path: root/src/engine/duel/ai/pkmn_powers.asm

; handle AI routines for Energy Trans.
; uses AI_ENERGY_TRANS_* constants as input:
;	- AI_ENERGY_TRANS_RETREAT: transfers enough Grass Energy cards to
;	Arena Pokemon for it to be able to pay the Retreat Cost;
;	- AI_ENERGY_TRANS_ATTACK: transfers enough Grass Energy cards to
;	Arena Pokemon for it to be able to use its second attack;
;	- AI_ENERGY_TRANS_TO_BENCH: transfers all Grass Energy cards from
;	Arena Pokemon to Bench in case Arena card will be KO'd.
HandleAIEnergyTrans:
	ld [wce06], a

; choose to randomly return
	farcall AIChooseRandomlyNotToDoAction
	ret c

	ld a, DUELVARS_NUMBER_OF_POKEMON_IN_PLAY_AREA
	call GetTurnDuelistVariable
	dec a
	ret z ; return if no Bench cards

	ld a, VENUSAUR2
	call CountPokemonIDInPlayArea
	ret nc ; return if no Venusaur2 found in own Play Area

	ld a, MUK
	call CountPokemonIDInBothPlayAreas
	ret c ; return if Muk found in any Play Area

	ld a, [wce06]
	cp AI_ENERGY_TRANS_RETREAT
	jr z, .check_retreat

	cp AI_ENERGY_TRANS_TO_BENCH
	jp z, AIEnergyTransTransferEnergyToBench

	; AI_ENERGY_TRANS_ATTACK
	call .CheckEnoughGrassEnergyCardsForAttack
	ret nc
	jr .TransferEnergyToArena

.check_retreat
	call .CheckEnoughGrassEnergyCardsForRetreatCost
	ret nc

; use Energy Trans to transfer number of Grass energy cards
; equal to input a from the Bench to the Arena card.
.TransferEnergyToArena
	ld [wAINumberOfEnergyTransCards], a

; look for Venusaur2 in Play Area
; so that its PKMN Power can be used.
	ld a, DUELVARS_NUMBER_OF_POKEMON_IN_PLAY_AREA
	call GetTurnDuelistVariable
	dec a
	ld b, a
.loop_play_area
	ld a, DUELVARS_ARENA_CARD
	add b
	call GetTurnDuelistVariable
	ldh [hTempCardIndex_ff9f], a
	call GetCardIDFromDeckIndex
	ld a, e
	cp VENUSAUR2
	jr z, .use_pkmn_power

	ld a, b
	or a
	ret z ; return when finished Play Area loop

	dec b
	jr .loop_play_area

; use Energy Trans Pkmn Power
.use_pkmn_power
	ld a, b
	ldh [hTemp_ffa0], a
	ld a, OPPACTION_USE_PKMN_POWER
	bank1call AIMakeDecision
	ld a, OPPACTION_EXECUTE_PKMN_POWER_EFFECT
	bank1call AIMakeDecision

	xor a ; PLAY_AREA_ARENA
	ldh [hAIEnergyTransPlayAreaLocation], a
	ld a, [wAINumberOfEnergyTransCards]
	ld d, a

; look for Grass energy cards that
; are currently attached to a Bench card.
	ld e, 0
.loop_deck_locations
	ld a, DUELVARS_CARD_LOCATIONS
	add e
	call GetTurnDuelistVariable
	and %00011111
	cp CARD_LOCATION_BENCH_1
	jr c, .next_card

	and %00001111
	ldh [hTempPlayAreaLocation_ffa1], a

	ld a, e
	push de
	call GetCardIDFromDeckIndex
	ld a, e
	pop de
	cp GRASS_ENERGY
	jr nz, .next_card

	; store the deck index of energy card
	ld a, e
	ldh [hAIEnergyTransEnergyCard], a

	push de
	ld d, 30
.small_delay_loop
	call DoFrame
	dec d
	jr nz, .small_delay_loop

	ld a, OPPACTION_6B15
	bank1call AIMakeDecision
	pop de
	dec d
	jr z, .done_transfer

.next_card
	inc e
	ld a, DECK_SIZE
	cp e
	jr nz, .loop_deck_locations

; transfer is done, perform delay
; and return to main scene.
.done_transfer
	ld d, 60
.big_delay_loop
	call DoFrame
	dec d
	jr nz, .big_delay_loop
	ld a, OPPACTION_DUEL_MAIN_SCENE
	bank1call AIMakeDecision
	ret

