Implement pgn move dump

chess/src/main/scala/Move.scala

@@ -13,5 +13,16 @@ case class Move(
 
     def withHistory(h: History) = copy(after = after withHistory h)
 
-    lazy val isCapture = capture.isDefined
+    def situation = before as piece.color
+
+    // does this move check the opponent?
+    def checks: Boolean = (after as !color).check
+
+    // does this move checkmate the opponent?
+    def checkMates: Boolean = (after as !color).checkMate
+
+    // does this move capture an opponent piece?
+    def captures = capture.isDefined
+
+    def color = piece.color
 }

chess/src/main/scala/Pos.scala

@@ -27,6 +27,7 @@ sealed case class Pos private (x: Int, y: Int) {
 
   def ?<(other: Pos) = x < other.x
   def ?>(other: Pos) = x > other.x
+  def ?|(other: Pos) = x == other.x
 
   def <->(other: Pos): Iterable[Pos] =
     min(x, other.x) to max(x, other.x) map { makePos(_, y) } flatten

chess/src/main/scala/Role.scala

@@ -4,6 +4,7 @@ import Pos._
 
 sealed trait Role {
   val forsyth: Char
+  lazy val pgn = forsyth.toUpper
   def dirs: List[Direction]
 }
 sealed trait PromotableRole extends Role

chess/src/main/scala/format/PgnDump.scala

@@ -0,0 +1,29 @@
+package lila.chess
+package format
+
+object PgnDump {
+
+  def move(m: Move): String = {
+    import m._
+
+    def disambiguate = {
+      val candidates = situation.actors filter { a ⇒
+        a.pos != orig && a.piece.role == piece.role && (a.destinations contains dest)
+      }
+      if (candidates.isEmpty) ""
+      else if (candidates exists (_.pos ?| orig)) orig.file + orig.rank else orig.file
+    }
+    def capturing = if (captures) "x" else ""
+    def checking = if (checkMates) "#" else if (checks) "+" else ""
+
+    ((promotion, piece.role) match {
+      case _ if castle           ⇒ if (orig ?> dest) "O-O-O" else "O-O"
+      case _ if enpassant        ⇒ orig.file + 'x' + dest.rank
+      case (Some(promotion), _)  ⇒ dest.key + promotion.pgn
+      case (_, Pawn) if captures ⇒ orig.file + 'x' + dest.key
+      case (_, Pawn)             ⇒ dest.key
+      case (_, role)             ⇒ role.pgn + disambiguate + capturing + dest.key
+      case _                     ⇒ "?"
+    }) + checking
+  }
+}