From 5c110716cfda6e616a795edd12f2012b132dca9f Mon Sep 17 00:00:00 2001
From: Joris
Date: Sun, 2 Apr 2017 17:51:12 +0200
Subject: Add a chart on payments by month by categories

---
 src/client/Chart/Model.elm | 73 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 src/client/Chart/Model.elm

(limited to 'src/client/Chart/Model.elm')

diff --git a/src/client/Chart/Model.elm b/src/client/Chart/Model.elm
new file mode 100644
index 0000000..b5c176f
--- /dev/null
+++ b/src/client/Chart/Model.elm
@@ -0,0 +1,73 @@
+module Chart.Model exposing
+  ( Chart
+  , Serie
+  , maxScale
+  , Vec2
+  , View
+  , mkView
+  , bounds
+  )
+
+import List.Extra as List
+
+type alias Chart =
+  { keys : List String
+  , series : List Serie
+  , size : Vec2
+  , title : String
+  , scaleColor : String
+  , formatOrdinate : Float -> String
+  , ordinateLines : Int
+  }
+
+type alias Serie =
+  { values : List Float
+  , color : String
+  , label : String
+  }
+
+maxScale : Chart -> Float
+maxScale { keys, series } =
+  List.range 0 (List.length keys - 1)
+    |> List.map (\i ->
+         series
+           |> List.map (truncate << Maybe.withDefault 0 << List.getAt i << .values)
+           |> List.maximum
+           |> Maybe.withDefault 0
+       )
+    |> List.maximum
+    |> Maybe.withDefault 0
+    |> upperBound
+
+upperBound : Int -> Float
+upperBound n = toFloat (upperBoundInt 0 n)
+
+upperBoundInt : Int -> Int -> Int
+upperBoundInt count n =
+  if n < 10
+    then
+      (n + 1) * (10 ^ count)
+    else
+      upperBoundInt (count + 1) (n // 10)
+
+type alias Vec2 =
+  { x : Float
+  , y : Float
+  }
+
+type alias View =
+  { fx : Float -> Float
+  , fy : Float -> Float
+  }
+
+mkView : Vec2 -> Vec2 -> View
+mkView p1 p2 =
+  { fx = \x -> p1.x + x * (p2.x - p1.x)
+  , fy = \y -> p1.y + y * (p2.y - p1.y)
+  }
+
+bounds : View -> (Vec2, Vec2)
+bounds { fx, fy } =
+  ( { x = fx 0, y = fy 0 }
+  , { x = fx 1, y = fy 1 }
+  )
-- 
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