From e0c704a49d903b98ec48fc931f8510cd94f4d340 Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@qvarnlabs.com>
Date: Sat, 21 Jul 2018 16:46:10 +0300
Subject: Change: make it possible to cache preprocssing output

This should reduce rebuild times a lot.
---
 ql-ikiwiki-preprocess | 77 ++++++++++++++++++++++++++++++++-------------------
 1 file changed, 48 insertions(+), 29 deletions(-)

diff --git a/ql-ikiwiki-preprocess b/ql-ikiwiki-preprocess
index 35174e2..03f3019 100755
--- a/ql-ikiwiki-preprocess
+++ b/ql-ikiwiki-preprocess
@@ -26,9 +26,7 @@ import tempfile
 import cliapp
 
 
-def write_temp(content, suffix, tgtdir):
-    fd, filename = tempfile.mkstemp(dir=tgtdir, suffix=suffix)
-    os.close(fd)
+def write_file(content, filename):
     with open(filename, 'w') as f:
         f.write(content)
     return filename
@@ -57,15 +55,17 @@ def remove_prefixes(lines):
     return ''.join(result)
 
 
-def process_uml(lines, tgtdir):
+def process_uml(lines, tgtdir, relative, mtime):
     title = get_uml_title(lines)
     uml_text = remove_prefixes(lines)
-    filename = write_temp(uml_text, '.uml', tgtdir)
-    format_uml(filename)
-    prefix, _ = os.path.splitext(filename)
-    image = prefix + '.png'
-    relative = make_relative(os.path.abspath(tgtdir), image)
-    include = '[[!img  {}]]\n'.format(relative)
+    uml_filename = os.path.join(tgtdir, relative + '.uml')
+    png_basename = os.path.join(relative + '.png')
+    png_filename = os.path.join(tgtdir, png_basename)
+
+    write_file(uml_text, uml_filename)
+    format_uml(uml_filename)
+
+    include = '[[!img  {}]]\n'.format(png_basename)
     return [include]
 
 
@@ -77,7 +77,7 @@ def format_roadmap(text):
     return '\n'.join(output_lines[1:-1])
 
 
-def process_roadmap(lines, tgtdir):
+def process_roadmap(lines, tgtdir, relative, mtime):
     roadmap_text = remove_prefixes(lines[1:-1])
     include = format_roadmap(roadmap_text)
     return ['[[!graph src="""\n', include, '"""]]\n']
@@ -123,19 +123,22 @@ def find_section(lines, sections):
     return 0, len(lines), None
 
 
-def preprocess_lines(lines, tgtdir):
+def preprocess_lines(lines, tgtdir, relative, mtime):
     sections = [
         ('@startuml\n', '@enduml\n', process_uml),
         ('@startroadmap\n', '@endroadmap\n', process_roadmap),
     ]
 
     result = []
+    counter = 0
     while lines:
         start, after, func = find_section(lines, sections)
         result.extend(lines[:start])
         section = lines[start:after]
         if func:
-            include = func(section, tgtdir)
+            counter += 1
+            output = '{}-{}'.format(relative, counter)
+            include = func(section, tgtdir, output, mtime)
             result.extend(include)
         else:
             result.extend(section)
@@ -143,28 +146,45 @@ def preprocess_lines(lines, tgtdir):
     return result
 
 
-def preprocess_mdwn(src, tgt):
-    lines = read_lines(src)
-    tgtdir = os.path.dirname(tgt)
-    lines = preprocess_lines(lines, tgtdir)
-    write_lines(tgt, lines)
-    shutil.copystat(src, tgt)
+def needs_preprocessing(src, tgt):
+    if not os.path.exists(tgt):
+        return True
+    src_mtime = os.path.getmtime(src)
+    tgt_mtime = os.path.getmtime(tgt)
+    return src_mtime != tgt_mtime
+
+
+def preprocess_mdwn(srcdir, tgtdir, relative):
+    src = make_absolute(srcdir, relative)
+    tgt = make_absolute(tgtdir, relative)
+
+    if needs_preprocessing(src, tgt):
+        src_mtime = os.path.getmtime(src)
+        lines = read_lines(src)
+        lines = preprocess_lines(lines, tgtdir, relative, src_mtime)
+        write_lines(tgt, lines)
+        shutil.copystat(src, tgt)
             
 
-def copy_file(src, tgt):
+def copy_file(srcdir, tgtdir, relative):
+    src = make_absolute(srcdir, relative)
+    tgt = make_absolute(tgtdir, relative)
     shutil.copy(src, tgt)
     shutil.copystat(src, tgt)
 
 
-def preprocess_file(src, tgt):
-    if src.endswith('.mdwn'):
-        preprocess_mdwn(src, tgt)
+def preprocess_file(srcdir, tgtdir, relative):
+    if relative.endswith('.mdwn'):
+        preprocess_mdwn(srcdir, tgtdir, relative)
     else:
-        copy_file(src, tgt)
+        copy_file(srcdir, tgtdir, relative)
 
 
-def copy_dir(src, tgt):
-    os.makedirs(tgt)
+def copy_dir(srcdir, tgtdir, relative):
+    src = make_absolute(srcdir, relative)
+    tgt = make_absolute(tgtdir, relative)
+    if not os.path.exists(tgt):
+        os.makedirs(tgt)
     return lambda: shutil.copystat(src, tgt)
 
 
@@ -210,15 +230,14 @@ def preprocess(srcdir, tgtdir):
     ]
 
     assert os.path.isdir(srcdir)
-    assert not os.path.exists(tgtdir)
+#    assert not os.path.exists(tgtdir)
     todo = []
     for pathname in find_relative(srcdir):
         src = make_absolute(srcdir, pathname)
         tgt = make_absolute(tgtdir, pathname)
-
         for func, callback in preprocessors:
             if func(src):
-                do = callback(src, tgt)
+                do = callback(srcdir, tgtdir, pathname)
                 if do is not None:
                     todo.append(do)
 
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