, mime-mail

    , network                   

    , sendgrid-haskell          >= 1.0

    , smtp-mail                 >= 0.1.4.5

sendgridUser = "example"
sendgridKey = "abcdefg"

smtpHost = "smtp.sendgrid.net"
# smtpPort = 25
smtpUser = "whoareyou"
smtpPass = "iami"

randomInvCode = InvitationCode <$> randBytes 256

randomInvCode = InvitationCode <$> randBytes 32

  if length code == 256

  if length code == 32

import qualified Network.Sendgrid.Api as Sendgrid

import qualified Network.Socket as NS
import qualified Network.Mail.SMTP as SMTP

  , sendgridAuth :: Sendgrid.Authentication

  , smtpConfig :: SmtpConfig

data SmtpConfig = SmtpConfig 
  { smtpHost :: NS.HostName
  , smtpPort :: Maybe NS.PortNumber
  , smtpUser :: SMTP.UserName 
  , smtpPass :: SMTP.Password 
  }

          <*> readSendgridAuth cfg

          <*> readSmtpConfig cfg

readSendgridAuth :: CT.Config -> IO Sendgrid.Authentication
readSendgridAuth cfg = 
  Sendgrid.Authentication <$> C.require cfg "sendgridUser"
                          <*> C.require cfg "sendgridKey"

readSmtpConfig :: CT.Config -> IO SmtpConfig
readSmtpConfig cfg = 
  SmtpConfig <$> C.require cfg "smtpHost"
             <*> ((fmap . fmap) fromInteger $ C.lookup cfg "smtpPort")
             <*> C.require cfg "smtpUser"
             <*> C.require cfg "smtpKey"

import qualified Network.Sendgrid.Api as Sendgrid

import Network.Mail.SMTP as SMTP
import Network.Mail.Mime

  inviteEmail <- liftIO $ 
    projectInviteEmail (templatePath cfg) (p ^. projectName) (u ^. userEmail) toEmail invCode
  maybeSuccess <- liftIO $ Sendgrid.sendEmail (sendgridAuth cfg) inviteEmail
  maybe
    (snapError 500 "The invitation record was created successfully, but the introductory email could not be sent.")
    (const $ pure ())
    maybeSuccess

  liftIO $ sendProjectInviteEmail cfg (p ^. projectName) (u ^. userEmail) toEmail invCode
sendProjectInviteEmail :: QConfig
                       -> ProjectName 
                       -> Email       -- Inviting user's email address
                       -> Email       -- Invitee's email address
                       -> InvitationCode 
                       -> IO ()
sendProjectInviteEmail cfg pn fromEmail toEmail invCode = 
  let SmtpConfig{..} = smtpConfig cfg
      mailer = maybe (sendMailWithLogin smtpHost) (sendMailWithLogin' smtpHost) smtpPort
  in  buildProjectInviteEmail (templatePath cfg) pn fromEmail toEmail invCode >>= 
      (mailer smtpUser smtpPass)
  

projectInviteEmail :: System.IO.FilePath 
                   -> ProjectName 
                   -> Email -> Email 
                   -> InvitationCode 
                   -> IO Sendgrid.EmailMessage 
projectInviteEmail templatePath pn from' to' invCode = do

buildProjectInviteEmail :: System.IO.FilePath 
                        -> ProjectName 
                        -> Email       -- Inviting user's email address
                        -> Email       -- Invitee's email address
                        -> InvitationCode 
                        -> IO Mail
buildProjectInviteEmail templatePath pn fromEmail toEmail invCode = do

  template <- maybe (fail "Could not find template for invitation email") pure $ 
    getStringTemplate "invitation_email" templates
  let setAttrs = setAttribute "from_email" (from' ^. _Email) .
                 setAttribute "project_name" pn .
                 setAttribute "to_email" (to' ^. _Email) .
                 setAttribute "inv_code" (renderInvCode invCode) 
  return $ Sendgrid.EmailMessage 
    { from = "invitations@aftok.com"
    , to = unpack $ to' ^. _Email
    , subject = unpack $ "Welcome to the "<>pn<>" Aftok!"
    , text = render $ setAttrs template
    }

  case getStringTemplate "invitation_email" templates of
    Nothing -> fail "Could not find template for invitation email"
    Just template ->
      let setAttrs = setAttribute "from_email" (fromEmail ^. _Email) .
                     setAttribute "project_name" pn .
                     setAttribute "to_email" (toEmail ^. _Email) .
                     setAttribute "inv_code" (renderInvCode invCode) 
          fromAddr = Address Nothing ("invitations@aftok.com")
          toAddr   = Address Nothing (toEmail ^. _Email)
          subject  = "Welcome toEmail the "<>pn<>" Aftok!"
          body     = plainTextPart . render $ setAttrs template
      in  pure $ SMTP.simpleMail fromAddr [toAddr] [] [] subject [body]