Heads-I-Lose

-module(headsilose).
-export([get_locations/0, get_locations/1, get_weather/1, headsilose/1]).
-include_lib("xmerl/include/xmerl.hrl").
-import(weather_types, [weather_type/1]).
-import(polyline, [decode/1]).
-import(osrm, [read_route/0]).

%Supply a direction and location and work out if head wind or not
%For now "know the location id" upfront, but ideally need to search for it at some point or present a choice.

%Initially based on: http://pragdave.pragprog.com/pragdave/2007/04/a_first_erlang_.html 

-define(BASE_URL,

	Found = lists:keyfind(noshell, 1, Args),
	if Found =:= false ->
		dont_quit;
	true -> init:stop()
	end.	



build_list_of_wind_directions(Wind_direction) ->


	%There is only one wind direction, but can build groups of directions that will count as head, side and tail winds

	Compass = ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"],
	%Quicker dirtier(?) way to do below would be: http://stackoverflow.com/a/6762191/208793
	Index = length(lists:takewhile(fun(X) -> X  =/= Wind_direction end, Compass))+1,
	%Since heading is to direction and winds are from, opposite is -2 to +2, or to make it easier to wrap, +14 +18
	%Since heading is to direction and winds are from, sidewinds are -5 to -3 and +3 to +5, or to make it easier to wrap, +14 +18
	%And so on
	HeadwindList = lists:seq(14,18),
	SidewindList = lists:seq(3,5)++lists:seq(11,13),
	TailwindList = lists:seq(6,10),
	[Headwinds, Sidewinds, Tailwinds] = lists:map(fun(WindList) ->
		lists:map(fun(X) ->
			nth_wrap(Index+X, Compass) end,
			WindList)
		end,
		[HeadwindList, SidewindList, TailwindList]).


convert_lats_longs_to_distance_heading([_, _, Rest])  -> 
	%All co-ords are diff, so just ignore first two
	convert_lats_longs_to_distance_heading_(Rest, []).
convert_lats_longs_to_distance_heading_([Lat, Lon, Rest], List_distance_headings) ->
	%Want to map through the list convert co-ords to distance and heading
	Distance = math:sqrt(math:pow(Lat,2) + math:pow(Lon,2)),
	Heading = math:atan2(Lon, Lat),
	Compass_direction = get_compass_direction_for(Heading),
	convert_lats_longs_to_distance_heading_(Rest, [{Distance, Compass_direction}]++List_distance_headings);
convert_lats_longs_to_distance_heading_([], List_distance_headings) ->
	lists:reverse(List_distance_headings).


get_compass_direction_for(Heading) ->
	%In a way this is a waste of time as could just do headwind, etc based on angles, but since already have some code, why not?
	Segment = 2*math:pi()/16,
	Segments = erlang:round(Heading/Segment),
	Compass = ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"],
	lists:nth(Segments, Compass).


head_side_or_tail_wind(Direction, [Headwinds, Sidewinds, Tailwinds]) ->
	[Headwind, Sidewind, Tailwind] = lists:map(fun(Winds) ->
		lists:member(Direction, Winds) end,
		[Headwinds, Sidewinds, Tailwinds]),
	if Headwind ->
		headwind;
	Sidewind ->

		sidewind;
	Tailwind ->
		tailwind
	end.
%Something like that?
	

headsilose(Location) ->
	{Direction, Speed, Gust, Weather, Temperature} = get_weather(Location),
	Weather_type = weather_types:weather_type(erlang:list_to_integer(Weather)),
	[Headwinds, Sidewinds, Tailwinds] = build_list_of_wind_directions(Direction),
	%Ok so now map this list over (like previous function) the headings list to get list of head, side, tail and distances?

	{_Checksum, Polyline} = osrm:read_route(),
	Polyline_decoded = polyline:decode(Polyline),
	List_of_distances_and_compass = convert_lats_longs_to_distance_heading(Polyline_decoded),
	%If now have a set of co-ords need to figure out distances and directions
	List_of_distances_and_wind = lists:map(fun({Compass, Distance}) ->
			Wind = head_side_or_tail_wind(Compass, [Headwinds, Sidewinds, Tailwinds]),
			{Wind, Distance}
		end,
		List_of_distances_and_compass),
	%lists:map to get distnaces only? Could also map each of the winds?
	%Figure out for headwinds only for now
	Headw = lists:filter(fun({Element, _}) ->
		Element == headwind end,
		List_of_distances_and_wind),
	Sum_of_Headw = lists:foldl(fun({_wind, Distance}, Sum) -> Distance + Sum end, 0, Headw),
	io:format(Sum_of_Headw).
	%io:format("Direction: ~s~nSpeed: ~s mph~nGust: ~s mph~nWeather type: ~s~nTemperature: ~s deg C~n", [Direction, Speed, Gust, Weather_type, Temperature]).


%Need to read API key from file
readapikey() ->
	{_Status, KeyB} = file:read_file(os:getenv("HOME") ++ "/.datapoint"),
	string:strip(erlang:binary_to_list(KeyB),right,$\n).