Preprocessing of template resources

In template resources (found under static/templates), strings of the
form "PATH/TO/STATIC/RESOURCE?KIWIXCACHEID" are expanded into
"PATH/TO/STATIC/RESOURCE?cacheid=CACHEIDVAL" where CACHEIDVAL is a
8-digit hexadecimal hash digest of the file at
static/PATH/TO/STATIC/RESOURCE.

scripts/kiwix-resources

@@ -0,0 +1,116 @@
+#!/usr/bin/env python3
+
+'''
+Copyright 2022 Veloman Yunkan <veloman.yunkan@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3 of the License, or any
+later version.
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA.
+'''
+
+import argparse
+import hashlib
+import os.path
+import re
+
+def read_resource_file(resource_file_path):
+    with open(resource_file_path, 'r') as f:
+        return [line.strip() for line in f]
+
+def list_resources(resource_file_path):
+    for resource_path in read_resource_file(resource_file_path):
+        print(resource_path)
+
+def get_resource_revision(base_dir, resource_path):
+    with open(os.path.join(base_dir, resource_path), 'rb') as f:
+        return hashlib.sha1(f.read()).hexdigest()[:8]
+
+resource_revisions = {}
+
+def fill_resource_revisions(resource_file_path):
+    base_dir = os.path.dirname(os.path.realpath(resource_file_path))
+    for resource in read_resource_file(resource_file_path):
+        resource_revisions[resource] = get_resource_revision(base_dir, resource)
+
+RESOURCE_WITH_CACHEID_URL_PATTERN=r'"([^"?]+)\?KIWIXCACHEID([^"]*)"'
+
+def set_cacheid(resource_matchobj):
+    path = resource_matchobj.group(1)
+    resource = path
+    root_prefix = '{{root}}/'
+    if resource.startswith(root_prefix):
+        resource = resource[len(root_prefix):]
+    extra_query = resource_matchobj.group(2)
+    cacheid = 'cacheid=' + resource_revisions[resource]
+    return f'"{path}?{cacheid}{extra_query}"'
+
+def preprocess_line(line):
+    if 'KIWIXCACHEID' in line:
+        line = re.sub(RESOURCE_WITH_CACHEID_URL_PATTERN, set_cacheid, line)
+        assert not 'KIWIXCACHEID' in line
+    return line
+
+def preprocess_template(srcpath, dstpath):
+    preprocessed_lines = []
+    with open(srcpath, 'r') as source:
+        for line in source:
+            preprocessed_lines.append(preprocess_line(line))
+
+    with open(dstpath, 'w') as target:
+        print("".join(preprocessed_lines), end='', file=target)
+
+def symlink_resource(src, resource_path):
+    if os.path.exists(resource_path):
+        if os.path.islink(resource_path) and os.readlink(resource_path) == src:
+            return
+        os.remove(resource_path)
+    os.symlink(src, resource_path)
+
+def preprocess_resource(srcdir, resource_path, outdir):
+    resource_dir = os.path.dirname(resource_path)
+    if resource_dir != '':
+        os.makedirs(os.path.join(outdir, resource_dir), exist_ok=True)
+    srcpath = os.path.join(srcdir, resource_path)
+    outpath = os.path.join(outdir, resource_path)
+    if resource_path.startswith('templates/'):
+        preprocess_template(srcpath, outpath)
+    else:
+        symlink_resource(srcpath, outpath)
+
+def copy_file(src_path, dst_path):
+    with open(src_path, 'rb') as src:
+        with open(dst_path, 'wb') as dst:
+            dst.write(src.read())
+
+def preprocess_resources(resource_file_path, outdir):
+    base_dir = os.path.dirname(os.path.realpath(resource_file_path))
+    resource_filename = os.path.basename(resource_file_path)
+    for resource in read_resource_file(resource_file_path):
+        preprocess_resource(base_dir, resource, outdir)
+    copy_file(resource_file_path, os.path.join(outdir, resource_filename))
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    commands = parser.add_mutually_exclusive_group()
+    commands.add_argument('--list-all', action='store_true')
+    commands.add_argument('--preprocess', action='store_true')
+    parser.add_argument('--outdir')
+    parser.add_argument('resource_file')
+    args = parser.parse_args()
+
+    if args.list_all:
+        list_resources(args.resource_file)
+    elif args.preprocess:
+        fill_resource_revisions(args.resource_file)
+        preprocess_resources(args.resource_file, args.outdir)