Initial Environment class and test

This implements the "resource-registry" and "parameters" section
I am holding off on the "properties" section until we really
know we need it.

blueprint environments
Change-Id: Ib6e9e5cd1c68c255dc048bdde21a6b3e1dc54243

diff --git a/heat/engine/environment.py b/heat/engine/environment.py
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+++ b/heat/engine/environment.py
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+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+# The environment should look like this:
+# Note: the base_url, urls and files should be handled earlier
+#       and by the time it gets to the engine they are all just names.
+#
+# Use case 1: I want to use all the resource types from provider X
+#resource_registry:
+#  "OS::*": "Dreamhost::*"
+#  # could also use a url like this (assuming they could all be
+#  # expressed in nested stacks)
+#  "OS::*": http://dreamhost.com/bla/resources-types/*"
+#
+# Use case 2: I want to use mostly the default resources except my
+# custom one for a particular resource in the template.
+#resource_registry:
+#  resources:
+#    my_db_server:
+#      "OS::DBInstance": file://~/all_my_cool_templates/db.yaml
+#
+# Use case 3: I always want to always map resource type X to Y
+#resource_registry:
+#  "OS::Networking::FloatingIP": "OS::Nova::FloatingIP"
+#  "OS::Loadbalancer": file://~/all_my_cool_templates/lb.yaml
+#
+# Use case 4: I use custom resources a lot and want to shorten the
+# url/path
+#resource_registry:
+#  base_url: http://bla.foo/long/url/
+#  resources:
+#    my_db_server:
+#      "OS::DBInstance": dbaas.yaml
+#
+# Use case 5: I want to put some common parameters in the environment
+#parameters:
+#  KeyName: heat_key
+#  InstanceType: m1.large
+#  DBUsername: wp_admin
+#  LinuxDistribution: F17
+
+
+class Environment(object):
+
+    def __init__(self, env=None):
+        """Create an Environment from a dict of varing format.
+        1) old-school flat parameters
+        2) or newer {resource_registry: bla, parameters: foo}
+
+        :param env: the json environment
+        """
+        if env is None:
+            env = {}
+        self.resource_registry = env.get('resource_registry', {})
+        if 'resources' not in self.resource_registry:
+            self.resource_registry['resources'] = {}
+        if 'parameters' in env:
+            self.params = env['parameters']
+        else:
+            self.params = dict((k, v) for (k, v) in env.iteritems()
+                               if k != 'resource_registry')
+
+    def get_resource_type(self, resource_type, resource_name):
+        """Get the specific resource type that the user wants to implement
+        'resource_type'.
+        """
+        impl = self.resource_registry['resources'].get(resource_name)
+        if impl and resource_type in impl:
+            return impl[resource_type]
+
+        # handle: "OS::Compute::Server" -> "Rackspace::Compute::Server"
+        impl = self.resource_registry.get(resource_type)
+        if impl:
+            return impl
+        # handle: "OS::*" -> "Dreamhost::*"
+        for k, v in iter(self.resource_registry.items()):
+            if k.endswith('*'):
+                orig_prefix = k[:-1]
+                if resource_type.startswith(orig_prefix):
+                    return v[:-1] + resource_type[len(orig_prefix):]
+        # no special handling, just return what we were given.
+        return resource_type
+
+    def user_env_as_dict(self):
+        """Get the environment as a dict, ready for storing in the db."""
+        return {'resource_registry': self.resource_registry,
+                'parameters': self.params}

diff --git a/heat/tests/test_environment.py b/heat/tests/test_environment.py
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+++ b/heat/tests/test_environment.py
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+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import testtools
+
+from heat.engine import environment
+
+
+class EnvironmentTest(testtools.TestCase):
+    def test_load_old_parameters(self):
+        old = {u'a': u'ff', u'b': u'ss'}
+        expected = {u'parameters': old,
+                    u'resource_registry': {u'resources': {}}}
+        env = environment.Environment(old)
+        self.assertEqual(expected, env.user_env_as_dict())
+
+    def test_load_new_env(self):
+        new_env = {u'parameters': {u'a': u'ff', u'b': u'ss'},
+                   u'resource_registry': {u'OS::Food': 'fruity'}}
+        env = environment.Environment(new_env)
+        self.assertEqual(new_env, env.user_env_as_dict())
+
+    def test_global_registry(self):
+        new_env = {u'parameters': {u'a': u'ff', u'b': u'ss'},
+                   u'resource_registry': {u'OS::*': 'CloudX::*'}}
+        env = environment.Environment(new_env)
+        self.assertEqual('CloudX::Compute::Server',
+                         env.get_resource_type('OS::Compute::Server',
+                                               'my_db_server'))
+
+    def test_map_one_resource_type(self):
+        new_env = {u'parameters': {u'a': u'ff', u'b': u'ss'},
+                   u'resource_registry': {u'resources':
+                                          {u'my_db_server':
+                                           {u'OS::DBInstance': 'db.yaml'}}}}
+        env = environment.Environment(new_env)
+        self.assertEqual('db.yaml',
+                         env.get_resource_type('OS::DBInstance',
+                                               'my_db_server'))
+        self.assertEqual('OS::Compute::Server',
+                         env.get_resource_type('OS::Compute::Server',
+                                               'my_other_server'))
+
+    def test_map_all_resources_of_type(self):
+        new_env = {u'parameters': {u'a': u'ff', u'b': u'ss'},
+                   u'resource_registry':
+                   {u'OS::Networking::FloatingIP': 'OS::Nova::FloatingIP',
+                    u'OS::Loadbalancer': 'lb.yaml'}}
+        env = environment.Environment(new_env)
+        self.assertEqual('OS::Nova::FloatingIP',
+                         env.get_resource_type('OS::Networking::FloatingIP',
+                                               'my_fip'))