From ef7fc36c80d27c7335d9c5c042952bb0d18e7034 Mon Sep 17 00:00:00 2001
From: SomeTroglodyte <63000004+SomeTroglodyte@users.noreply.github.com>
Date: Sat, 28 Aug 2021 21:26:00 +0200
Subject: [PATCH] Harden automateImprovementPlacer and detect Mod problems with
 these (#5010)

---
 .../logic/automation/SpecificUnitAutomation.kt     |  6 ++++--
 core/src/com/unciv/models/ruleset/Ruleset.kt       | 14 ++++++++++++--
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/core/src/com/unciv/logic/automation/SpecificUnitAutomation.kt b/core/src/com/unciv/logic/automation/SpecificUnitAutomation.kt
index cd88c0adc0..291618b9c5 100644
--- a/core/src/com/unciv/logic/automation/SpecificUnitAutomation.kt
+++ b/core/src/com/unciv/logic/automation/SpecificUnitAutomation.kt
@@ -9,6 +9,7 @@ import com.unciv.logic.map.MapUnit
 import com.unciv.logic.map.TileInfo
 import com.unciv.models.ruleset.tile.ResourceType
 import com.unciv.models.ruleset.tile.TileResource
+import com.unciv.models.stats.Stat
 import com.unciv.models.stats.Stats
 import com.unciv.ui.worldscreen.unit.UnitActions
 
@@ -217,8 +218,9 @@ object SpecificUnitAutomation {
 
     fun automateImprovementPlacer(unit: MapUnit) {
         val improvementName = unit.getMatchingUniques("Can construct []").first().params[0]
-        val improvement = unit.civInfo.gameInfo.ruleSet.tileImprovements[improvementName]!!
-        val relatedStat = improvement.maxByOrNull { it.value }!!.key
+        val improvement = unit.civInfo.gameInfo.ruleSet.tileImprovements[improvementName]
+            ?: return
+        val relatedStat = improvement.maxByOrNull { it.value }?.key ?: Stat.Culture
 
         val citiesByStatBoost = unit.civInfo.cities.sortedByDescending {
             val stats = Stats()
diff --git a/core/src/com/unciv/models/ruleset/Ruleset.kt b/core/src/com/unciv/models/ruleset/Ruleset.kt
index 18fcbb5bcc..7e3a945e78 100644
--- a/core/src/com/unciv/models/ruleset/Ruleset.kt
+++ b/core/src/com/unciv/models/ruleset/Ruleset.kt
@@ -299,7 +299,7 @@ class Ruleset {
         val lines = ArrayList<String>()
         var warningCount = 0
 
-        // Checks for all mods
+        // Checks for all mods - only those that can succeed without loading a base ruleset
         for (unit in units.values) {
             if (unit.upgradesTo == unit.name)
                 lines += "${unit.name} upgrades to itself!"
@@ -327,9 +327,10 @@ class Ruleset {
             }
         }
 
+        // Quit here when no base ruleset is loaded - references cannot be checked
         if (!modOptions.isBaseRuleset) return CheckModLinksResult(warningCount, lines)
 
-        val baseRuleset = RulesetCache.getBaseRuleset()
+        val baseRuleset = RulesetCache.getBaseRuleset()  // for UnitTypes fallback
 
         for (unit in units.values) {
             if (unit.requiredTech != null && !technologies.containsKey(unit.requiredTech!!))
@@ -348,6 +349,15 @@ class Ruleset {
                     lines += "${unit.name} contains promotion $promotion which does not exist!"
             if (!unitTypes.containsKey(unit.unitType) && !baseRuleset.unitTypes.containsKey(unit.unitType))
                 lines += "${unit.name} is of type ${unit.unitType}, which does not exist!"
+            for (unique in unit.getMatchingUniques("Can construct []")) {
+                val improvementName = unique.params[0]
+                if (improvementName !in tileImprovements)
+                    lines += "${unit.name} can place improvement $improvementName which does not exist!"
+                else if (tileImprovements[improvementName]!!.firstOrNull() == null && !unit.hasUnique("Bonus for units in 2 tile radius 15%")) {
+                    lines += "${unit.name} can place improvement $improvementName which has no stats, preventing unit automation!"
+                    warningCount++
+                }
+            }
         }
 
         for (building in buildings.values) {