FileHttp.elm

module FileHttp exposing
  ( get
  , getString
  )

import Http
import HttpBuilder exposing (..)
import Json.Decode exposing (Decoder)
import Task exposing (Task, andThen, onError, mapError, map)

{-| Send a GET request to the given URL. You also specify how to decode the
response.
    import Json.Decode (list, string)
    hats : Task Error (List String)
    hats =
        get (list string) "http://example.com/hat-categories.json"

Unlike the standard library, an HTTP status code of 0 will *not* result in an error, but will
be intercepted and turned into a 200.  This allows you to access file:// resources transparently.
-}
get : Decoder value -> String -> Task Http.Error value
get decoder url =
  let
    getTask =
      HttpBuilder.get url
        |> send (jsonReader decoder) (jsonReader decoder)
  in
  makeTask getTask


{-| Send a GET request to the given URL. You will get the entire response as a
string.
    hats : Task Error String
    hats =
        getString "http://example.com/hat-categories.markdown"

Unlike the standard library, an HTTP status code of 0 will *not* result in an error, but will
be intercepted and turned into a 200.  This allows you to access file:// resources transparently.
-}
getString : String -> Task Http.Error String
getString url =
  Task.succeed ""
{-  let
    getTask =
      // TODO
  in
  makeTask getTask-}


{-| Given a task, return a new task that copes with status of 0
-}
makeTask : Task (Error r) (Response r) -> Task Http.Error r
makeTask task =
  task
    `onError` recoverIfStatusZero
    |> mapError builderErrorToHttpError
    |> map (\response -> response.data)


{-| Turn a Response with status 0 into a Response with status 200
-}
recoverIfStatusZero : Error r -> Task (Error r) (Response r)
recoverIfStatusZero error =
  case error of
    BadResponse response ->
      if (response.status == 0) then
        Task.succeed
          { data = response.data
          , status = 200
          , statusText = response.statusText
          , headers = response.headers
          , url = response.url
          }
      else
        Task.fail error

    _ ->
      Task.fail error


{-| Convert a HttpBuilder.Error into and Http.Error so that the rest of the application doesn't need to
know that anything has changed.
-}
builderErrorToHttpError : Error a -> Http.Error
builderErrorToHttpError error =
  case error of
    UnexpectedPayload str ->
      Http.UnexpectedPayload str

    NetworkError ->
      Http.NetworkError

    Timeout ->
      Http.Timeout

    BadResponse response ->
      Http.BadResponse response.status response.statusText