[gnome-photos] google: Look at the cache before hitting the network

[Debarshi Ray <debarshir src gnome org>]

commit 1f2d4d29b83c00f15af3e2142cdf78e5f9b2e558
Author: Debarshi Ray <debarshir gnome org>
Date:   Mon May 25 16:10:50 2015 +0200

    google: Look at the cache before hitting the network
    
    This makes sense because network and server failures should not fail
    the operation if we have an entry in the cache.
    
    This changes the cache structure. Instead of using
    GDataEntry:content-uri as the file name, we use a hash of the
    nao:identifier. Hashing is necessary because the nao:identifier is not
    a valid file name.

 src/photos-google-item.c |   54 ++++++++++++++++++++++++++++-----------------
 1 files changed, 33 insertions(+), 21 deletions(-)
---
diff --git a/src/photos-google-item.c b/src/photos-google-item.c
index a5eb27b..f4e8752 100644
--- a/src/photos-google-item.c
+++ b/src/photos-google-item.c
@@ -1,6 +1,6 @@
 /*
  * Photos - access, organize and share your photos on GNOME
- * Copyright © 2014 Red Hat, Inc.
+ * Copyright © 2014, 2015 Red Hat, Inc.
  * Copyright © 2014 Saurav Agarwalla
  *
  * This program is free software; you can redistribute it and/or
@@ -198,43 +198,53 @@ photos_google_item_download (PhotosBaseItem *item, GCancellable *cancellable, GE
   GFile *local_file = NULL;
   GFile *remote_file = NULL;
   const gchar *cache_dir;
+  const gchar *identifier;
+  const gchar *mime_type;
   const gchar *uri;
+  gchar *extension = NULL;
+  gchar *identifier_hash = NULL;
   gchar *local_dir = NULL;
   gchar *local_filename = NULL;
   gchar *local_path = NULL;
   gchar *ret_val = NULL;
 
+  cache_dir = g_get_user_cache_dir ();
+  local_dir = g_build_filename (cache_dir, PACKAGE_TARNAME, "google", NULL);
+  g_mkdir_with_parents (local_dir, 0700);
+
+  identifier = photos_base_item_get_identifier (item);
+  identifier_hash = g_compute_checksum_for_string (G_CHECKSUM_SHA1, identifier, -1);
+  mime_type = photos_base_item_get_mime_type (item);
+  extension = photos_utils_get_extension_from_mime_type (mime_type);
+  if (extension == NULL)
+    extension = g_strdup ("tmp");
+  local_filename = g_strdup_printf ("%s.%s", identifier_hash, extension);
+  local_path = g_build_filename (local_dir, local_filename, NULL);
+  if (g_file_test (local_path, G_FILE_TEST_EXISTS))
+    goto end;
+
   entry = photos_google_get_picasaweb_file (item, cancellable, error);
   if (entry == NULL)
     goto out;
 
   uri = gdata_entry_get_content_uri (entry);
   remote_file = g_file_new_for_uri (uri);
-  cache_dir = g_get_user_cache_dir ();
-
-  local_dir = g_build_filename (cache_dir, PACKAGE_TARNAME, "google", NULL);
-  g_mkdir_with_parents (local_dir, 0700);
-
-  local_filename = g_file_get_basename (remote_file);
-  local_path = g_build_filename (local_dir, local_filename, NULL);
   local_file = g_file_new_for_path (local_path);
 
-  if (!g_file_test (local_path, G_FILE_TEST_EXISTS))
+  photos_debug (PHOTOS_DEBUG_NETWORK, "Downloading %s from Google to %s", uri, local_path);
+  if (!g_file_copy (remote_file,
+                    local_file,
+                    G_FILE_COPY_ALL_METADATA | G_FILE_COPY_OVERWRITE,
+                    cancellable,
+                    NULL,
+                    NULL,
+                    error))
     {
-      photos_debug (PHOTOS_DEBUG_NETWORK, "Downloading %s from Google to %s", uri, local_path);
-      if (!g_file_copy (remote_file,
-                        local_file,
-                        G_FILE_COPY_ALL_METADATA | G_FILE_COPY_OVERWRITE,
-                        cancellable,
-                        NULL,
-                        NULL,
-                        error))
-        {
-          g_file_delete (local_file, NULL, NULL);
-          goto out;
-        }
+      g_file_delete (local_file, NULL, NULL);
+      goto out;
     }
 
+ end:
   ret_val = local_path;
   local_path = NULL;
 
@@ -242,6 +252,8 @@ photos_google_item_download (PhotosBaseItem *item, GCancellable *cancellable, GE
   g_free (local_path);
   g_free (local_filename);
   g_free (local_dir);
+  g_free (identifier_hash);
+  g_free (extension);
   g_clear_object (&local_file);
   g_clear_object (&remote_file);
   g_clear_object (&entry);