-- SPDX-FileCopyrightText: 2020 Tocqueville Group
--
-- SPDX-License-Identifier: LicenseRef-MIT-TQ

module Morley.Michelson.Parser
  ( -- * Main parser type
    Parser

  -- * Parsers
  , program
  , value

  -- * Errors
  , CustomParserException (..)
  , ParseErrorBundle
  , ParserException (..)
  , StringLiteralParserException (..)

  -- * Additional helpers
  , MichelsonSource (..)
  , codeSrc
  , parseNoEnv
  , parseValue
  , parseExpandValue

  -- * For tests
  , codeEntry
  , ops
  , type_
  , letInner
  , letType
  , stringLiteral
  , bytesLiteral
  , intLiteral
  , parsedOp
  , printComment

  -- * Quoters
  , utypeQ
  , uparamTypeQ

  -- * Re-exports
  , errorBundlePretty
  ) where

import Prelude hiding (try)

import Fmt (pretty)
import qualified Language.Haskell.TH.Lift as TH
import qualified Language.Haskell.TH.Quote as TH
import Text.Megaparsec
  (Parsec, choice, customFailure, eitherP, eof, errorBundlePretty, getSourcePos, hidden, lookAhead,
  parse, sepEndBy, try)
import Text.Megaparsec.Pos (SourcePos(..), unPos)

import Morley.Michelson.ErrorPos (SrcPos(..), unsafeMkPos)
import Morley.Michelson.Macro
  (LetMacro, Macro(..), ParsedInstr, ParsedOp(..), ParsedValue, expandValue)
import Morley.Michelson.Parser.Annotations (noteF)
import Morley.Michelson.Parser.Common
import Morley.Michelson.Parser.Error
import Morley.Michelson.Parser.Ext
import Morley.Michelson.Parser.Instr
import Morley.Michelson.Parser.Let
import Morley.Michelson.Parser.Lexer
import Morley.Michelson.Parser.Macro
import Morley.Michelson.Parser.Type
import Morley.Michelson.Parser.Types
import Morley.Michelson.Parser.Value
import Morley.Michelson.Untyped
import qualified Morley.Michelson.Untyped as U

----------------------------------------------------------------------------
-- Helpers
----------------------------------------------------------------------------

-- | Parse with empty environment
parseNoEnv ::
     Parser a
  -> MichelsonSource
  -> Text
  -> Either (ParseErrorBundle Text CustomParserException) a
parseNoEnv p src = parse (runReaderT p noLetEnv <* eof) (pretty src)

-------------------------------------------------------------------------------
-- Parsers
-------------------------------------------------------------------------------

-- Contract
------------------

-- | Michelson contract with let definitions
program :: Parsec CustomParserException Text (Contract' ParsedOp)
program = runReaderT programInner noLetEnv <* eof
  where
    programInner :: Parser (Contract' ParsedOp)
    programInner = do
      mSpace
      env <- fromMaybe noLetEnv <$> (optional (letBlock parsedOp))
      local (const env) contract

cbParameter :: Parser ParameterType
cbParameter = symbol "parameter" *> cbParameterBare

cbParameterBare :: Parser ParameterType
cbParameterBare = do
  prefixRootAnn <- optional noteF
  (inTypeRootAnn, t) <- field
  rootAnn <- case (prefixRootAnn, inTypeRootAnn) of
    -- TODO: [#310] Handle cases where there are 2 empty root annotations.
    -- For example: root % (unit %) which should throw the error.
    (Just a, b) | a == noAnn && b == noAnn -> pure noAnn
    (Just a, b) | b == noAnn -> pure a
    (Nothing, b) -> pure b
    (Just _, _) -> customFailure MultiRootAnnotationException
  pure $ ParameterType t rootAnn

cbStorage :: Parser Ty
cbStorage = symbol "storage" *> type_

cbCode :: Parser [ParsedOp]
cbCode = symbol "code" *> codeEntry

cbView :: Parser (View' ParsedOp)
cbView = do
  symbol "view"
  viewName <- viewName_
  viewArgument <- type_
  viewReturn <- type_
  viewCode <- ops
  return View{..}

contractBlock :: Parser (ContractBlock ParsedOp)
contractBlock = choice
  [ (CBParam <$> cbParameter)
  , (CBStorage <$> cbStorage)
  , (CBCode <$> cbCode)
  , (CBView <$> cbView)
  ]

-- | This ensures that the error message will point to the correct line.
ensureNotDuplicate :: [ContractBlock ParsedOp] -> ContractBlock ParsedOp -> Parser ()
ensureNotDuplicate blocks result =
  let
    failDuplicateField a = fail $ "Duplicate contract field: " <> a
  in
    case (result, blocks) of
      (CBParam _, CBParam _ : _) -> failDuplicateField "parameter"
      (CBStorage _, CBStorage _: _) -> failDuplicateField "storage"
      (CBCode _, CBCode _: _) -> failDuplicateField "code"
      (CBView _, _) -> pure ()
      (_, _:xs) -> ensureNotDuplicate xs result
      (_, []) -> pure ()

-- | Michelson contract
contract :: Parser (Contract' ParsedOp)
contract = do
  mSpace
  result <- braces contractTuple <|> contractTuple
  case orderContractBlock result of
    Just contract' ->
      return contract'
    Nothing ->
      fail $ "Duplicate contract field: " <> show result
  where
    -- | @ensureNotDuplicate@ provides a better message and point to the correct line
    -- when the parser fails.
    contractTuple = fmap reverse . executingStateT [] $ do
      (`sepEndBy` lift semicolon) $ do
        r <- lift contractBlock
        get >>= \prev -> lift $ ensureNotDuplicate prev r
        modify (r :)

