Lock a law group for 3 days after it changes

src/main/java/net/tfminecraft/simplefactions/Cache.java

@@ -39,6 +39,7 @@ public class Cache {
 	public static int maxUntitledProvinces;
 	public static int maxFreeTitles;
 	public static double deJureRequirement;
+	public static double lawSwitchLockDays = 3.0;
 	public static boolean mapEnabled;
 	public static boolean provincesEnabled = true;
 	public static boolean chronicleEnabled = true;

src/main/java/net/tfminecraft/simplefactions/database/Database.java

@@ -163,6 +163,12 @@ public void loadFactions() {
                         data.laws,
                         data.governmentData
                 );
+                if (data.lawChangedAt != null) {
+                    for (Map.Entry<String, Long> entry : data.lawChangedAt.entrySet()) {
+                        LawGroup group = f.getLawHandler().getGroup(entry.getKey());
+                        if (group != null && entry.getValue() != null) group.setChangedAt(entry.getValue());
+                    }
+                }
 
                 // --- Rank / founding ---
                 // Rank is derived state that only climbs one level per updatePrestige, so it
@@ -452,6 +458,9 @@ public void saveFaction(Faction f) {
                 if (current != null) {
                     data.laws.add(group.getId() + ":" + current.getId());
                 }
+                if (group.getChangedAt() > 0) {
+                    data.lawChangedAt.put(group.getId(), group.getChangedAt());
+                }
             }
 
             data.overlord = RelationManager.getOverlord(f);

src/main/java/net/tfminecraft/simplefactions/database/FactionData.java

@@ -2,6 +2,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 import java.util.HashMap;
 
 import com.google.gson.annotations.SerializedName;
@@ -84,6 +85,9 @@ public class FactionData {
 
     public List<String> laws = new ArrayList<>();
 
+    @SerializedName("law changed at")
+    public Map<String, Long> lawChangedAt = new HashMap<>();
+
     @SerializedName("war reparations")
     public List<WarReparationsObligationData> warReparationsObligations = new ArrayList<>();
 }

src/main/java/net/tfminecraft/simplefactions/government/proposal/Proposal.java

@@ -12,6 +12,7 @@
 import net.tfminecraft.simplefactions.objects.Faction;
 import net.tfminecraft.simplefactions.utils.EconomicImpact;
 import net.tfminecraft.simplefactions.utils.EconomicImpactService;
+import net.tfminecraft.simplefactions.laws.CanHaveLaw;
 import net.tfminecraft.simplefactions.laws.LawGroup;
 
 import net.tfminecraft.simplefactions.war.core.War;
@@ -42,6 +43,11 @@ public String getProposer() {
 
     public void apply(Cause cause) {
         if (isLawProposal()) {
+            // The group may have been switched by a coup, war or movement since this was proposed.
+            // Movements (cause != null) override the lock.
+            if (cause == null && CanHaveLaw.lockReason(gov.getFaction(), law, System.currentTimeMillis()) != null) {
+                return;
+            }
             LawGroup group = gov.getFaction().getLawHandler().getGroup(law.getGroup());
             gov.getFaction().applyLaw(law, group);
         } else if (isTaxProposal()) {

src/main/java/net/tfminecraft/simplefactions/laws/CanHaveLaw.java

@@ -18,13 +18,43 @@ public static String blockReason(Faction faction, Law law) {
 		if (isCurrentInGroup(faction, law)) {
 			return null;
 		}
+		String lockReason = lockReason(faction, law, System.currentTimeMillis());
+		if (lockReason != null) {
+			return lockReason;
+		}
 		String requirementReason = requirementsReason(faction, law);
 		if (requirementReason != null) {
 			return requirementReason;
 		}
 		return compatibilityReason(faction, law);
 	}
 
+	/** Why the law's group cannot be switched yet, or null if it can. */
+	public static String lockReason(Faction faction, Law law, long now) {
+		if (faction == null || faction.getLawHandler() == null || law == null || law.getGroup() == null) {
+			return null;
+		}
+		LawGroup group = faction.getLawHandler().getGroup(law.getGroup());
+		if (group == null) {
+			return null;
+		}
+		long remaining = group.lockRemaining(now);
+		if (remaining <= 0) {
+			return null;
+		}
+		return "§cThis law was changed recently. It can change again in " + formatRemaining(remaining) + ".";
+	}
+
+	static String formatRemaining(long millis) {
+		long minutes = Math.max(1, (millis + 59_999) / 60_000);
+		long days = minutes / 1440;
+		long hours = minutes % 1440 / 60;
+		long mins = minutes % 60;
+		if (days > 0) return days + "d " + hours + "h";
+		if (hours > 0) return hours + "h " + mins + "m";
+		return mins + "m";
+	}
+
 	private static boolean isCurrentInGroup(Faction faction, Law law) {
 		Law current = currentInGroup(faction, law);
 		return current != null && current.getId() != null && current.getId().equalsIgnoreCase(law.getId());

src/main/java/net/tfminecraft/simplefactions/laws/LawGroup.java

@@ -7,6 +7,7 @@
 
 import org.bukkit.configuration.ConfigurationSection;
 
