Compute cumulative income with a DB query

1 files changed, 47 insertions, 11 deletions

diff --git a/server/src/Persistence/Income.hs b/server/src/Persistence/Income.hs
index ba7ad19..e689505 100644
--- a/server/src/Persistence/Income.hs
+++ b/server/src/Persistence/Income.hs
@@ -1,21 +1,24 @@
 module Persistence.Income
   ( count
   , list
-  , listAll
   , listModifiedSince
   , create
   , edit
   , delete
   , definedForAll
+  , getCumulativeIncome
   ) where
 
 import qualified Data.List              as L
+import           Data.Map               (Map)
+import qualified Data.Map               as M
 import qualified Data.Maybe             as Maybe
 import qualified Data.Text              as T
 import           Data.Time.Calendar     (Day)
 import           Data.Time.Clock        (UTCTime)
 import           Data.Time.Clock        (getCurrentTime)
-import           Database.SQLite.Simple (FromRow (fromRow), Only (Only))
+import           Database.SQLite.Simple (FromRow (fromRow), NamedParam ((:=)),
+                                         Only (Only))
 import qualified Database.SQLite.Simple as SQLite
 import           Prelude                hiding (id, until)
 
@@ -58,13 +61,6 @@ list page perPage =
         (perPage, (page - 1) * perPage)
   )
 
-listAll :: Query [Income]
-listAll =
-  Query (\conn ->
-    map (\(Row i) -> i) <$>
-      SQLite.query_ conn "SELECT * FROM income WHERE deleted_at IS NULL"
-  )
-
 listModifiedSince :: UTCTime -> Query [Income]
 listModifiedSince since =
   Query (\conn ->
@@ -79,7 +75,7 @@ listModifiedSince since =
           ,   "OR edited_at >= ?"
           ,   "OR deleted_at >= ?"
           ])
-        (Only since)
+        (since, since, since)
   )
 
 create :: UserId -> Day -> Int -> Query Income
@@ -156,6 +152,46 @@ definedForAll users =
   where
     fromRows rows =
       if L.sort users == L.sort (map fst rows) then
-        Maybe.listToMaybe . L.sort . map snd $ rows
+        Maybe.listToMaybe . reverse . L.sort . map snd $ rows
       else
         Nothing
+
+getCumulativeIncome :: Day -> Day -> Query (Map UserId Int)
+getCumulativeIncome start end =
+  Query (\conn -> M.fromList <$> SQLite.queryNamed conn (SQLite.Query query) parameters)
+  where
+    query =
+      T.intercalate "\n" $
+        [ "SELECT user_id, CAST(ROUND(SUM(count)) AS INTEGER) FROM ("
+        , "  SELECT"
+        , "    I1.user_id,"
+        , "    ((JULIANDAY(MIN(I2.date)) - JULIANDAY(I1.date)) * I1.amount * 12 / 365) AS count"
+        , "  FROM (" <> (selectBoundedIncomes ">" ":start") <> ") AS I1"
+        , "  INNER JOIN (" <> (selectBoundedIncomes "<" ":end") <> ") AS I2"
+        , "  ON I2.date > I1.date AND I2.user_id == I1.user_id"
+        , "  GROUP BY I1.date, I1.user_id"
+        , ") GROUP BY user_id"
+        ]
+
+    selectBoundedIncomes op param =
+      T.intercalate "\n" $
+        [ "    SELECT user_id, date, amount FROM ("
+        , "      SELECT"
+        , "        i.user_id, " <> param <> " AS date, i.amount"
+        , "      FROM"
+        , "        (SELECT id, MAX(date) AS max_date"
+        , "        FROM income"
+        , "        WHERE date <= " <> param <> " AND deleted_at IS NULL"
+        , "        GROUP BY user_id) AS m"
+        , "      INNER JOIN income AS i"
+        , "      ON i.id = m.id AND i.date = m.max_date"
+        , "    ) UNION"
+        , "    SELECT user_id, date, amount"
+        , "    FROM income"
+        , "    WHERE date " <> op <> " " <> param <> " AND deleted_at IS NULL"
+        ]
+
+    parameters =
+      [ ":start" := start
+      , ":end" := end
+      ]