Add server-side support for PLAY_FREE_DISCARDED special ability

So far, there was no "turn" generated for the player who could play a
free card from the discarded pile.

12 files changed, 153 insertions, 50 deletions

diff --git a/sw-bot/src/main/kotlin/org/luxons/sevenwonders/bot/SevenWondersBot.kt b/sw-bot/src/main/kotlin/org/luxons/sevenwonders/bot/SevenWondersBot.kt
index c58eaea8..80bad9e4 100644
--- a/sw-bot/src/main/kotlin/org/luxons/sevenwonders/bot/SevenWondersBot.kt
+++ b/sw-bot/src/main/kotlin/org/luxons/sevenwonders/bot/SevenWondersBot.kt
@@ -59,6 +59,7 @@ class SevenWondersBot(
     private suspend fun SevenWondersSession.playTurn(turn: PlayerTurnInfo): Boolean {
         when (turn.action) {
             Action.PLAY, Action.PLAY_2, Action.PLAY_LAST -> prepareMove(createPlayCardMove(turn))
+            Action.PLAY_FREE_DISCARDED -> prepareMove(createPlayFreeDiscardedMove(turn))
             Action.PICK_NEIGHBOR_GUILD -> prepareMove(createPickGuildMove(turn))
             Action.SAY_READY -> sayReady()
             Action.WAIT -> Unit
@@ -84,5 +85,10 @@ private fun createPlayCardMove(turnInfo: PlayerTurnInfo): PlayerMove {
     }
 }
 
