From e7bae376e923937f3b62bd83a4a812aea8084a53 Mon Sep 17 00:00:00 2001
From: RunasSudo <runassudo@yingtongli.me>
Date: Fri, 20 Aug 2021 02:06:45 +1000
Subject: [PATCH] Fix error with forwards/backwards tiebreaking on first stage

---
 src/ties.rs | 52 +++++++++++++++++++++++++++++++---------------------
 1 file changed, 31 insertions(+), 21 deletions(-)

diff --git a/src/ties.rs b/src/ties.rs
index ab3a775..76b23c5 100644
--- a/src/ties.rs
+++ b/src/ties.rs
@@ -67,30 +67,40 @@ impl TieStrategy {
 	pub fn choose_highest<'c, N: Number>(&self, state: &mut CountState<N>, opts: &STVOptions, candidates: &Vec<&'c Candidate>, prompt_text: &str) -> Result<&'c Candidate, STVError> {
 		match self {
 			Self::Forwards => {
-				let mut candidates = candidates.clone();
-				candidates.sort_unstable_by(|a, b|
-					// Compare b to a to sort high-to-low
-					state.forwards_tiebreak.as_ref().unwrap()[b]
-						.cmp(&state.forwards_tiebreak.as_ref().unwrap()[a])
-					);
-				if state.forwards_tiebreak.as_ref().unwrap()[candidates[0]] == state.forwards_tiebreak.as_ref().unwrap()[candidates[1]] {
-					return Err(STVError::UnresolvedTie);
-				} else {
-					state.logger.log_literal(format!("Tie between {} broken forwards.", smart_join(&candidates.iter().map(|c| c.name.as_str()).collect())));
-					return Ok(candidates[0]);
+				match &state.forwards_tiebreak {
+					Some(tb) => {
+						let mut candidates = candidates.clone();
+						// Compare b to a to sort high-to-low
+						candidates.sort_unstable_by(|a, b| tb[b].cmp(&tb[a]));
+						if tb[candidates[0]] == tb[candidates[1]] {
+							return Err(STVError::UnresolvedTie);
+						} else {
+							state.logger.log_literal(format!("Tie between {} broken forwards.", smart_join(&candidates.iter().map(|c| c.name.as_str()).collect())));
+							return Ok(candidates[0]);
+						}
+					}
+					None => {
+						// First stage
+						return Err(STVError::UnresolvedTie);
+					}
 				}
 			}
 			Self::Backwards => {
-				let mut candidates = candidates.clone();
-				candidates.sort_unstable_by(|a, b|
-					state.backwards_tiebreak.as_ref().unwrap()[b]
-						.cmp(&state.backwards_tiebreak.as_ref().unwrap()[a])
-					);
-				if state.backwards_tiebreak.as_ref().unwrap()[candidates[0]] == state.backwards_tiebreak.as_ref().unwrap()[candidates[1]] {
-					return Err(STVError::UnresolvedTie);
-				} else {
-					state.logger.log_literal(format!("Tie between {} broken backwards.", smart_join(&candidates.iter().map(|c| c.name.as_str()).collect())));
-					return Ok(candidates[0]);
+				match &state.backwards_tiebreak {
+					Some(tb) => {
+						let mut candidates = candidates.clone();
+						candidates.sort_unstable_by(|a, b| tb[b].cmp(&tb[a]));
+						if tb[candidates[0]] == tb[candidates[1]] {
+							return Err(STVError::UnresolvedTie);
+						} else {
+							state.logger.log_literal(format!("Tie between {} broken backwards.", smart_join(&candidates.iter().map(|c| c.name.as_str()).collect())));
+							return Ok(candidates[0]);
+						}
+					}
+					None => {
+						// First stage
+						return Err(STVError::UnresolvedTie);
+					}
 				}
 			}
 			Self::Random(_) => {