api: allow a start time (&start=...), end time (&end=...) and

resolution(&resolution=...) to be specified

Either an interval or start parameter is required, while the end
parameter is optional when start is specified. Start and end should both
be specified in unix time format. Resolution is in seconds and should be
one of [60 | 900 | 86400 | 604800] meaning [minute | 15min | day | week]
resolution respectively.

The [time, power] pairs returned by the api will be aligned to multiples
of the specified resolution, or maximum resolution available for the
requested time interval.

web/api/flukso/src/flukso_resource.erl

@@ -11,6 +11,7 @@
         {rrdSensor,
          rrdStart,
          rrdEnd,
+         rrdResolution,
          rrdFactor,
          token,
          jsonpCallback}).
@@ -24,12 +25,18 @@ allowed_methods(ReqData, State) ->
 malformed_request(ReqData, _State) ->
     {_Version, ValidVersion} = check_version(wrq:get_req_header("X-Version", ReqData), wrq:get_qs_value("version", ReqData)),
     {RrdSensor, ValidSensor} = check_sensor(wrq:path_info(sensor, ReqData)),
-    {RrdStart, RrdEnd, ValidTime} = check_time(wrq:get_qs_value("interval", ReqData), wrq:get_qs_value("start", ReqData), wrq:get_qs_value("end", ReqData)),
+    {RrdStart, RrdEnd, RrdResolution, ValidTime} = check_time(wrq:get_qs_value("interval", ReqData), wrq:get_qs_value("start", ReqData), wrq:get_qs_value("end", ReqData), wrq:get_qs_value("resolution", ReqData)),
     {RrdFactor, ValidUnit} = check_unit(wrq:get_qs_value("unit", ReqData)),
     {Token, ValidToken} = check_token(wrq:get_req_header("X-Token", ReqData), wrq:get_qs_value("token", ReqData)),
     {JsonpCallback, ValidJsonpCallback} = check_jsonp_callback(wrq:get_qs_value("jsonp_callback", ReqData)),
 
-    State = #state{rrdSensor = RrdSensor, rrdStart = RrdStart, rrdEnd = RrdEnd, rrdFactor = RrdFactor, token = Token, jsonpCallback = JsonpCallback},
+    State = #state{rrdSensor = RrdSensor, 
+                   rrdStart = RrdStart,
+                   rrdEnd = RrdEnd,
+                   rrdResolution = RrdResolution,
+                   rrdFactor = RrdFactor,
+                   token = Token,
+                   jsonpCallback = JsonpCallback},
 
     {case {ValidVersion, ValidSensor, ValidTime, ValidUnit, ValidToken, ValidJsonpCallback}  of
 	{true, true, true, true, true, true} -> false;
@@ -49,15 +56,15 @@ is_authorized(ReqData, #state{rrdSensor = RrdSensor, token = Token} = State) ->
 content_types_provided(ReqData, State) -> 
     {[{"application/json", to_json}], ReqData, State}.
 
-to_json(ReqData, #state{rrdSensor = RrdSensor, rrdStart = RrdStart, rrdEnd = RrdEnd, rrdFactor = RrdFactor, jsonpCallback = JsonpCallback} = State) -> 
+to_json(ReqData, #state{rrdSensor = RrdSensor, rrdStart = RrdStart, rrdEnd = RrdEnd, rrdResolution = RrdResolution, rrdFactor = RrdFactor, jsonpCallback = JsonpCallback} = State) -> 
     case wrq:get_qs_value("interval", ReqData) of
         "night"   -> Path = "var/data/night/";
         _Interval -> Path = "var/data/base/"
     end,
 
-%% debugging: io:format("~s~n", [erlrrd:c([[Path, [RrdSensor|".rrd"]], "AVERAGE", ["-s", RrdStart], ["-e", RrdEnd]])]),
+%% debugging: io:format("~s~n", [erlrrd:c([[Path, [RrdSensor|".rrd"]], "AVERAGE", ["-s ", RrdStart], ["-e ", RrdEnd], ["-r ", RrdResolution]])]),
 
-    case erlrrd:fetch(erlrrd:c([[Path, [RrdSensor|".rrd"]], "AVERAGE", ["-s", RrdStart], ["-e", RrdEnd]])) of
+    case erlrrd:fetch(erlrrd:c([[Path, [RrdSensor|".rrd"]], "AVERAGE", ["-s ", RrdStart], ["-e ", RrdEnd], ["-r ", RrdResolution]])) of
         {ok, Response} ->
             Filtered = [re:split(X, "[:][ ]", [{return,list}]) || [X] <- Response, string:str(X, ":") == 11],
             Datapoints = [[list_to_integer(X), round(list_to_float(Y) * RrdFactor)] || [X, Y] <- Filtered, string:len(Y) /= 3],
@@ -73,7 +80,7 @@ to_json(ReqData, #state{rrdSensor = RrdSensor, rrdStart = RrdStart, rrdEnd = Rrd
             {{halt, 404}, ReqData, State}
     end.
 