; checks if the Arena card needs energy for its second attack,
; and if it does, return carry if transferring Grass energy from Bench
; would be enough to use it. Outputs number of energy cards needed in a.
.CheckEnoughGrassEnergyCardsForAttack ; 22246 (8:6246)
	ld a, DUELVARS_ARENA_CARD
	call GetTurnDuelistVariable
	call GetCardIDFromDeckIndex
	ld a, e
	cp EXEGGUTOR
	jr z, .is_exeggutor

	xor a ; PLAY_AREA_ARENA
	ldh [hTempPlayAreaLocation_ff9d], a
	ld a, SECOND_ATTACK
	ld [wSelectedAttack], a
	farcall CheckEnergyNeededForAttack
	jr nc, .attack_false ; return if no energy needed

; check if colorless energy is needed...
	ld a, c
	or a
	jr nz, .count_if_enough

; ...otherwise check if basic energy card is needed
; and it's grass energy.
	ld a, b
	or a
	jr z, .attack_false
	ld a, e
	cp GRASS_ENERGY
	jr nz, .attack_false
	ld c, b
	jr .count_if_enough

.attack_false
	or a
	ret

.count_if_enough
; if there's enough Grass energy cards in Bench
; to satisfy the attack energy cost, return carry.
	push bc
	call .CountGrassEnergyInBench
	pop bc
	cp c
	jr c, .attack_false
	ld a, c
	scf
	ret

.is_exeggutor
; in case it's Exeggutor in Arena, return carry
; if there are any Grass energy cards in Bench.
	call .CountGrassEnergyInBench
	or a
	jr z, .attack_false

	scf
	ret

; outputs in a the number of Grass energy cards
; currently attached to Bench cards.
.CountGrassEnergyInBench ; 22286 (8:6286)
	lb de, 0, 0
.count_loop
	ld a, DUELVARS_CARD_LOCATIONS
	add e
	call GetTurnDuelistVariable
	and %00011111
	cp CARD_LOCATION_BENCH_1
	jr c, .count_next

; is in bench
	ld a, e
	push de
	call GetCardIDFromDeckIndex
	ld a, e
	pop de
	cp GRASS_ENERGY
	jr nz, .count_next
	inc d
.count_next
	inc e
	ld a, DECK_SIZE
	cp e
	jr nz, .count_loop
	ld a, d
	ret

; returns carry if there are enough Grass energy cards in Bench
; to satisfy the retreat cost of the Arena card.
; if so, output the number of energy cards still needed in a.
.CheckEnoughGrassEnergyCardsForRetreatCost ; 222a9 (8:62a9)
	xor a ; PLAY_AREA_ARENA
	ldh [hTempPlayAreaLocation_ff9d], a
	call GetPlayAreaCardRetreatCost
	ld b, a
	ld e, PLAY_AREA_ARENA
	farcall CountNumberOfEnergyCardsAttached
	cp b
	jr nc, .retreat_false ; return if enough to retreat

; see if there's enough Grass energy cards
; in the Bench to satisfy retreat cost
	ld c, a
	ld a, b
	sub c
	ld c, a
	push bc
	call .CountGrassEnergyInBench
	pop bc
	cp c
	jr c, .retreat_false ; return if less cards than needed

; output number of cards needed to retreat
	ld a, c
	scf
	ret
.retreat_false
	or a
	ret

; AI logic to determine whether to use Energy Trans Pkmn Power
; to transfer energy cards attached from the Arena Pokemon to
; some card in the Bench.
AIEnergyTransTransferEnergyToBench:
	xor a ; PLAY_AREA_ARENA
	ldh [hTempPlayAreaLocation_ff9d], a
	farcall CheckIfDefendingPokemonCanKnockOut
	ret nc ; return if Defending can't KO

; processes attacks and see if any attack would be used by AI.
; if so, return.
	farcall AIProcessButDontUseAttack
	ret c

; return if Arena card has no Grass energy cards attached.
	ld e, PLAY_AREA_ARENA
	call GetPlayAreaCardAttachedEnergies
	ld a, [wAttachedEnergies + GRASS]
	or a
	ret z

; if no energy card attachment is needed, return.
	farcall AIProcessButDontPlayEnergy_SkipEvolutionAndArena
	ret nc

; AI decided that an energy card is needed
; so look for Venusaur2 in Play Area
; so that its PKMN Power can be used.
	ld a, DUELVARS_NUMBER_OF_POKEMON_IN_PLAY_AREA
	call GetTurnDuelistVariable
	dec a
	ld b, a
.loop_play_area
	ld a, DUELVARS_ARENA_CARD
	add b
	call GetTurnDuelistVariable
	ldh [hTempCardIndex_ff9f], a
	ld [wAIVenusaur2DeckIndex], a
	call GetCardIDFromDeckIndex
	ld a, e
	cp VENUSAUR2
	jr z, .use_pkmn_power

	ld a, b
	or a
	ret z ; return when Play Area loop is ended

	dec b
	jr .loop_play_area

; use Energy Trans Pkmn Power
.use_pkmn_power
	ld a, b
	ldh [hTemp_ffa0], a
	ld [wAIVenusaur2PlayAreaLocation], a
	ld a, OPPACTION_USE_PKMN_POWER
	bank1call AIMakeDecision
	ld a, OPPACTION_EXECUTE_PKMN_POWER_EFFECT
	bank1call AIMakeDecision

