From 4b3c6afe7599ae65749724d6e12ade060e943863 Mon Sep 17 00:00:00 2001
From: Simon Michael <simon@joyful.com>
Date: Tue, 3 Apr 2018 13:06:52 +0100
Subject: [PATCH] lib: new generic PeriodicReport, and some report-related type
 aliases

---
 hledger-lib/Hledger/Reports.hs             |  2 ++
 hledger-lib/Hledger/Reports/ReportTypes.hs | 40 ++++++++++++++++++++++
 hledger-lib/hledger-lib.cabal              |  8 +++++
 hledger-lib/package.yaml                   |  2 ++
 4 files changed, 52 insertions(+)
 create mode 100644 hledger-lib/Hledger/Reports/ReportTypes.hs

diff --git a/hledger-lib/Hledger/Reports.hs b/hledger-lib/Hledger/Reports.hs
index 4a9131486..17e80d9e1 100644
--- a/hledger-lib/Hledger/Reports.hs
+++ b/hledger-lib/Hledger/Reports.hs
@@ -10,6 +10,7 @@ javascript, or whatever.
 
 module Hledger.Reports (
   module Hledger.Reports.ReportOptions,
+  module Hledger.Reports.ReportTypes,
   module Hledger.Reports.EntriesReport,
   module Hledger.Reports.PostingsReport,
   module Hledger.Reports.TransactionsReports,
@@ -25,6 +26,7 @@ where
 import Test.HUnit
 
 import Hledger.Reports.ReportOptions
+import Hledger.Reports.ReportTypes
 import Hledger.Reports.EntriesReport
 import Hledger.Reports.PostingsReport
 import Hledger.Reports.TransactionsReports
diff --git a/hledger-lib/Hledger/Reports/ReportTypes.hs b/hledger-lib/Hledger/Reports/ReportTypes.hs
new file mode 100644
index 000000000..787cf5f80
--- /dev/null
+++ b/hledger-lib/Hledger/Reports/ReportTypes.hs
@@ -0,0 +1,40 @@
+{- |
+New common report types, used by the BudgetReport for now, perhaps all reports later.
+-}
+
+module Hledger.Reports.ReportTypes
+where
+
+import Data.Decimal
+import Hledger.Data
+
+type Percentage = Decimal
+
+type Change  = MixedAmount  -- ^ A change in balance during a certain period.
+type Balance = MixedAmount  -- ^ An ending balance as of some date.
+type Total   = MixedAmount  -- ^ The sum of 'Change's in a report or a report row. Does not make sense for 'Balance's.
+type Average = MixedAmount  -- ^ The average of 'Change's or 'Balance's in a report or report row.
+
+-- | A generic tabular report of some value, where each row corresponds to an account
+-- and each column is a date period. The column periods are usually consecutive subperiods
+-- formed by splitting the overall report period by some report interval (daily, weekly, etc.)
+-- Depending on the value type, this can be a report of balance changes, ending balances,
+-- budget performance, etc. Successor to MultiBalanceReport.
+data PeriodicReport a =
+  PeriodicReport
+    ( [DateSpan]            -- ^ The subperiods formed by spliting the overall report period by the report interval.
+                            --   For ending-balance reports, only the end date is significant.
+                            --   Usually displayed as report columns.
+    , [PeriodicReportRow a] -- ^ One row per account in the report.
+    , PeriodicReportRow a   -- ^ The grand totals row. The account name in this row is always empty.
+    )
+   deriving (Show)
+
+type PeriodicReportRow a =
+  ( AccountName  -- ^ A full account name.
+  , AccountName  -- ^ Shortened form of the account name to display in tree mode. Usually the leaf name, possibly with parent accounts prefixed.
+  , Int          -- ^ Indent level for displaying this account name in tree mode. 0, 1, 2... 
+  , [a]          -- ^ The data value for each subperiod.
+  , a            -- ^ The total of this row's values.
+  , a            -- ^ The average of this row's values.
+  )
diff --git a/hledger-lib/hledger-lib.cabal b/hledger-lib/hledger-lib.cabal
index 9fda2022f..cefa19d37 100644
--- a/hledger-lib/hledger-lib.cabal
+++ b/hledger-lib/hledger-lib.cabal
@@ -131,6 +131,8 @@ library
       Hledger.Utils.UTF8IOCompat
       Text.Megaparsec.Compat
   other-modules:
+      Hledger.Reports.BudgetReport
+      Hledger.Reports.ReportTypes
       Paths_hledger_lib
   default-language: Haskell2010
 
@@ -209,10 +211,12 @@ test-suite doctests
       Hledger.Reports
       Hledger.Reports.BalanceHistoryReport
       Hledger.Reports.BalanceReport
+      Hledger.Reports.BudgetReport
       Hledger.Reports.EntriesReport
       Hledger.Reports.MultiBalanceReports
       Hledger.Reports.PostingsReport
       Hledger.Reports.ReportOptions
+      Hledger.Reports.ReportTypes
       Hledger.Reports.TransactionsReports
       Hledger.Utils
       Hledger.Utils.Color
@@ -301,10 +305,12 @@ test-suite easytests
       Hledger.Reports
       Hledger.Reports.BalanceHistoryReport
       Hledger.Reports.BalanceReport
+      Hledger.Reports.BudgetReport
       Hledger.Reports.EntriesReport
       Hledger.Reports.MultiBalanceReports
       Hledger.Reports.PostingsReport
       Hledger.Reports.ReportOptions
+      Hledger.Reports.ReportTypes
       Hledger.Reports.TransactionsReports
       Hledger.Utils
       Hledger.Utils.Color
@@ -394,10 +400,12 @@ test-suite hunittests
       Hledger.Reports
       Hledger.Reports.BalanceHistoryReport
       Hledger.Reports.BalanceReport
+      Hledger.Reports.BudgetReport
       Hledger.Reports.EntriesReport
       Hledger.Reports.MultiBalanceReports
       Hledger.Reports.PostingsReport
       Hledger.Reports.ReportOptions
+      Hledger.Reports.ReportTypes
       Hledger.Reports.TransactionsReports
       Hledger.Utils
       Hledger.Utils.Color
diff --git a/hledger-lib/package.yaml b/hledger-lib/package.yaml
index fa063c212..51277fee0 100644
--- a/hledger-lib/package.yaml
+++ b/hledger-lib/package.yaml
@@ -122,8 +122,10 @@ library:
   - Hledger.Read.TimeclockReader
   - Hledger.Reports
   - Hledger.Reports.ReportOptions
+  - Hledger.Reports.ReportTypes
   - Hledger.Reports.BalanceHistoryReport
   - Hledger.Reports.BalanceReport
+  - Hledger.Reports.BudgetReport
   - Hledger.Reports.EntriesReport
   - Hledger.Reports.MultiBalanceReports
   - Hledger.Reports.PostingsReport