[Simulated AI] Refactor code to create a Plan object.

This allows coming up with a multi-step planning and caching it, so it doesn't need to be re-computed at subsequent steps if nothing meaningful changed.

.gitattributes

@@ -156,6 +156,7 @@ forge-ai/src/main/java/forge/ai/ability/ZoneExchangeAi.java -text
 forge-ai/src/main/java/forge/ai/simulation/GameCopier.java -text
 forge-ai/src/main/java/forge/ai/simulation/GameSimulator.java -text
 forge-ai/src/main/java/forge/ai/simulation/GameStateEvaluator.java -text
+forge-ai/src/main/java/forge/ai/simulation/Plan.java -text
 forge-ai/src/main/java/forge/ai/simulation/PossibleTargetSelector.java -text
 forge-ai/src/main/java/forge/ai/simulation/SimulationController.java -text
 forge-ai/src/main/java/forge/ai/simulation/SpellAbilityPicker.java -text

forge-ai/src/main/java/forge/ai/simulation/GameSimulator.java

@@ -192,7 +192,7 @@ public class GameSimulator {
         }
         controller.printState(score, origSa);
         if (controller.shouldRecurse() && !simGame.isGameOver()) {
-            controller.push(sa);
+            controller.push(sa, score);
             SpellAbilityPicker sim = new SpellAbilityPicker(simGame, aiPlayer);
             CardCollection cards = ComputerUtilAbility.getAvailableCards(simGame, aiPlayer);
             List<SpellAbility> all = ComputerUtilAbility.getSpellAbilities(cards, aiPlayer);

forge-ai/src/main/java/forge/ai/simulation/GameStateEvaluator.java

@@ -79,9 +79,9 @@ public class GameStateEvaluator {
         for (Card c : game.getCardsIn(ZoneType.Battlefield)) {
             int value = evalCard(game, aiPlayer, c, combat);
             int summonSickValue = value;
-            // To make the AI hold-off on playing creatures in MAIN1 if they give no other benefits,
+            // To make the AI hold-off on playing creatures before MAIN2 if they give no other benefits,
             // keep track of the score while treating summon sick creatures as having a value of 0.
-            if (gamePhase == PhaseType.MAIN1 && c.isSick() && c.getController() == aiPlayer) {
+            if (gamePhase.isBefore(PhaseType.MAIN2) && c.isSick() && c.getController() == aiPlayer) {
                 summonSickValue = 0;
             }
             String str = c.getName();
@@ -167,7 +167,6 @@ public class GameStateEvaluator {
     public static class Score {
         public final int value;
         public final int summonSickValue;
-        public String choice;
         
         public Score(int value) {
             this.value = value;

forge-ai/src/main/java/forge/ai/simulation/Plan.java

@@ -0,0 +1,78 @@
+package forge.ai.simulation;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import forge.ai.simulation.GameStateEvaluator.Score;
+import forge.game.card.Card;
+import forge.game.spellability.SpellAbility;
+
+public class Plan {
+    private List<Decision> decisions;
+    private int nextDecisionIndex;
+    private Decision selectedDecision;
+
+    public Plan(ArrayList<Decision> decisions) {
+        this.decisions = decisions;
+    }
+    
+    public List<Decision> getDecisions() {
+        return decisions;
+    }
+    
+    public boolean hasNextDecision() {
+        return nextDecisionIndex < decisions.size();
+    }
+
+    public Decision selectNextDecision() {
+        selectedDecision = decisions.get(nextDecisionIndex);
+        nextDecisionIndex++;
+        return selectedDecision;
+    }
+    
+    public Decision getSelectedDecision() {
+        return selectedDecision;
+    }
+
+    public int getNextDecisionIndex() {
+        return nextDecisionIndex;
+    }
+
+    public static class Decision {
+        final Decision prevDecision;
+        final Score initialScore;
+
+        final String sa;
+        PossibleTargetSelector.Targets targets;
+        String choice;
+
+        public Decision(Score initialScore, Decision prevDecision, SpellAbility sa) {
+            this.initialScore = initialScore;
+            this.prevDecision = prevDecision;
+            this.sa = sa.toString();
+            this.targets = null;
+            this.choice = null;
+        }
+        
+        public Decision(Score initialScore, Decision prevDecision, PossibleTargetSelector.Targets targets) {
+            this.initialScore = initialScore;
+            this.prevDecision = prevDecision;
+            this.sa = null;
+            this.targets = targets;
+            this.choice = null;
+        }
+        
+        public Decision(Score initialScore, Decision prevDecision, Card choice) {
+            this.initialScore = initialScore;
+            this.prevDecision = prevDecision;
+            this.sa = null;
+            this.targets = null;
+            this.choice = choice.getName();
+        }
+
+        @Override
+        public String toString() {
+            return "[initScore=" + initialScore + " " + sa + " " + targets + " " + choice + "]";
+        }
+    }
+}

