defmodule CljElixir.NReplTest do
  use ExUnit.Case, async: false

  alias CljElixir.NRepl.{Bencode, Server, SessionManager, Handler}

  # --- Bencode Tests ---

  describe "Bencode encoding" do
    test "encode string" do
      assert Bencode.encode("hello") == "5:hello"
      assert Bencode.encode("") == "0:"
    end

    test "encode integer" do
      assert Bencode.encode(42) == "i42e"
      assert Bencode.encode(0) == "i0e"
      assert Bencode.encode(-7) == "i-7e"
    end

    test "encode list" do
      assert Bencode.encode([1, 2, 3]) == "li1ei2ei3ee"
      assert Bencode.encode([]) == "le"
      assert Bencode.encode(["hello", 42]) == "l5:helloi42ee"
    end

    test "encode dict" do
      assert Bencode.encode(%{"op" => "eval"}) == "d2:op4:evale"
    end

    test "encode nested" do
      msg = %{"op" => "eval", "code" => "(+ 1 2)", "id" => "1"}
      encoded = Bencode.encode(msg)
      assert is_binary(encoded)
      assert String.starts_with?(encoded, "d")
      assert String.ends_with?(encoded, "e")
    end

    test "encode atom keys" do
      assert Bencode.encode(%{op: "eval"}) == "d2:op4:evale"
    end
  end

  describe "Bencode decoding" do
    test "decode string" do
      assert Bencode.decode("5:hello") == "hello"
      assert Bencode.decode("0:") == ""
    end

    test "decode integer" do
      assert Bencode.decode("i42e") == 42
      assert Bencode.decode("i-7e") == -7
    end

    test "decode list" do
      assert Bencode.decode("li1ei2ei3ee") == [1, 2, 3]
    end

    test "decode dict" do
      result = Bencode.decode("d2:op4:evale")
      assert result == %{"op" => "eval"}
    end

    test "roundtrip" do
      original = %{"op" => "eval", "code" => "(+ 1 2)", "id" => "msg-1"}
      assert Bencode.decode(Bencode.encode(original)) == original
    end

    test "roundtrip nested" do
      original = %{"ops" => %{"eval" => %{}, "clone" => %{}}, "status" => ["done"]}
      assert Bencode.decode(Bencode.encode(original)) == original
    end
  end

  # --- Session Manager Tests ---

  describe "SessionManager" do
    setup do
      {:ok, manager} = SessionManager.start_link()
      %{manager: manager}
    end

    test "create session", %{manager: manager} do
      id = SessionManager.create_session(manager)
      assert is_binary(id)
      assert String.length(id) > 0
    end

    test "list sessions", %{manager: manager} do
      assert SessionManager.list_sessions(manager) == []
      id = SessionManager.create_session(manager)
      assert SessionManager.list_sessions(manager) == [id]
    end

    test "eval in session", %{manager: manager} do
      id = SessionManager.create_session(manager)
      assert {:ok, "3"} = SessionManager.eval(manager, id, "(+ 1 2)")
    end

    test "session state persists", %{manager: manager} do
      id = SessionManager.create_session(manager)

      {:ok, _} =
        SessionManager.eval(manager, id, """
        (defmodule NReplSessionTest
          (defn hello [] :hi))
        """)

      {:ok, result} = SessionManager.eval(manager, id, "(NReplSessionTest/hello)")
      assert result == ":hi"
    end

    test "close session", %{manager: manager} do
      id = SessionManager.create_session(manager)
      assert :ok = SessionManager.close_session(manager, id)
      assert SessionManager.list_sessions(manager) == []
    end

    test "independent sessions", %{manager: manager} do
      id1 = SessionManager.create_session(manager)
      id2 = SessionManager.create_session(manager)
      assert id1 != id2
      {:ok, "3"} = SessionManager.eval(manager, id1, "(+ 1 2)")
      {:ok, "7"} = SessionManager.eval(manager, id2, "(+ 3 4)")
    end
  end

