feat: add smtp settings

lib/mv/mailer.ex

@@ -4,27 +4,194 @@ defmodule Mv.Mailer do
 
   Use `mail_from/0` for the configured sender address (join confirmation,
   user confirmation, password reset).
+
+  ## Sender identity
+
+  The "from" address is determined by priority:
+  1. `MAIL_FROM_EMAIL` / `MAIL_FROM_NAME` environment variables
+  2. Settings database (`smtp_from_email`, `smtp_from_name`)
+  3. Hardcoded default (`"Mila"`, `"noreply@example.com"`)
+
+  **Important:** On most SMTP servers the sender email must be owned by the
+  authenticated SMTP user. Set `smtp_from_email` to the same address as
+  `smtp_username` (or an alias allowed by the server).
+
+  ## SMTP adapter configuration
+
+  The SMTP adapter can be configured via:
+  - **Environment variables** at boot (`SMTP_HOST`, `SMTP_PORT`, `SMTP_USERNAME`,
+    `SMTP_PASSWORD`, `SMTP_PASSWORD_FILE`, `SMTP_SSL`) — configured in `runtime.exs`.
+  - **Admin Settings** (database) — read at send time via `Mv.Config.smtp_*()` helpers.
+    Settings-based config is passed per-send via `smtp_config/0`.
+
+  ENV takes priority over Settings (same pattern as OIDC and Vereinfacht).
   """
   use Swoosh.Mailer, otp_app: :mv
 
-  @doc """
-  Returns the configured "from" address for transactional emails.
+  import Swoosh.Email
+  use Gettext, backend: MvWeb.Gettext, otp_app: :mv
 
-  Configure in config.exs or runtime.exs as `config :mv, :mail_from, {name, email}`.
-  Default: `{"Mila", "noreply@example.com"}`.
+  require Logger
+
+  @email_regex ~r/^[^\s@]+@[^\s@]+\.[^\s@]+$/
+
+  @doc """
+  Returns the configured "from" address for transactional emails as `{name, email}`.
+
+  Priority: ENV `MAIL_FROM_NAME`/`MAIL_FROM_EMAIL` > Settings `smtp_from_name`/`smtp_from_email` > defaults.
   """
+  @spec mail_from() :: {String.t(), String.t()}
   def mail_from do
-    Application.get_env(:mv, :mail_from, {"Mila", "noreply@example.com"})
+    {Mv.Config.mail_from_name(), Mv.Config.mail_from_email() || "noreply@example.com"}
   end
 
   @doc """
   Sends a test email to the given address. Used from Global Settings SMTP section.
 
