/-
Copyright (c) 2020 Wojciech Nawrocki. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.

Authors: Wojciech Nawrocki, Marc Huisinga
-/
import Lean.Server.Utils
import Lean.Server.Snapshots
import Lean.Server.AsyncList

namespace Lean.Server.FileWorker
open Snapshots
open IO

def logSnapContent (s : Snapshot) (text : FileMap) : IO Unit :=
  IO.eprintln s!"[{s.beginPos}, {s.endPos}]: ```\n{text.source.extract s.beginPos (s.endPos-1)}\n```"

inductive ElabTaskError where
  | aborted
  | eof
  | ioError (e : IO.Error)

instance : Coe IO.Error ElabTaskError :=
  ⟨ElabTaskError.ioError⟩

structure CancelToken where
  ref : IO.Ref Bool
  deriving Inhabited

namespace CancelToken

def new : IO CancelToken :=
  CancelToken.mk <$> IO.mkRef false

def check [MonadExceptOf ElabTaskError m] [MonadLiftT (ST RealWorld) m] [Monad m] (tk : CancelToken) : m Unit := do
  let c ← tk.ref.get
  if c then
    throw ElabTaskError.aborted

def set (tk : CancelToken) : IO Unit :=
  tk.ref.set true

end CancelToken

/-- A document editable in the sense that we track the environment
and parser state after each command so that edits can be applied
without recompiling code appearing earlier in the file. -/
structure EditableDocument where
  meta       : DocumentMeta
  /- The first snapshot is that after the header. -/
  headerSnap : Snapshot
  /- Subsequent snapshots occur after each command. -/
  cmdSnaps   : AsyncList ElabTaskError Snapshot
  cancelTk   : CancelToken
  deriving Inhabited

end Lean.Server.FileWorker