From 4f2cbe0c537c9f417aae310cc3b89f84e0915103 Mon Sep 17 00:00:00 2001
From: Keith Packard <keithp@keithp.com>
Date: Mon, 18 Sep 2017 09:57:41 -0700
Subject: [PATCH] altoslib: Avoid crashing when computing stats for empty
 flight logs

Signed-off-by: Keith Packard <keithp@keithp.com>
---
 altoslib/AltosFlightStats.java | 20 ++++++++++++--------
 altoslib/AltosTimeSeries.java  |  8 ++++++--
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/altoslib/AltosFlightStats.java b/altoslib/AltosFlightStats.java
index c2e4e2a3..ea1a9675 100644
--- a/altoslib/AltosFlightStats.java
+++ b/altoslib/AltosFlightStats.java
@@ -212,8 +212,11 @@ public class AltosFlightStats {
 					add_times(series, (int) prev.value, prev.time, state.time);
 				prev = state;
 			}
-			if (prev != null)
-				add_times(series, (int) prev.value, prev.time, series.accel_series.last().time);
+			if (prev != null) {
+				AltosTimeValue last_accel = series.accel_series.last();
+				if (last_accel != null)
+					add_times(series, (int) prev.value, prev.time, last_accel.time);
+			}
 		}
 
 		for (int s = 0; s <= AltosLib.ao_flight_invalid; s++) {
@@ -245,14 +248,15 @@ public class AltosFlightStats {
 			has_gps = true;
 			lat = pad_lat = gps.lat;
 			lon = pad_lon = gps.lon;
-			for (AltosGPSTimeValue gtv : series.gps_series) {
-				gps = gtv.gps;
-				if (gps.locked && gps.nsat >= 4) {
-					lat = gps.lat;
-					lon = gps.lon;
+			if (series.gps_series != null) {
+				for (AltosGPSTimeValue gtv : series.gps_series) {
+					gps = gtv.gps;
+					if (gps.locked && gps.nsat >= 4) {
+						lat = gps.lat;
+						lon = gps.lon;
+					}
 				}
 			}
-
 		}
 
 		max_height = AltosLib.MISSING;
diff --git a/altoslib/AltosTimeSeries.java b/altoslib/AltosTimeSeries.java
index b3c432fc..9f3b4d80 100644
--- a/altoslib/AltosTimeSeries.java
+++ b/altoslib/AltosTimeSeries.java
@@ -151,11 +151,15 @@ public class AltosTimeSeries implements Iterable<AltosTimeValue>, Comparable<Alt
 	}
 
 	public AltosTimeValue first() {
-		return values.get(0);
+		if (values.size() > 0)
+			return values.get(0);
+		return null;
 	}
 
 	public AltosTimeValue last() {
-		return values.get(values.size() - 1);
+		if (values.size() > 0)
+			return values.get(values.size() - 1);
+		return null;
 	}
 
 	public double average() {
-- 
2.30.2