-- SPDX-FileCopyrightText: 2021 Oxhead Alpha
-- SPDX-License-Identifier: LicenseRef-MIT-OA

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_
  , stringLiteral
  , bytesLiteral
  , intLiteral
  , parsedOp
  , cbParameterBare

  -- * Quoters
  , utypeQ
  , uparamTypeQ
  , notes

  -- * Re-exports
  , errorBundlePretty
  ) where

import Prelude hiding (try)

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

import Morley.Michelson.ErrorPos (SrcPos(..), mkPos)
import Morley.Michelson.Macro (Macro(..), ParsedInstr, ParsedOp(..), ParsedValue, expandValue)
import Morley.Michelson.Parser.Common
import Morley.Michelson.Parser.Error
import Morley.Michelson.Parser.Instr
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.Typed.Extract (withUType)
import Morley.Michelson.Untyped
import Morley.Michelson.Untyped qualified as U

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

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

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

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

-- | Michelson contract
program :: Parsec CustomParserException Text (Contract' ParsedOp)
program = programInner <* eof

programInner :: Parser (Contract' ParsedOp)
programInner = mSpace *> contract

cbParameter :: Parser ParameterType
cbParameter = symbol1 "parameter" *> cbParameterBare

cbParameterBare :: Parser ParameterType
cbParameterBare = uncurry ParameterType . swap <$> field

cbStorage :: Parser Ty
cbStorage = symbol1 "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 result
      (CBStorage _, CBStorage _: _) -> failDuplicateField result
      (CBCode _, CBCode _: _) -> failDuplicateField result
      (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: " <> pretty 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}" & either (putStrLn . displayException) (const $ pure ())
-- 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

-- |
-- >>> parseNoEnv parsedOp "" "{a}" & either (putStrLn . displayException . ParserException) (const $ pure ())
-- 1:2:
--   |
-- 1 | {a}
--   |  ^
-- unexpected 'a'
-- expecting '{', '}', macro, or primitive instruction
-- <BLANKLINE>
parsedOp :: Parser ParsedOp
parsedOp = do
  pos <- getSrcPos
  choice
    [ flip Prim pos <$> prim
    , flip Mac pos <$> macro parsedOp
    , primOrMac
    , flip Seq pos <$> bracewrappedOps
    ]

getSrcPos :: Parser SrcPos
getSrcPos = do
  sp <- getSourcePos
  let l = unPos $ sourceLine sp
  let c = unPos $ sourceColumn sp
  -- reindexing starting from 0
  pure . unsafe $ SrcPos <$> (mkPos $ l - 1) <*> (mkPos $ 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 :: Parser (TH.Q TH.Exp) -> TH.QuasiQuoter
parserToQuasiQuoter parser = TH.QuasiQuoter
  { TH.quoteExp = \s ->
      case parseNoEnv (mSpace *> parser) "quasi-quoter" (toText s) of
        Left err -> fail $ errorBundlePretty err
        Right qexp -> qexp
  , 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| or (int :a) (nat :b) |]
-- Ty (TOr (UnsafeAnnotation @FieldTag "") (UnsafeAnnotation @FieldTag "") (Ty TInt (UnsafeAnnotation @TypeTag "a")) (Ty TNat (UnsafeAnnotation @TypeTag "b"))) (UnsafeAnnotation @TypeTag "")
--
-- >>> [utypeQ|a|]
-- <BLANKLINE>
-- ...
--   |
-- 1 | a
--   | ^
-- unexpected 'a'
-- expecting type
-- ...
utypeQ :: TH.QuasiQuoter
utypeQ = parserToQuasiQuoter (TH.lift <$> type_)

-- | Creates 'U.ParameterType' by its Morley representation.
uparamTypeQ :: TH.QuasiQuoter
uparamTypeQ = parserToQuasiQuoter (TH.lift <$> cbParameterBare)

-- | Parses and typechecks a 'Morley.Michelson.Typed.Notes'.
--
-- >>> [notes|int :ty|]
-- NTInt (UnsafeAnnotation @TypeTag "ty")
notes :: TH.QuasiQuoter
notes =
  parserToQuasiQuoter do
    t <- type_
    pure $ withUType t TH.lift