------------------------------------------------------------------------------
--- This library defines I/O actions to read and write
--- type-annotated FlatCurry programs.
---
--- @author Michael Hanus
--- @version July 2020
------------------------------------------------------------------------------

module FlatCurry.Annotated.Files where

import Directory       ( doesFileExist )
import FileGoodies     ( getFileInPath)
import FilePath        ( takeFileName, (</>), (<.>) )
import ReadShowTerm    ( readUnqualifiedTerm, showTerm ) -- for faster reading

import System.CurryPath    ( inCurrySubdir, stripCurrySuffix
                           , lookupModuleSourceInLoadPath, getLoadPathForModule
                           )
import System.FrontendExec ( FrontendParams, FrontendTarget (..)
                           , defaultParams, setQuiet, callFrontendWithParams )

import FlatCurry.Annotated.Types

--- Transforms a name of a Curry program (with or without suffix ".curry"
--- or ".lcurry") into the name of the file containing the
--- corresponding type-annotated FlatCurry program.
typedFlatCurryFileName :: String -> String
typedFlatCurryFileName prog = inCurrySubdir (stripCurrySuffix prog) <.> "tfcy"

--- Gets the standard type-annotated FlatCurry file location
--- for a given Curry module name.
--- The Curry source program must exist in the Curry load path,
--- otherwise an error is raised.
typedFlatCurryFilePath :: String -> IO String
typedFlatCurryFilePath mname = do
  mbsrc <- lookupModuleSourceInLoadPath mname
  case mbsrc of
    Nothing      -> error $ "Curry source file for module '" ++ mname ++
                            "' not found!"
    Just (dir,_) -> return (typedFlatCurryFileName (dir </> mname))

--- I/O action which parses a Curry program and returns the corresponding
--- type-annotated FlatCurry program.
--- The argument is the module path (without suffix ".curry"
--- or ".lcurry") and the result is a type-annotated FlatCurry term
--- representing this program.
readTypedFlatCurry :: String -> IO (AProg TypeExpr)
readTypedFlatCurry progname =
   readTypedFlatCurryWithParseOptions progname (setQuiet True defaultParams)

--- I/O action which parses a Curry program
--- with respect to some parser options and returns the
--- corresponding FlatCurry program.
--- This I/O action is used by `readTypedFlatCurry`.
--- @param progfile - the program file name (without suffix ".curry")
--- @param options - parameters passed to the front end
readTypedFlatCurryWithParseOptions :: String -> FrontendParams
                                   -> IO (AProg TypeExpr)
readTypedFlatCurryWithParseOptions progname options = do
  mbsrc <- lookupModuleSourceInLoadPath progname
  case mbsrc of
    Nothing -> do -- no source file, try to find FlatCurry file in load path:
      loadpath <- getLoadPathForModule progname
      filename <- getFileInPath (typedFlatCurryFileName (takeFileName progname))
                                [""]
                                loadpath
      readTypedFlatCurryFile filename
    Just (dir,_) -> do
      callFrontendWithParams TFCY options progname
      readTypedFlatCurryFile
        (typedFlatCurryFileName (dir </> takeFileName progname))

--- Reads a type-annotated FlatCurry program from a file in `.tfcy` format
--- where the file name is provided as the argument.
readTypedFlatCurryFile :: String -> IO (AProg TypeExpr)
readTypedFlatCurryFile filename = do
  filecontents <- readTypedFlatCurryFileRaw filename
  -- ...with generated Read class instances (slow!):
  --return (read filecontents)
  -- ...with built-in generic read operation (faster):
  return (readUnqualifiedTerm ["FlatCurry.Annotated.Types", "FlatCurry.Types",
                               "Prelude"]
                              filecontents)
 where
  readTypedFlatCurryFileRaw fname = do
    extfcy <- doesFileExist fname
    if extfcy
      then readFile fname
      else do
        let subdirfilename = inCurrySubdir fname
        exdirtfcy <- doesFileExist subdirfilename
        if exdirtfcy
          then readFile subdirfilename
          else error $ "EXISTENCE ERROR: Typed FlatCurry file '" ++
                       fname ++ "' does not exist"

--- Writes a type-annotated FlatCurry program into a file in `.tfcy` format.
--- The file is written in the standard location for intermediate files,
--- i.e., in the 'typedFlatCurryFileName' relative to the directory of the
--- Curry source program (which must exist!).
writeTypedFlatCurry :: AProg TypeExpr -> IO ()
writeTypedFlatCurry prog@(AProg mname _ _ _ _) = do
  fname <- typedFlatCurryFilePath mname
  writeTypedFlatCurryFile fname prog

--- Writes a type-annotated FlatCurry program into a file in ".tfcy" format.
--- The first argument must be the name of the target file
--- (with suffix `.fcy`).
writeTypedFlatCurryFile :: String -> AProg TypeExpr -> IO ()
writeTypedFlatCurryFile file prog = writeFile file (showTerm prog)