web: show one line per commodity in charts. Needs more polish, but fixes #109.

hledger-lib/Hledger/Reports.hs

@@ -34,7 +34,8 @@ module Hledger.Reports (
   TransactionsReport,
   TransactionsReportItem,
   triDate,
-  triBalance,
+  triSimpleBalance,
+  transactionsReportByCommodity,
   journalTransactionsReport,
   accountTransactionsReport,
   -- * Accounts report
@@ -435,8 +436,38 @@ type TransactionsReportItem = (Transaction -- the corresponding transaction
                               )
 
 triDate (t,_,_,_,_,_) = tdate t
-triBalance (_,_,_,_,_,Mixed a) = case a of [] -> "0"
+triAmount (_,_,_,_,a,_) = a
-                                           (Amount{aquantity=q}):_ -> show q
+triSimpleBalance (_,_,_,_,_,Mixed a) = case a of [] -> "0"
+                                                 (Amount{aquantity=q}):_ -> show q
+
+-- Split a transactions report whose items may involve several commodities,
+-- into one or more single-commodity transactions reports.
+transactionsReportByCommodity :: TransactionsReport -> [TransactionsReport]
+transactionsReportByCommodity tr =
+  [filterTransactionsReportByCommodity c tr | c <- transactionsReportCommodities tr]
+  where
+    transactionsReportCommodities (_,items) =
+      nub $ sort $ map acommodity $ concatMap (amounts . triAmount) items
+
+-- Remove transaction report items and item amount components that
+-- don't involve the specified commodity. Other item fields like the
+-- running balance and the transaction are left unchanged.
+filterTransactionsReportByCommodity :: Commodity -> TransactionsReport -> TransactionsReport
+filterTransactionsReportByCommodity c (label,items) =
+  (label, fixTransactionsReportItemBalances $ concat [filterTransactionsReportItemByCommodity c i | i <- items])
+  where
+    filterTransactionsReportItemByCommodity c (t,t2,s,o,Mixed as,bal)
+      | c `elem` cs = [item']
+      | otherwise   = []
+      where
+        cs = map acommodity as
+        item' = (t,t2,s,o,Mixed as',bal)
+        as' = filter ((==c).acommodity) as
+    fixTransactionsReportItemBalances is = reverse $ go nullmixedamt $ reverse is
+      where
+        go _ [] = []
+        go bal ((t,t2,s,o,amt,_):is) = (t,t2,s,o,amt,bal'):go bal' is
+          where bal' = bal + amt
 
 -- | Select transactions from the whole journal for a transactions report,
 -- with no \"current\" account. The end result is similar to

hledger-web/Handler/Common.hs

@@ -423,8 +423,8 @@ $forall p' <- tpostings t
 
 -- Generate html for an account register, including a balance chart and transaction list.
 registerReportHtml :: WebOpts -> ViewData -> TransactionsReport -> HtmlUrl AppRoute
-registerReportHtml opts vd r@(_,items) = [hamlet|
+registerReportHtml opts vd r = [hamlet|
- ^{registerChartHtml items}
+ ^{registerChartHtml $ map snd $ transactionsReportByCommodity r}
  ^{registerItemsHtml opts vd r}
 |]
 
@@ -486,8 +486,8 @@ $forall p' <- tpostings t
                --                      Data.Foldable.Foldable t1 =>
                --                      t1 (Transaction, t2, t3, t4, t5, MixedAmount)
                --                      -> t -> Text.Blaze.Internal.HtmlM ()
-registerChartHtml :: [TransactionsReportItem] -> HtmlUrl AppRoute
+registerChartHtml :: [[TransactionsReportItem]] -> HtmlUrl AppRoute
-registerChartHtml items =
+registerChartHtml itemss =
  -- have to make sure plot is not called when our container (maincontent)
  -- is hidden, eg with add form toggled
  [hamlet|
@@ -499,10 +499,11 @@ registerChartHtml items =
    if (chartdiv.is(':visible'))
      \$.plot(chartdiv,
              [
-              [
+              $forall items <- itemss
-               $forall i <- items
+               [
-                [#{dayToJsTimestamp $ triDate i}, #{triBalance i}],
+                $forall i <- items
-              ]
+                 [#{dayToJsTimestamp $ triDate i}, #{triSimpleBalance i}],
+               ],
              ],
              {
                xaxis: {