defmodule Mv.Smtp.ConfigBuilderTest do
  @moduledoc """
  Unit tests for Mv.Smtp.ConfigBuilder.build_opts/1.

  Ensures the single source of truth for SMTP opts correctly handles:
  - Port 587 (TLS): sockopts must NOT contain :verify (gen_tcp rejects it).
  - Port 465 (SSL): sockopts MUST contain :verify for initial ssl:connect.
  """
  use ExUnit.Case, async: true

  alias Mv.Smtp.ConfigBuilder

  describe "build_opts/1" do
    test "port 587 (TLS): does not include :verify in sockopts" do
      opts =
        ConfigBuilder.build_opts(
          host: "smtp.example.com",
          port: 587,
          username: "user",
          password: "secret",
          ssl_mode: "tls",
          verify_mode: :verify_none
        )

      sockopts = Keyword.get(opts, :sockopts, [])
      refute Keyword.has_key?(sockopts, :verify), "for 587 sockopts must not contain :verify"
      assert Keyword.get(opts, :tls) == :always
      assert Keyword.get(opts, :ssl) == false
    end

    test "port 465 (SSL): includes :verify in sockopts" do
      opts =
        ConfigBuilder.build_opts(
          host: "smtp.example.com",
          port: 465,
          username: "user",
          password: "secret",
          ssl_mode: "ssl",
          verify_mode: :verify_peer
        )

      sockopts = Keyword.get(opts, :sockopts, [])
      assert Keyword.has_key?(sockopts, :verify), "for 465 sockopts must contain :verify"
      assert Keyword.get(sockopts, :verify) == :verify_peer
      assert Keyword.get(opts, :ssl) == true
      assert Keyword.get(opts, :tls) == :never
    end

    test "strips nil values" do
      opts =
        ConfigBuilder.build_opts(
          host: "smtp.example.com",
          port: 587,
          username: nil,
          password: nil,
          ssl_mode: "tls",
          verify_mode: :verify_none
        )

      refute Keyword.has_key?(opts, :username)
      refute Keyword.has_key?(opts, :password)
      assert Keyword.get(opts, :relay) == "smtp.example.com"
    end

    test "includes adapter and required keys" do
      opts =
        ConfigBuilder.build_opts(
          host: "mail.example.com",
          port: 587,
          username: "u",
          password: "p",
          ssl_mode: "tls",
          verify_mode: :verify_none
        )

      assert Keyword.get(opts, :adapter) == Swoosh.Adapters.SMTP
      assert Keyword.get(opts, :relay) == "mail.example.com"
      assert Keyword.get(opts, :port) == 587
      assert Keyword.get(opts, :auth) == :always
      assert Keyword.get(opts, :tls_options) == [verify: :verify_none]
    end
  end
end