From 95ceab6991b5b491ebe39374989d3bcf7d12314c Mon Sep 17 00:00:00 2001
From: Jaro <jaro@argonaut-constellation.org>
Date: Sat, 17 Jun 2023 00:10:44 +0200
Subject: [PATCH] Implement calculation of safe paragraph width.

---
 .../Internal/Rich/ParagraphLayout.hs          | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/Data/Text/ParagraphLayout/Internal/Rich/ParagraphLayout.hs b/src/Data/Text/ParagraphLayout/Internal/Rich/ParagraphLayout.hs
index 719a6de..30bd3fa 100644
--- a/src/Data/Text/ParagraphLayout/Internal/Rich/ParagraphLayout.hs
+++ b/src/Data/Text/ParagraphLayout/Internal/Rich/ParagraphLayout.hs
@@ -7,6 +7,7 @@ module Data.Text.ParagraphLayout.Internal.Rich.ParagraphLayout
     , paragraphLayout
     , paragraphOriginX
     , paragraphOriginY
+    , paragraphSafeWidth
     , shapedRuns
     )
 where
@@ -72,3 +73,25 @@ appendFragments (ParagraphLayout _ a) (ParagraphLayout _ b) =
 -- | Return all shaped runs in the paragraph.
 shapedRuns :: ParagraphLayout d -> [ShapedRun]
 shapedRuns pl = map shapedRun $ paragraphFragments pl
+
+-- | Width of the widest line, including spacing.
+--
+-- This is the smallest `Data.Text.ParagraphLayout.Rich.paragraphMaxWidth`
+-- that will not introduce new line breaks.
+--
+-- When `Data.Text.ParagraphLayout.Rich.paragraphMaxWidth` is set to `maxBound`,
+-- `paragraphSafeWidth` can be used to determine the @max-content@ width of the
+-- paragraph for CSS.
+paragraphSafeWidth :: ParagraphLayout d -> Int32
+paragraphSafeWidth pl = maximum $ map (lineWidth pl) $ lineNumbers pl
+
+lineWidth :: ParagraphLayout d -> Int -> Int32
+lineWidth pl line = sum $ map fragmentWidth $ lineFragments pl line
+
+fragmentWidth :: Fragment d -> Int32
+fragmentWidth f = width $ fragmentSpacedRect f
+
+lineFragments :: ParagraphLayout d -> Int -> [Fragment d]
+lineFragments pl line = filter byLine $ paragraphFragments pl
+    where
+        byLine frag = line == fragmentLine frag
-- 
2.30.2