From e5143a86ad615c66c7531924796b19831365f22c Mon Sep 17 00:00:00 2001
From: giuliof <giulio@glgprograms.it>
Date: Sat, 4 Sep 2021 00:19:06 +0200
Subject: [PATCH] Tentativo di implementazione fetching remoto .tc. Da testare
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- Richiesta HTTP (o via webdav, è equivalente).
- Uso del Last-modified nell'header HTTP per il rinnovo della cache.
---
 conf/conf.ini |  4 +++-
 main.py       | 41 +++++++++++++++++++++++++++++++----------
 2 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/conf/conf.ini b/conf/conf.ini
index 67763ad..ca856c4 100644
--- a/conf/conf.ini
+++ b/conf/conf.ini
@@ -9,7 +9,9 @@
 [default]
 
     # Path to Tellico .tc database to use
-    path = /path/to/some/tellico.tc
+    path = http://path/to/some/tellico.tc
+    user = user
+    pswd = pswd
 
     # Path to output directory for images and temporary data
     # Must be accessible by webserver
diff --git a/main.py b/main.py
index 9659f4d..5cbbc0a 100755
--- a/main.py
+++ b/main.py
@@ -20,9 +20,14 @@ import json
 import sys
 import cgitb, cgi
 import zipfile
+from io import BytesIO
 import shutil as sh
 import os
 import time
+# Connection to remote library file
+import requests
+# Parsing of HTTP RFC 1123 datetime format
+from email.utils import parsedate_to_datetime
 
 # Our custom library (again no pun intended)
 import tcparser
@@ -52,19 +57,35 @@ luh = open(glob.conf['default']['outdir'] + '/lastupdate.txt', 'r')
 lu = int(float(luh.read()))
 luh.close()
 
-mtime = os.path.getmtime(glob.conf['default']['path'])
+# Fetch last modified from HTTP header
+path = glob.conf['default']['path']
+user = glob.conf['default']['user']
+pswd = glob.conf['default']['pswd']
+req  = requests.head(path, auth=(user, pswd))
 
-if int(lu) < int(mtime):
-    # Unzip Tellico .tc database
-    zipHandler = zipfile.ZipFile(glob.conf['default']['path'], 'r')
-    zipHandler.extractall(glob.conf['default']['outdir'])
-    zipHandler.close()
-    luh = open(glob.conf['default']['outdir'] + '/lastupdate.txt', 'w')
-    luh.write(str(time.time()))
-    luh.close()
+cachefile = glob.conf['default']['outdir'] + "/tellico.xml"
+
+# If header fetch fails I can't update cache.
+# Try with current one, if exists
+if req.status_code == 200 and 'Last-modified' in req.headers:
+    mtime = parsedate_to_datetime(req.headers['Last-modified']).timestamp()
+
+    # If local xml is out-of-date or missing, try download it
+    if int(lu) < int(mtime) or not os.path.isfile(cachefile):
+        # Download Tellico .tc database
+        req = requests.get(path, auth=(user, pswd))
+        if req.status_code == 200 and req.content != None:    
+            # Unzip Tellico .tc database and "cache it" locally
+            zipHandler = zipfile.ZipFile(BytesIO(req.content), 'r')
+            zipHandler.extractall(glob.conf['default']['outdir'])
+            zipHandler.close()
+            luh = open(glob.conf['default']['outdir'] + '/lastupdate.txt', 'w')
+            luh.write(int(mtime))
+            luh.close()
 
 # Get a Python-friendly library struct from XML file
-library = tcparser.getLibrary(glob.conf['default']['outdir'] + "/tellico.xml", lu)
+library = tcparser.getLibrary(cachefile, lu)
+# TODO: properly handle missing file errors or things like this
 
 ### Get filters to search for books ###
 try: