lib: get effective report start/end dates

hledger-lib/Hledger/Reports/ReportOptions.hs

@@ -22,6 +22,9 @@ module Hledger.Reports.ReportOptions (
   queryOptsFromOpts,
   transactionDateFn,
   postingDateFn,
+  reportStartDate,
+  reportEndDate,
+  reportStartEndDates,
 
   tests_Hledger_Reports_ReportOptions
 )
@@ -354,6 +357,33 @@ tests_queryOptsFromOpts = [
                                                              })
  ]
 
+-- | The effective report start date is the one specified by options or queries,
+-- otherwise the earliest transaction or posting date in the journal,
+-- otherwise (for an empty journal) nothing.
+-- Needs IO to parse smart dates in options/queries.
+reportStartDate :: Journal -> ReportOpts -> IO (Maybe Day)
+reportStartDate j ropts = (fst <$>) <$> reportStartEndDates j ropts
+
+-- | The effective report end date is the one specified by options or queries,
+-- otherwise the latest transaction or posting date in the journal,
+-- otherwise (for an empty journal) nothing.
+-- Needs IO to parse smart dates in options/queries.
+reportEndDate :: Journal -> ReportOpts -> IO (Maybe Day)
+reportEndDate j ropts = (fst <$>) <$> reportStartEndDates j ropts
+
+reportStartEndDates :: Journal -> ReportOpts -> IO (Maybe (Day,Day))
+reportStartEndDates j ropts = do
+  today <- getCurrentDay
+  let
+    q = queryFromOpts today ropts
+    mrequestedstartdate = queryStartDate False q
+    mrequestedenddate = queryEndDate False q
+  return $
+    case journalDateSpan False j of  -- don't bother with secondary dates
+      DateSpan (Just journalstartdate) (Just journalenddate) ->
+        Just (fromMaybe journalstartdate mrequestedstartdate, fromMaybe journalenddate mrequestedenddate)
+      _ -> Nothing
+
 
 tests_Hledger_Reports_ReportOptions :: Test
 tests_Hledger_Reports_ReportOptions = TestList $