module App.Validation.DNS where

import Prelude (apply, between, bind, map, pure, ($), (-), (<), (<>), (==))

import Control.Alt ((<|>))
import Data.Array as A
import Data.Either (Either(..))
import Data.Maybe (Maybe(..), maybe, fromMaybe)
import Data.String.CodeUnits as CU
import Data.String as S
import Data.Validation.Semigroup (V, invalid, toEither)

import App.Type.ResourceRecord (ResourceRecord, emptyRR, Mechanism, Modifier)
import App.Type.ResourceRecord (MechanismType(..), ModifierType(..)) as RR
import GenericParser.SomeParsers as SomeParsers
import GenericParser.Parser as G
import GenericParser.DomainParser.Common (DomainError) as DomainParser
import GenericParser.DomainParser (name, sub_eof) as DomainParser
import GenericParser.IPAddress as IPAddress
import GenericParser.RFC5234 as RFC5234

import App.Type.DKIM as DKIM
import App.Type.DMARC as DMARC
import App.Type.CAA as CAA

import Utils (id)

data Error
  = UNKNOWN
  | VENameServer1 (G.Error DomainParser.DomainError)
  | VENameServer2 (G.Error DomainParser.DomainError)

validationCNAME :: ResourceRecord -> V (Array Error) ResourceRecord
validationCNAME form = ado
  name   <- parse DomainParser.name form.name VEName
  ttl    <- is_between min_ttl max_ttl form.ttl      VETTL
  target <- parse DomainParser.sub_eof form.target VECNAME
  in emptyRR { rrid = form.rrid, readonly = form.readonly, rrtype = "CNAME", name = name, ttl = ttl, target = target }

is_between :: Int -> Int -> Int -> (Int -> Int -> Int -> Error) -> V (Array Error) Int
is_between min max n ve = if between min max n
                          then pure n
                          else invalid [ve min max n]

validationSRV :: ResourceRecord -> V (Array Error) ResourceRecord
validationSRV form = ado
  name     <- parse DomainParser.name form.name     VEName
  in emptyRR { rrid = form.rrid, readonly = form.readonly, rrtype = "SRV"
             , name = name, ttl = ttl, target = target
             , priority = Just priority, port = Just port, protocol = form.protocol, weight = Just weight }

validation_nameservers :: ResourceRecord -> V (Array Error) ResourceRecord
validation_nameservers form = ado
  nameserver1 <- parse DomainParser.name form.name VEName
  nameserver2 <- parse DomainParser.name form.name VEName
  in emptyRR { rrid = form.rrid, readonly = form.readonly, rrtype = "SPF"
             , name = name, ttl = ttl, target = "" -- `target` is discarded!
             , v = form.v, mechanisms = Just mechanisms
             , modifiers = Just modifiers, q = form.q }

-- | `validation` provides a way to validate the content of a RR.
validation :: ResourceRecord -> Either (Array Error) ResourceRecord
validation entry = toEither $ validation_nameservers   entry
  "DKIM"  -> toEither $ validationDKIM  entry
  "DMARC" -> toEither $ validationDMARC entry
  _       -> toEither $ invalid [UNKNOWN]