From 2c660f07d5264782b01049ccdfa4846b3578e3dd Mon Sep 17 00:00:00 2001
From: Luke Meyers <n.luke.meyers@gmail.com>
Date: Fri, 7 Feb 2020 20:28:49 -0800
Subject: [PATCH] AI don't attempt illegal moves

---
 game/ai.go   |  3 +++
 game/game.go | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/game/ai.go b/game/ai.go
index cb9ea52..50e53f4 100644
--- a/game/ai.go
+++ b/game/ai.go
@@ -36,6 +36,9 @@ func smartChooseCommand(s State, teamID int) command {
 
 	log.Printf("team %d base score: %d", teamID, score(s, teamID))
 	for _, cmd := range []command{speedUp, slowDown, left, right} {
+		if !legalMove(s, teamID, cmd) {
+			continue
+		}
 		ss := doCommand(cmd, s, teamID)
 		n := score(ss, teamID)
 		log.Printf("team %d score %s: %d", teamID, cmd, n)
diff --git a/game/game.go b/game/game.go
index ca68e01..b6d9309 100644
--- a/game/game.go
+++ b/game/game.go
@@ -107,6 +107,22 @@ func gameOver(s State) bool {
 	return false
 }
 
+func legalMove(s State, teamID int, cmd command) bool {
+	b := ActiveBot(s.Teams[teamID])
+	if b == nil {
+		return false
+	}
+
+	switch cmd {
+	case left:
+		return b.Position.Lane < NumLanes-1
+	case right:
+		return b.Position.Lane > 0
+
+	}
+	return true
+}
+
 func abs(n int) int {
 	if n < 0 {
 		return -n