qraphqlexample.elm

import Html exposing (..)
import String
import List
import Color exposing (Color)

--
infixl 2 =>
(=>) = (,)

--

type Query 
  = Object String QueryParameters (List Query)
  
  
type alias QueryParameters = List (String, String)


field : String -> Query
field name =
  Object name [] []
  
  
query : String -> List (String, String) -> List Query -> Query
query = 
  Object
  

render : Query -> String 
render query = 
  let 
      ntabs n = 
        String.repeat n " "
        
      renderParam (name, value) = 
        name ++ " : " ++ value
        
      renderParams params = 
        if List.isEmpty params 
        then 
          ""
        else
          "(" 
            ++ (List.map renderParam params |> String.join ", ")
            ++ ")"
  
      renderWithTab n q = 
        case q of 
          Object name params qs ->
            ntabs n 
              ++ name
              ++ renderParams params 
              ++ renderQueries n qs
              
              
      renderQueries n queries = 
        if List.isEmpty queries 
        then 
          ""
        else 
          "{\n" 
            ++ (List.map (renderWithTab (n + 2)) queries |> String.join "\n")
            ++ "\n" 
            ++ ntabs n 
            ++ "}"
              
              
  in 
      renderWithTab 0 query

--------------------

profilePic = 
  query "ProfilePic" []
    [ field "source"
    , field "width"
    , field "height"
    , field "description"
    ]
    
friendInfo = 
  query "FriendInfo" [ ]
    [ field "name"
    , field "age"
    ]

friendListItem id = 
  query "FriendListItem" [ ("id", toString id) ]
    [ profilePic
    , friendInfo
    ]


friendList = 
  query "FriendList" []
    ( List.map friendListItem [1..10] )


--main = 
--  pre []
--    [ text (render friendList) ]


----------------------

type alias Transaction state effect = 
  { state  : state 
  , effect : Maybe effect
  }
  
request : state -> effect -> Transaction state effect
request state effect = 
  { state  = state
  , effect = Just effect 
  }
  

----------------------

initImage options = 
  let 
      state = 
        { color  = options.color
        , width  = options.width
        , height = options.height
        , source = Nothing
        , description = Nothing
        }
        
      effect = 
        query "Image" 
          [ "id"     => toString options.id
          , "width"  => toString options.width
          , "height" => toString options.height
          ]
          [ field "source"
          , field "description"
          ]
          
  in 
      request state effect 


initCarousel options = 
  let 
      makeImageOptions id = 
        { id = id 
        , width = 200
        , height = 200
        , color = options.color
        }
        
      imageOptions = 
        List.map makeImageOptions [1..10]
        
      transactions = 
        List.map initImage imageOptions
        
      imageStates = 
        List.map .state transactions
        
      imageQueries = 
        List.map .effect transactions
        |> keepJusts
        
      state = 
        { images = imageStates }
        
      effect = 
        query "Carousel" 
          [ "id" => toString options.id ]
          ( imageQueries )
          
  in 
      request state effect
      
      
  
keepJusts list = 
  case list of 
    [] ->
      []
      
    m :: ms -> 
      case m of 
        Nothing ->
          keepJusts ms
          
        Just x ->
          x :: keepJusts ms
        
        
        
carousel = 
  initCarousel { color = Color.blue, id = 3389744 }
  
  

main = 
  case carousel.effect of   
    Nothing ->
      text ""
      
    Just effect ->
      pre []
        [ text (render effect) ]