landsandboat/scripts/combat/basic/damage_multipliers.lua

-----------------------------------
xi = xi or {}
xi.combat = xi.combat or {}
xi.combat.damage = xi.combat.damage or {}
-----------------------------------

xi.combat.damage.physicalElementSDT = function(target, physicalElement)
    if
        physicalElement < xi.damageType.PIERCING or
        physicalElement > xi.damageType.HAND_TO_HAND
    then
        return 1
    end

    local physicalElementSDTModifier =
    {
        [xi.damageType.PIERCING    ] = xi.mod.PIERCE_SDT,
        [xi.damageType.SLASHING    ] = xi.mod.SLASH_SDT,
        [xi.damageType.BLUNT       ] = xi.mod.IMPACT_SDT,
        [xi.damageType.HAND_TO_HAND] = xi.mod.HTH_SDT,
    }

    local sdt = 1 + target:getMod(physicalElementSDTModifier[physicalElement]) / 10000

    return utils.clamp(sdt, 0, 3)
end

xi.combat.damage.magicalElementSDT = function(target, magicalElement)
    if magicalElement < xi.element.FIRE then
        return 1
    end

    if magicalElement > xi.element.DARK then
        return 1
    end

    local sdt = 1 + target:getMod(xi.data.element.getElementalSDTModifier(magicalElement)) / 10000

    return utils.clamp(sdt, 0, 3)
end

xi.combat.damage.calculateDamageAdjustment = function(target, isPhysical, isMagical, isRanged, isBreath)
    -- NOTE: -2500 -> 25% less damage taken by target. 2500 -> 25% more damage taken  by target.
    local targetDamageTaken = 1

    -- "Damage Taken -x%"
    local globalDamageTaken           = target:getMod(xi.mod.DMG) / 10000

    -- "Physical Damage Taken -X%", "Physical Damage Taken II -X%"
    local physicalDamageTaken         = isPhysical and target:getMod(xi.mod.DMGPHYS) / 10000 or 0
    local physicalDamageTakenII       = isPhysical and target:getMod(xi.mod.DMGPHYS_II) / 10000 or 0
    local physicalDamageTakenUncapped = isPhysical and target:getMod(xi.mod.UDMGPHYS) / 10000 or 0

    -- "Magic Damage Taken -X%", "Magic Damage Taken II -X%"
    local magicDamageTaken            = isMagical and target:getMod(xi.mod.DMGMAGIC) / 10000 or 0
    local magicDamageTakenII          = isMagical and target:getMod(xi.mod.DMGMAGIC_II) / 10000 or 0
    local magicDamageTakenUncapped    = isMagical and target:getMod(xi.mod.UDMGMAGIC) / 10000 or 0

    -- "Ranged Damage Taken -X%" (Doesn't actually exist in gear. Physical damage taken has both.)
    local rangedDamageTaken           = isRanged and target:getMod(xi.mod.DMGRANGE) / 10000 or 0
    local rangedDamageTakenUncapped   = isRanged and target:getMod(xi.mod.UDMGRANGE) / 10000 or 0

    -- "Breath Damage Taken -X%"
    local breathDamageTaken           = isBreath and target:getMod(xi.mod.DMGBREATH) / 10000 or 0
    local breathDamageTakenUncapped   = isBreath and target:getMod(xi.mod.UDMGBREATH) / 10000 or 0

     -- The combination of regular "Damage Taken" and "<type> Damage Taken" caps at 50% both ways.
    local combinedDamageTaken = utils.clamp(globalDamageTaken + physicalDamageTaken + magicDamageTaken + rangedDamageTaken + breathDamageTaken, -0.5, 0.5)

    -- "<type> Damage Taken II" bypasses the regular cap, but combined cap is 87.5% both ways.
    targetDamageTaken = utils.clamp(targetDamageTaken + combinedDamageTaken + physicalDamageTakenII + magicDamageTakenII, 0.125, 1.875)

     -- Uncapped damage modifiers. Cap is 100% both ways anyway, just in case.
    targetDamageTaken = utils.clamp(targetDamageTaken + physicalDamageTakenUncapped + magicDamageTakenUncapped + rangedDamageTakenUncapped + breathDamageTakenUncapped, 0, 2)

    return targetDamageTaken
end

xi.combat.damage.ecosystemMultiplier = function(actor, target, actionEcosystem)
    local ecosystemMultiplier = 1
    local actorEcosystem      = actor:getEcosystem()
    local targetEcosystem     = target:getEcosystem()
    local actorNMFactor       = actor:isNM() and 1 or 0
    local targetNMFactor      = target:isNM() and 1 or 0