-- Value
------------------

value :: Parser ParsedValue
value = value' parsedOp

-- | Parse untyped value from text which comes from something that is
-- not a file (which is often the case). So we assume it does not need
-- any parsing environment.
--
-- >>> parseValue MSUnspecified "{PUSH int aaa}"
-- Left 1:11:
--   |
-- 1 | {PUSH int aaa}
--   |           ^^^^
-- unexpected "aaa}"
-- expecting value
-- <BLANKLINE>
parseValue :: MichelsonSource -> Text -> Either ParserException ParsedValue
parseValue = first ParserException ... parseNoEnv value

-- | Like 'parseValue', but also expands macros.
parseExpandValue :: MichelsonSource -> Text -> Either ParserException U.Value
parseExpandValue = fmap expandValue ... parseValue

-- Primitive instruction
------------------

prim :: Parser ParsedInstr
prim = primInstr contract parsedOp

-- Parsed operations (primitive instructions, macros, extras, etc.)
------------------

-- | Parses code block after "code" keyword of a contract.
--
-- This function is part of the module API, its semantics should not change.
codeEntry :: Parser [ParsedOp]
codeEntry = bracewrappedOps

bracewrappedOps :: Parser [ParsedOp]
bracewrappedOps = lookAhead (symbol "{") *> ops

-- |
-- >>> first ParserException $ parseNoEnv parsedOp "" "{a}"
-- Left 1:2:
--   |
-- 1 | {a}
--   |  ^
-- unexpected 'a'
-- expecting '{', '}', macro, morley instruction, or primitive instruction
-- <BLANKLINE>
parsedOp :: Parser ParsedOp
parsedOp = do
  lms <- asks letMacros
  pos <- getSrcPos
  choice
    [ flip Prim pos <$> (EXT <$> extInstr ops)
    , lmacWithPos (mkLetMac lms)
    , flip Prim pos <$> prim
    , flip Mac pos <$> macro parsedOp
    , primOrMac
    , flip Seq pos <$> bracewrappedOps
    ]
  where
    lmacWithPos :: Parser LetMacro -> Parser ParsedOp
    lmacWithPos act = do
      srcPos <- getSrcPos
      flip LMac srcPos <$> act

getSrcPos :: Parser SrcPos
getSrcPos = do
  sp <- getSourcePos
  let l = unPos $ sourceLine sp
  let c = unPos $ sourceColumn sp
  -- reindexing starting from 0
  pure $ SrcPos (unsafeMkPos $ l - 1) (unsafeMkPos $ c - 1)

primWithPos :: Parser ParsedInstr -> Parser ParsedOp
primWithPos act = do
  srcPos <- getSrcPos
  flip Prim srcPos <$> act

macWithPos :: Parser Macro -> Parser ParsedOp
macWithPos act = do
  srcPos <- getSrcPos
  flip Mac srcPos <$> act

ops :: Parser [ParsedOp]
ops = ops' parsedOp

-------------------------------------------------------------------------------
-- Mixed parsers
-- These are needed for better error messages
-------------------------------------------------------------------------------

ifOrIfX :: Parser ParsedOp
ifOrIfX = do
  pos <- getSrcPos
  symbol' "IF"
  a <- eitherP cmpOp ops
  case a of
    Left cmp -> flip Mac pos <$> (IFX cmp <$> ops <*> ops)
    Right op -> flip Prim pos <$> (IF op <$> ops)

-- Some of the operations and macros have the same prefixes in their names
-- So this case should be handled separately
primOrMac :: Parser ParsedOp
primOrMac = hidden
   $  (macWithPos (ifCmpMac parsedOp) <|> ifOrIfX)
  <|> (macWithPos (mapCadrMac parsedOp) <|> primWithPos (mapOp parsedOp))
  <|> (try (primWithPos pairOp) <|> try (primWithPos pairNOp) <|> macWithPos pairMac)
  <|> (try (macWithPos duupMac) <|> primWithPos dupOp)
  <|> (try (macWithPos carnMac) <|> try (macWithPos cdrnMac) <|> try (macWithPos cadrMac) <|> primWithPos carOp <|> primWithPos cdrOp)

-------------------------------------------------------------------------------
-- Safe construction of Haskell values
-------------------------------------------------------------------------------

parserToQuasiQuoter :: TH.Lift a => Parser a -> TH.QuasiQuoter
parserToQuasiQuoter parser = TH.QuasiQuoter
  { TH.quoteExp = \s ->
      case parseNoEnv (mSpace *> parser) "quasi-quoter" (toText s) of
        Left err -> fail $ errorBundlePretty err
        Right res -> [e| res |]
  , TH.quotePat = \_ -> fail "Cannot be used as pattern"
  , TH.quoteType = \_ -> fail "Cannot be used as type"
  , TH.quoteDec = \_ -> fail "Cannot be used as declaration"
  }

-- | Creates 'U.Ty' by its Morley representation.
--
-- >>> [utypeQ| (int :a | nat :b) |]
-- Ty (TOr % % (Ty TInt :a) (Ty TNat :b)) :
--
-- >>> [utypeQ|a|]
-- <BLANKLINE>
-- ...
--   |
-- 1 | a
--   | ^
-- unexpected 'a'
-- expecting type
-- ...
utypeQ :: TH.QuasiQuoter
utypeQ = parserToQuasiQuoter type_

-- | Creates 'U.ParameterType' by its Morley representation.
uparamTypeQ :: TH.QuasiQuoter
uparamTypeQ = parserToQuasiQuoter cbParameterBare