--[[-----------------------------------------
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 )