+private fun createPlayFreeDiscardedMove(turn: PlayerTurnInfo): PlayerMove {
+    val card = turn.discardedCards?.random() ?: error("No discarded card to play")
+    return PlayerMove(MoveType.PLAY_FREE_DISCARDED, card.name)
+}
+
 private fun createPickGuildMove(turnInfo: PlayerTurnInfo): PlayerMove =
     PlayerMove(MoveType.COPY_GUILD, turnInfo.neighbourGuildCards.random().name)
diff --git a/sw-common-model/src/commonMain/kotlin/org/luxons/sevenwonders/model/Moves.kt b/sw-common-model/src/commonMain/kotlin/org/luxons/sevenwonders/model/Moves.kt
index d5503bc9..12084539 100644
--- a/sw-common-model/src/commonMain/kotlin/org/luxons/sevenwonders/model/Moves.kt
+++ b/sw-common-model/src/commonMain/kotlin/org/luxons/sevenwonders/model/Moves.kt
@@ -15,6 +15,7 @@ enum class Action(val message: String) {
     PLAY("Pick the card you want to play or discard."),
     PLAY_2("Pick the first card you want to play or discard. Note that you have the ability to play these 2 last cards. You will choose how to play the last one during your next turn."),
     PLAY_LAST("You have the special ability to play your last card. Choose how you want to play it."),
+    PLAY_FREE_DISCARDED("Pick a card from the discarded deck, you can play it for free."),
     PICK_NEIGHBOR_GUILD("Choose a Guild card (purple) that you want to copy from one of your neighbours."),
     WAIT("Please wait for other players to perform extra actions."),
     WATCH_SCORE("The game is over! Look at the scoreboard to see the final ranking!")
@@ -27,7 +28,8 @@ data class PlayerTurnInfo(
     val action: Action,
     val hand: List<HandCard>?,
     val preparedMove: PlayedMove?,
-    val neighbourGuildCards: List<TableCard>,
+    val neighbourGuildCards: List<HandCard>,
+    val discardedCards: List<HandCard>?, // only present when the player can actually see them
     val scoreBoard: ScoreBoard? = null
 ) {
     val currentAge: Int = table.currentAge
@@ -62,6 +64,7 @@ data class PlayerMove(
 enum class MoveType {
     PLAY,
     PLAY_FREE,
+    PLAY_FREE_DISCARDED,
     UPGRADE_WONDER,
     DISCARD,
     COPY_GUILD;
diff --git a/sw-common-model/src/commonMain/kotlin/org/luxons/sevenwonders/model/cards/Cards.kt b/sw-common-model/src/commonMain/kotlin/org/luxons/sevenwonders/model/cards/Cards.kt
index fdb4d11b..5c7616a1 100644
--- a/sw-common-model/src/commonMain/kotlin/org/luxons/sevenwonders/model/cards/Cards.kt
+++ b/sw-common-model/src/commonMain/kotlin/org/luxons/sevenwonders/model/cards/Cards.kt
@@ -55,6 +55,7 @@ data class CardBack(val image: String)
 enum class PlayabilityLevel(val message: String) {
     CHAINABLE("free because of a card on the board"),
     NO_REQUIREMENTS("free"),
+    SPECIAL_FREE("free because of a special ability"),
     ENOUGH_RESOURCES("free"),
     ENOUGH_GOLD("enough gold"),
     ENOUGH_GOLD_AND_RES("enough gold and resources"),
diff --git a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/Game.kt b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/Game.kt
index f7c29214..b9daf53f 100644
--- a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/Game.kt
+++ b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/Game.kt
@@ -5,20 +5,17 @@ import org.luxons.sevenwonders.engine.boards.Table
 import org.luxons.sevenwonders.engine.cards.Card
 import org.luxons.sevenwonders.engine.cards.Decks
 import org.luxons.sevenwonders.engine.cards.Hands
-import org.luxons.sevenwonders.engine.converters.toTableState
+import org.luxons.sevenwonders.engine.converters.toHandCard
 import org.luxons.sevenwonders.engine.converters.toPlayedMove
-import org.luxons.sevenwonders.engine.converters.toTableCard
+import org.luxons.sevenwonders.engine.converters.toTableState
 import org.luxons.sevenwonders.engine.data.LAST_AGE
 import org.luxons.sevenwonders.engine.effects.SpecialAbility
 import org.luxons.sevenwonders.engine.moves.Move
 import org.luxons.sevenwonders.engine.moves.resolve
-import org.luxons.sevenwonders.model.score.ScoreBoard
-import org.luxons.sevenwonders.model.Action
-import org.luxons.sevenwonders.model.TableState
-import org.luxons.sevenwonders.model.PlayerMove
-import org.luxons.sevenwonders.model.PlayerTurnInfo
+import org.luxons.sevenwonders.model.*
 import org.luxons.sevenwonders.model.cards.CardBack
 import org.luxons.sevenwonders.model.cards.HandCard
+import org.luxons.sevenwonders.model.score.ScoreBoard
 
 class Game internal constructor(
     val id: Long,
@@ -44,10 +41,25 @@ class Game internal constructor(
     }
 
     private fun startNewTurn() {
-        currentTurnInfo = players.map { createPlayerTurnInfo(it) }
+        currentTurnInfo = players.map {
+            val hand = hands.createHand(it)
+            val action = determineAction(hand, it.board)
+            createPlayerTurnInfo(it, action, hand)
+        }
     }
 
-    private fun startEndGame() {
+    private fun startPlayDiscardedTurn() {
+        currentTurnInfo = players.map {
+            val action = if (it.board.hasSpecial(SpecialAbility.PLAY_DISCARDED)) {
+                Action.PLAY_FREE_DISCARDED
+            } else {
+                Action.WAIT
+            }
+            createPlayerTurnInfo(it, action, null)
+        }
+    }
+
+    private fun startEndGameTurn() {
         // some player may need to do additional stuff
         startNewTurn()
         val allDone = currentTurnInfo.all { it.action == Action.WAIT }
@@ -60,17 +72,20 @@ class Game internal constructor(
         }
     }
 
