-- | Helpers for dealing with HTTP requests.
module Strive.Internal.HTTP
  ( delete,
    get,
    post,
    put,
    buildRequest,
    performRequest,
    handleResponse,
    decodeValue,
  )
where

import Data.Aeson (FromJSON, eitherDecode)
import Data.ByteString.Char8 (unpack)
import Data.ByteString.Lazy (ByteString)
import Network.HTTP.Client
  ( Request,
    Response,
    method,
    parseRequest,
    responseBody,
  )
import Network.HTTP.Types
  ( Method,
    Query,
    QueryLike,
    methodDelete,
    methodGet,
    methodPost,
    methodPut,
    renderQuery,
    toQuery,
  )
import Strive.Aliases (Result)
import Strive.Client (Client (client_accessToken, client_requester))

-- | Perform an HTTP DELETE request.
delete :: (QueryLike q, FromJSON j) => Client -> String -> q -> IO (Result j)
delete = http methodDelete

-- | Perform an HTTP GET request.
get :: (QueryLike q, FromJSON j) => Client -> String -> q -> IO (Result j)
get = http methodGet

-- | Perform an HTTP POST request.
post :: (QueryLike q, FromJSON j) => Client -> String -> q -> IO (Result j)
post = http methodPost

-- | Perform an HTTP PUT request.
put :: (QueryLike q, FromJSON j) => Client -> String -> q -> IO (Result j)
put = http methodPut

-- | Perform an HTTP request.
http ::
  (QueryLike q, FromJSON j) =>
  Method ->
  Client ->
  String ->
  q ->
  IO (Result j)
http httpMethod client resource query = do
  request <- buildRequest httpMethod client resource query
  response <- performRequest client request
  pure (handleResponse response)

-- | Build a request.
buildRequest :: (QueryLike q) => Method -> Client -> String -> q -> IO Request
buildRequest httpMethod client resource query = do
  request <- parseRequest (buildUrl client resource query)
  pure request {method = httpMethod}

-- | Build a URL.
buildUrl :: (QueryLike q) => Client -> String -> q -> String
buildUrl client resource query =
  concat
    [ "https://www.strava.com/",
      resource,
      unpack (renderQuery True (buildQuery client <> toQuery query))
    ]

-- | Build a query.
buildQuery :: Client -> Query
buildQuery client = toQuery [("access_token", client_accessToken client)]

-- | Actually perform an HTTP request.
performRequest :: Client -> Request -> IO (Response ByteString)
performRequest = client_requester

-- | Handle decoding a potentially failed response.
handleResponse :: (FromJSON j) => Response ByteString -> Result j
handleResponse response = case decodeValue response of
  Left message -> Left (response, message)
  Right value -> Right value

-- | Decode a response body as JSON.
decodeValue :: (FromJSON j) => Response ByteString -> Either String j
decodeValue response = eitherDecode (responseBody response)