    -- Killer effects can be augmented to apply damage bonuses. (Ex: Ferine, Nukumi Gausapes or Founder's Breastplate)
    local actorKillerMod    = xi.data.entityCorrelation.getEcosystemKillerMod(actorEcosystem)
    local targetKillerMod   = xi.data.entityCorrelation.getEcosystemKillerMod(targetEcosystem)
    local actorKillerBonus  = actor:getMod(targetKillerMod) * (actor:getMod(xi.mod.AUGMENT_KILLER_EFFECTS) / (1 + targetNMFactor)) / 100
    local targetKillerBonus = target:getMod(actorKillerMod) * (target:getMod(xi.mod.AUGMENT_KILLER_EFFECTS) / (1 + actorNMFactor)) / 100

    ecosystemMultiplier = ecosystemMultiplier + math.floor(actorKillerBonus) / 100 - math.floor(targetKillerBonus) / 100

    -- Circles apply an additive damage multiplier and also a damage reduction.
    local damageMultiplierMod   = xi.data.entityCorrelation.getEcosystemDamageMultiplierMod(targetEcosystem)
    local damageResistanceMod   = xi.data.entityCorrelation.getEcosystemDamageReductionMod(actorEcosystem)
    local damageMultiplierValue = actor:getMod(damageMultiplierMod) / (1 + targetNMFactor)
    local damageResistanceValue = target:getMod(damageResistanceMod) / (1 + actorNMFactor)

    ecosystemMultiplier = ecosystemMultiplier + math.floor(damageMultiplierValue) / 100 - math.floor(damageResistanceValue) / 100

    -- Action ecosystem property. Mostly blue spells. Can be positive or negative. Additive to everything else, not multiplicative.
    if actionEcosystem > 0 then
        local strongAgainstEco = xi.data.entityCorrelation.getEcosystemStrongAgainst(actionEcosystem)
        local weakAgainstEco   = xi.data.entityCorrelation.getEcosystemWeakAgainst(actionEcosystem)

        -- This action property is strong against target's ecosystem.
        if strongAgainstEco and strongAgainstEco == targetEcosystem then
            ecosystemMultiplier = ecosystemMultiplier + 0.25 + actor:getMerit(xi.merit.MONSTER_CORRELATION) / 100

        -- This action property is weak against target's ecosystem.
        elseif weakAgainstEco and weakAgainstEco == targetEcosystem then
            ecosystemMultiplier = ecosystemMultiplier - 0.25
        end
    end

    -- Final multiplier caps. TODO: confirm.
    ecosystemMultiplier = utils.clamp(ecosystemMultiplier, 0.5, 1.5)

    return ecosystemMultiplier
end

xi.combat.damage.scarletDeliriumMultiplier = function(actor)
    -- Scarlet delirium are 2 different status effects. SCARLET_DELIRIUM_1 is the one that boosts power.
    if not actor:hasStatusEffect(xi.effect.SCARLET_DELIRIUM_1) then
        return 1
    end

    local scarletDeliriumMultiplier = 1 + actor:getStatusEffect(xi.effect.SCARLET_DELIRIUM_1):getPower() / 1000

    return scarletDeliriumMultiplier
end

-- Handles Automaton attachment "Steam Jacket", which reduces damage from consecutive elemental damage.
xi.combat.damage.steamJacketMultiplier = function(target, magicalElement)
    -- Early return: Action isn't elemental.
    if magicalElement < xi.element.FIRE then
        return 1
    end

    -- Early return: Action isn't elemental.
    if magicalElement > xi.element.DARK then
        return 1
    end

    -- Early return: Target can't track an element.
    local steamJacketModifierValue = target:getMod(xi.mod.AUTO_STEAM_JACKET_REDUCTION)
    if steamJacketModifierValue <= 0 then
        return 1
    end

    -- Handle element tracking.
    local trackedElement = target:getLocalVar('[steamJacket]Element')
    target:setLocalVar('[steamJacket]Element', magicalElement)

    -- Early return: Action element doesn't match Steam Jacket's element.
    if trackedElement ~= magicalElement then
        return 1
    end

    return 1 - steamJacketModifierValue / 100
end