1 files changed, 144 insertions, 6 deletions
diff --git a/requests/cache.py b/requests/cache.py
index 5be1dfbe..373e53c3 100644
--- a/requests/cache.py
+++ b/requests/cache.py
@@ -7,7 +7,11 @@ requests.cache
 
 Requests caching layer.
 """
+
+import time
 import hashlib
+import calendar
+import email
 from .packages.cachecore import SimpleCache
 
 DEFAULT_CACHE = SimpleCache
@@ -25,20 +29,16 @@ def expand_cache(c):
     if c is False:
         return Cache(backend=False)
 
-def request_hash(r, type=''):
-    """Returns a SHA256(type-method-url) for cache keys."""
-
-    s = '{0}-{1}-{2}'.format(type, r.request.method, r.request.full_url)
 
-    return hashlib.sha256(s).hexdigest()
 
 
 class Cache(object):
     """A Cache session."""
-    def __init__(self, backend=None, conditional=None, content=True):
+    def __init__(self, backend=None, conditional=None, content=True, handler=None):
 
         self.conditional = None
         self.content = None
+        self.handler = handler
 
         # Default to backend if True.
         if not backend is None:
@@ -54,3 +54,141 @@ class Cache(object):
         if content is not True:
             self.content = content
 
+        if handler is None:
+            self.handler = CacheHandler()
+
+
+
+class CacheHandler(object):
+
+
+    @staticmethod
+    def request_hash(r, type=''):
+        """Returns a SHA256(type-method-url) for cache keys."""
+
+        s = '{0}-{1}-{2}'.format(type, r.request.method, r.request.full_url)
+        return hashlib.sha256(s).hexdigest()
+
+
+    @staticmethod
+    def _parse_cache_control(headers):
+        """
+        Parse the cache control headers returning a dictionary with values
+        for the different directives.
+        """
+        retval = {}
+        if 'cache-control' in headers:
+            parts = headers['cache-control'].split(',')
+            parts_with_args = [
+                tuple([x.strip().lower() for x in part.split("=", 1)])
+                for part in parts if -1 != part.find("=")]
+            parts_wo_args = [(name.strip().lower(), 1)
+                             for name in parts if -1 == name.find("=")]
+            retval = dict(parts_with_args + parts_wo_args)
+        return retval
+
+    def cache_request(self, r, cache):
+        """See if we should use a cached response."""
+
+        return True
+        cache_hash = self.request_hash(r)
+        cc = self._parse_cache_control(r.headers)
+
+        # non-caching states
+        no_cache = False
+        if 'no-cache' in cc:
+            no_cache = True
+        if 'max-age' in cc and cc['max-age'] == 0:
+            no_cache = True
+
+        # see if it is in the cache anyways
+        in_cache = cache.get(cache_hash)
+        if no_cache or not in_cache:
+            return False
+
+        # It is in the cache, so lets see if it is going to be
+        # fresh enough
+        resp = cache.get(cache_hash)
+        now = time.time()
+        date = calendar.timegm(
+            email.Utils.parsedate_tz(resp.headers['date']))
+        current_age = max(0, now - date)
+
+        resp_cc = self._parse_cache_control(resp.headers)
+
+
+        # determine freshness
+        freshness_lifetime = 0
+        if 'max-age' in resp_cc:
+            try:
+                freshness_lifetime = int(resp_cc['max-age'])
+            except ValueError:
+                pass
+        elif 'expires' in resp.headers:
+            expires = email.Utils.parsedate_tz(resp.headers['expires'])
+            if expires != None:
+                expire_time = calendar.timegm(expires) - date
+                freshness_lifetime = max(0, expire_time)
+
+        # determine if we are setting freshness limit in the req
+        if 'max-age' in cc:
+            try:
+                freshness_lifetime = int(cc['max-age'])
+            except ValueError:
+                freshness_lifetime = 0
+
+        if 'min-fresh' in cc:
+            try:
+                min_fresh = int(cc['min-fresh'])
+            except ValueError:
+                min_fresh = 0
+            # adjust our current age by our min fresh
+            current_age += min_fresh
+
+        # see how fresh we actually are
+        fresh = (freshness_lifetime > current_age)
+
+        if fresh:
+            # make sure we set the from_cache to true
+            resp.from_cache = True
+            return resp
+
+        # we're not fresh, clean out the junk
+        cache.delete(cache_hash)
+
+        # return the original handler
+        return False
+
+
+    def cache_response(self, r, cache):
+        """Algorithm for caching requests."""
+
+        if r.status_code not in [200, 203]:
+            return
+
+        cc_req = self._parse_cache_control(r.request.headers)
+        cc = self._parse_cache_control(r.headers)
+
+        # cache_url = self.cache_url(r.request.full_url)
+        cache_hash = self.request_hash(r)
+
+        # Delete it from the cache if we happen to have it stored there
+        no_store = cc.get('no-store') or cc_req.get('no-store')
+        if no_store and cache.get(cache_hash):
+            cache.delete(cache_hash)
+
+        # Add to the cache if the response headers demand it. If there
+        # is no date header then we can't do anything about expiring
+        # the cache.
+        if 'date' in r.headers:
+
+            # cache when there is a max-age > 0
+            if cc and cc.get('max-age'):
+                if int(cc['max-age']) > 0:
+                    cache.set(cache_hash, r)
+
+            # If the request can expire, it means we should cache it
+            # in the meantime.
+            elif 'expires' in r.headers:
+                if int(r.headers['expires']) > 0:
+                    cache.set(cache_hash, r)