--
-- MinIO Haskell SDK, (C) 2017, 2018 MinIO, Inc.
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
--     http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--

module Network.Minio.API
  ( connect
  , S3ReqInfo(..)
  , runMinio
  , executeRequest
  , mkStreamRequest
  , getLocation

  , isValidBucketName
  , checkBucketNameValidity
  , isValidObjectName
  , checkObjectNameValidity
  ) where

import           Control.Retry             (fullJitterBackoff,
                                            limitRetriesByCumulativeDelay,
                                            retrying)
import qualified Data.ByteString           as B
import qualified Data.Char                 as C
import qualified Data.Conduit              as C
import qualified Data.Map                  as Map
import qualified Data.Text                 as T
import qualified Data.Time.Clock           as Time

import           Network.HTTP.Conduit      (Response)
import qualified Network.HTTP.Conduit      as NC
import qualified Network.HTTP.Types        as HT
import           Network.HTTP.Types.Header (hHost)

import           Lib.Prelude

import           Network.Minio.APICommon
import           Network.Minio.Data
import           Network.Minio.Errors
import           Network.Minio.Sign.V4
import           Network.Minio.Utils
import           Network.Minio.XmlParser

-- | Fetch bucket location (region)
getLocation :: Bucket -> Minio Region
getLocation bucket = do
  resp <- executeRequest $ defaultS3ReqInfo {
      riBucket = Just bucket
    , riQueryParams = [("location", Nothing)]
    , riNeedsLocation = False
    }
  parseLocation $ NC.responseBody resp


-- | Looks for region in RegionMap and updates it using getLocation if
-- absent.
discoverRegion :: S3ReqInfo -> Minio (Maybe Region)
discoverRegion ri = runMaybeT $ do
  bucket <- MaybeT $ return $ riBucket ri
  regionMay <- lift $ lookupRegionCache bucket
  maybe (do
            l <- lift $ getLocation bucket
            lift $ addToRegionCache bucket l
            return l
        ) return regionMay


buildRequest :: S3ReqInfo -> Minio NC.Request
buildRequest ri = do
  maybe (return ()) checkBucketNameValidity $ riBucket ri
  maybe (return ()) checkObjectNameValidity $ riObject ri

  ci <- asks mcConnInfo

               -- getService/makeBucket/getLocation -- don't need
               -- location
  region <- if | not $ riNeedsLocation ri ->
                   return $ Just $ connectRegion ci

               -- if autodiscovery of location is disabled by user
               | not $ connectAutoDiscoverRegion ci ->
                   return $ Just $ connectRegion ci

               -- discover the region for the request
               | otherwise -> discoverRegion ri

  regionHost <- case region of
    Nothing ->  return $ connectHost ci
    Just r -> if "amazonaws.com" `T.isSuffixOf` connectHost ci
              then maybe
                   (throwIO $ MErrVRegionNotSupported r)
                   return
                   (Map.lookup r awsRegionMap)
              else return $ connectHost ci

  sha256Hash <- if | connectIsSecure ci ->
                       -- if secure connection
                       return "UNSIGNED-PAYLOAD"

                   -- otherwise compute sha256
                   | otherwise -> getPayloadSHA256Hash (riPayload ri)

  timeStamp <- liftIO Time.getCurrentTime

  let hostHeader = (hHost, getHostAddr ci)
      newRi = ri { riPayloadHash = Just sha256Hash
                 , riHeaders = hostHeader
                             : sha256Header sha256Hash
                             : riHeaders ri
                 , riRegion = region
                 }
      newCi = ci { connectHost = regionHost }
      signReq = toRequest newCi newRi
      sp = SignParams (connectAccessKey ci) (connectSecretKey ci)
           timeStamp (riRegion newRi) Nothing (riPayloadHash newRi)
  let signHeaders = signV4 sp signReq