-    private fun createPlayerTurnInfo(player: Player): PlayerTurnInfo {
-        val hand = hands.createHand(player)
-        val action = determineAction(hand, player.board)
-        val neighbourGuildCards = table.getNeighbourGuildCards(player.index).map { it.toTableCard(null) }
-
+    private fun createPlayerTurnInfo(player: Player, action: Action, hand: List<HandCard>?): PlayerTurnInfo {
+        val neighbourGuildCards = table.getNeighbourGuildCards(player.index).map { it.toHandCard(player, true) }
+        val exposedDiscardedCards = if (action == Action.PLAY_FREE_DISCARDED) {
+            discardedCards.map { it.toHandCard(player, true) }
+        } else {
+            null
+        }
         return PlayerTurnInfo(
             playerIndex = player.index,
             table = table.toTableState(),
             action = action,
             hand = hand,
             preparedMove = preparedMoves[player.index]?.toPlayedMove(),
+            discardedCards = exposedDiscardedCards,
             neighbourGuildCards = neighbourGuildCards
         )
     }
@@ -102,13 +117,18 @@ class Game internal constructor(
      * @return the back of the card that is prepared on the table
      */
     fun prepareMove(playerIndex: Int, move: PlayerMove): CardBack {
-        val card = decks.getCard(table.currentAge, move.cardName)
+        val card = move.findCard()
         val context = PlayerContext(playerIndex, table, hands[playerIndex])
-        val resolvedMove = move.type.resolve(move, card, context)
+        val resolvedMove = move.type.resolve(move, card, context, discardedCards)
         preparedMoves[playerIndex] = resolvedMove
         return card.back
     }
 
+    private fun PlayerMove.findCard() = when (type) {
+        MoveType.PLAY_FREE_DISCARDED -> discardedCards.first { it.name == cardName }
+        else -> decks.getCard(table.currentAge, cardName)
+    }
+
     fun unprepareMove(playerIndex: Int) {
         preparedMoves.remove(playerIndex)
     }
@@ -132,13 +152,17 @@ class Game internal constructor(
         if (endOfAgeReached()) {
             executeEndOfAgeEvents()
             if (endOfGameReached()) {
-                startEndGame()
+                startEndGameTurn()
             } else {
                 startNewAge()
             }
         } else {
-            rotateHandsIfRelevant()
-            startNewTurn()
+            if (shouldStartPlayDiscardedTurn()) {
+                startPlayDiscardedTurn()
+            } else {
+                rotateHandsIfRelevant()
+                startNewTurn()
+            }
         }
         return table.toTableState()
     }
@@ -173,6 +197,19 @@ class Game internal constructor(
 
     fun endOfGameReached(): Boolean = endOfAgeReached() && table.currentAge == LAST_AGE
 
+    private fun shouldStartPlayDiscardedTurn(): Boolean {
+        val boardsWithPlayDiscardedAbility = table.boards.filter { it.hasSpecial(SpecialAbility.PLAY_DISCARDED) }
+        if (boardsWithPlayDiscardedAbility.isEmpty()) {
+            return false
+        }
+        if (discardedCards.isEmpty()) {
+            // it was wasted for this turn, no discarded card to play
+            boardsWithPlayDiscardedAbility.forEach { it.removeSpecial(SpecialAbility.PLAY_DISCARDED) }
+            return false
+        }
+        return true
+    }
+
     private fun rotateHandsIfRelevant() {
         // we don't rotate hands if some player can play his last card (with the special ability)
         if (!hands.maxOneCardRemains()) {
diff --git a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/boards/Board.kt b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/boards/Board.kt
index 4c67be82..3f8f0437 100644
--- a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/boards/Board.kt
+++ b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/boards/Board.kt
@@ -63,6 +63,10 @@ internal class Board(val wonder: Wonder, val playerIndex: Int, settings: Setting
         specialAbilities.add(specialAbility)
     }
 
