landsandboat/scripts/utils/combat_utils.lua

---@class utils
utils = utils or {}

-- A mechanic that will occasionaly reduce shadows consumed when hit by an AOE skill.
---@nodiscard
---@param actor CBaseEntity
---@param attemptedRemovals integer
---@return integer
function utils.attemptShadowMitigation(actor, attemptedRemovals)
    if attemptedRemovals <= 0 then
        return 0
    end

    -- TODO: Does this mechanic work on players who are not NIN main or sub? If so remove NIN requirement.
    -- See Yagyu Darkblade: https://www.bg-wiki.com/ffxi/Yagyu_Darkblade
    local isNIN       = actor:getMainJob() == xi.job.NIN or actor:getSubJob() == xi.job.NIN
    local hasUtsusemi = actor:getMod(xi.mod.UTSUSEMI) > 0

    if
        not isNIN or
        not hasUtsusemi -- Only works with Utsusemi
    then
        return 0
    end

    -- TODO: Currently unknown exactly what stats affect procChance and by how much. SE mentions Ninjutsu Skill affects this to some degree.
    -- Note: 50% was calculated from data with a relatively low Ninjutsu skill (Between 50-110~ skill range vs Lv. 75+ Targets) so this will likely lean on the conservative side (Weighted against players).
    local procChance = 50

    local mitigated  = 0

    -- Through research, a skill's shadowBehavior acts as a counter for how many shadow mitigation attempts are made(attemptedRemovals).
    -- Example: An AoE skill that takes 4 shadows will attempt the mitgation step below 4 times. A shadow will only be mitigated if it passes the proc chance check.
    for i = 1, attemptedRemovals do
        if math.random(1, 100) <= procChance then
            mitigated = mitigated + 1
        end
    end

    local maxMitigatable = attemptedRemovals - 1

    return math.min(mitigated, maxMitigatable)
end

-- TODO: Marked for retirement. See: utils.shadowAbsorb() below.
--       Some abilities and skills still use this but will need to be slightly reworked to use utils.shadowAbsorb().
-- Calculate shadow consumption/damage absorbtion.
---@param actor CBaseEntity
---@param damage integer
---@param shadowsToRemove integer?
---@return integer damage
---@return integer shadowsUsed
function utils.takeShadows(actor, damage, shadowsToRemove)
    shadowsToRemove = shadowsToRemove or 1

    -- Check for Utsusemi first, then Blink.
    local shadowPower = actor:getMod(xi.mod.UTSUSEMI)
    local shadowType  = xi.mod.UTSUSEMI

    if shadowPower == 0 then
        shadowPower = actor:getMod(xi.mod.BLINK)
        shadowType  = xi.mod.BLINK
    end

    -- No shadows, return full damage
    if shadowPower == 0 then
        return damage, 0
    end

    local shadowsRemaining = shadowPower
    local shadowsUsed      = 0

    -- Handle Blink shadow removal
    if shadowType == xi.mod.BLINK then
        for _ = 1, shadowsToRemove do
            if shadowsRemaining > 0 and math.random(1, 100) <= 80 then
                shadowsRemaining = shadowsRemaining - 1
                shadowsUsed      = shadowsUsed + 1
            end
        end

        if shadowsUsed >= shadowsToRemove then
            damage = 0
        else
            damage = damage * ((shadowsToRemove - shadowsUsed) / shadowsToRemove)
        end
    else
        -- Handle Utsusemi removal
        if shadowPower >= shadowsToRemove then
            shadowsRemaining = shadowPower - shadowsToRemove
            shadowsUsed      = shadowsToRemove
            damage           = 0

            -- Update remaining Copy Image icon
            if shadowsRemaining > 0 then
                local effect = actor:getStatusEffect(xi.effect.COPY_IMAGE)
                if effect then
                    local iconMap =
                    {
                        [1] = xi.effect.COPY_IMAGE,
                        [2] = xi.effect.COPY_IMAGE_2,
                        [3] = xi.effect.COPY_IMAGE_3,
                        -- Note: 4+ use the same icon.
                    }

                    effect:setIcon(iconMap[shadowsRemaining] or xi.effect.COPY_IMAGE_4)
                end
            end
        else
            -- Partial shadow consumption, take damage.
            shadowsUsed      = shadowPower
            damage           = damage * ((shadowsToRemove - shadowPower) / shadowsToRemove)
            shadowsRemaining = 0
        end
    end

    actor:setMod(shadowType, shadowsRemaining)

    if shadowsRemaining <= 0 then
        actor:delStatusEffect(xi.effect.COPY_IMAGE)
        actor:delStatusEffect(xi.effect.BLINK)
    end

    return damage, shadowsUsed
end

-- Calculate shadow consumption
---@param target CBaseEntity
---@param shadowsToRemove number
---@return boolean, number
function utils.shadowAbsorb(target, shadowsToRemove)
    local utsusemiMod = target:getMod(xi.mod.UTSUSEMI)
    local blinkMod    = target:getMod(xi.mod.BLINK)

    -- Early return: Target has no shadows.
    if
        utsusemiMod == 0 and
        blinkMod == 0
    then
        return false, 0
    end

    local targetShadows   = 0
    local shadowsConsumed = 0
    local absorbHit       = false

