From 481c40ca2ff88d0ecc8b60a82c978306e5a91ff8 Mon Sep 17 00:00:00 2001
From: Simon Michael <simon@joyful.com>
Date: Sat, 12 Dec 2020 11:51:25 -0800
Subject: [PATCH] ;ui: refactor toggleForecast

---
 hledger-ui/Hledger/UI/UIState.hs | 39 +++++++++++++++-----------------
 1 file changed, 18 insertions(+), 21 deletions(-)

diff --git a/hledger-ui/Hledger/UI/UIState.hs b/hledger-ui/Hledger/UI/UIState.hs
index 1cb95bbdb..0f4a4db2b 100644
--- a/hledger-ui/Hledger/UI/UIState.hs
+++ b/hledger-ui/Hledger/UI/UIState.hs
@@ -163,28 +163,25 @@ toggleHistorical ui@UIState{aopts=uopts@UIOpts{cliopts_=copts@CliOpts{reportspec
     b | balancetype_ ropts == HistoricalBalance = PeriodChange
       | otherwise                               = HistoricalBalance
 
--- | Toggle hledger-ui's "forecast mode". In forecast mode, periodic
--- transactions (generated by periodic rules) are enabled (as with
--- hledger --forecast), and also future transactions in general
--- (including non-periodic ones) are displayed. In normal mode, all
--- future transactions (periodic or not) are suppressed (unlike
--- command-line hledger).
---
--- After toggling this, we do a full reload of the journal from disk
--- to make it take effect; currently that's done in the callers (cf
--- AccountsScreen, RegisterScreen) where it's easier. This is
--- overkill, probably we should just hide/show the periodic
--- transactions with a query for their special tag.
---
+-- | Toggle hledger-ui's "forecast/future mode". When this mode is enabled,
+-- hledger-shows regular transactions which have future dates, and
+-- "forecast" transactions generated by periodic transaction rules
+-- (which are usually but not necessarily future-dated).
+-- In normal mode, both of these are hidden.
 toggleForecast :: Day -> UIState -> UIState
-toggleForecast d ui@UIState{aopts=uopts@UIOpts{cliopts_=copts@CliOpts{reportspec_=rspec@ReportSpec{rsOpts=ropts}}}} =
-  ui{aopts=uopts{cliopts_=copts'}}
-  where
-    copts' = copts{reportspec_=rspec{rsOpts=ropts{forecast_=forecast'}}}
-    forecast' =
-      case forecast_ ropts of
-        Just _  -> Nothing
-        Nothing -> Just $ fromMaybe nulldatespan $ forecastPeriodFromRawOpts d $ rawopts_ copts
+toggleForecast d ui@UIState{aopts=UIOpts{cliopts_=copts@CliOpts{reportspec_=ReportSpec{rsOpts=ropts}}}} =
+  uiSetForecast ui $
+    case forecast_ ropts of
+      Just _  -> Nothing
+      Nothing -> Just $ fromMaybe nulldatespan $ forecastPeriodFromRawOpts d $ rawopts_ copts
+
+-- | Helper: set forecast mode (with the given forecast period) on or off in the UI state.
+uiSetForecast :: UIState -> Maybe DateSpan -> UIState
+uiSetForecast
+  ui@UIState{aopts=uopts@UIOpts{cliopts_=copts@CliOpts{reportspec_=rspec@ReportSpec{rsOpts=ropts}}}}
+  mforecast =
+  -- we assume forecast mode has no effect on ReportSpec's derived fields
+  ui{aopts=uopts{cliopts_=copts{reportspec_=rspec{rsOpts=ropts{forecast_=mforecast}}}}}
 
 -- | Toggle between showing all and showing only real (non-virtual) items.
 toggleReal :: UIState -> UIState