From 06087f861064e39aca13d6e10131c873e97dd9fd Mon Sep 17 00:00:00 2001
From: Volker Mische <vmx@couchbase.com>
Date: Fri, 10 Jun 2016 12:48:35 +0200
Subject: [PATCH] CBIDXT-253: Encode geometries as WKB (Well-Known Binary)

The geometries were stored as Erlang terms on disk. This is bad for
interoperability. The geometries are now stored as WKB (Well-Known Binary).

This is a port of 59fa3590a43386d59f757604d99c8f051ea00752 to the
Apache CouchDB compatible version for GeoCouch.

Change-Id: I76b834461bd14b5ac684b6b4f52d3da8db8b8f95
---
 gc-couchdb/src/couch_spatial_updater.erl | 34 +++---------------------
 gc-couchdb/src/couch_spatial_util.erl    | 16 +++--------
 2 files changed, 6 insertions(+), 44 deletions(-)

diff --git a/gc-couchdb/src/couch_spatial_updater.erl b/gc-couchdb/src/couch_spatial_updater.erl
index 6357e74..54b2b3a 100644
--- a/gc-couchdb/src/couch_spatial_updater.erl
+++ b/gc-couchdb/src/couch_spatial_updater.erl
@@ -18,11 +18,8 @@
 
 -export([start_update/3, process_doc/3, finish_update/1]).
 
-% for output (couch_http_spatial, couch_http_spatial_list)
--export([geocouch_to_geojsongeom/1]).
-
 % for polygon search
--export([extract_bbox/2, geojsongeom_to_geocouch/1]).
+-export([extract_bbox/2]).
 
 -include("couch_db.hrl").
 -include("couch_spatial.hrl").
@@ -313,7 +310,7 @@ process_result([[{Geo}|Rest]|[Value]]) ->
 % The multidimensional case without a geometry
 process_result([MultiDim|[Value]]) when is_list(MultiDim) ->
     Tuples = process_range(MultiDim),
-    {Tuples, {nil, Value}};
+    {Tuples, {<<>>, Value}};
 % There old case when only two dimensions were supported
 process_result([{Geo}|[Value]]) ->
     {Bbox, Geom} = process_geometry(Geo),
@@ -377,7 +374,7 @@ process_geometry(Geo) ->
     catch _:badarg ->
         throw({emit_key, <<"The supplied geometry must be valid GeoJSON.">>})
     end,
-    Geom = geojsongeom_to_geocouch(Geo),
+    {ok, Geom} = wkb_writer:geojson_to_wkb({Geo}),
     {Bbox, Geom}.
 
 
@@ -415,28 +412,3 @@ bbox([Coords|Rest], Range) ->
             {erlang:min(Coord, Min), erlang:max(Coord, Max)}
         end, Coords, Range),
     bbox(Rest, Range2).
-
-
-% @doc Transforms a GeoJSON geometry (as Erlang terms), to an internal
-% structure
-geojsongeom_to_geocouch(Geom) ->
-    Type = proplists:get_value(<<"type">>, Geom),
-    Coords = case Type of
-    <<"GeometryCollection">> ->
-        Geometries = proplists:get_value(<<"geometries">>, Geom),
-        [geojsongeom_to_geocouch(G) || {G} <- Geometries];
-    _ ->
-        proplists:get_value(<<"coordinates">>, Geom)
-    end,
-    {binary_to_atom(Type, utf8), Coords}.
-
-% @doc Transforms internal structure to a GeoJSON geometry (as Erlang terms)
-geocouch_to_geojsongeom({Type, Coords}) ->
-    Coords2 = case Type of
-    'GeometryCollection' ->
-        Geoms = [geocouch_to_geojsongeom(C) || C <- Coords],
-        {<<"geometries">>, Geoms};
-    _ ->
-        {<<"coordinates">>, Coords}
-    end,
-    {[{<<"type">>, Type}, Coords2]}.
diff --git a/gc-couchdb/src/couch_spatial_util.erl b/gc-couchdb/src/couch_spatial_util.erl
index d3f3525..e635ec7 100644
--- a/gc-couchdb/src/couch_spatial_util.erl
+++ b/gc-couchdb/src/couch_spatial_util.erl
@@ -342,22 +342,12 @@ expand_dups([KV | Rest], Acc) ->
 
 
 row_to_ejson({Mbb, DocId, Geom, Value}) ->
-    % If there's no geometry in the output, there's no bbox to add
     GeomData = case Geom of
-    nil ->
+    <<>> ->
         [];
     _ ->
-        % XXX NOTE vmx 2012-11-28: Currently the first two dimensions are
-        %     expected to be the bounding box of the geometry
-        % XXX vmx 2012-11-28: I'm not sure if a bounding box should be
-        %     emitted at all. It's duplicated information you can get from
-        %     the key yourself.
-        {[{W, E}, {S, N}], _} = lists:split(2, Mbb),
-        [
-            {<<"bbox">>, [W, S, E, N]},
-            {<<"geometry">>,
-                couch_spatial_updater:geocouch_to_geojsongeom(Geom)}
-        ]
+        {ok, JsonGeom} = wkb_reader:wkb_to_geojson(Geom),
+        [{<<"geometry">>, JsonGeom}]
     end,
     {[
         {<<"id">>, DocId},