{-# LANGUAGE ConstraintKinds, DataKinds, GADTs, RankNTypes, ScopedTypeVariables, TypeFamilies, TypeOperators #-}
module Parser
( Parser(..)
, SomeParser(..)
, someParser
-- Syntax parsers
, syntaxParserForLanguage
-- À la carte parsers
, goParser
, jsonParser
, markdownParser
, pythonParser
, rubyParser
, typescriptParser
) where

import qualified CMarkGFM
import Data.Functor.Classes (Eq1)
import Data.Kind
import Data.Ix
import Data.Record
import qualified Data.Syntax as Syntax
import Data.Syntax.Assignment
import Data.Term
import Data.Union
import Foreign.Ptr
import Info hiding (Empty, Go)
import Language
import qualified Language.Go.Assignment as Go
import qualified Language.JSON.Assignment as JSON
import qualified Language.Markdown.Assignment as Markdown
import qualified Language.Python.Assignment as Python
import qualified Language.Ruby.Assignment as Ruby
import qualified Language.TypeScript.Assignment as TypeScript
import Syntax hiding (Go)
import qualified TreeSitter.Language as TS (Language, Symbol)
import TreeSitter.Go
import TreeSitter.Python
import TreeSitter.Ruby
import TreeSitter.TypeScript
import TreeSitter.JSON

-- | A parser from 'Source' onto some term type.
data Parser term where
  -- | A parser producing 'AST' using a 'TS.Language'.
  ASTParser :: (Bounded grammar, Enum grammar) => Ptr TS.Language -> Parser (AST [] grammar)
  -- | A parser producing an à la carte term given an 'AST'-producing parser and an 'Assignment' onto 'Term's in some syntax type.
  AssignmentParser :: (Enum grammar, Ix grammar, Show grammar, TS.Symbol grammar, Syntax.Error :< fs, Eq1 ast, Apply Foldable fs, Apply Functor fs, Foldable ast, Functor ast)
                   => Parser (Term ast (Node grammar))                           -- ^ A parser producing AST.
                   -> Assignment ast grammar (Term (Union fs) (Record Location)) -- ^ An assignment from AST onto 'Term's.
                   -> Parser (Term (Union fs) (Record Location))                 -- ^ A parser producing 'Term's.
  -- | A tree-sitter parser.
  TreeSitterParser :: Ptr TS.Language -> Parser (Term Syntax (Record DefaultFields))
  -- | A parser for 'Markdown' using cmark.
  MarkdownParser :: Parser (Term (TermF [] CMarkGFM.NodeType) (Node Markdown.Grammar))

-- | Apply all of a list of typeclasses to all of a list of functors using 'Apply'. Used by 'someParser' to constrain all of the language-specific syntax types to the typeclasses in question.
type family ApplyAll (typeclasses :: [(* -> *) -> Constraint]) (functors :: [* -> *]) :: Constraint where
  ApplyAll (typeclass ': typeclasses) functors = (Apply typeclass functors, ApplyAll typeclasses functors)
  ApplyAll '[] functors = ()

-- | A parser for some specific language, producing 'Term's whose syntax satisfies a list of typeclass constraints.
--
--   This enables us to abstract over the details of the specific syntax types in cases where we can describe all the requirements on the syntax with a list of typeclasses.
data SomeParser typeclasses where
  SomeParser :: ApplyAll typeclasses fs => { unSomeParser :: Parser (Term (Union fs) (Record Location)) } -> SomeParser typeclasses

-- | Construct a 'SomeParser' given a proxy for a list of typeclasses and the 'Language' to be parsed, all of which must be satisfied by all of the types in the syntaxes of our supported languages.
--
--   This can be used to perform operations uniformly over terms produced by blobs with different 'Language's, and which therefore have different types in general. For example, given some 'Blob', we can parse and 'show' the parsed & assigned 'Term' like so:
--
--   > case someParser (Proxy :: Proxy '[Show1]) (blobLanguage language) of { Just (SomeParser parser) -> runTask (parse parser blob) >>= putStrLn . show ; _ -> return () }
someParser :: ( ApplyAll typeclasses Go.Syntax
              , ApplyAll typeclasses JSON.Syntax
              , ApplyAll typeclasses Markdown.Syntax
              , ApplyAll typeclasses Python.Syntax
              , ApplyAll typeclasses Ruby.Syntax
              , ApplyAll typeclasses TypeScript.Syntax
              )
           => proxy typeclasses              -- ^ A proxy for the list of typeclasses required, e.g. @(Proxy :: Proxy '[Show1])@.
           -> Language                       -- ^ The 'Language' to select.
           -> Maybe (SomeParser typeclasses) -- ^ 'Maybe' a 'SomeParser' abstracting the syntax type to be produced.
someParser _ Go         = Just (SomeParser goParser)
someParser _ JavaScript = Just (SomeParser typescriptParser)
someParser _ JSON       = Just (SomeParser jsonParser)
someParser _ JSX        = Just (SomeParser typescriptParser)
someParser _ Markdown   = Just (SomeParser markdownParser)
someParser _ Python     = Just (SomeParser pythonParser)
someParser _ Ruby       = Just (SomeParser rubyParser)
someParser _ TypeScript = Just (SomeParser typescriptParser)

-- | Return a 'Language'-specific 'Parser', if one exists.
syntaxParserForLanguage :: Language -> Maybe (Parser (Term Syntax (Record DefaultFields)))
syntaxParserForLanguage language = case language of
  Go         -> Just (TreeSitterParser tree_sitter_go)
  JavaScript -> Just (TreeSitterParser tree_sitter_typescript)
  JSON       -> Just (TreeSitterParser tree_sitter_json)
  JSX        -> Just (TreeSitterParser tree_sitter_typescript)
  Ruby       -> Just (TreeSitterParser tree_sitter_ruby)
  TypeScript -> Just (TreeSitterParser tree_sitter_typescript)
  _ -> Nothing

goParser :: Parser Go.Term
goParser = AssignmentParser (ASTParser tree_sitter_go) Go.assignment

rubyParser :: Parser Ruby.Term
rubyParser = AssignmentParser (ASTParser tree_sitter_ruby) Ruby.assignment

pythonParser :: Parser Python.Term
pythonParser = AssignmentParser (ASTParser tree_sitter_python) Python.assignment

jsonParser :: Parser JSON.Term
jsonParser = AssignmentParser (ASTParser tree_sitter_json) JSON.assignment

typescriptParser :: Parser TypeScript.Term
typescriptParser = AssignmentParser (ASTParser tree_sitter_typescript) TypeScript.assignment

markdownParser :: Parser Markdown.Term
markdownParser = AssignmentParser MarkdownParser Markdown.assignment