From a939e6503c2106003a65aae59138993429fa6c4e Mon Sep 17 00:00:00 2001
From: Bastian Venthur <venthur@debian.org>
Date: Sat, 6 Aug 2022 21:56:41 +0200
Subject: [PATCH] rebuild only files that need re-building

we compare the mtimes of src and dst
---
 blag/blag.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/blag/blag.py b/blag/blag.py
index e84bc2b..c47fc2b 100644
--- a/blag/blag.py
+++ b/blag/blag.py
@@ -293,6 +293,18 @@ def process_markdown(convertibles, input_dir, output_dir,
     for src, dst in convertibles:
         logger.debug(f'Processing {src}')
 
+        # see first if the dst actually needs re-building. for that we compare
+        # the mtimes and assume mtime_dst > mtime_src means that it needs not
+        # to be rebuilt
+        if os.path.exists(f'{output_dir}/{dst}'):
+            mtime_src = os.stat(f'{input_dir}/{src}').st_mtime
+            mtime_dst = os.stat(f'{output_dir}/{dst}').st_mtime
+            if mtime_dst >= mtime_src:
+                logger.debug(
+                    'Skipping, as target exists and is newer than source.'
+                )
+                continue
+
         with open(f'{input_dir}/{src}', 'r') as fh:
             body = fh.read()