module RecipeCost where

-- * Data types definition
data Ingredient = Ingredient { ingredientName :: String
                             , unit_cost :: Double
                             }deriving (Show)

data UsedIngredient = UsedIngredient { ingredient :: Ingredient, quantityUsed :: Double }deriving (Show)

data Recipe = Recipe { recipeName :: String
                     , billOfMaterial :: [ UsedIngredient ]
                     , finalQuantity :: Double
                     , useNumber :: Double
                     }deriving (Show)

-- * Calculations
recipeCost :: Recipe -> Double
recipeCost (Recipe _ bom _ _) = sum . map ingredientCost $ bom

ingredientCost :: UsedIngredient -> Double
ingredientCost (UsedIngredient (Ingredient _ uCost) qtt) = uCost * qtt

unitCost :: Recipe -> Double -> Double
unitCost (Recipe _ _ qtt _) totalCost = totalCost / qtt

useCost :: Recipe -> Double -> Double
useCost (Recipe _ _ _ uses) totalCost = totalCost / uses

(→) :: Ingredient -> Double -> UsedIngredient
(→) ingredient qtt = UsedIngredient ingredient qtt