package input

import "github.com/alpacahq/alpacadecimal"

type shieldChangeEffect interface {
	ShieldChange(before, after alpacadecimal.Decimal) bool
}

func (our *Input) CurrentShield() alpacadecimal.Decimal {
	currentPet := our.PrimaryCurPet()
	if currentPet == nil {
		return alpacadecimal.Zero
	}
	return currentPet.Shield
}

func (our *Input) HasShield() bool {
	return our.CurrentShield().Cmp(alpacadecimal.Zero) > 0
}

func (our *Input) AddShield(value alpacadecimal.Decimal) bool {
	currentPet := our.PrimaryCurPet()
	if currentPet == nil {
		return false
	}
	if value.Cmp(alpacadecimal.Zero) <= 0 {
		return false
	}
	before := currentPet.Shield
	currentPet.Shield = currentPet.Shield.Add(value)
	our.notifyShieldChange(before, currentPet.Shield)
	return true
}

func (our *Input) AbsorbShieldDamage(damage alpacadecimal.Decimal) alpacadecimal.Decimal {
	currentPet := our.PrimaryCurPet()
	if currentPet == nil {
		return alpacadecimal.Zero
	}
	if damage.Cmp(alpacadecimal.Zero) <= 0 || currentPet.Shield.Cmp(alpacadecimal.Zero) <= 0 {
		return alpacadecimal.Zero
	}

	before := currentPet.Shield
	absorbed := alpacadecimal.Min(currentPet.Shield, damage)
	currentPet.Shield = currentPet.Shield.Sub(absorbed)
	if currentPet.Shield.Cmp(alpacadecimal.Zero) < 0 {
		currentPet.Shield = alpacadecimal.Zero
	}
	our.notifyShieldChange(before, currentPet.Shield)
	return absorbed
}

func (our *Input) ConsumeAllShield() alpacadecimal.Decimal {
	currentPet := our.PrimaryCurPet()
	if currentPet == nil {
		return alpacadecimal.Zero
	}

	before := currentPet.Shield
	value := currentPet.Shield
	currentPet.Shield = alpacadecimal.Zero
	our.notifyShieldChange(before, currentPet.Shield)
	return value
}

func (our *Input) notifyShieldChange(before, after alpacadecimal.Decimal) {
	if our == nil || before.Cmp(after) == 0 {
		return
	}

	for _, effect := range our.Effects {
		if effect == nil || !effect.Alive() {
			continue
		}
		hook, ok := effect.(shieldChangeEffect)
		if !ok {
			continue
		}

		effect.Ctx().Our = our
		effect.Ctx().Opp = our.Opp
		hook.ShieldChange(before, after)
	}
}