-%% internal functions
+%% checks
 check_version(undefined, undefined) ->
     {false, false};
 check_version(Version, undefined) ->
@@ -92,28 +99,42 @@ check_sensor(Sensor) ->
         _ -> {false, false}
     end.
 
-check_time(undefined, undefined, undefined) ->
+check_time(undefined, undefined, _End, _Resolution) ->
-    {false, false, false};
+    {false, false, false, false};
-check_time(Interval, undefined, undefined) ->
+check_time(Interval, undefined, undefined, undefined) ->
-    Intervals = [{"hour", "end-1h"},
+    check_time(Interval, undefined, undefined, "");
-                 {"day", "end-1d"},
+check_time(Interval, undefined, undefined, Resolution) ->
-                 {"month", "end-30d"},
+    Now = unix_time(),
-                 {"year", "end-1y"},
-                 {"night", "end-30d"}],
 
-    case lists:keyfind(Interval, 1, Intervals) of
+    Intervals = [{"hour", "end-1h", 60},
-        false -> {false, false, false};
+                 {"day", "end-1d", 900},
-        {_Interval, Start} -> {Start, "now", true}
+                 {"month", "end-30d", 86400},
+                 {"year", "end-1y", 604800},
+                 {"night", "end-30d", 86400}],
+
+    case {lists:keyfind(Interval, 1, Intervals), re:run(Resolution, "[0-9]+", [])} of
+        {false, _} -> {false, false, false, false};
+        {{_Interval, Start, _DefResolution}, {match, [{0,_}]}} ->
+            AlignedEnd = integer_to_list(time_align(Now, list_to_integer(Resolution))),
+            {Start, AlignedEnd, Resolution, true};
+        {{_Interval, Start, DefResolution}, _} ->
+            AlignedEnd = integer_to_list(time_align(Now, DefResolution)),
+            {Start, AlignedEnd, integer_to_list(DefResolution), true}
     end;
-check_time(undefined, Start, undefined) ->
+check_time(undefined, Start, undefined, Resolution) ->
-    check_time(undefined, Start, "now");
+    check_time(undefined, Start, integer_to_list(unix_time()), Resolution);
-check_time(undefined, Start, End) ->
+check_time(undefined, Start, End, undefined) ->
-    case {re:run(Start, "[0-9]+", []), re:run(End, "[0-9a-z]+", [])} of
+    check_time(undefined, Start, End, "60");
-        {{match, [{0,_}]}, {match, [{0,_}]}} -> {Start, End, true};
+check_time(undefined, Start, End, Resolution) ->
-        _ -> {false, false, false}
+    case {re:run(Start, "[0-9]+", []), re:run(End, "[0-9]+", []), re:run(Resolution, "[0-9]+", [])} of
+        {{match, [{0,_}]}, {match, [{0,_}]}, {match, [{0,_}]}} ->
+            AlignedStart = integer_to_list(time_align(list_to_integer(Start), list_to_integer(Resolution))),
+            AlignedEnd = integer_to_list(time_align(list_to_integer(End), list_to_integer(Resolution))),
+            {AlignedStart, AlignedEnd, Resolution, true};
+        _ -> {false, false, false, false}
     end;
-check_time(_, _, _) ->
+check_time(_, _, _, _) ->
-    {false, false, false}.
+    {false, false, false, false}.
 
 check_unit(Unit) ->
     Units = [{"watt", 3600},
@@ -144,3 +165,11 @@ check_jsonp_callback(JsonpCallback) ->
         {match, [{0, Length}]} -> {JsonpCallback, true};
         _ -> {false, false}
     end.
+
+%% helper functions
+unix_time() ->
+    {Megaseconds, Seconds, _Microseconds} = erlang:now(),
+    Megaseconds*1000000 + Seconds.
+
+time_align(Time, Resolution) ->
+    (Time div Resolution) * Resolution.