lichess: added lichess integration

Lichess is a free and open source platform to play chess.
Connection is realized via the berserk python plugin that uses the lichess api.

README.md

@@ -11,6 +11,12 @@ ychess is a chess implementation and engine written in nim.
 To play chess in the commandline simply download the code and run `nim c -r game.nim`.
 You can either play the 1v1 hotseat mode or a single player mode vs the engine.
 
+### Lichess
+
+ychess uses the lichess api with the python plugin [berserk](https://github.com/rhgrant10/berserk).
+An instance of the engine occasionally plays on [lichess](https://lichess.org/@/tiyn-ychess).
+To get into the whitelist just write a ingame message to the account.
+
 ## Testing
 
 Testing is done by `einheit` by [jyapayne](https://github.com/jyapayne/einheit).

src/chess.nim

@@ -201,6 +201,19 @@ proc notationToMove*(notation: string, color: Color): Move =
     move = getMove(start, dest, prom, color)
   return move
 
+proc moveToNotation*(move: Move): string =
+  ## Convert and return a `move` object to simplified algebraic chess notation.
+  var res = ""
+  var start = indToField(move.start)
+  res.add(start)
+  var dest = indToField(move.dest)
+  res.add(dest)
+  var color = move.color
+  var prom = PieceChar[move.prom]
+  if (color == Color.White and dest[1] == '8') or (color == Color.Black and dest[1] == '1'):
+    res.add(prom)
+  return res
+
 proc initBoard(): Board =
   ## Create and return a board with pieces in starting position.
   let board = [

src/engine.nim

@@ -1,4 +1,3 @@
-import sequtils
 import ./chess
 
 type

src/lichess.nim

@@ -0,0 +1,71 @@
+import nimpy
+import asyncnet, asyncdispatch
+
+import ./secret.nim
+import ./chess.nim
+import ./engine.nim
+
+let berserk = pyImport("berserk")
+
+var session = berserk.TokenSession(secret.api_token)
+var client = berserk.Client(session=session)
+
+let engineID = "tiyn-ychess"
+let engineDifficulty = 5
+let toAccept = ["tiynger"]
+
+
+proc playGame(id: string) {.async.} =
+  ## Plays a lichess game with `id` asynchronously.
+  var color: Color
+  var game = initGame()
+  for event in client.bots.stream_game_state(id):
+    echo(event)
+    if $event["type"] in ["gameState", "gameFull"]:
+      var movesString: PyObject
+      if $event["type"] == "gameFull":
+        echo("gameFull received")
+        movesString = event["state"]["moves"]
+        if $event["white"]["id"] == engineID:
+          echo("white assigned")
+          color = Color.White
+        if $event["black"]["id"] == engineID:
+          echo("black assigned")
+          color = Color.Black
+      else:
+        echo("gameState received")
+        movesString = event["moves"]
+        echo("movesString",movesString)
+      if $movesString != "":
+        echo("movestring not empty")
+        var moves = movesString.split(" ")
+        game.checkedMove(notationToMove($moves[-1], game.toMove))
+        game.echoBoard(game.toMove)
+      echo("toMove", game.toMove)
+      echo("color", color)
+      if game.toMove == color:
+        echo("engine has to make a move")
+        var bestMove = moveToNotation(game.bestMove(engineDifficulty))
+        echo(bestMove)
+        discard client.bots.make_move(id, bestMove)
+
+proc acceptChallenge(whiteList: openArray[string]): void =
+  ## Accepts a challenge of users in a `whiteList` and starts the
+  ## game process for each.
+  var events = client.bots.stream_incoming_events()
+  for event in events:
+    echo(event)
+    if $event["type"] == "challenge":
+      var challenger = $event["challenge"]["challenger"]["id"]
+      var id = $event["challenge"]["id"]
+      var speed = $event["challenge"]["speed"]
+      if challenger in whiteList and speed == "correspondence":
+        echo("challenge of ", challenger, " whiteList: ", id)
+        discard client.bots.accept_challenge(id)
+        discard playGame($event["challenge"]["id"])
+      else:
+        discard client.bots.decline_challenge(id)
+        echo("challenge of ", challenger, " whiteList: ", id)
+
+
+acceptChallenge(toAccept)