+    fun removeSpecial(specialAbility: SpecialAbility) {
+        specialAbilities.remove(specialAbility)
+    }
+
     fun hasSpecial(specialAbility: SpecialAbility): Boolean = specialAbilities.contains(specialAbility)
 
     fun canPlayFreeCard(age: Age): Boolean =
diff --git a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/cards/Cards.kt b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/cards/Cards.kt
index cfa46d27..cc00123e 100644
--- a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/cards/Cards.kt
+++ b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/cards/Cards.kt
@@ -20,8 +20,9 @@ internal data class Card(
     val image: String,
     val back: CardBack
 ) {
-    fun computePlayabilityBy(player: Player): CardPlayability = when {
+    fun computePlayabilityBy(player: Player, forceSpecialFree: Boolean = false): CardPlayability = when {
         isAlreadyOnBoard(player.board) -> Playability.incompatibleWithBoard() // cannot play twice the same card
+        forceSpecialFree -> Playability.specialFree()
         isParentOnBoard(player.board) -> Playability.chainable()
         else -> Playability.requirementDependent(requirements.assess(player))
     }
@@ -45,13 +46,13 @@ internal data class Card(
 
 private object Playability {
 
-    internal fun incompatibleWithBoard(): CardPlayability =
+    fun incompatibleWithBoard(): CardPlayability =
         CardPlayability(
             isPlayable = false,
             playabilityLevel = PlayabilityLevel.INCOMPATIBLE_WITH_BOARD
         )
 
-    internal fun chainable(): CardPlayability =
+    fun chainable(): CardPlayability =
         CardPlayability(
             isPlayable = true,
             isChainable = true,
@@ -60,7 +61,7 @@ private object Playability {
             playabilityLevel = PlayabilityLevel.CHAINABLE
         )
 
-    internal fun requirementDependent(satisfaction: RequirementsSatisfaction): CardPlayability =
+    fun requirementDependent(satisfaction: RequirementsSatisfaction): CardPlayability =
         CardPlayability(
             isPlayable = satisfaction.satisfied,
             isChainable = false,
@@ -68,4 +69,13 @@ private object Playability {
             cheapestTransactions = satisfaction.cheapestTransactions,
             playabilityLevel = satisfaction.level
         )
+
+    fun specialFree(): CardPlayability =
+        CardPlayability(
+            isPlayable = true,
+            isChainable = false,
+            minPrice = 0,
+            cheapestTransactions = setOf(noTransactions()),
+            playabilityLevel = PlayabilityLevel.SPECIAL_FREE
+        )
 }
diff --git a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/cards/Hands.kt b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/cards/Hands.kt
index f1f49cd8..b024848d 100644
--- a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/cards/Hands.kt
+++ b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/cards/Hands.kt
@@ -25,7 +25,7 @@ internal class Hands(private val hands: List<List<Card>>) {
         return Hands(mutatedHands)
     }
 
-    fun createHand(player: Player): List<HandCard> = hands[player.index].map { c -> c.toHandCard(player) }
+    fun createHand(player: Player): List<HandCard> = hands[player.index].map { c -> c.toHandCard(player, false) }
 
     fun rotate(direction: HandRotationDirection): Hands {
         val newHands = when (direction) {
diff --git a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/converters/Cards.kt b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/converters/Cards.kt
index 3d3471bf..f0e17515 100644
--- a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/converters/Cards.kt
+++ b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/converters/Cards.kt
@@ -18,7 +18,7 @@ internal fun Card.toTableCard(lastMove: Move? = null): TableCard =
         playedDuringLastMove = lastMove != null && this.name == lastMove.card.name
     )
 
-internal fun Card.toHandCard(player: Player): HandCard =
+internal fun Card.toHandCard(player: Player, forceSpecialFree: Boolean): HandCard =
     HandCard(
         name = name,
         color = color,
@@ -27,5 +27,5 @@ internal fun Card.toHandCard(player: Player): HandCard =
         chainChildren = chainChildren,
         image = image,
         back = back,
-        playability = computePlayabilityBy(player)
+        playability = computePlayabilityBy(player, forceSpecialFree)
     )
diff --git a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/moves/Move.kt b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/moves/Move.kt
index 6ae92b9a..1035c1b8 100644
--- a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/moves/Move.kt
+++ b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/moves/Move.kt
@@ -25,10 +25,12 @@ class InvalidMoveException internal constructor(move: Move, message: String) : I
     "Player ${move.playerContext.index} cannot perform move ${move.type}: $message"
 )
 
