walls.lua

--[[-----------------------------------------
Name:        GetCivSpecificUnit
Purpose:     Get the UnitType for a specific
civ from a UnitClassType.
-------------------------------------------]]
function fnGetCivSpecificUnit(pPly, sUnitClass) -- Thanks whoward69

    -- BEGIN DEFINES
    local sUnitType = nil
    local sCivType = GameInfo.Civilizations[pPly:GetCivilizationType()].Type
    -- END DEFINES

    -- Loop through civilization-specific UnitClass overrides, id est their unique units, and yield to be returned the proper UnitType.
    for pOverride in GameInfo.Civilization_UnitClassOverrides{CivilizationType = sCivType, UnitClassType = sUnitClass} do
        sUnitType = pOverride.UnitType
        break
    end

    -- If we didn't get anything, yield to be returned the default UnitType for the UnitClass.
    if (sUnitType == nil) then
        sUnitType = GameInfo.UnitClasses[sUnitClass].DefaultUnit
    end

    -- Give whatever function called this the UnitType we yielded.
    return sUnitType
end

--[[-----------------------------------------
Name:       ReturnBestInfantryUnit
Purpose:    Return the best land melee unit
that a city can build.
-------------------------------------------]]
function fnReturnBestInfantryUnit( pCity )

    --BEGIN DEFINES
    local pPly = pCity:GetOwner()

    local possibleUnitClasses = {
    GameInfoTypes.UNITCLASS_MECH,
    GameInfoTypes.UNITCLASS_MECHANIZED_INFANTRY,
    GameInfoTypes.UNITCLASS_INFANTRY,
    GameInfotypes.UNITCLASS_GREAT_WAR_INFANTRY,
    GameInfoTypes.UNITCLASS_RIFLEMAN,
    GameInfoTypes.UNITCLASS_MUSKETMAN,
    GameInfoTypes.UNITCLASS_LONGSWORDSMAN,
    GameInfoTypes.UNITCLASS_PIKEMAN,
    GameInfoTypes.UNITCLASS_SWORDSMAN,
    GameInfoTypes.UNITCLASS_SPEARMAN,
    GameInfoTypes.UNITCLASS_WARRIOR
    } -- Thanks whoward69
    --END DEFINES

    -- Loop through each UnitClassType in the above defined table, see if the city can
    -- train it's owner's specific UnitType.  Yield to be returned the best land melee
    -- UnitType the city can build.
    for _, iUnitClass in ipairs(possibleUnitClasses) do -- Thanks whoward69
        if pCity:CanTrain( fn_GetCivSpecificUnit( pPly, iUnitClass ) ) then
            return fn_GetCivSpecificUnit( pPly, iUnitClass )
        end
    end

    -- Uh-oh!
    return -1
end

GameEvents.SetPopulation.Add( function( xOffset, yOffset, fOldPop, fNewPop )

    -- BEGIN DEFINES
    local pPlot             = Map.GetPlot( xOffset, yOffset )
    local pCity             = pPlot:GetPlotCity()
    local pPly              = pCity:GetOwner()
    local iUnitMostCurrent  = nil
    local nTrait            = GameInfo.Traits[pPly].UnitPerCapitalGrowths
    local sUnitAIType       = GameInfo.UnitAITypes.UNITAI_DEFENSE.ID
    local nZenith           = math.floor( pCity:GetHighestPopulation() )
    -- END DEFINES

    -- On every growth of every city, run through the following list of conditions:
    -- 1:  Does the city's owner have the trait, and is its population evenly divisible by the trait?
    -- 2:  Is the city a capital?
    -- 3:  Has the city grown instead of shrinking, and is this the city's highest population?
    -- If all of the above are true, get the best land infantry unit we can, and spawn it at the city.
    if ( nTrait > 0 &&
    ( math.floor( fNewPop ) % nTrait ) == 0 ) && then
        if pCity:IsCapital() then
            if ( fNewPop > fOldPop ) &&
            fNewPop >= nZenith then
                iFreeUnit = fnReturnBestInfantryUnit( pCity )

                pPly:AddFreeUnit( iFreeUnit, iUnitAIType ) -- What are the implications of this line?
            end
        end
    end
end )