From 103a52cff5cc257dc6689d4872eb26bba4269aa7 Mon Sep 17 00:00:00 2001
From: Julian Simioni <julian@simioni.org>
Date: Fri, 4 Sep 2015 15:22:13 -0400
Subject: [PATCH] Calculate intersection of types requested by source and
 layers params

---
 helper/types.js           | 24 ++++++++++++++++++++++--
 test/unit/helper/types.js | 29 +++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/helper/types.js b/helper/types.js
index 20443ad9..a87a65b8 100644
--- a/helper/types.js
+++ b/helper/types.js
@@ -1,12 +1,32 @@
 var valid_types = require( '../query/types' );
 
+/**
+ * Calculate the set-style intersection of two arrays
+ */
+var intersection = function intersection(set1, set2) {
+  return set2.filter(function(value) {
+      return set1.indexOf(value) !== -1;
+  });
+};
+
 module.exports = function calculate_types(clean_types) {
   if (!clean_types) {
     return undefined;
   }
 
-  if (clean_types.from_layers) {
-    return clean_types.from_layers;
+
+  if (clean_types.from_layers || clean_types.from_source) {
+    var types = valid_types;
+
+    if (clean_types.from_layers) {
+      types = intersection(types, clean_types.from_layers);
+    }
+
+    if (clean_types.from_source) {
+      types = intersection(types, clean_types.from_source);
+    }
+
+    return types;
   }
 
   if (clean_types.from_address_parser) {
diff --git a/test/unit/helper/types.js b/test/unit/helper/types.js
index d56f12d2..2398c6bb 100644
--- a/test/unit/helper/types.js
+++ b/test/unit/helper/types.js
@@ -55,6 +55,35 @@ module.exports.tests.layers_parameter_and_address_parser = function(test, common
   });
 };
 
+module.exports.tests.source_parameter = function(test, common) {
+  test('source parameter specified', function(t) {
+    var cleaned_types = {
+      from_source: ['openaddresses']
+    };
+
+    var actual = types(cleaned_types);
+
+    var expected = ['openaddresses'];
+    t.deepEqual(actual, expected, 'type parameter set to types specified by source');
+    t.end();
+  });
+};
+
+module.exports.tests.source_and_layers_parameters = function(test, common) {
+  test('source and layers parameter both specified', function(t) {
+    var cleaned_types = {
+      from_source: ['openaddresses'],
+      from_layers: ['osmaddress', 'openaddresses']
+    };
+
+    var actual = types(cleaned_types);
+
+    var expected = ['openaddresses'];
+    t.deepEqual(actual, expected, 'type set to intersection of source and layer types');
+    t.end();
+  });
+};
+
 module.exports.all = function (tape, common) {
 
   function test(name, testFunction) {