map_field_exact, [type1, type2]}) do
-    "required(#{type_to_string(type1)}) => #{type_to_string(type2)}"
-  end
-
-  defp type_to_string({:type, _, :map_field_assoc, [type1, type2]}) do
-    "optional(#{type_to_string(type1)}) => #{type_to_string(type2)}"
-  end
-
-  defp type_to_string(type) do
-    dbg(type)
-    # We really want to access Code.Typespec.typespec_to_quoted/1 here but it's
-    # private... this hack needs to suffice.
-    {:foo, type, []}
-    |> Code.Typespec.type_to_quoted()
-    |> IO.inspect(label: :type_to_quoted)
-    |> Macro.to_string()
-    |> IO.inspect(label: :macro_to_string)
-    |> String.split("\n")
-    |> Enum.map_join(&String.replace(&1, ~r/ +/, " "))
-    |> IO.inspect(label: :before_split)
-    |> String.split(" :: ", parts: 3)
-    |> IO.inspect(label: :split)
-    |> case do
-      [_, type_string] -> type_string
-      [_, type_name, type_string] -> "#{type_string} (\"#{type_name}\")"
-    end
-  end
 end
diff --git a/lib/ham/utils.ex b/lib/ham/utils.ex
index 18198cb..bb47131 100644
--- a/lib/ham/utils.ex
+++ b/lib/ham/utils.ex
@@ -63,4 +63,38 @@ defmodule Ham.Utils do
   defp suffix(2), do: "nd"
   defp suffix(3), do: "rd"
   defp suffix(_), do: "th"
+
+  def type_to_string(type) do
+    # We really want to access Code.Typespec.typespec_to_quoted/1 here but it's
+    # private... this hack needs to suffice.
+    macro =
+      {:foo, type, []}
+      |> Code.Typespec.type_to_quoted()
+
+    macro
+    |> Macro.to_string()
+    |> String.split("\n")
+    |> Enum.map_join(&String.replace(&1, ~r/ +/, " "))
+    |> String.split(" :: ", parts: type_parts(macro))
+    |> case do
+      [_foo, type_string] -> type_string
+      [_foo, type_name, type_string] -> "#{type_string} (\"#{type_name}\")"
+    end
+  end
+
+  def type_to_string({:type, _, :map_field_exact, [type1, type2]}) do
+    "required(#{type_to_string(type1)}) => #{type_to_string(type2)}"
+  end
+
+  def type_to_string({:type, _, :map_field_assoc, [type1, type2]}) do
+    "optional(#{type_to_string(type1)}) => #{type_to_string(type2)}"
+  end
+
+  defp type_parts(macro) do
+    case macro do
+      # The type has a name
+      {:"::", [], [{:foo, [], []}, {:"::", _, _}]} -> 3
+      _ -> 2
+    end
+  end
 end
diff --git a/src/test.erl b/src/test.erl
new file mode 100644
index 0000000..48e2fae
--- /dev/null
+++ b/src/test.erl
@@ -0,0 +1,6 @@
+-module(test).
+-type req() :: #{
+  binary() => binary(),
+  _ => _
+}.
+-export_type([req/0]).
diff --git a/test/ham/type_checker_test.exs b/test/ham/type_checker_test.exs
index 41aa8a3..2442b80 100644
--- a/test/ham/type_checker_test.exs
+++ b/test/ham/type_checker_test.exs
@@ -1274,11 +1274,16 @@ defmodule Ham.TypeCheckerTest do
 
   describe "multiple options" do
     test "pass" do
-      assert_pass(:foo_multiple_options, [], {:ok, "a", "b"})
+      assert_pass(:foo_multiple_options_annotated, [], {:ok, "a", "b"})
     end
 
     test "fail" do
-      assert_fail(:foo_multiple_options, [], :ok, "error")
+      assert_fail(
+        :foo_multiple_options_annotated,
+        [],
+        :ok,
+        ~r/type \{:ok, binary\(\), req :: binary\(\)\} | \{:more, binary\(\), req :: binary\(\)\} \("result"\)/
+      )
     end
   end
 
diff --git a/test/ham/utils_test.exs b/test/ham/utils_test.exs
new file mode 100644
index 0000000..e471345
--- /dev/null
+++ b/test/ham/utils_test.exs
@@ -0,0 +1,17 @@
+defmodule Ham.UtilsTest do
+  use ExUnit.Case, async: true
+  alias Ham.Utils
+
+  describe "type_to_string/1" do
+    test "complex type" do
+      {:ok, [type: {:complex_with_name, type_with_name, _}, type: {:complex, type, _}]} =
+        Code.Typespec.fetch_types(Complex)
+
+      assert Utils.type_to_string(type) ==
+               "{:ok, binary(), req :: binary()} | {:more, binary(), req :: binary()}"
+
+      assert Utils.type_to_string(type_with_name) ==
+               "{:ok, binary(), req :: binary()} | {:more, binary(), req :: binary()} (\"result\")"
+    end
+  end
+end
diff --git a/test/support/module.ex b/test/support/module.ex
index 5ffb8ef..217937e 100644
--- a/test/support/module.ex
+++ b/test/support/module.ex
@@ -244,7 +244,17 @@ defmodule Ham.Test.TestModule do
   @spec map_type_with_underscore() :: :test.req()
   def map_type_with_underscore, do: %{method: "GET"}
 
+  @spec foo_multiple_options_annotated ::
+          result :: {:ok, binary(), req :: binary()} | {:more, binary(), req :: binary()}
+  def foo_multiple_options_annotated, do: {:ok, "a", "b"}
+
   @spec foo_multiple_options ::
-          {:ok, binary(), req :: binary()} | {:more, binary(), req :: binary()}
+          result :: {:ok, binary(), req :: binary()} | {:more, binary(), req :: binary()}
   def foo_multiple_options, do: {:ok, "a", "b"}
 end
+
+defmodule Complex do
+  @type complex :: {:ok, binary(), req :: binary()} | {:more, binary(), req :: binary()}
+  @type complex_with_name ::
+          result :: {:ok, binary(), req :: binary()} | {:more, binary(), req :: binary()}
+end