Fallback to exercise HRV data #42

As explained in the added code comments, sometimes Polar devices
generate a separate rrsamples data file which is just a flat list of
R-R intervals.  However, other times, Polar devices include HRV data
interspersed with other exercise sample data.

With this change, the TrainingSession::toHRM function will use the
separate rrsamples file when available (existing behaviour), and
fallback to using the HRV data dispersed throughout the execerise data,
if present.

Note, other output formats, such as GPX and TCX do not include
heartrate variability (HRV) data, so those are unaffected.

Finally, this change also fixes a minor issue that prevented unit tests
recording temporary debug data for `*.rr.hrm` files in some cases.

src/polar/v2/trainingsession.cpp

@@ -1767,6 +1767,25 @@ QDomDocument TrainingSession::toGPX(const QDateTime &creationTime) const
     return doc;
 }
 
+// Sometimes Polar devices generate a separate rrsamples data file which is just
+// a flat list of R-R intervals.  However, other times, Polar devices include HRV
+// data interspersed with other exercise sample data - which is a bit odd considering
+// that R-R intervals are, by there very nature, not sampled at regular intervals as
+// all of the other exercise sample data is.  Anyway, toHRM will use rrsamples if
+// available, and fallback to exercise sample HRM values if not. To assist in the
+// latter case, this funciton flattens the exercise sample HRV data into a list
+// of intervals the same as the rrsample data files would, making both sources look
+// the same throughout the toHRM function.
+QVariantList flattenHrvSamplesForHrm(const QVariantMap &samples)
+{
+    QVariantList rrsamples;
+    foreach (const QVariant &hrv, samples.value(QLatin1String("heartrate-variability")).toList()) {
+        rrsamples.append(hrv.toMap().value(QLatin1String("intervals")).toList());
+        // Note, ignorig hrv["offline"] values - no way to apply them to HRM.
+    }
+    return rrsamples;
+}
+
 /// @see http://www.polar.com/files/Polar_HRM_file%20format.pdf
 QStringList TrainingSession::toHRM(const bool rrDataOnly) const
 {
@@ -1781,7 +1800,9 @@ QStringList TrainingSession::toHRM(const bool rrDataOnly) const
         const QVariantMap stats      = map.value(STATISTICS).toMap();
         const QVariantMap zones      = map.value(ZONES).toMap();
 
-        const QVariantList rrsamples  = map.value(RRSAMPLES).toMap().value(QLatin1String("value")).toList();
+        const QVariantList rrsamples = map.contains(RRSAMPLES)
+            ? map.value(RRSAMPLES).toMap().value(QLatin1String("value")).toList()
+            : flattenHrvSamplesForHrm(samples);
 
         const bool haveAltitude     = ((!rrDataOnly) && (haveAnySamples(samples, QLatin1String("speed"))));
         const bool haveCadence      = ((!rrDataOnly) && (haveAnySamples(samples, QLatin1String("cadence"))));