Fix supply search optimization.

1 files changed, 12 insertions, 3 deletions

diff --git a/rules.js b/rules.js
index d6efbf3..88a977f 100644
--- a/rules.js
+++ b/rules.js
@@ -1361,9 +1361,18 @@ function trace_unit_supply_line(path, here, here_move, ssrc) {
 		if (next_move === TRACE_ABORT)
 			continue
 
-		// reached supply source, or reached supplied highway (that we searched before)
-		/* if (next === ssrc) -- fallback without short cut in case the optimization below is wrong... */
-		if (next === ssrc || (hex_road[next] === HIGHWAY && supply_net[next] === 2)) {
+		let reached = (next === ssrc)
+		if (!reached) {
+			// Stop searching if we reach a supplied highway,
+			// but only if we can't continue by trail or track.
+			// Example: Tobruk - EL Adem - Sidi Rezegh - Ft. Capuzzo
+			if (hex_road[next] === HIGHWAY && supply_net[next] === 2)
+				if (next_move === BACK_HIGHWAY_3 || next_move === BACK_STOP)
+					reached = true
+		}
+
+		// reached supply source
+		if (reached) {
 			for (let x of path)
 				supply_line[x] = 2
 			supply_line[side] = 2