filter.hs

{-# LANGUAGE NamedFieldPuns #-}

module Filter where

import Prelude hiding (floor)
import qualified Prelude

import Predicate

data Bezirk
  = Mitte
  | Friedrichshain
  | Kreuzberg
  | PrenzlauerBerg
  | Charlottenburg
  | Spandau
  | Schöneberg
  | Neukölln
  | MarzahnHellersdorf
  | Lichtenberg
  | Reinickendorf
  deriving (Show, Eq)

data Floor
  = Ground
  | Floor Int
  | Attic
  deriving (Show, Eq, Ord)

-- instance Ord Floor where
--   compare Ground Ground = EQ
--   compare Ground _ = LT
--   compare Attic Attic = EQ
--   compare Attic _ = GT
--   compare (Floor a) (Floor b) = compare a b
--   compare (Floor _) Ground = GT
--   compare (Floor _) Attic = LT

data Apartment = Apartment
  { address :: String
  , rooms   :: Int
  , rent    :: Float
  , bezirk  :: Bezirk
  , area    :: Float
  , floor   :: Floor
  , lift    :: Bool
  } deriving (Show)

data Filter a
  = Condition (Predicate a)
  | And [Filter a]
  | Or [Filter a]
  | Not (Filter a)

runFilter :: Filter a -> a -> Bool
runFilter (Condition pr) value = pr value
runFilter (And filters)  value = and $ map (flip runFilter $ value) filters
runFilter (Or filters)   value = or  $ map (flip runFilter $ value) filters
runFilter (Not f)        value = not $ runFilter f value

invert :: Filter a -> Filter a
invert (Condition pr) = Condition $ not' pr
invert (And filters)  = Or $ map invert filters
invert (Or filters)   = And $ map invert filters
invert (Not f)        = f

rentFilter :: Filter Apartment
rentFilter = Condition $ rent `is` (< 500.0)

preciseArea :: Filter Apartment
preciseArea = Condition $ \(Apartment {area}) -> Prelude.floor area /= ceiling area

inCharlottenburg :: Filter Apartment
inCharlottenburg = Condition $ bezirk `equals` Charlottenburg

isGroundFloor :: Filter Apartment
isGroundFloor = Condition $ floor `equals` Ground

hasLift :: Filter Apartment
hasLift = Condition $ lift `equals` True

eurPerSqm :: Apartment -> Float
eurPerSqm (Apartment {area, rent}) = rent / area

is :: (r -> a) -> Predicate a -> Predicate r
is = flip (.)

bezirkFilter :: [Bezirk] -> Filter Apartment
bezirkFilter = oneOf bezirk

oneOf :: (Eq a) => (r -> a) -> [a] -> Filter r
oneOf f = Or . map (Condition . equals f)

equals :: (Eq a) => (r -> a) -> a -> Predicate r
equals f v = is f (== v)

aptFilter :: Filter Apartment
aptFilter = invert $ And
              [ Not isGroundFloor
              , Or
                  [ Condition $ floor `is` (< Floor 4)
                  , hasLift
                  ]
              , Condition $ eurPerSqm `is` (< 13.0)
              , bezirkFilter [Charlottenburg, Kreuzberg, Neukölln]
              , Condition $ rooms `is` (>= 3)
              ]

apartments :: [Apartment]
apartments =
  [ Apartment
    { address = "Otto-Suhr-Allee 114"
    , rooms   = 1
    , rent    = 620.0
    , bezirk  = Charlottenburg
    , area    = 50.0
    , floor   = Ground
    , lift    = False
    }
  , Apartment
    { address = "Wilmersdorfer Straße 37"
    , rooms   = 3
    , rent    = 1400.0
    , bezirk  = Charlottenburg
    , area    = 89.0
    , floor   = Floor 4
    , lift    = False
    }
  , Apartment
    { address = "Nogatstraße 31"
    , rooms   = 1
    , rent    = 516.0
    , bezirk  = Neukölln
    , area    = 43.0
    , floor   = Floor 3
    , lift    = False
    }
  , Apartment
    { address = "Beethovenstr. 16"
    , rooms   = 3
    , rent    = 1093.0
    , bezirk  = Schöneberg
    , area    = 99.83
    , floor   = Floor 3
    , lift    = False
    }
  , Apartment
    { address = "Mehringdamm 43"
    , rooms   = 3
    , rent    = 740.0
    , bezirk  = Kreuzberg
    , area    = 85.0
    , floor   = Floor 3
    , lift    = True
    }
  , Apartment
    { address = "Tempelhofer Feld"
    , rooms   = 2
    , rent    = 780.0
    , bezirk  = Neukölln
    , area    = 71.0
    , floor   = Ground
    , lift    = False
    }
  , Apartment
    { address = "Marienfelder Allee 27"
    , rooms   = 2
    , rent    = 600.0
    , bezirk  = Neukölln
    , area    = 52.5
    , floor   = Floor 4
    , lift    = True
    }
  , Apartment
    { address = "Dietrich-Bonhoeffer-Straße 2"
    , rooms   = 2
    , rent    = 702.0
    , bezirk  = PrenzlauerBerg
    , area    = 54
    , floor   = Floor 1
    , lift    = True
    }
  , Apartment
    { address = "Kurfürstenstr. 15"
    , rooms   = 2
    , rent    = 1300.0
    , bezirk  = Mitte
    , area    = 110
    , floor   = Floor 4
    , lift    = True
    }
  , Apartment
    { address = "Dahlmannstrasse 2"
    , rooms   = 2
    , rent    = 850.0
    , bezirk  = Charlottenburg
    , area    = 72
    , floor   = Floor 3
    , lift    = True
    }
  , Apartment
    { address = "Alt Moabit 37"
    , rooms   = 2
    , rent    = 389.62
    , bezirk  = Charlottenburg
    , area    = 59.85
    , floor   = Floor 3
    , lift    = False
    }
  , Apartment
    { address = "Rauschener Alle 1"
    , rooms   = 2
    , rent    = 800.0
    , bezirk  = Charlottenburg
    , area    = 58.0
    , floor   = Floor 3
    , lift    = False
    }
  , Apartment
    { address = "Kurfürstendamm 74"
    , rooms   = 3
    , rent    = 1055.0
    , bezirk  = Charlottenburg
    , area    = 84.41
    , floor   = Floor 2
    , lift    = False
    }
  , Apartment
    { address = "Freiheitsweg 13"
    , rooms   = 1
    , rent    = 313.48
    , bezirk  = Reinickendorf
    , area    = 37.21
    , floor   = Attic
    , lift    = False
    }
  , Apartment
    { address = "Steglitzer Damm 51B"
    , rooms   = 2
    , rent    = 768.5
    , bezirk  = Reinickendorf
    , area    = 58.0
    , floor   = Floor 1
    , lift    = True
    }
  , Apartment
    { address = "Kurfürstendamm 105"
    , rooms   = 1
    , rent    = 495.0
    , bezirk  = Charlottenburg
    , area    = 41.0
    , floor   = Floor 3
    , lift    = True
    }
  , Apartment
    { address = "Breite Straße 29"
    , rooms   = 4
    , rent    = 820.0
    , bezirk  = Spandau
    , area    = 84.0
    , floor   = Floor 2
    , lift    = True
    }
  , Apartment
    { address = "Müllerstr. 29"
    , rooms   = 2
    , rent    = 628.0
    , bezirk  = PrenzlauerBerg
    , area    = 56.13
    , floor   = Ground
    , lift    = False
    }

  ]