+import net.tfminecraft.simplefactions.Cache;
 import net.tfminecraft.simplefactions.guild.income.IncomePreviewContext;
 import net.tfminecraft.simplefactions.objects.Faction;
 import net.tfminecraft.simplefactions.objects.handler.TaxHandler;
@@ -17,6 +18,7 @@ public class LawGroup {
     private String id;
     private String name;
     private Law current;
+    private long changedAt; // epoch millis of the last switch, 0 if never
     private Map<String, Law> laws = new LinkedHashMap<>();
     private List<String> description = new ArrayList<>();
 
@@ -68,4 +70,21 @@ public void setCurrent(Law law) {
         if(!laws.containsValue(law)) return;
         current = law;
     }
+
+    /** Sets the law and, if it differs from the current one, starts the switch lock. */
+    public void switchTo(Law law, long now) {
+        if(!laws.containsValue(law)) return;
+        if(law != current) changedAt = now;
+        current = law;
+    }
+
+    public long getChangedAt() { return changedAt; }
+    public void setChangedAt(long changedAt) { this.changedAt = changedAt; }
+
+    /** Millis left before this group may be switched again, 0 if it may be now. */
+    public long lockRemaining(long now) {
+        if(changedAt <= 0 || Cache.lawSwitchLockDays <= 0) return 0;
+        long until = changedAt + (long) (Cache.lawSwitchLockDays * 86_400_000L);
+        return Math.max(0, until - now);
+    }
 }

src/main/java/net/tfminecraft/simplefactions/loaders/ConfigLoader.java

@@ -39,6 +39,7 @@ public void loadConfig(File configFile) {
 		Cache.maxExtraNodeCapacity = config.getInt("max-extra-node-capacity", 0);
 
 		Cache.deJureRequirement = config.getDouble("de-jure-requirement", 100.0);
+		Cache.lawSwitchLockDays = config.getDouble("law-switch-lock-days", 3.0);
 		Cache.maxUntitledProvinces = config.getInt("max-untitled-provinces", 5);
 		Cache.maxFreeTitles = config.getInt("max-free-titles", 3);
 		Cache.mapEnabled = config.getBoolean("enable-map", false);

src/main/java/net/tfminecraft/simplefactions/objects/Faction.java

@@ -975,7 +975,7 @@ public boolean canVote(String p) {
 	public LawHandler getLawHandler() { return lawHandler; }
 
 	public void applyLaw(Law law, LawGroup group) {
-		group.setCurrent(law);
+		group.switchTo(law, System.currentTimeMillis());
 
 		LawEffect effect = law.getScopedEffects().get(Scope.FACTION);
 		if (effect == null) {

src/main/java/net/tfminecraft/simplefactions/war/civilwar/CivilWarStartService.java

@@ -543,7 +543,7 @@ static String applyConfiguredVassalage(Faction rebels) {
 		if (law.getScopedEffects() != null && law.getScopedEffects().get(Scope.FACTION) != null) {
 			rebels.applyLaw(law, group);
 		} else {
-			group.setCurrent(law);
+			group.switchTo(law, System.currentTimeMillis());
 		}
 		return null;
 	}

src/main/resources/config.yml

@@ -58,6 +58,9 @@ starting-year: "372 AE"
 
 max-extra-node-capacity: 0
 de-jure-requirement: 75.0
+# Days after a law group changes before the faction can switch it again.
+# Coups, movements, war outcomes and admin commands ignore it. 0 disables it.
+law-switch-lock-days: 3
 