-internal fun MoveType.resolve(move: PlayerMove, card: Card, context: PlayerContext): Move = when (this) {
-    MoveType.PLAY -> PlayCardMove(move, card, context)
-    MoveType.PLAY_FREE -> PlayFreeCardMove(move, card, context)
-    MoveType.UPGRADE_WONDER -> BuildWonderMove(move, card, context)
-    MoveType.DISCARD -> DiscardMove(move, card, context)
-    MoveType.COPY_GUILD -> CopyGuildMove(move, card, context)
-}
+internal fun MoveType.resolve(move: PlayerMove, card: Card, context: PlayerContext, discardedCards: List<Card>): Move =
+    when (this) {
+        MoveType.PLAY -> PlayCardMove(move, card, context)
+        MoveType.PLAY_FREE -> PlayFreeCardMove(move, card, context)
+        MoveType.PLAY_FREE_DISCARDED -> PlayFreeDiscardedCardMove(move, card, context, discardedCards)
+        MoveType.UPGRADE_WONDER -> BuildWonderMove(move, card, context)
+        MoveType.DISCARD -> DiscardMove(move, card, context)
+        MoveType.COPY_GUILD -> CopyGuildMove(move, card, context)
+    }
diff --git a/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/moves/PlayFreeDiscardedCardMove.kt b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/moves/PlayFreeDiscardedCardMove.kt
new file mode 100644
index 00000000..5147ed82
--- /dev/null
+++ b/sw-engine/src/main/kotlin/org/luxons/sevenwonders/engine/moves/PlayFreeDiscardedCardMove.kt
@@ -0,0 +1,36 @@
+package org.luxons.sevenwonders.engine.moves
+
+import org.luxons.sevenwonders.engine.PlayerContext
+import org.luxons.sevenwonders.engine.Settings
+import org.luxons.sevenwonders.engine.cards.Card
+import org.luxons.sevenwonders.engine.effects.SpecialAbility
+import org.luxons.sevenwonders.model.PlayerMove
+
+internal class PlayFreeDiscardedCardMove(
+    move: PlayerMove,
+    card: Card,
+    playerContext: PlayerContext,
+    discardedCards: List<Card>
+) : Move(move, card, playerContext) {
+
+    init {
+        val board = playerContext.board
+        if (!board.hasSpecial(SpecialAbility.PLAY_DISCARDED)) {
+            throw InvalidMoveException(this, "no special ability to play a discarded card")
+        }
+        if (card !in discardedCards) {
+            throw InvalidMoveException(this, "Card $card is not among the discard cards")
+        }
+    }
+
+    override fun place(discardedCards: MutableList<Card>, settings: Settings) {
+        discardedCards.remove(card)
+        playerContext.board.addCard(card)
+    }
+
+    override fun activate(discardedCards: List<Card>, settings: Settings) {
+        // only apply effects, without paying the cost
+        card.effects.forEach { it.applyTo(playerContext) }
+        playerContext.board.removeSpecial(SpecialAbility.PLAY_DISCARDED)
+    }
+}
diff --git a/sw-engine/src/test/kotlin/org/luxons/sevenwonders/engine/GameTest.kt b/sw-engine/src/test/kotlin/org/luxons/sevenwonders/engine/GameTest.kt
index 320b3e94..e1a1b4a7 100644
--- a/sw-engine/src/test/kotlin/org/luxons/sevenwonders/engine/GameTest.kt
+++ b/sw-engine/src/test/kotlin/org/luxons/sevenwonders/engine/GameTest.kt
@@ -50,17 +50,18 @@ class GameTest {
         GameDefinition.load().initGame(0, testCustomizableSettings(), nbPlayers)
 
     private fun playAge(nbPlayers: Int, game: Game, age: Int) {
-        repeat(6) {
-            playTurn(nbPlayers, game, age, 7 - it)
-        }
+        do {
+            playTurn(nbPlayers, game, age)
+        } while (!game.getCurrentTurnInfo().first().isStartOfAge(age + 1))
     }
 
