Implement Same-majority-religion-based diplomatic modifier (#11415)

* implement BelieveSameReligion/BelieveDifferentReligion DiplomaticModifiers

* implemented feedbacks

* remove unuseful val instanciation/assignment

* add getMajorityReligion() in ReligionManager.kt

* fixing code style

core/src/com/unciv/logic/civilization/diplomacy/DiplomacyManager.kt

@@ -102,6 +102,7 @@ enum class DiplomaticModifiers(val text: String) {
     GaveUsUnits("You gave us units!"),
     GaveUsGifts("We appreciate your gifts"),
     ReturnedCapturedUnits("You returned captured units to us"),
+    BelieveSameReligion("We believe in the same religion"),
 
 }
 
@@ -276,6 +277,14 @@ class DiplomacyManager() : IsPartOfGameInfoSerialization {
         }
     }
 
+    private fun believesSameReligion(): Boolean {
+        // what is the majorityReligion of civInfo? If it is null, we immediately return false
+        val civMajorityReligion = civInfo.religionManager.getMajorityReligion() ?: return false
+        // if not yet returned false from previous line, return the Boolean isMajorityReligionForCiv
+        // true if majorityReligion of civInfo is also majorityReligion of otherCiv, false otherwise
+        return otherCiv().religionManager.isMajorityReligionForCiv(civMajorityReligion)
+    }
+
     /** Returns the number of turns to degrade from Ally or from Friend */
     fun getTurnsToRelationshipChange(): Int {
         if (otherCiv().isCityState())
@@ -587,6 +596,14 @@ class DiplomacyManager() : IsPartOfGameInfoSerialization {
         }
     }
 
+    internal fun setReligionBasedModifier() {
+        if (civInfo.getDiplomacyManager(otherCiv()).believesSameReligion())
+            // they share same majority religion
+            setModifier(DiplomaticModifiers.BelieveSameReligion, 5f)
+        else
+            // their majority religions differ or one or both don't have a majority religion at all
+            removeModifier(DiplomaticModifiers.BelieveSameReligion)
+    }
 
     fun denounce() {
         setModifier(DiplomaticModifiers.Denunciation, -35f)

core/src/com/unciv/logic/civilization/diplomacy/DiplomacyTurnManager.kt

@@ -291,6 +291,8 @@ object DiplomacyTurnManager {
 
         setDefensivePactBasedModifier()
 
+        setReligionBasedModifier()
+
         if (!hasFlag(DiplomacyFlags.DeclarationOfFriendship))
             revertToZero(DiplomaticModifiers.DeclarationOfFriendship, 1 / 2f) //decreases slowly and will revert to full if it is declared later
 

core/src/com/unciv/logic/civilization/managers/ReligionManager.kt

@@ -478,6 +478,26 @@ class ReligionManager : IsPartOfGameInfoSerialization {
         if (religion == null) return null
         return civInfo.gameInfo.getCities().firstOrNull { it.isHolyCityOf(religion!!.name) }
     }
+
+    fun getMajorityReligion(): Religion? {
+        // let's count for each religion (among those actually presents in civ's cities)
+        val religionCounter = Counter<Religion>()
+        for (city in civInfo.cities) {
+            // if city's majority Religion is null, let's just continue to next loop iteration
+            val cityMajorityReligion = city.religion.getMajorityReligion() ?: continue
+            // if not yet continued to next iteration from previous line, let's add the Religion to religionCounter
+            religionCounter.add(cityMajorityReligion, 1)
+        }
+        // let's get the max-counted Religion if there is one, null otherwise; if null, return null
+        val maxReligionCounterEntry = religionCounter.maxByOrNull { it.value } ?: return null
+        // if not returned null from prev. line, check if the maxReligion is in most of the cities
+        return if (maxReligionCounterEntry.value > civInfo.cities.size / 2)
+        // if maxReligionCounterEntry > half-cities-count we return the Religion of maxReligionCounterEntry
+            maxReligionCounterEntry.key
+        else
+        // if maxReligionCounterEntry <= half-cities-count we just return null
+            null
+    }
 }
 
 enum class ReligionState : IsPartOfGameInfoSerialization {