import Lean.Elab.Frontend

open Lean Elab

unsafe def processInput (input : String) (initializers := false)  :
    IO (Environment × List Message) := do
  let fileName   := "<input>"
  let inputCtx   := Parser.mkInputContext input fileName
  if initializers then enableInitializersExecution
  let (header, parserState, messages) ← Parser.parseHeader inputCtx
  let (env, messages) ← processHeader header {} messages inputCtx
  let s ← IO.processCommands inputCtx parserState (Command.mkState env messages {}) <&> Frontend.State.commandState
  pure (s.env, s.messages.toList)

open System in
def findLean (mod : Name) : IO FilePath := do
  let olean ← findOLean mod
  -- Remove a ".lake/build/lib/lean" substring from the path.
  let lean := olean.toString.replace (toString (FilePath.mk ".lake" / "build" / "lib" / "lean") ++ FilePath.pathSeparator.toString) ""
  return FilePath.mk lean |>.withExtension "lean"

/-- Read the source code of the named module. -/
def moduleSource (mod : Name) : IO String := do
  IO.FS.readFile (← findLean mod)

unsafe def compileModule (mod : Name) (initializers := false) :
    IO (Environment × List Message) := do
  processInput (← moduleSource mod) initializers