From a32504eab6b7211bede7450e0ef3735199b2a64e Mon Sep 17 00:00:00 2001
From: Arnout Engelen <arnout@bzzt.net>
Date: Fri, 29 Jan 2021 11:58:26 +0100
Subject: [PATCH] Hide chart when more than one commodity present

Since the result would be hard to understand anyway
---
 hledger-web/Hledger/Web/Handler/RegisterR.hs | 21 ++++++++++++++------
 hledger-web/templates/piechart.hamlet        |  2 +-
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/hledger-web/Hledger/Web/Handler/RegisterR.hs b/hledger-web/Hledger/Web/Handler/RegisterR.hs
index a282503d7e6..babaa28ef9f 100644
--- a/hledger-web/Hledger/Web/Handler/RegisterR.hs
+++ b/hledger-web/Hledger/Web/Handler/RegisterR.hs
@@ -119,19 +119,28 @@ registerChartHtml q title percommoditytxnreports = $(hamletFile "templates/chart
 
 data PieHalf = Positive | Negative
 
+moreThanOne :: Eq a => [a] -> Bool
+moreThanOne [] = False
+moreThanOne (x : xs) = rec xs
+  where
+    rec [] = False
+    rec (y : ys) = x /= y || (rec ys)
+
 -- | Generate javascript/html for a mockup pie chart
 registerPieChartHtml :: PieHalf -> Text -> BalanceReport -> HtmlUrl AppRoute
 registerPieChartHtml half q (items, _) = $(hamletFile "templates/piechart.hamlet")
   where
     charttitle = "Pie Chart" :: String
-    labelDataTuples =
+    labelData =
       reverse $
-      sortOn snd $
-      filter (\(_, quant) -> case half of Positive -> quant >= 0
-                                          Negative -> quant < 0) $
+      sortOn (\(_, quant, _) -> quant) $
+      filter (\(_, quant, _) -> case half of Positive -> quant >= 0
+                                             Negative -> quant < 0) $
       flip concatMap items $ \(accname, _, _, Mixed as) ->
-        flip map as $ \a -> (accname, aquantity a)
-    showChart = if ((length labelDataTuples) > 1) then "true" else "false" :: String
+        flip map as $ \a -> (accname, aquantity a, acommodity a)
+    moreThanOneAcct = moreThanOne $ map (\(acct, _, _) -> acct) labelData
+    moreThanOneCommodity = moreThanOne $ map (\(_, _, com) -> com) labelData
+    showChart = if (moreThanOneAcct && not moreThanOneCommodity) then "true" else "false" :: String
     noacctlink = (RegisterR, [("q", T.unwords $ removeInacct q)])
     chartId = case half of Positive -> "postive" :: String
                            Negative -> "negative" :: String
diff --git a/hledger-web/templates/piechart.hamlet b/hledger-web/templates/piechart.hamlet
index e688568f633..c268248a09f 100644
--- a/hledger-web/templates/piechart.hamlet
+++ b/hledger-web/templates/piechart.hamlet
@@ -9,7 +9,7 @@
      \$chartdiv.show();
      var data =
        [
-         $forall (label, dat) <- labelDataTuples
+         $forall (label, dat, _) <- labelData
            { label: "#{label}", data: #{dat} },
        ];
      function legendFormatter(label, series) {