Show Improvements that are buildable after Removing TerrainFeature (#6149)

* Initial working version!

* More comments

* Add missing .tr() translation calls

* add brackets

* Fixed

* Optimize checking for removable last feature
More complete tileInfo.clone()

Co-authored-by: itanasi <spellman23@gmail.com>

android/assets/jsons/translations/template.properties

@@ -809,6 +809,7 @@ Provides [resource] =
 Provides [amount] [resource] = 
 Replaces [improvement] = 
 Pick now! = 
+Remove [feature] first = 
 Build [building] = 
 Train [unit] = 
 Produce [thingToProduce] = 

core/src/com/unciv/logic/map/TileInfo.kt

@@ -92,6 +92,14 @@ open class TileInfo {
 
     fun clone(): TileInfo {
         val toReturn = TileInfo()
+        toReturn.tileMap = tileMap
+        toReturn.ruleset = ruleset
+        toReturn.isCityCenterInternal = isCityCenterInternal
+        toReturn.owningCity = owningCity
+        toReturn.baseTerrainObject = baseTerrainObject
+        toReturn.isLand = isLand
+        toReturn.isWater = isWater
+        toReturn.isOcean = isOcean
         if (militaryUnit != null) toReturn.militaryUnit = militaryUnit!!.clone()
         if (civilianUnit != null) toReturn.civilianUnit = civilianUnit!!.clone()
         for (airUnit in airUnits) toReturn.airUnits.add(airUnit.clone())

core/src/com/unciv/ui/pickerscreens/ImprovementPickerScreen.kt

@@ -51,12 +51,27 @@ class ImprovementPickerScreen(val tileInfo: TileInfo, unit: MapUnit, val onAccep
 
         val regularImprovements = Table()
         regularImprovements.defaults().pad(5f)
+        
+        // clone tileInfo without "top" feature if it could be removed
+        // Keep this copy around for speed
+        val tileInfoNoLast:TileInfo = tileInfo.clone()
+        if (ruleSet.tileImprovements.any{it.key == Constants.remove + tileInfoNoLast.getLastTerrain().name}) {
+            tileInfoNoLast.terrainFeatures.remove(tileInfoNoLast.getLastTerrain().name)
+        }
 
         for (improvement in ruleSet.tileImprovements.values) {
+            var suggestRemoval:Boolean = false
             // canBuildImprovement() would allow e.g. great improvements thus we need to exclude them - except cancel
             if (improvement.turnsToBuild == 0 && improvement.name != Constants.cancelImprovementOrder) continue
             if (improvement.name == tileInfo.improvement) continue // also checked by canImprovementBeBuiltHere, but after more expensive tests
-            if (!tileInfo.canBuildImprovement(improvement, currentPlayerCiv)) continue
+            if (!tileInfo.canBuildImprovement(improvement, currentPlayerCiv)){
+                // if there is an improvement that could remove that terrain
+                if(tileInfoNoLast.canBuildImprovement(improvement, currentPlayerCiv)) {
+                    suggestRemoval = true
+                } else {
+                    continue
+                }
+            }
             if (!unit.canBuildImprovement(improvement)) continue
 
             val image = ImageGetter.getImprovementIcon(improvement.name, 30f)
@@ -89,9 +104,12 @@ class ImprovementPickerScreen(val tileInfo: TileInfo, unit: MapUnit, val onAccep
                     && improvement.name != Constants.cancelImprovementOrder)
             if (tileInfo.improvement != null && removeImprovement) labelText += "\n" + "Replaces [${tileInfo.improvement}]".tr()
 
-            val pickNow = if (tileInfo.improvementInProgress != improvement.name)
+            val pickNow = if (suggestRemoval)
+                (Constants.remove + "[" + tileInfo.getLastTerrain().name + "] first").toLabel()
+            else if (tileInfo.improvementInProgress != improvement.name)
                 "Pick now!".toLabel().onClick { accept(improvement) }
-            else "Current construction".toLabel()
+            else
+                "Current construction".toLabel()
 
             val statIcons = getStatIconsTable(provideResource, removeImprovement)
 
@@ -118,6 +136,9 @@ class ImprovementPickerScreen(val tileInfo: TileInfo, unit: MapUnit, val onAccep
             }
 
             if (improvement.name == tileInfo.improvementInProgress) improvementButton.color = Color.GREEN
+            if (suggestRemoval){
+                improvementButton.disable()
+            }
             regularImprovements.add(improvementButton)
 
             if (shortcutKey != null) {