    -- Utsusemi takes precedence over blink.
    if utsusemiMod > 0 then
        shadowsConsumed = utils.clamp(shadowsToRemove, 0, utsusemiMod) -- How many shadows were consumed (Used for SHADOW_ABSORB messaging later).
        targetShadows   = utsusemiMod - shadowsConsumed                -- How many shadows left after the attack.
        absorbHit       = utsusemiMod >= shadowsToRemove               -- Check to see if the target had enough shadows to block the attack.

        local effect = target:getStatusEffect(xi.effect.COPY_IMAGE)
        if effect then
            if targetShadows == 0 then
                target:delStatusEffect(xi.effect.COPY_IMAGE)
            elseif targetShadows == 1 then
                effect:setIcon(xi.effect.COPY_IMAGE)
            elseif targetShadows == 2 then
                effect:setIcon(xi.effect.COPY_IMAGE_2)
            elseif targetShadows == 3 then
                effect:setIcon(xi.effect.COPY_IMAGE_3)
            else
                effect:setIcon(xi.effect.COPY_IMAGE_4) -- 4 or more shadows active use the same "4+" icon.
            end
        end

        target:setMod(xi.mod.UTSUSEMI, targetShadows)

    -- Blink has a random chance of triggering when no utsusemi is present.
    elseif blinkMod > 0 then
        if math.random(1, 100) <= 20 then
            absorbHit = false

            return absorbHit, 0
        end

        shadowsConsumed = utils.clamp(shadowsToRemove, 0, blinkMod) -- How many shadows were consumed by the attack (Used for SHADOW_ABSORB messaging later)
        targetShadows   = blinkMod - shadowsConsumed                -- How many shadows left over after the attack.
        absorbHit       = blinkMod >= shadowsToRemove               -- Check to see if the target had enough shadows to fully block the attack.

        if targetShadows == 0 then
            target:delStatusEffect(xi.effect.BLINK)
        end

        target:setMod(xi.mod.BLINK, targetShadows)

        -- Retail Testing Notes:
        -- Tested with WHM spell Blink
        -- 1 hit skills took 1 shadow.
        -- TODO: When hit by a 2 hit skill, it was observed to consume 2 blink shadows, however the message returned was SKILL_MISS rather than SHADOW_ABSORB.
        -- Did not block 3+ hit mob skills. (Player Weaponskills untested)
        -- AOE skills delete Blink.

        -- TODO: Test Zephyr Mantle proc rate.
        -- TODO: Test player Weapon Skills on mob/players with Blink/Zephyr Mantle.
        -- Note: JPWiki/FFXIPedia repeatedly mentions that Blink can block multi hit skills, but this was not observed in testing. Needs further testing.
    end

    return absorbHit, shadowsConsumed
end

-- Calculates Phalanx damage reduction.
---@nodiscard
---@param actor CBaseEntity
---@param damage integer
---@return integer
function utils.handlePhalanx(actor, damage)
    if damage <= 0 then
        return damage
    end

    return utils.clamp(damage - actor:getMod(xi.mod.PHALANX), 0, 99999)
end

-- Returns reduced magic damage from RUN buff, 'One for All'
---@nodiscard
---@param actor CBaseEntity
---@param damage integer
---@return integer
function utils.handleOneForAll(actor, damage)
    if damage <= 0 then
        return damage
    end

    local oneForAllEffect = actor:getStatusEffect(xi.effect.ONE_FOR_ALL)
    if not oneForAllEffect then
        return damage
    end

    return utils.clamp(damage - oneForAllEffect:getPower(), 0, 99999)
end

-- Calculates Stoneskin damage reduction.
---@nodiscard
---@param actor CBaseEntity
---@param damage integer
---@return integer
function utils.handleStoneskin(actor, damage)
    if damage <= 0 then
        return damage
    end

    local stoneskinRemaining = actor:getMod(xi.mod.STONESKIN)
    if stoneskinRemaining <= 0 then
        return damage
    end

    -- Absorb all damage
    if stoneskinRemaining > damage then
        actor:delMod(xi.mod.STONESKIN, damage)

        return 0

    -- Wear off if mitigated damage exceeds stoneskin.
    else
        actor:delStatusEffect(xi.effect.STONESKIN)
        actor:setMod(xi.mod.STONESKIN, 0)

        return damage - stoneskinRemaining
    end
end

-- Handles Automaton attachment "Analyzer", which decreases damage from successive special attacks.
---@param actor CBaseEntity
---@param skill CPetSkill|CMobSkill
---@param damage integer
---@return integer
function utils.handleAutomatonAutoAnalyzer(actor, skill, damage)
    local analyzerModifier = actor:getMod(xi.mod.AUTO_ANALYZER)

    -- If no Analyzer equipped, return unmodified damage.
    if analyzerModifier <= 0 then
        return damage
    end

    local incomingSkill      = skill:getID()
    local analyzedSkillCount = math.min(analyzerModifier, 6)

    -- Check if the incoming skill matches any of the analyzed skills. If so, apply the damage reduction.
    for i = 1, analyzedSkillCount do
        if incomingSkill == actor:getLocalVar('analyzedSkill' .. i) then
            return math.floor(damage * 0.6)
        end
    end

    return damage
end