From 8d4f373257c9f287794e895afa88cdf9e0755328 Mon Sep 17 00:00:00 2001
From: Andrew Bruce <me@andrewbruce.net>
Date: Mon, 14 Oct 2024 16:45:44 +0100
Subject: [PATCH] Raise exception when font not set

---
 lib/mudbrick.ex             | 51 ++++++++++++++++++++-----------------
 lib/mudbrick/font.ex        |  4 +++
 test/mudbrick/font_test.exs | 24 +++++++++++++++++
 3 files changed, 56 insertions(+), 23 deletions(-)

diff --git a/lib/mudbrick.ex b/lib/mudbrick.ex
index c0186e8..4869629 100644
--- a/lib/mudbrick.ex
+++ b/lib/mudbrick.ex
@@ -1,6 +1,7 @@
 defmodule Mudbrick do
   alias Mudbrick.ContentStream
   alias Mudbrick.Document
+  alias Mudbrick.Font
   alias Mudbrick.Page
 
   @dpi 72
@@ -57,7 +58,7 @@ defmodule Mudbrick do
         )
 
       :error ->
-        raise Mudbrick.Font.Unregistered, "Unregistered font: #{user_identifier}"
+        raise Font.Unregistered, "Unregistered font: #{user_identifier}"
     end
   end
 
@@ -72,29 +73,33 @@ defmodule Mudbrick do
         &match?(%ContentStream.Tf{}, &1)
       )
 
-    [first_part | parts] = String.split(text, "\n")
+    if latest_font_setting == nil do
+      raise Font.NotSet, "No font chosen"
+    else
+      [first_part | parts] = String.split(text, "\n")
 
-    context
-    |> ContentStream.add(
-      ContentStream.TL,
-      leading: latest_font_setting.size * 1.2
-    )
-    |> ContentStream.add(
-      ContentStream.Tj,
-      font: latest_font_setting.font,
-      text: first_part
-    )
-    |> then(fn context ->
-      for part <- parts, reduce: context do
-        acc ->
-          ContentStream.add(
-            acc,
-            ContentStream.Apostrophe,
-            font: latest_font_setting.font,
-            text: part
-          )
-      end
-    end)
+      context
+      |> ContentStream.add(
+        ContentStream.TL,
+        leading: latest_font_setting.size * 1.2
+      )
+      |> ContentStream.add(
+        ContentStream.Tj,
+        font: latest_font_setting.font,
+        text: first_part
+      )
+      |> then(fn context ->
+        for part <- parts, reduce: context do
+          acc ->
+            ContentStream.add(
+              acc,
+              ContentStream.Apostrophe,
+              font: latest_font_setting.font,
+              text: part
+            )
+        end
+      end)
+    end
   end
 
   def render({doc, _page}) do
diff --git a/lib/mudbrick/font.ex b/lib/mudbrick/font.ex
index 014996f..74371a9 100644
--- a/lib/mudbrick/font.ex
+++ b/lib/mudbrick/font.ex
@@ -15,6 +15,10 @@ defmodule Mudbrick.Font do
     :parsed
   ]
 
+  defmodule NotSet do
+    defexception [:message]
+  end
+
   defmodule Unregistered do
     defexception [:message]
   end
diff --git a/test/mudbrick/font_test.exs b/test/mudbrick/font_test.exs
index c9f4192..a1c264d 100644
--- a/test/mudbrick/font_test.exs
+++ b/test/mudbrick/font_test.exs
@@ -87,6 +87,30 @@ defmodule Mudbrick.FontTest do
     assert Document.object_with_ref(doc, file.ref)
   end
 
+  test "forgetting to set the font is an error" do
+    import Mudbrick
+
+    chain =
+      new()
+      |> page(
+        fonts: %{
+          helvetica: [
+            name: :Helvetica,
+            type: :TrueType,
+            encoding: :PDFDocEncoding
+          ]
+        }
+      )
+      |> contents()
+
+    e =
+      assert_raise Font.NotSet, fn ->
+        chain |> text("hi there")
+      end
+
+    assert e.message == "No font chosen"
+  end
+
   test "asking for an unregistered font is an error" do
     import Mudbrick