forge-ai/src/main/java/forge/ai/simulation/PossibleTargetSelector.java

@@ -16,23 +16,43 @@ public class PossibleTargetSelector {
     private int targetIndex;
     private List<GameObject> validTargets;
 
+    public static class Targets {
+        final int originalTargetCount;
+        final int targetIndex;
+        final String description;
+        
+        private Targets(int originalTargetCount, int targetIndex, String description)  {
+            this.originalTargetCount = originalTargetCount;
+            this.targetIndex = targetIndex;
+            this.description = description;
+
+            if (targetIndex < 0 || targetIndex >= originalTargetCount) {
+                throw new IllegalArgumentException("Invalid targetIndex=" + targetIndex);
+            }
+        }
+        
+        @Override
+        public String toString() {
+            return description;
+        }
+    }
+
     public PossibleTargetSelector(Game game, Player self, SpellAbility sa) {
         this.sa = sa;
         this.tgt = sa.getTargetRestrictions();
         this.targetIndex = 0;
         this.validTargets = new ArrayList<GameObject>();
+        sa.resetTargets();
         sa.setActivatingPlayer(self);
         for (GameObject o : tgt.getAllCandidates(sa, true)) {
             validTargets.add(o);
         }
     }
 
-    public boolean selectNextTargets() {
-        if (targetIndex >= validTargets.size()) {
-            return false;
-        }
+    private void selectTargetsByIndex(int index) {
         sa.resetTargets();
-        int index = targetIndex;
+
+        // TODO: smarter about multiple targets, identical targets, etc...
         while (sa.getTargets().getNumTargeted() < tgt.getMaxTargets(sa.getHostCard(), sa) && index < validTargets.size()) {
             sa.getTargets().add(validTargets.get(index++));
         }
@@ -53,8 +73,25 @@ public class PossibleTargetSelector {
                 }
             }
         }
+    }
 
-        // TODO: smarter about multiple targets, identical targets, etc...
+    public Targets getLastSelectedTargets() {
+        return new Targets(validTargets.size(), targetIndex - 1, sa.getTargets().getTargetedString());
+    }
+
+    public boolean selectTargets(Targets targets) {
+        if (targets.originalTargetCount != validTargets.size()) {
+            return false;
+        }
+        selectTargetsByIndex(targets.targetIndex);
+        return true;
+    }
+ 
+    public boolean selectNextTargets() {
+        if (targetIndex >= validTargets.size()) {
+            return false;
+        }
+        selectTargetsByIndex(targetIndex);
         targetIndex++;
         return true;
     }

forge-ai/src/main/java/forge/ai/simulation/SimulationController.java

@@ -1,6 +1,11 @@
 package forge.ai.simulation;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
 import forge.ai.simulation.GameStateEvaluator.Score;
+import forge.game.card.Card;
 import forge.game.spellability.SpellAbility;
 
 public class SimulationController {
@@ -8,21 +13,93 @@ public class SimulationController {
     
     private int recursionDepth;
 
-    public SimulationController() {
+    private List<Plan.Decision> currentStack;
+    private List<Score> scoreStack;
+    private Plan.Decision bestSequence; // last action of sequence
+    private Score bestScore;
+    
+    public SimulationController(Score score) {
+        bestScore = score;
+        scoreStack = new ArrayList<Score>();
+        scoreStack.add(score);
+        currentStack = new ArrayList<Plan.Decision>();
     }
     
     public boolean shouldRecurse() {
         return recursionDepth < MAX_DEPTH;
     }
     