  # --- Handler Tests ---

  describe "Handler" do
    setup do
      {:ok, manager} = SessionManager.start_link()
      %{manager: manager}
    end

    test "clone creates session", %{manager: manager} do
      [response] = Handler.handle(%{"op" => "clone", "id" => "1"}, manager)
      assert response["status"] == ["done"]
      assert is_binary(response["new-session"])
    end

    test "describe returns ops", %{manager: manager} do
      [response] = Handler.handle(%{"op" => "describe", "id" => "1"}, manager)
      assert response["status"] == ["done"]
      assert is_map(response["ops"])
      assert Map.has_key?(response["ops"], "eval")
      assert Map.has_key?(response["ops"], "clone")
    end

    test "eval returns value", %{manager: manager} do
      [clone_resp] = Handler.handle(%{"op" => "clone", "id" => "1"}, manager)
      session = clone_resp["new-session"]

      responses =
        Handler.handle(
          %{
            "op" => "eval",
            "code" => "(+ 1 2)",
            "session" => session,
            "id" => "2"
          },
          manager
        )

      # Should have value response and done response
      values = Enum.filter(responses, &Map.has_key?(&1, "value"))
      dones = Enum.filter(responses, fn r -> r["status"] == ["done"] end)

      assert length(values) == 1
      assert hd(values)["value"] == "3"
      assert length(dones) == 1
    end

    test "eval captures stdout", %{manager: manager} do
      [clone_resp] = Handler.handle(%{"op" => "clone", "id" => "1"}, manager)
      session = clone_resp["new-session"]

      responses =
        Handler.handle(
          %{
            "op" => "eval",
            "code" => "(println \"hello from nrepl\")",
            "session" => session,
            "id" => "2"
          },
          manager
        )

      outs = Enum.filter(responses, &Map.has_key?(&1, "out"))
      assert length(outs) >= 1
      assert hd(outs)["out"] =~ "hello from nrepl"
    end

    test "eval error", %{manager: manager} do
      [clone_resp] = Handler.handle(%{"op" => "clone", "id" => "1"}, manager)
      session = clone_resp["new-session"]

      responses =
        Handler.handle(
          %{
            "op" => "eval",
            "code" => "(defmodule HandlerErrTest (bad-syntax",
            "session" => session,
            "id" => "2"
          },
          manager
        )

      errs = Enum.filter(responses, &Map.has_key?(&1, "err"))
      assert length(errs) >= 1
    end

    test "ls-sessions", %{manager: manager} do
      [clone1] = Handler.handle(%{"op" => "clone", "id" => "1"}, manager)
      [clone2] = Handler.handle(%{"op" => "clone", "id" => "2"}, manager)

      [response] = Handler.handle(%{"op" => "ls-sessions", "id" => "3"}, manager)
      sessions = response["sessions"]

      assert length(sessions) == 2
      assert clone1["new-session"] in sessions
      assert clone2["new-session"] in sessions
    end

    test "close session", %{manager: manager} do
      [clone_resp] = Handler.handle(%{"op" => "clone", "id" => "1"}, manager)
      session = clone_resp["new-session"]

      [close_resp] =
        Handler.handle(
          %{
            "op" => "close",
            "session" => session,
            "id" => "2"
          },
          manager
        )

      assert close_resp["status"] == ["done"]

      [ls_resp] = Handler.handle(%{"op" => "ls-sessions", "id" => "3"}, manager)
      assert ls_resp["sessions"] == []
    end

    test "unknown op", %{manager: manager} do
      [response] = Handler.handle(%{"op" => "bogus", "id" => "1"}, manager)
      assert "unknown-op" in response["status"]
    end

    test "eval returns actual ns after ns declaration", %{manager: manager} do
      [clone_resp] = Handler.handle(%{"op" => "clone", "id" => "1"}, manager)
      session = clone_resp["new-session"]

      # Default ns is "user"
      responses =
        Handler.handle(
          %{"op" => "eval", "code" => "(+ 1 2)", "session" => session, "id" => "2"},
          manager
        )

      values = Enum.filter(responses, &Map.has_key?(&1, "value"))
      assert hd(values)["ns"] == "user"

