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{-# LANGUAGE OverloadedStrings #-}
module Mail
( mailSubject
, mailBody
) where
import Data.Text (Text)
import qualified Data.Text as T
import Date
import Birthdate
mailSubject :: [Birthdate] -> Text
mailSubject birthdates =
let count = length birthdates
in T.concat
[ "Hey, "
, if count > 1 then "there are" else "there is"
, " "
, T.pack . show $ count
, " birthday"
, if count > 1 then "s" else ""
, " today!"
]
mailBody :: Date -> [Birthdate] -> Text
mailBody currentDate birthdates =
let count = length birthdates
birthdatesWithLines = map (mapFst getLine) . zip [1..] $ birthdates
getLine 1 = if count == 1 then SingleLine else FirstLine
getLine line = if line == count then LastLine else MiddleLine
in T.concat $ map (mailLine currentDate) birthdatesWithLines
mapFst :: (a -> c) -> (a, b) -> (c, b)
mapFst f (x, y) = (f x, y)
data Line =
SingleLine
| FirstLine
| MiddleLine
| LastLine
deriving (Eq, Show)
mailLine :: Date -> (Line, Birthdate) -> Text
mailLine date (SingleLine, birthdate) =
T.concat
[ fullname birthdate
, " is now "
, T.pack . show $ age date birthdate
, " years old."
]
mailLine date (FirstLine, birthdate) =
T.concat
[ fullname birthdate
, " is now "
, T.pack . show $ age date birthdate
, " years old"
]
mailLine date (MiddleLine, birthdate) =
T.concat
[ ", "
, fullname birthdate
, " is "
, T.pack . show $ age date birthdate
, " years old"
]
mailLine date (LastLine, birthdate) =
T.concat
[ " and "
, fullname birthdate
, " is "
, T.pack . show $ age date birthdate
, " years old."
]
|
