-module(day2).

-export([solve/1]).

solve(InputData) ->
	RoundData = binary:split(InputData, <<$\n>>, [trim_all, global]),
	Rounds = lists:map(fun parse_round/1, RoundData),
	RoundPoints = lists:map(fun score_round/1, Rounds),

	Rounds2 = lists:map(fun parse_round2/1, RoundData),
	RoundPoints2 = lists:map(fun score_round/1, Rounds2),
	{lists:sum(RoundPoints), lists:sum(RoundPoints2)}.

parse_round(<<TheirCode, $\s, YourCode>>) -> {parse_theirs(TheirCode), parse_yours(YourCode)}.

parse_round2(<<TheirCode, $\s, OutcomeCode>>) ->
	OutcomeScore = parse_outcome_points(OutcomeCode),
	TheirShape = parse_theirs(TheirCode),
	[YourShape] = [Shape || Shape <- [rock, paper, scissors], round_points({TheirShape, Shape}) == OutcomeScore],
	{TheirShape, YourShape}.

score_round(Round = {_Theirs, Yours}) -> round_points(Round) + shape_points(Yours).

parse_theirs($A) -> rock;
parse_theirs($B) -> paper;
parse_theirs($C) -> scissors.

parse_yours($X) -> rock;
parse_yours($Y) -> paper;
parse_yours($Z) -> scissors.

parse_outcome_points($X) -> 0;
parse_outcome_points($Y) -> 3;
parse_outcome_points($Z) -> 6.

round_points({rock, paper}) -> 6;
round_points({paper, scissors}) -> 6;
round_points({scissors, rock}) -> 6;
round_points({Shape, Shape}) -> 3;
round_points({_Theirs, _Yours}) -> 0.

shape_points(rock) -> 1;
shape_points(paper) -> 2;
shape_points(scissors) -> 3.