-    public void push(SpellAbility sa) {
+    private Plan.Decision getLastDecision() {
+        if (currentStack.isEmpty()) {
+            return null;
+        }
+        return currentStack.get(currentStack.size() - 1);
+    }
+    
+    private Score getCurrentScore() {
+        return scoreStack.get(scoreStack.size() - 1);
+    }
+    
+    public void evaluateSpellAbility(SpellAbility sa) {
+        currentStack.add(new Plan.Decision(getCurrentScore(), getLastDecision(), sa));
+    }
+    
+    public void evaluateCardChoice(Card choice) {
+        currentStack.add(new Plan.Decision(getCurrentScore(), getLastDecision(), choice));
+    }
+    
+    public void evaluateTargetChoices(PossibleTargetSelector.Targets targets) {
+        currentStack.add(new Plan.Decision(getCurrentScore(), getLastDecision(), targets));
+    }
+
+    public void doneEvaluating(Score score) {
+        if (score.value > bestScore.value) {
+            bestScore = score;
+            bestSequence = currentStack.get(currentStack.size() - 1);
+        }
+        currentStack.remove(currentStack.size() - 1);
+    }
+    
+    public Score getBestScore() {
+        return bestScore;
+    }
+    
+    public Plan getBestPlan() {
+        ArrayList<Plan.Decision> sequence = new ArrayList<Plan.Decision>();
+        Plan.Decision current = bestSequence;
+        while (current != null) {
+            sequence.add(current);
+            current = current.prevDecision;
+        }
+        Collections.reverse(sequence);
+        // Merge targets & choices into their parents.
+        int writeIndex = 0;
+        for (int i = 0; i < sequence.size(); i++) {
+            Plan.Decision d = sequence.get(i);
+            System.out.println("SeqInput: " + d);
+            if (d.sa != null) {
+                sequence.set(writeIndex, d);
+                writeIndex++;
+            } else if (d.targets != null) {
+                sequence.get(writeIndex - 1).targets = d.targets;
+            } else if (d.choice != null) {
+                sequence.get(writeIndex - 1).choice = d.choice;
+            }
+        }
+        sequence.subList(writeIndex, sequence.size()).clear();
+        return new Plan(sequence);
+    }
+    
+    public void push(SpellAbility sa, Score score) {
         GameSimulator.debugPrint("Recursing DEPTH=" + recursionDepth);
         GameSimulator.debugPrint("  With: " + sa);
         recursionDepth++;
+        scoreStack.add(score);
     }
 
     public void pop(Score score, SpellAbility nextSa) {
         recursionDepth--;
+        scoreStack.remove(scoreStack.size() - 1);
         GameSimulator.debugPrint("DEPTH"+recursionDepth+" best score " + score + " " + nextSa);
     }
 

forge-ai/src/main/java/forge/ai/simulation/SpellAbilityPicker.java

@@ -1,6 +1,5 @@
 package forge.ai.simulation;
 
-import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 
@@ -26,6 +25,8 @@ public class SpellAbilityPicker {
     private boolean printOutput;
     private Interceptor interceptor;
 
+    private Plan plan;
+
     public SpellAbilityPicker(Game game, Player player) {
         this.game = game;
         this.player = player;
@@ -41,21 +42,19 @@ public class SpellAbilityPicker {
         }
     }
 
-    public SpellAbility chooseSpellAbilityToPlay(SimulationController controller, final List<SpellAbility> all, boolean skipCounter) {
-        printOutput = false;
-        if (controller == null) {
-            controller = new SimulationController();
-            printOutput = true;
-        }
+    private void printPhaseInfo() {
         String phaseStr = game.getPhaseHandler().getPhase().toString();
         if (game.getPhaseHandler().getPlayerTurn() != player) {
             phaseStr = "opponent " + phaseStr;
         }
         print("---- choose ability  (phase = " + phaseStr + ")");
+    }
     
-        long startTime = System.currentTimeMillis();
-        List<SpellAbility> candidateSAs = new ArrayList<>();
-        for (final SpellAbility sa : ComputerUtilAbility.getOriginalAndAltCostAbilities(all, player)) {
+    private List<SpellAbility> getCandidateSpellsAndAbilities(List<SpellAbility> all) {
+        List<SpellAbility> candidateSAs = ComputerUtilAbility.getOriginalAndAltCostAbilities(all, player);
+        int writeIndex = 0;
+        for (int i = 0; i < candidateSAs.size(); i++) {
+            SpellAbility sa = candidateSAs.get(i);
             if (sa.isManaAbility()) {
                 continue;
             }
@@ -68,20 +67,59 @@ public class SpellAbilityPicker {
             