      # After ns declaration, ns should update
      responses =
        Handler.handle(
          %{
            "op" => "eval",
            "code" => "(ns NReplNsTest)\n(defn hi [] :hey)",
            "session" => session,
            "id" => "3"
          },
          manager
        )

      values = Enum.filter(responses, &Map.has_key?(&1, "value"))
      assert hd(values)["ns"] == "NReplNsTest"
    end

    test "incremental def in ns via nrepl", %{manager: manager} do
      [clone_resp] = Handler.handle(%{"op" => "clone", "id" => "1"}, manager)
      session = clone_resp["new-session"]

      # Set up namespace
      Handler.handle(
        %{
          "op" => "eval",
          "code" => "(ns NReplIncrTest)\n(defn foo [] :original)",
          "session" => session,
          "id" => "2"
        },
        manager
      )

      # Add a new function without ns
      Handler.handle(
        %{
          "op" => "eval",
          "code" => "(defn bar [] :added)",
          "session" => session,
          "id" => "3"
        },
        manager
      )

      # Both should work
      responses =
        Handler.handle(
          %{
            "op" => "eval",
            "code" => "(NReplIncrTest/bar)",
            "session" => session,
            "id" => "4"
          },
          manager
        )

      values = Enum.filter(responses, &Map.has_key?(&1, "value"))
      assert hd(values)["value"] == ":added"

      responses =
        Handler.handle(
          %{
            "op" => "eval",
            "code" => "(NReplIncrTest/foo)",
            "session" => session,
            "id" => "5"
          },
          manager
        )

      values = Enum.filter(responses, &Map.has_key?(&1, "value"))
      assert hd(values)["value"] == ":original"
    end
  end

  # --- TCP Integration Test ---

  describe "TCP server" do
    test "server starts and accepts connections" do
      {:ok, server} = Server.start_link(port: 0)
      port = Server.port(server)
      assert port > 0

      # Connect as a client
      {:ok, socket} = :gen_tcp.connect(~c"127.0.0.1", port, [:binary, active: false])

      # Send clone request
      clone_msg = Bencode.encode(%{"op" => "clone", "id" => "1"})
      :ok = :gen_tcp.send(socket, clone_msg)

      # Read response
      {:ok, data} = :gen_tcp.recv(socket, 0, 5000)
      response = Bencode.decode(data)

      assert response["status"] == ["done"]
      assert is_binary(response["new-session"])

      :gen_tcp.close(socket)
      GenServer.stop(server)
    end

    test "full eval over TCP" do
      {:ok, server} = Server.start_link(port: 0)
      port = Server.port(server)

      {:ok, socket} = :gen_tcp.connect(~c"127.0.0.1", port, [:binary, active: false])

      # Clone
      :ok = :gen_tcp.send(socket, Bencode.encode(%{"op" => "clone", "id" => "1"}))
      {:ok, clone_data} = :gen_tcp.recv(socket, 0, 5000)
      clone_resp = Bencode.decode(clone_data)
      session = clone_resp["new-session"]

      # Eval
      eval_msg =
        Bencode.encode(%{
          "op" => "eval",
          "code" => "(+ 21 21)",
          "session" => session,
          "id" => "2"
        })

      :ok = :gen_tcp.send(socket, eval_msg)

      # Read all responses (value + done)
      responses = read_all_responses(socket)

      values = Enum.filter(responses, &Map.has_key?(&1, "value"))
      assert length(values) >= 1
      assert hd(values)["value"] == "42"

      :gen_tcp.close(socket)
      GenServer.stop(server)
    end
  end

  # Helper to read multiple bencode responses
  defp read_all_responses(socket, acc \\ [], buffer \\ "") do
    case :gen_tcp.recv(socket, 0, 2000) do
      {:ok, data} ->
        new_buffer = buffer <> data
        {msgs, rest} = decode_available(new_buffer)
        new_acc = acc ++ msgs

        if Enum.any?(new_acc, fn r -> r["status"] == ["done"] end) do
          new_acc
        else
          read_all_responses(socket, new_acc, rest)
        end

      {:error, :timeout} ->
        {msgs, _rest} = decode_available(buffer)
        acc ++ msgs

      {:error, _} ->
        acc
    end
  end

  defp decode_available(data, acc \\ []) do
    try do
      {msg, rest} = Bencode.decode_one(data)
      decode_available(rest, acc ++ [msg])
    rescue
      _ -> {acc, data}
    end
  end
end