Exception based scheduling

pom.xml

@@ -268,7 +268,7 @@
             <groupId>com.github.conveyal</groupId>
             <artifactId>gtfs-lib</artifactId>
             <!-- Latest dev build on jitpack.io -->
-            <version>a3e5707</version>
+            <version>ba747df</version>
             <!-- Exclusions added in order to silence SLF4J warnings about multiple bindings:
                 http://www.slf4j.org/codes.html#multiple_bindings
             -->

src/main/java/com/conveyal/datatools/manager/jobs/feedmerge/CalendarDatesMergeLineContext.java

@@ -87,6 +87,7 @@ private boolean checkCalendarDatesIds(FieldContext fieldContext) throws IOExcept
         // the valid date range, i.e., before the future feed's first date.
         if (!shouldSkipRecord && fieldContext.nameEquals(SERVICE_ID)) {
             mergeFeedsResult.serviceIds.add(fieldContext.getValueToWrite());
+            mergeFeedsResult.calendarDatesServiceIds.add(fieldContext.getValueToWrite());
         }
 
         return !shouldSkipRecord;

src/main/java/com/conveyal/datatools/manager/jobs/feedmerge/CalendarMergeLineContext.java

@@ -111,6 +111,7 @@ private boolean checkCalendarIds(Set<NewGTFSError> idErrors, FieldContext fieldC
         // If service is going to be cloned, add to the output service ids.
         if (!shouldSkipRecord && fieldContext.nameEquals(SERVICE_ID)) {
             mergeFeedsResult.serviceIds.add(fieldContext.getValueToWrite());
+            mergeFeedsResult.calendarServiceIds.add(fieldContext.getValueToWrite());
         }
 
         return !shouldSkipRecord;

src/main/java/com/conveyal/datatools/manager/jobs/feedmerge/MergeFeedsResult.java

@@ -21,10 +21,21 @@ public class MergeFeedsResult implements Serializable {
     /** Contains the set of IDs for records that were excluded in the merged feed */
     public Set<String> skippedIds = new HashSet<>();
     /**
-     * Track the set of service IDs to end up in the merged feed in order to determine which calendar_dates and trips
-     * records should be retained in the merged result.
+     * Track the set of service IDs to end up in the merged feed in order to determine which calendar, calendar_dates and
+     * trip records should be retained in the merged result.
      */
     public Set<String> serviceIds  = new HashSet<>();
+
+    /**
+     * Track the set of service IDs obtained from calendar records.
+     */
+    public Set<String> calendarServiceIds = new HashSet<>();
+
+    /**
+     * Track the set of service IDs obtained from calendar date records.
+     */
+    public Set<String> calendarDatesServiceIds = new HashSet<>();
+
     /**
      * Track the set of route IDs to end up in the merged feed in order to determine which route_attributes
      * records should be retained in the merged result.

src/main/java/com/conveyal/datatools/manager/jobs/feedmerge/MergeLineContext.java

@@ -237,10 +237,75 @@ public void startNewRow() throws IOException {
             .collect(Collectors.toList());
     }
 
+    public enum ReferenceTableLookup {
+        TRIP_SERVICE_ID_KEY(
+            String.join(":", Table.TRIPS.name, SERVICE_ID, Table.CALENDAR.name, Table.CALENDAR_DATES.name)
+        );
+
+        private final String value;
+
+        ReferenceTableLookup(String value) {
+            this.value = value;
+        }
+
+        public String getValue() {
+            return value;
+        }
+
+        public static ReferenceTableLookup fromValue(String key) {
+            for (ReferenceTableLookup ref: ReferenceTableLookup.values()) {
+                if (ref.getValue().equals(key)) {
+                    return ref;
+                }
+            }
+            throw new UnsupportedOperationException(String.format("Unsupported reference table combination: %s.", key));
+        }
+    }
+
+    /**
+     * Determine which reference table to use. If there is only one reference use this. If there are multiple references
+     * determine the context and then the correct reference table to use.
+     */
+    private Table getReferenceTable(FieldContext fieldContext, Field field) {
+        if (field.referenceTables.size() == 1) {
+            return field.referenceTables.iterator().next();
+        }
+
+        // A table reference is still required even if no match is found.
+        Table defaultTable = null;
+        switch (ReferenceTableLookup.fromValue(createKey(field))) {
+            case TRIP_SERVICE_ID_KEY:
+                boolean isCalendarServiceId = mergeFeedsResult.calendarServiceIds.contains(fieldContext.getValueToWrite());
+                boolean isCalendarDatesServiceId = mergeFeedsResult.calendarDatesServiceIds.contains(fieldContext.getValueToWrite());
+                if (isCalendarServiceId && !isCalendarDatesServiceId) {
+                    return Table.CALENDAR;
+                } else if (!isCalendarServiceId && isCalendarDatesServiceId) {
+                    return Table.CALENDAR_DATES;
+                } else {
+                    // For this case it doesn't seem to matter which is returned so going with calendar.
+                    defaultTable = Table.CALENDAR;
+                }
+            // Add other cases as multiple references are added e.g. flex!.
+        }
+        return defaultTable;
+    }
+
+    /**
+     * Create a unique key for this table, field and reference tables.
+     */
+    private String createKey(Field field) {
+        return String.format(
+            "%s:%s:%s",
+            table.name,
+            field.name,
+            field.referenceTables.stream().map(r -> r.name).collect(Collectors.joining(":"))
+        );
+    }
+
     public boolean checkForeignReferences(FieldContext fieldContext) throws IOException {
         Field field = fieldContext.getField();
         if (field.isForeignReference()) {
-            String key = getTableScopedValue(field.referenceTable, fieldContext.getValue());
+            String key = getTableScopedValue(getReferenceTable(fieldContext, field), fieldContext.getValue());
             // Check if we're performing a service period merge, this ref field is a service_id, and it
             // is not found in the list of service_ids (e.g., it was removed).
             boolean isValidServiceId = mergeFeedsResult.serviceIds.contains(fieldContext.getValueToWrite());