             if (opinion != AiPlayDecision.WillPlay)
                 continue;
-            candidateSAs.add(sa);
+            candidateSAs.set(writeIndex,  sa);
+            writeIndex++;
+        }
+        candidateSAs.subList(writeIndex, candidateSAs.size()).clear();
+        return candidateSAs;
+    }
+
+    public SpellAbility chooseSpellAbilityToPlay(SimulationController controller, List<SpellAbility> all, boolean skipCounter) {
+        printOutput = (controller == null);
+
+        // FIXME: This is wasteful, we should re-use the same simulator...
+        GameSimulator simulator = new GameSimulator(controller, game, player);
+        Score origGameScore = simulator.getScoreForOrigGame();
+        List<SpellAbility> candidateSAs = getCandidateSpellsAndAbilities(all);
+        if (controller != null) {
+            // This is a recursion during a higher-level simulation. Just return the head of the best
+            // sequence directly, no need to create a Plan object.
+            return chooseSpellAbilityToPlayImpl(controller, candidateSAs, origGameScore);
         }
 
-        if (candidateSAs.isEmpty()) {
-            return null;
+        printPhaseInfo();
+        SpellAbility sa = getPlannedSpellAbility(origGameScore, candidateSAs);
+        if (sa != null) {
+            return sa;
         }
+        createNewPlan(origGameScore, candidateSAs);
+        return getPlannedSpellAbility(origGameScore, candidateSAs);
+    }
+
+    private void createNewPlan(Score origGameScore, List<SpellAbility> candidateSAs) {
+        plan = null;
+        SimulationController controller = new SimulationController(origGameScore);
+        SpellAbility sa = chooseSpellAbilityToPlayImpl(controller, candidateSAs, origGameScore);
+        if (sa == null) {
+            print("No good plan at this time");
+            return;
+        }
+
+        plan = controller.getBestPlan();
+        print("New plan with score " + controller.getBestScore() + ":");
+        int i = 0;
+        for (Plan.Decision d : plan.getDecisions()) {
+            print(++i + ". " + d);
+        }
+    }
+
+    private SpellAbility chooseSpellAbilityToPlayImpl(SimulationController controller, List<SpellAbility> candidateSAs, Score origGameScore) {
+        long startTime = System.currentTimeMillis();
+
         SpellAbility bestSa = null;
-        GameSimulator simulator = new GameSimulator(controller, game, player);
-        // FIXME: This is wasteful, we should re-use the same simulator...
-        Score origGameScore = simulator.getScoreForOrigGame();
         Score bestSaValue = origGameScore;
         print("Evaluating... (orig score = " + origGameScore +  ")");
         for (final SpellAbility sa : candidateSAs) {
-            print(abilityToString(sa));;
             Score value = evaluateSa(controller, sa);
             if (value.value > bestSaValue.value) {
                 bestSaValue = value;
@@ -104,6 +142,41 @@ public class SpellAbilityPicker {
         return bestSa;
     }
 
+    private SpellAbility getPlannedSpellAbility(Score origGameScore, List<SpellAbility> availableSAs) {
+        if (plan != null && plan.hasNextDecision()) {
+            boolean badTargets = false;
+            boolean saNotFound = false;
+            Plan.Decision decision = plan.selectNextDecision();
+            if (decision.initialScore.equals(origGameScore)) {
+                // TODO: Other safeguards like list of SAs and maybe the index and such?
+                for (final SpellAbility sa : availableSAs) {
+                    if (sa.toString().equals(decision.sa)) {
+                        if (decision.targets != null) {
+                            PossibleTargetSelector selector = new PossibleTargetSelector(game, player, sa);
+                            if (!selector.selectTargets(decision.targets)) {
+                                badTargets = true;
+                                break;
+                            }
+                        }
+                        print("Planned decision " + plan.getNextDecisionIndex() + ": " + abilityToString(sa) + " " + decision.choice);
+                        return sa;
+                    }
+                }
+                saNotFound = true;
+            }
+            print("Failed to continue planned action (" + decision.sa + "). Cause:");
+            if (badTargets) {
+                print("  Bad targets!");
+            } else if (saNotFound) {
+                print("  Couldn't find spell/ability!");
+            } else {
+                print("  Unexpected game score (" + decision.initialScore + " vs. expected " + origGameScore + ")!");
+            }
+            plan = null;
+        }
+        return null;
+    }
+ 
     public Score getScoreForChosenAbility() {
         return bestScore;
     }
@@ -161,12 +234,11 @@ public class SpellAbilityPicker {
         return AiPlayDecision.WillPlay;
     }
 