-    private fun playTurn(nbPlayers: Int, game: Game, ageToCheck: Int, handSize: Int) {
+    private fun PlayerTurnInfo.isStartOfAge(age: Int) = action == Action.WATCH_SCORE || currentAge == age
+
+    private fun playTurn(nbPlayers: Int, game: Game, ageToCheck: Int) {
         val turnInfos = game.getCurrentTurnInfo()
         assertEquals(nbPlayers, turnInfos.size)
         turnInfos.forEach {
             assertEquals(ageToCheck, it.currentAge)
-            assertEquals(handSize, it.hand?.size)
         }
 
         val moveExpectations = turnInfos.mapNotNull { it.firstAvailableMove() }
@@ -76,6 +77,7 @@ class GameTest {
 
     private fun PlayerTurnInfo.firstAvailableMove(): MoveExpectation? = when (action) {
         Action.PLAY, Action.PLAY_2, Action.PLAY_LAST -> createPlayCardMove(this)
+        Action.PLAY_FREE_DISCARDED -> createPlayFreeDiscardedMove(this)
         Action.PICK_NEIGHBOR_GUILD -> createPickGuildMove(this)
         Action.WAIT, Action.SAY_READY -> null
         Action.WATCH_SCORE -> fail("should not have WATCH_SCORE action before end of game")
@@ -95,6 +97,15 @@ class GameTest {
         }
     }
 
+    private fun createPlayFreeDiscardedMove(turn: PlayerTurnInfo): MoveExpectation {
+        val card = turn.discardedCards?.random() ?: error("No discarded card to play")
+        return MoveExpectation(
+            turn.playerIndex,
+            PlayerMove(MoveType.PLAY_FREE_DISCARDED, card.name, noTransactions()),
+            PlayedMove(turn.playerIndex, MoveType.PLAY_FREE_DISCARDED, card.toPlayedCard(), noTransactions())
+        )
+    }
+
     private fun planMove(
         turnInfo: PlayerTurnInfo,
         moveType: MoveType,
@@ -111,18 +122,11 @@ class GameTest {
 
         // the game should send action WAIT if no guild cards are available around
         assertFalse(neighbourGuilds.isEmpty())
+        val card = neighbourGuilds.first()
         return MoveExpectation(
             turnInfo.playerIndex,
-            PlayerMove(
-                MoveType.COPY_GUILD,
-                neighbourGuilds.first().name
-            ),
-            PlayedMove(
-                turnInfo.playerIndex,
-                MoveType.COPY_GUILD,
-                neighbourGuilds.first(),
-                noTransactions()
-            )
+            PlayerMove(MoveType.COPY_GUILD, card.name),
+            PlayedMove(turnInfo.playerIndex, MoveType.COPY_GUILD, card.toPlayedCard(), noTransactions())
         )
     }
 
diff --git a/sw-engine/src/test/kotlin/org/luxons/sevenwonders/engine/test/TestUtils.kt b/sw-engine/src/test/kotlin/org/luxons/sevenwonders/engine/test/TestUtils.kt
index 7c1935ae..cc97dc54 100644
--- a/sw-engine/src/test/kotlin/org/luxons/sevenwonders/engine/test/TestUtils.kt
+++ b/sw-engine/src/test/kotlin/org/luxons/sevenwonders/engine/test/TestUtils.kt
@@ -129,7 +129,7 @@ internal fun playCardWithEffect(player: Player, color: Color, effect: Effect) {
 }
 
 internal fun createMove(context: PlayerContext, card: Card, type: MoveType): Move =
-    type.resolve(PlayerMove(type, card.name), card, context)
+    type.resolve(PlayerMove(type, card.name), card, context, emptyList())
 
 internal fun singleBoardPlayer(board: Board): Player = object : Player {
     override val index = 0