  -- Update signReq with Authorization header containing v4 signature
  return signReq {
      NC.requestHeaders = riHeaders newRi ++ mkHeaderFromPairs signHeaders
      }
  where
    toRequest :: ConnectInfo -> S3ReqInfo -> NC.Request
    toRequest ci s3Req = NC.defaultRequest {
          NC.method = riMethod s3Req
        , NC.secure = connectIsSecure ci
        , NC.host = encodeUtf8 $ connectHost ci
        , NC.port = connectPort ci
        , NC.path = getS3Path (riBucket s3Req) (riObject s3Req)
        , NC.requestHeaders = riHeaders s3Req
        , NC.queryString = HT.renderQuery False $ riQueryParams s3Req
        , NC.requestBody = getRequestBody (riPayload s3Req)
        }


retryAPIRequest :: Minio a -> Minio a
retryAPIRequest apiCall = do
  resE <- retrying retryPolicy (const shouldRetry) $
          const $ try apiCall
  either throwIO return resE
  where
    -- Retry using the full-jitter backoff method for up to 10 mins
    -- total
    retryPolicy = limitRetriesByCumulativeDelay tenMins
                  $ fullJitterBackoff oneMilliSecond

    oneMilliSecond = 1000 -- in microseconds
    tenMins = 10 * 60 * 1000000 -- in microseconds
    -- retry on connection related failure
    shouldRetry :: Either NC.HttpException a -> Minio Bool
    shouldRetry resE =
      case resE of
        -- API request returned successfully
        Right _ -> return False
        -- API request failed with a retryable exception
        Left httpExn@(NC.HttpExceptionRequest _ exn) ->
          case (exn :: NC.HttpExceptionContent) of
            NC.ResponseTimeout     -> return True
            NC.ConnectionTimeout   -> return True
            NC.ConnectionFailure _ -> return True
            -- We received an unexpected exception
            _                      -> throwIO httpExn
        -- We received an unexpected exception
        Left someOtherExn -> throwIO someOtherExn


executeRequest :: S3ReqInfo -> Minio (Response LByteString)
executeRequest ri = do
  req <- buildRequest ri
  mgr <- asks mcConnManager
  retryAPIRequest $ httpLbs req mgr

mkStreamRequest :: S3ReqInfo
                -> Minio (Response (C.ConduitM () ByteString Minio ()))
mkStreamRequest ri = do
  req <- buildRequest ri
  mgr <- asks mcConnManager
  retryAPIRequest $ http req mgr

-- Bucket name validity check according to AWS rules.
isValidBucketName :: Bucket -> Bool
isValidBucketName bucket =
  not (or [ len < 3 || len > 63
          , or (map labelCheck labels)
          , or (map labelCharsCheck labels)
          , isIPCheck
          ])
  where
    len = T.length bucket
    labels = T.splitOn "." bucket

    -- does label `l` fail basic checks of length and start/end?
    labelCheck l = T.length l == 0 || T.head l == '-' || T.last l == '-'

    -- does label `l` have non-allowed characters?
    labelCharsCheck l = isJust $ T.find (\x -> not (C.isAsciiLower x ||
                                                    x == '-' ||
                                                    C.isDigit x)) l

    -- does label `l` have non-digit characters?
    labelNonDigits l = isJust $ T.find (not . C.isDigit) l
    labelAsNums = map (not . labelNonDigits) labels

    -- check if bucket name looks like an IP
    isIPCheck = and labelAsNums && length labelAsNums == 4

-- Throws exception iff bucket name is invalid according to AWS rules.
checkBucketNameValidity :: MonadIO m => Bucket -> m ()
checkBucketNameValidity bucket =
  when (not $ isValidBucketName bucket) $
  throwIO $ MErrVInvalidBucketName bucket

isValidObjectName :: Object -> Bool
isValidObjectName object =
  T.length object > 0 && B.length (encodeUtf8 object) <= 1024

checkObjectNameValidity :: MonadIO m => Object -> m ()
checkObjectNameValidity object =
  when (not $ isValidObjectName object) $
  throwIO $ MErrVInvalidObjectName object