-  Returns `{:ok, email}` on success, `{:error, reason}` on failure (e.g. invalid address,
-  SMTP not configured, connection error). Stub: always returns error until implemented.
+  Returns `{:ok, email}` on success, `{:error, reason}` on failure.
+  The `reason` is a classified atom for known error categories, or `{:smtp_error, message}`
+  for SMTP-level errors with a human-readable message, or the raw term for unknown errors.
   """
-  @spec send_test_email(String.t()) :: {:ok, Swoosh.Email.t()} | {:error, term()}
-  def send_test_email(_to_email) do
-    {:error, :not_implemented}
+  @spec send_test_email(String.t()) ::
+          {:ok, Swoosh.Email.t()} | {:error, atom() | {:smtp_error, String.t()} | term()}
+  def send_test_email(to_email) when is_binary(to_email) do
+    if valid_email?(to_email) do
+      subject = gettext("Mila – Test email")
+
+      body =
+        gettext(
+          "This is a test email sent from Mila. If you received this, your SMTP configuration is working correctly."
+        )
+
+      email =
+        new()
+        |> from(mail_from())
+        |> to(to_email)
+        |> subject(subject)
+        |> text_body(body)
+        |> html_body("<p>#{body}</p>")
+
+      case deliver(email, smtp_config()) do
+        {:ok, _} = ok ->
+          ok
+
+        {:error, reason} ->
+          classified = classify_smtp_error(reason)
+          Logger.warning("SMTP test email failed: #{inspect(reason)}")
+          {:error, classified}
+      end
+    else
+      {:error, :invalid_email_address}
+    end
   end
+
+  def send_test_email(_), do: {:error, :invalid_email_address}
+
+  @doc """
+  Builds the per-send SMTP config from `Mv.Config` when SMTP is configured via
+  Settings only (not boot-time ENV). Returns an empty list when the mailer is
+  already configured at boot (ENV-based), so Swoosh uses the Application config.
+
+  The return value must be a flat keyword list (adapter, relay, port, ...).
+  Swoosh merges it with Application config; top-level keys override the mailer's
+  default adapter (e.g. Local in dev), so this delivery uses SMTP.
+  """
+  @spec smtp_config() :: keyword()
+  def smtp_config do
+    if Mv.Config.smtp_configured?() and not boot_smtp_configured?() do
+      host = Mv.Config.smtp_host()
+      port = Mv.Config.smtp_port() || 587
+      username = Mv.Config.smtp_username()
+      password = Mv.Config.smtp_password()
+      ssl_mode = Mv.Config.smtp_ssl() || "tls"
+
+      [
+        adapter: Swoosh.Adapters.SMTP,
+        relay: host,
+        port: port,
+        ssl: ssl_mode == "ssl",
+        tls: if(ssl_mode == "tls", do: :always, else: :never),
+        auth: :always,
+        username: username,
+        password: password,
+        # OTP 26+ enforces verify_peer; allow self-signed / internal certs.
+        # tls_options: STARTTLS upgrade (port 587); sockopts: direct SSL connect (port 465).
+        tls_options: [verify: :verify_none],
+        sockopts: [verify: :verify_none]
+      ]
+      |> Enum.reject(fn {_k, v} -> is_nil(v) end)
+    else
+      []
+    end
+  end
+
+  # ---------------------------------------------------------------------------
+  # SMTP error classification
+  # Maps raw gen_smtp error terms to human-readable atoms / structs.
+  # ---------------------------------------------------------------------------
+
+  @doc false
+  @spec classify_smtp_error(term()) ::
+          :sender_rejected
+          | :auth_failed
+          | :recipient_rejected
+          | :tls_failed
+          | :connection_failed
+          | {:smtp_error, String.t()}
+          | term()
+  def classify_smtp_error({:retries_exceeded, {:temporary_failure, _host, :tls_failed}}),
+    do: :tls_failed
+
+  def classify_smtp_error({:retries_exceeded, {:network_failure, _host, _}}),
+    do: :connection_failed
+
+  def classify_smtp_error({:send, {:permanent_failure, _host, msg}}) do
+    str = if is_list(msg), do: List.to_string(msg), else: to_string(msg)
+    classify_permanent_failure_message(str)
+  end
+
+  def classify_smtp_error(reason), do: reason
+
+  # ---------------------------------------------------------------------------
+  # Private helpers
+  # ---------------------------------------------------------------------------
+
+  defp classify_permanent_failure_message(str) do
+    cond do
+      smtp_auth_failure?(str) -> :auth_failed
+      smtp_sender_rejected?(str) -> :sender_rejected
+      smtp_recipient_rejected?(str) -> :recipient_rejected
+      true -> {:smtp_error, String.trim(str)}
+    end
+  end
+
+  defp smtp_auth_failure?(str),
+    do:
+      String.contains?(str, "535") or String.contains?(str, "authentication") or
+        String.contains?(str, "Authentication")
+
+  defp smtp_sender_rejected?(str),
+    do:
+      String.contains?(str, "553") or String.contains?(str, "Sender address rejected") or
+        String.contains?(str, "not owned")
+
+  defp smtp_recipient_rejected?(str),
+    do:
+      String.contains?(str, "550") or String.contains?(str, "No such user") or
+        String.contains?(str, "no such user") or String.contains?(str, "User unknown")
+
+  # Returns true when the SMTP adapter has been configured at boot time via ENV
+  # (i.e. the Application config is already set to the SMTP adapter).
+  defp boot_smtp_configured? do
+    case Application.get_env(:mv, __MODULE__) do
+      config when is_list(config) -> Keyword.get(config, :adapter) == Swoosh.Adapters.SMTP
+      _ -> false
+    end
+  end
+
+  defp valid_email?(email) when is_binary(email) do
+    Regex.match?(@email_regex, String.trim(email))
+  end
+
+  defp valid_email?(_), do: false
 end