{-|
Module:             AWSMachine
Description:        Basic wrappers around the AWS library with Machine support.
Copyright:          © 2017 All rights reserved.
License:            GPL-3
Maintainer:         Evan Cofsky <>
Stability:          experimental
Portability:        POSIX
-}

module Network.AWS.Machines.AWS (
    AWSProcessT,
    AWSSourceT,
    RequestMod,
    M,
    withAWS,
    withAWSEnv,
    awsSource,
    pagedSource,
    liftAWS,
    liftIO,
    MonadIO,
    MonadAWS,
    MonadBaseControl,
    AWST',
    Env,
    ResourceT,
    MonadCatch
    ) where

import Lawless hiding (
    fold,
    argument,
    mapping,
    filtered,
    dropping,
    droppingWhile,
    taking,
    takingWhile,
    cycled,
    iterated,
    repeated,
    replicated,
    (<~),
    (<>)
    )
import IO
import Text
import Machine
import Network.AWS.Machines.Types

default (Text)

-- | Run an AWSProcessT.
withAWS ∷ (MonadCatch m, MonadIO m, M m) ⇒
    Credentials → Logger → Region → AWSProcessT m a b → m [b]
withAWS creds lgr reg f = do
    env <- set envRegion reg ∘ set envLogger lgr <$> newEnv creds
    withAWSEnv env f

-- | Run an AWSProcessT with an 'Env' that's already set up.
withAWSEnv ∷ (MonadCatch m, MonadIO m, M m) ⇒
    Env → AWSProcessT m a b → m [b]
withAWSEnv env f =
    runResourceT $ runAWST env $ runT f

awsSource ∷
    (AWSRequest a, Foldable f) ⇒
    GetResponse f a c
    → [RequestMod a]
    → a
    → AWSSourceT m c
awsSource i ms r =
    let
        r0 = modRequest ms r
        unf _ rs = Just (rs ^. i, Nothing)
        nr = \case
            Nothing → return Nothing
            Just q → liftAWS $ send q >>= return ∘ unf q
    in
        unfoldT nr (Just r0) >~> asParts

-- | Stream an 'AWSPager' instance.
pagedSource ∷
    (Foldable f, AWSPager a) ⇒
    GetResponse f a c -- ^ Accessor for the list of ∈ in the response.
    → [RequestMod a] -- ^ Request modifiers
    → a -- ^ The initial request.
    → AWSSourceT m c
    -- ^ A 'Source' of each ∈ in each page.
pagedSource i ms r =
    let
        -- Extract the response to yield, and prepare the next
        -- iteration of 'unfoldT'.
        unf rq rs = Just (rs ^. i, page rq rs)

        -- For each request, if mr isn't Nothing:
        --    1. send the request
        --    2. unfold the response
        -- Otherwise:
        --    return 'Nothing' to end the machine.
        nr mr =
            case mr of
                Nothing → return Nothing
                Just q → liftAWS $ send q >>= return ∘ unf q

        -- The initial request
        r0 = modRequest ms r
    in
        unfoldT nr (Just r0) >~> asParts

modRequest ∷
    [RequestMod a] → a → a
modRequest [] rq = rq
modRequest (m:ms) rq = modRequest ms $ m rq