module Registry.Registry where 

import qualified Text.ParserCombinators.Parsec as Parsec
import qualified System.IO
import Data.Maybe 
import Registry.Types
import Registry.Utils
import Registry.Grammar (registry, member, parse)
import Types
import Grammar

defaultInfile = "./language-subtag-registry"

type Result = (Bool, String)

-- Combines a former result with a new result, yielding a result.
combine :: Result -> Result -> Result
combine (True, _) (False, s) = (False, s)
combine (False, s1) (False, s2) = (False, s1 ++ "; " ++ s2)
combine (False, s) (True, _) = (False, s)
combine (True, _) (True, _) = (True, "")

readRegistry filename = do
  input <- System.IO.readFile filename
  return (getRegistry input)

getRegistry input =
    let reg = Registry.Grammar.parse input in
    if not (checkOK reg) then
          error "Illegal registry"
    else
          registryOf reg    

dateOf (Date d) = d 

isValidLanguage l dict =
    if length (filter (onlyThisValue "language" l) dict) == 1 then
       (True, "")
    else
       (False, "Unknown language " ++ l)

isValidScript Nothing _ = (True, "")
isValidScript s dict =
    if length (filter (onlyThisValue "script" (fromJust s)) dict) == 1 then
        (True, "")
    else
        (False, "Unknown script " ++ (fromJust s))

isValidRegion Nothing _ = (True, "")
isValidRegion r dict =
    if length (filter (onlyThisValue "region" (fromJust r)) dict) == 1 then
        (True, "")
    else
        (False, "Unknown region " ++ (fromJust r))

isValidVariants [] _ = (True, "")
isValidVariants v dict = foldl combine (True, "") (map (isValidVariant dict) v)

isValidVariant dict v =
    if length (filter (onlyThisValue "variant" v) dict) == 1 then
        (True, "")
    else
        (False, "Unknown variant " ++ v)

isValidExtension _ _ = (True, "")
-- TODO: a better test

-- Semantic testing

-- Only one extension by the same singleton
correctNumber :: [Singleton] -> Singleton -> Bool
correctNumber l s = length (filter (\c -> (c == s)) l) == 1

getSingleton :: Types.Extension -> Singleton
getSingleton (singleton, names) = singleton

norepeat :: Extensions -> Bool
norepeat extensions = 
       let singletons = map getSingleton extensions in
          and (map (correctNumber singletons) singletons)

semanticTests (Tag lang extlang script region variants extensions) = 
    if norepeat extensions then
        (True, "")
    else
        (False, "Repeated extension singleton")
semanticTests _ = (True, "") -- No tests for privateuse and grandfathered

isValid :: Registry -> Tag -> Result
isValid reg (Tag l el s r v e) =
    let languages = filter (onlyThisType "language") reg in
    let scripts = filter (onlyThisType "script") reg in
    let regions = filter (onlyThisType "region") reg in
    let variants = filter (onlyThisType "variant") reg in
    let extensions = filter (onlyThisType "extension") reg in
    semanticTests (Tag l el s r v e) `combine`
    (isValidLanguage l languages) `combine` (isValidScript s scripts) `combine`
           (isValidRegion r regions) `combine` (isValidVariants v variants) `combine` 
           (isValidExtension e extensions)

isValid reg (Types.GF tag) =
        (True, "")
        -- It is passed well-formedness (syntactic) tests, it is good

isValid reg (Priv p) = 
     (True, "") -- By definition, private tags are always valid

testTag :: Registry -> String -> Bool
testTag reg tag =
        case (Parsec.parse Grammar.tag "" tag) of
            Left err -> False
            Right t  -> if fst (semanticTests t) then
                            fst (isValid reg t)
                        else
                            False

checkOK (Success p) = True
checkOK _ = False

messageOf (Success p) = error "Check was a success, no message available"
messageOf (SyntaxError s) = s
messageOf (SemanticError s) = s

registryOf (Success p) = p
registryOf _ = error "Check was a failure, no registry available"

semanticCheck :: Registry -> CheckResult
semanticCheck r = 
    -- TODO: test that the extlangs exist
    oneDateTest r `combineC` prefixesExist r `combineC` 
      scriptsExist r `combineC` noDuplicates r `combineC` preferredValuesExist r
                   `combineC` macrolanguagesExist r

oneDateTest reg =
   if (length (filter onlyDate reg) == 1) then
        Success reg
   else
        SemanticError "One and only one Field-Date record authorized"

macrolanguageExist reg language =
   let macrolang = lang'macroLanguage (languageFrom language) in
   if isJust macrolang then
      length (filter (onlyThisValue "language" (fromJust macrolang)) 
                                  (filter onlyLang reg)) > 0
   else
       True

macrolanguagesExist reg =
   let languages = filter onlyLang reg in
   let missing = filter (not.macrolanguageExist reg) languages in
   if length missing == 0 then
      Success reg
   else
      SemanticError ("Some languages have a Macrolanguage which does not appear in the registry: " ++
                    (show missing))

-- Extracts the langage subtag, the first one
languageOf tag =
    takeWhile (/= '-') tag

prefixExist reg variant =
   -- TODO: We test only that the language part of the prefix is OK, we should test
   -- the rest
   and (map (\r -> length (filter (onlyThisValue "language" (languageOf r)) 
                                  (filter onlyLang reg)) > 0) 
            (variant'prefix (variantFrom variant)))

prefixesExist reg =
   let variants = filter onlyVariant reg in
   let missing = filter (not.prefixExist reg) variants in
   if length missing == 0 then
      Success reg
   else
      SemanticError ("Some variants have a Prefix which does not appear in the registry: " ++
                    (show missing))

scriptExist reg language =
   let script = lang'script (languageFrom language) in
   if isJust script then
      length (filter (onlyThisValue "script" (fromJust script)) 
                                  (filter onlyScript reg)) > 0
   else
      True

scriptsExist reg =
   let languages = filter onlyLang reg in
   let missing = filter (not.scriptExist reg) languages in
   if length missing == 0 then
      Success reg
   else
      SemanticError ("Some languages have a Suppress-script which does not appear in the registry: " ++
                    (show missing))

preferredLangValueExist reg language =
   let preferredValue = lang'preferredValue (languageFrom language) in
   if isJust preferredValue then
      length (filter (onlyThisValue "language" (fromJust preferredValue)) 
                                  (filter onlyLang reg)) > 0
   else
      True

preferredValuesExist reg =
   -- TODO: test also regions and scripts
   let languages = filter onlyLang reg in
   let missing = filter (not.preferredLangValueExist reg) languages in
   if length missing == 0 then
      Success reg
   else
      SemanticError ("Some records have a Preferred-value which does not appear in the registry: " ++
                    (show missing))

otherRecord reg category val = 
        tail (filter (onlyThisValue category val) (filter (onlyThisType category) reg))

duplicate reg category =
  case category of
    "language" -> 
       filter (\t -> length t > 0) (map (otherRecord reg category) 
                                         (map (lang'subtag.languageFrom)
                                           (filter (onlyThisType category) reg)))
    _ -> [] -- TODO: implements them, too

noDuplicates reg =
  let duplicates = concat (map (duplicate reg) 
                         ["language", "script", "variant", "region", "grandfathered"]) in
  if length duplicates == 0 then
      Success reg
  else
      SemanticError ("Duplicate values: " ++ (show duplicates))

-- TODO: tests Preferred-value