PR MegaMek/mekhq#8544: Implement BV Calculation for TO:AR Advanced Buildings and Replace Generic BV

[psikomonkie]

Support for Advanced Building Gun Emplacement RAT and Experimental Rule to enable them in campaigns. Required for MegaMek/mekhq#8544 to function properly. A Generic BV of 0 causes an infinite loop when creating a scenario. I don't really know how it was calculated for other units, so for now I'm just returning the actual BV.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 29.72%. Comparing base (a388152) to head (24e55ee).
⚠️ Report is 46 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #7861      +/-   ##
============================================
- Coverage     29.81%   29.72%   -0.09%     
- Complexity    16235    16263      +28     
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  Files          3125     3130       +5     
  Lines        300415   301766    +1351     
  Branches      52538    52836     +298     
============================================
+ Hits          89569    89714     +145     
- Misses       201616   202777    +1161     
- Partials       9230     9275      +45     

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[Copilot]

Pull request overview

This PR implements Battle Value (BV) calculation for TO:AR Advanced Buildings by creating a new AbstractBuildingEntityBVCalculator class and updating BuildingEntity to return a non-zero generic BV. The primary motivation is to fix an infinite loop that occurred when generic BV was 0 during scenario creation.

Key Changes:

• New AbstractBuildingEntityBVCalculator implementing TO:AUE rules for structure BV calculation (Defensive BV = (Armor × 2.5 + CF × 1.5) × 0.5; Offensive BV = (Weapon BV + Hex Count × 50) × Speed Factor)
• BuildingEntity.getGenericBattleValue() now returns calculateBattleValue() instead of 0
• BVCalculator factory updated to route AbstractBuildingEntity instances to the new calculator

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
AbstractBuildingEntityBVCalculator.java	New BV calculator implementing TO:AUE structure-specific rules with custom armor, structure, and weight processing
BuildingEntity.java	Changed getGenericBattleValue() to return calculated BV instead of 0 to prevent infinite loops
BVCalculator.java	Added instanceof check to route AbstractBuildingEntity to new calculator before fallback to CombatVehicleBVCalculator
BuildingEntityTest.java	Updated test expectation to match new behavior where generic BV equals calculated BV

Critical Issues Found in New AbstractBuildingEntityBVCalculator (Cannot comment directly on new files):

The new AbstractBuildingEntityBVCalculator has two critical bugs that will cause incorrect BV calculations for multi-hex buildings:

1. Line 68: processArmor() uses entity.getOArmor(0) which only retrieves armor from location 0. Buildings can span multiple hexes with different armor values per location. This will significantly undercount total armor for multi-hex buildings. Should use entity.getTotalOArmor() instead to sum armor across all locations.

2. Lines 82-84: processStructure() retrieves CF from only the first hex: building.getCoordsList().get(0) and then building.getCurrentCF(firstHex). For multi-hex buildings, this only accounts for one hex's construction factor. Should use entity.getTotalOInternal() to sum CF across all locations.

These bugs mean that any building spanning more than one hex will have drastically undercounted defensive BV, making them appear much weaker than they should be for game balance purposes.

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[psikomonkie]

Critical Issues Found in New AbstractBuildingEntityBVCalculator (Cannot comment directly on new files):

The new AbstractBuildingEntityBVCalculator has two critical bugs that will cause incorrect BV calculations for multi-hex buildings:

1. **Line 68**: `processArmor()` uses `entity.getOArmor(0)` which only retrieves armor from location 0. Buildings can span multiple hexes with different armor values per location. This will significantly undercount total armor for multi-hex buildings. Should use `entity.getTotalOArmor()` instead to sum armor across all locations.

2. **Lines 82-84**: `processStructure()` retrieves CF from only the first hex: `building.getCoordsList().get(0)` and then `building.getCurrentCF(firstHex)`. For multi-hex buildings, this only accounts for one hex's construction factor. Should use `entity.getTotalOInternal()` to sum CF across all locations.

These bugs mean that any building spanning more than one hex will have drastically undercounted defensive BV, making them appear much weaker than they should be for game balance purposes.

The "critical issue" here is incorrect. The CF & Armor value are not scaled per hex, the hex scaling is handled elsewhere.

[Sleet01]

LGTM