-    private Score evaluateSa(SimulationController controller, SpellAbility sa) {
-        GameSimulator.debugPrint("Evaluate SA: " + sa);
+    private Score evaluateSa(final SimulationController controller, SpellAbility sa) {
+        controller.evaluateSpellAbility(sa);
 
         Score bestScore = new Score(Integer.MIN_VALUE);
         if (!sa.usesTargeting()) {
-            // TODO: Refactor this into a general decision tree.
             Interceptor interceptor = new Interceptor() {
                 private int numChoices = -1;
                 private int nextChoice = 0;
@@ -185,7 +257,9 @@ public class SpellAbilityPicker {
                     }
                     numChoices = uniqueCards.size();
                     nextChoice++;
-                    GameSimulator.debugPrint("Trying out choice " + choice);
+                    if (choice != null) {
+                        controller.evaluateCardChoice(choice);
+                    }
                     return choice;
                 }
 
@@ -204,30 +278,33 @@ public class SpellAbilityPicker {
                 GameSimulator simulator = new GameSimulator(controller, game, player);
                 simulator.setInterceptor(interceptor);
                 Score score = simulator.simulateSpellAbility(sa);
+                if (interceptor.getLastChoice() != null) {
+                    controller.doneEvaluating(score);
+                }
                 if (score.value > bestScore.value) {
                     bestScore = score;
-                    Card choice = interceptor.getLastChoice();
-                    if (choice != null) {
-                        bestScore.choice = choice.getName();
-                    }
                 }
             } while (interceptor.hasMoreChoices());
+            controller.doneEvaluating(bestScore);
             return bestScore;
         }
 
-        GameSimulator.debugPrint("Checking out targets");
         PossibleTargetSelector selector = new PossibleTargetSelector(game, player, sa);
         TargetChoices tgt = null;
         while (selector.selectNextTargets()) {
-            GameSimulator.debugPrint("Trying targets: " + sa.getTargets().getTargetedString());
+            controller.evaluateTargetChoices(selector.getLastSelectedTargets());
             GameSimulator simulator = new GameSimulator(controller, game, player);
             Score score = simulator.simulateSpellAbility(sa);
+            controller.doneEvaluating(score);
+            // TODO: Get rid of the below when no longer needed.
             if (score.value > bestScore.value) {
                 bestScore = score;
                 tgt = sa.getTargets();
                 sa.resetTargets();
             }
         }
+        controller.doneEvaluating(bestScore);
+
         if (tgt != null) {
             sa.setTargets(tgt);
         }
@@ -240,12 +317,15 @@ public class SpellAbilityPicker {
             return interceptor.chooseCard(fetchList);
         }
         // TODO: Make the below more robust?
-        if (bestScore != null && bestScore.choice != null) {
+        if (plan != null && plan.getSelectedDecision() != null) {
+            String choice = plan.getSelectedDecision().choice;
             for (Card c : fetchList) {
-                if (c.getName().equals(bestScore.choice)) {
+                if (c.getName().equals(choice)) {
+                    print("  Planned choice: " + c);
                     return c;
                 }
             }
+            print("Failed to use planned choice (" + choice + "). Not found!");
         }
         return ChangeZoneAi.chooseCardToHiddenOriginChangeZone(destination, origin, sa, fetchList, player2, decider);
     }

forge-gui-desktop/src/test/java/forge/ai/simulation/GameSimulatorTest.java

@@ -10,6 +10,7 @@ import forge.GuiBase;
 import forge.GuiDesktop;
 import forge.ai.ComputerUtilAbility;
 import forge.ai.LobbyPlayerAi;
+import forge.ai.simulation.GameStateEvaluator.Score;
 import forge.card.CardStateName;
 import forge.deck.Deck;
 import forge.game.Game;
@@ -51,7 +52,7 @@ public class GameSimulatorTest extends TestCase {
     }
 
     private GameSimulator createSimulator(Game game, Player p) {
-        return new GameSimulator(new SimulationController(), game, p);
+        return new GameSimulator(new SimulationController(new Score(0)), game, p);
     }
 
     private Card findCardWithName(Game game, String name) {