Detectable Damaging Aura

scope Ability initializer init

    //========================================
    // You will need to make ABIL_ID and 
    // BUFF_ID the rawcodes to your aura's
    // ability ID and the associated buff ID.
    // It may still have some bugs, so PM me
    // if there are any kinks.

    globals
        private constant integer     ABIL_ID        = 'A000'
        private constant integer     BUFF_ID        = 'B000'

        private constant real         DAMAGE_INTERVAL        = 1.0
        private constant real         AURA_RANGE        = 350.0
        private constant real        PERCENT_PER_LEVEL    = 0.02
    endglobals

    private struct Data
        unit hero        = null
        integer level

        private timer t        = CreateTimer()
        private trigger    onDeath    = CreateTrigger()
    
        method start takes nothing returns nothing
            call TimerStart(.t, DAMAGE_INTERVAL, true, function Data.Loop)
        endmethod

        method stop takes nothing returns nothing
            call PauseTimer(.t)
        endmethod

        static method Loop takes nothing returns nothing
            local Data data = 1

            local group gEnum = CreateGroup()
            local unit uEnum

            local real damage

            loop
                exitwhen data.t == GetExpiredTimer()
                set data = data + 1
            endloop
            
            call GroupEnumUnitsInRange(gEnum, GetUnitX(data.hero), GetUnitY(data.hero), AURA_RANGE, null)
            loop
                set uEnum = FirstOfGroup(gEnum)
                exitwhen uEnum == null
                if GetUnitAbilityLevel(uEnum, BUFF_ID) > 0.0 then
                    set damage = (data.level * PERCENT_PER_LEVEL) * GetUnitState(uEnum, UNIT_STATE_MAX_LIFE)
                    call UnitDamageTarget(data.hero, uEnum, damage, false, false, ATTACK_TYPE_SPELL, DAMAGE_TYPE_NORMAL, null)
                    call DestroyEffect(AddSpecialEffect(GetAbilityEffect(ABIL_ID, EFFECT_TYPE_SPECIAL, 0), uEnum, "origin"))
                endif
                call GroupRemoveUnit(gEnum, uEnum)
            endloop
            call DestroyGroup(gEnum)
            set gEnum = null
            set uEnum = null
        endmethod
            
        static method OnDeath takes nothing returns nothing
            local Data data = 1
            loop
                exitwhen data.onDeath == GetTriggeringTrigger()
                set data = data + 1
            endloop
            call data.stop()
        endmethod

        static method create takes unit hero, integer level returns Data
            local Data data = Data.allocate()
            set data.hero = hero
            set data.level = level

            call TriggerRegisterUnitEvent(data.onDeath, hero, EVENT_UNIT_DEATH)
            call TriggerAddAction(data.onDeath, function Data.OnDeath)

            call TimerStart(data.t, DAMAGE_INTERVAL, true, function Data.Loop)
            return data
        endmethod

        method onDestroy takes nothing returns nothing
            call PauseTimer(.t)
            call DestroyTimer(.t)
            set .hero = null    // So that the hero is recycled if the struct is destroyed.
        endmethod
    endstruct

    private function filter takes nothing returns nothing
        return GetSpellAbilityId()==ABIL_ID
    endfunction

    private function main takes nothing returns nothing
        local unit caster = GetTriggerUnit()
        local Data data    = 1

        loop
            exitwhen data.hero == null
            exitwhen data.hero == caster
            set data = data + 1
        endloop
        
        if data.hero == caster then
            call data.destroy()
        endif
        call data.create(caster, GetUnitAbilityLevel(caster, ABIL_ID))
        set caster = null
    endfunction

    private function check takes nothing returns boolean
        local Data data = 1
        loop
            exitwhen data.hero == GetTriggerUnit()
            exitwhen data.hero == null
            set data = data + 1
        endloop
        return data.hero == GetTriggerUnit()
    endfunction

    private function OnEnter takes nothing returns nothing
        local Data data = 1
        loop
            exitwhen data.hero == GetTriggerUnit()
            set data = data + 1
        endloop
        call data.start()
    endfunction

    private function init takes nothing returns nothing
        local trigger t = CreateTrigger()
        local integer i = 0

        local trigger onEnter = CreateTrigger()
        local region regMap = CreateRegion()

        loop
            exitwhen i == 12
            call TriggerRegisterPlayerUnitEvent(t, Player(i), EVENT_PLAYER_HERO_LEARN, null)
            set i = i + 1
        endloop
        call TriggerAddCondition(t, Filter(function filter))
        call TriggerAddAction(t, function main)

        call RegionAddRect(regMap, GetWorldBounds())
        call TriggerRegisterEnterRegion(onEnter, regMap, null)
        call TriggerAddCondition(onEnter, Filter(function check))
        call TriggerAddAction(onEnter, function OnEnter)
    endfunction

endscope