From 558138de5accceb10eeb454a77385c9e823f1b1c Mon Sep 17 00:00:00 2001
From: Dominik Moritz <domoritz@gmail.com>
Date: Fri, 26 Oct 2012 12:45:59 +0200
Subject: [PATCH] Simplified plugins interface

---
 ckan/controllers/package.py |  3 ++-
 ckan/lib/helpers.py         | 34 ++++++++++++++--------------------
 ckan/plugins/interfaces.py  | 10 +++++-----
 3 files changed, 21 insertions(+), 26 deletions(-)

diff --git a/ckan/controllers/package.py b/ckan/controllers/package.py
index 709064a088f..c7082617732 100644
--- a/ckan/controllers/package.py
+++ b/ckan/controllers/package.py
@@ -1334,7 +1334,6 @@ def resource_datapreview(self, id, resource_id):
             c.resource = get_action('resource_show')(context,
                                                      {'id': resource_id})
             c.package = get_action('package_show')(context, {'id': id})
-            c.resource_json = json.dumps(c.resource)
 
             plugins = ckanplugins.PluginImplementations(ckanplugins.IResourcePreview)
             plugins_that_can_preview = [p for p in plugins if p.can_preview(c.resource)]
@@ -1346,6 +1345,8 @@ def resource_datapreview(self, id, resource_id):
             plugin = plugins_that_can_preview[0]
             plugin.setup_template_variables(context, {'resource': c.resource, 'package': c.package})
 
+            c.resource_json = json.dumps(c.resource)
+
         except NotFound:
             abort(404, _('Resource not found'))
         except NotAuthorized:
diff --git a/ckan/lib/helpers.py b/ckan/lib/helpers.py
index 1169d7e021a..ff411d96deb 100644
--- a/ckan/lib/helpers.py
+++ b/ckan/lib/helpers.py
@@ -1265,19 +1265,23 @@ def format_resource_items(items):
     return sorted(output, key=lambda x: x[0])
 
 
-def _can_be_previewed(resource, is_same_domain):
+def _can_be_previewed(resource):
     '''
     Determines whether there is an extension that can preview the resource.
-
-    :param resource: a resource dictionary
-    :param is_same_domain: True if the resource is on the
-                    same domain (same url as CKAN itself)
     '''
+    # compare CKAN domain and resource URL
+    import ckan.plugins.toolkit as toolkit
+    ckan_domain = toolkit.request.environ['HTTP_HOST'].lower()
+    request_protocol = toolkit.request.environ['SERVER_PROTOCOL'].lower()
+
+    parsed = urlparse.urlparse(resource['url'])
+    resource_domain = (parsed.hostname + ':' + str(parsed.port)).lower()
+
+    resource['on_same_domain'] = (ckan_domain == resource_domain
+            and parsed.scheme.lower() in request_protocol)
+
     plugins = ckanplugins.PluginImplementations(ckanplugins.IResourcePreview)
-    for plugin in plugins:
-        if plugin.can_preview(resource) and (is_same_domain or not plugin.requires_same_orign(resource)):
-            return True
-    return False
+    return any(plugin.can_preview(resource) for plugin in plugins)
 
 
 def resource_preview(resource, pkg_id):
@@ -1298,17 +1302,7 @@ def resource_preview(resource, pkg_id):
     directly = False
     url = ''
 
-    # compare CKAN domain and resource URL
-    import ckan.plugins.toolkit as toolkit
-    ckan_domain = toolkit.request.environ['HTTP_HOST'].lower()
-    request_protocol = toolkit.request.environ['SERVER_PROTOCOL'].lower()
-
-    parsed = urlparse.urlparse(resource['url'])
-    resource_domain = (parsed.hostname + ':' + str(parsed.port)).lower()
-
-    is_same_domain = ckan_domain == resource_domain and parsed.scheme.lower() in request_protocol
-
-    if _can_be_previewed(resource, is_same_domain):
+    if _can_be_previewed(resource):
         url = url = url_for(controller='package', action='resource_datapreview',
             resource_id=resource['id'], id=pkg_id, qualified=True)
     elif format_lower in DIRECT_EMBEDS:
diff --git a/ckan/plugins/interfaces.py b/ckan/plugins/interfaces.py
index c52ef3bdaa2..b067b41b181 100644
--- a/ckan/plugins/interfaces.py
+++ b/ckan/plugins/interfaces.py
@@ -201,17 +201,17 @@ class IResourcePreview(Interface):
     def can_preview(self, resource):
         '''
         Return True if the extension can preview the resource.
-        '''
 
-    def requires_same_orign(self, resource):
-        '''
-        Return True if the extension cannot preview the resource from
-        a different domain because of the same origin policy.
+        Make sure you also make sure to ckeck the ``on_same_domain`` value of the
+        resource or the url if your preview requires the resource to be on
+        the same domain because of the same origin policy.
         '''
 
     def setup_template_variables(self, context, data_dict):
         '''
         Add variables to c just prior to the template being rendered.
+
+        Change the url to a proxied domain if necessary.
         '''
 
     def preview_template(self, context):