 # Map platform (step 42) — requires TFMCWeb softdepend + api.base-url configured
 enable-map: true

src/test/java/net/tfminecraft/simplefactions/laws/LawSwitchLockTest.java

@@ -0,0 +1,128 @@
+package net.tfminecraft.simplefactions.laws;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.util.List;
+
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+import net.tfminecraft.simplefactions.Cache;
+import net.tfminecraft.simplefactions.objects.Faction;
+import net.tfminecraft.simplefactions.objects.handler.LawHandler;
+
+class LawSwitchLockTest {
+
+	private static final long DAY = 86_400_000L;
+	private static final long NOW = 1_000L * DAY;
+
+	private final double savedDays = Cache.lawSwitchLockDays;
+
+	@AfterEach
+	void restore() {
+		Cache.lawSwitchLockDays = savedDays;
+	}
+
+	@Test
+	void neverSwitched_notLocked() {
+		Cache.lawSwitchLockDays = 3;
+		assertEquals(0, lawGroup().lockRemaining(NOW));
+	}
+
+	@Test
+	void switching_startsLockForConfiguredDays() {
+		Cache.lawSwitchLockDays = 3;
+		LawGroup group = lawGroup();
+		group.switchTo(group.getLaw("high"), NOW);
+
+		assertEquals(3 * DAY, group.lockRemaining(NOW));
+		assertEquals(DAY, group.lockRemaining(NOW + 2 * DAY));
+		assertEquals(0, group.lockRemaining(NOW + 3 * DAY));
+	}
+
+	@Test
+	void reapplyingSameLaw_doesNotRestartLock() {
+		Cache.lawSwitchLockDays = 3;
+		LawGroup group = lawGroup();
+		group.switchTo(group.getLaw("high"), NOW);
+		group.switchTo(group.getLaw("high"), NOW + 2 * DAY);
+
+		assertEquals(NOW, group.getChangedAt());
+	}
+
+	@Test
+	void setCurrent_doesNotStartLock() {
+		Cache.lawSwitchLockDays = 3;
+		LawGroup group = lawGroup();
+		group.setCurrent(group.getLaw("high"));
+
+		assertEquals(0, group.lockRemaining(NOW));
+	}
+
+	@Test
+	void zeroDays_disablesLock() {
+		Cache.lawSwitchLockDays = 0;
+		LawGroup group = lawGroup();
+		group.switchTo(group.getLaw("high"), NOW);
+
+		assertEquals(0, group.lockRemaining(NOW));
+	}
+
+	@Test
+	void lockReason_blocksOtherLawsInLockedGroup() {
+		Cache.lawSwitchLockDays = 3;
+		LawGroup group = lawGroup();
+		group.switchTo(group.getLaw("high"), NOW);
+		Faction faction = factionWith(group);
+
+		String reason = CanHaveLaw.lockReason(faction, group.getLaw("low"), NOW + DAY);
+		assertNotNull(reason);
+		assertTrue(reason.contains("2d 0h"), reason);
+		assertNull(CanHaveLaw.lockReason(faction, group.getLaw("low"), NOW + 3 * DAY));
+	}
+
+	@Test
+	void blockReason_currentLawStillAvailableWhileLocked() {
+		Cache.lawSwitchLockDays = 3;
+		LawGroup group = lawGroup();
+		group.switchTo(group.getLaw("high"), System.currentTimeMillis());
+		Faction faction = factionWith(group);
+
+		assertNull(CanHaveLaw.blockReason(faction, group.getLaw("high")));
+		assertNotNull(CanHaveLaw.blockReason(faction, group.getLaw("low")));
+	}
+
+	@Test
+	void formatRemaining_roundsUpToMinutes() {
+		assertEquals("2d 5h", CanHaveLaw.formatRemaining(2 * DAY + 5 * 3_600_000L + 1));
+		assertEquals("3h 1m", CanHaveLaw.formatRemaining(3 * 3_600_000L + 1));
+		assertEquals("1m", CanHaveLaw.formatRemaining(1));
+	}
+
+	private static Faction factionWith(LawGroup group) {
+		Faction faction = mock(Faction.class);
+		LawHandler handler = mock(LawHandler.class);
+		when(faction.getLawHandler()).thenReturn(handler);
+		when(handler.getGroup("taxes")).thenReturn(group);
+		when(handler.getCurrentLaws()).thenReturn(List.of(group.getCurrent()));
+		return faction;
+	}
+
+	private static LawGroup lawGroup() {
+		YamlConfiguration config = new YamlConfiguration();
+		config.set("name", "Taxes");
+		for (String id : List.of("low", "high")) {
+			config.createSection("laws." + id);
+			config.set("laws." + id + ".name", id);
+		}
+		LawGroup group = new LawGroup("taxes", config);
+		group.setCurrent(group.getLaw("low"));
+		return group;
+	}
+}

src/test/java/net/tfminecraft/simplefactions/war/civilwar/CivilWarStartServiceTest.java

@@ -411,7 +411,7 @@ void applyConfiguredVassalage_setsLawFromCacheIds() {
 		Faction rebels = mock(Faction.class);
 		stubRebelVassalage(rebels);
 		assertNull(CivilWarStartService.applyConfiguredVassalage(rebels));
-		verify(rebels.getLawHandler().getGroup("vassalage")).setCurrent(org.mockito.ArgumentMatchers.any());
+		verify(rebels.getLawHandler().getGroup("vassalage")).switchTo(org.mockito.ArgumentMatchers.any(), org.mockito.ArgumentMatchers.anyLong());
 	}
 
 	private static Movement baseMovement(Action action, Member leaderRelation) {