; loop for each energy cards that are going to be transferred.
.loop_energy
	xor a
	ldh [hTempPlayAreaLocation_ffa1], a
	ld a, [wAIVenusaur2PlayAreaLocation]
	ldh [hTemp_ffa0], a

	; returns when Arena card has no Grass energy cards attached.
	ld e, PLAY_AREA_ARENA
	call GetPlayAreaCardAttachedEnergies
	ld a, [wAttachedEnergies + GRASS]
	or a
	jr z, .done_transfer

; look for Grass energy cards that
; are currently attached to Arena card.
	ld e, 0
.loop_deck_locations
	ld a, DUELVARS_CARD_LOCATIONS
	add e
	call GetTurnDuelistVariable
	cp CARD_LOCATION_ARENA
	jr nz, .next_card

	ld a, e
	push de
	call GetCardIDFromDeckIndex
	ld a, e
	pop de
	cp GRASS_ENERGY
	jr nz, .next_card

	; store the deck index of energy card
	ld a, e
	ldh [hAIEnergyTransEnergyCard], a
	jr .transfer

.next_card
	inc e
	ld a, DECK_SIZE
	cp e
	jr nz, .loop_deck_locations
	jr .done_transfer

.transfer
; get the Bench card location to transfer Grass energy card to.
	farcall AIProcessButDontPlayEnergy_SkipEvolutionAndArena
	jr nc, .done_transfer
	ldh a, [hTempPlayAreaLocation_ff9d]
	ldh [hAIEnergyTransPlayAreaLocation], a

	ld d, 30
.small_delay_loop
	call DoFrame
	dec d
	jr nz, .small_delay_loop

	ld a, [wAIVenusaur2DeckIndex]
	ldh [hTempCardIndex_ff9f], a
	ld d, a
	ld e, FIRST_ATTACK_OR_PKMN_POWER
	call CopyAttackDataAndDamage_FromDeckIndex
	ld a, OPPACTION_6B15
	bank1call AIMakeDecision
	jr .loop_energy

; transfer is done, perform delay
; and return to main scene.
.done_transfer
	ld d, 60
.big_delay_loop
	call DoFrame
	dec d
	jr nz, .big_delay_loop
	ld a, OPPACTION_DUEL_MAIN_SCENE
	bank1call AIMakeDecision
	ret

; handles AI logic for using some Pkmn Powers.
; Pkmn Powers handled here are:
;	- Heal;
;	- Shift;
;	- Peek;
;	- Strange Behavior;
;	- Curse.
; returns carry if turn ended.
HandleAIPkmnPowers:
	ld a, MUK
	call CountPokemonIDInBothPlayAreas
	ccf
	ret nc ; return no carry if Muk is in play

	farcall AIChooseRandomlyNotToDoAction
	ccf
	ret nc ; return no carry if AI randomly decides to

	ld a, DUELVARS_NUMBER_OF_POKEMON_IN_PLAY_AREA
	call GetTurnDuelistVariable
	ld b, a
	ld c, PLAY_AREA_ARENA
	ld a, DUELVARS_ARENA_CARD_STATUS
	call GetTurnDuelistVariable
	and CNF_SLP_PRZ
	jr nz, .next_2

.loop_play_area
	ld a, DUELVARS_ARENA_CARD
	add c
	call GetTurnDuelistVariable
	ld [wce08], a

	push af
	push bc
	ld d, a
	ld a, c
	ldh [hTempPlayAreaLocation_ff9d], a
	ld e, FIRST_ATTACK_OR_PKMN_POWER
	call CopyAttackDataAndDamage_FromDeckIndex
	ld a, [wLoadedAttackCategory]
	cp POKEMON_POWER
	jr z, .execute_effect
	pop bc
	jr .next_3

.execute_effect
	ld a, EFFECTCMDTYPE_INITIAL_EFFECT_2
	bank1call TryExecuteEffectCommandFunction
	pop bc
	jr c, .next_3

; TryExecuteEffectCommandFunction was successful,
; so check what Pkmn Power this is through card's ID.
	pop af
	call GetCardIDFromDeckIndex
	ld a, e
	push bc

; check heal
	cp VILEPLUME
	jr nz, .check_shift
	call HandleAIHeal
	jr .next_1
.check_shift
	cp VENOMOTH
	jr nz, .check_peek
	call HandleAIShift
	jr .next_1
.check_peek
	cp MANKEY
	jr nz, .check_strange_behavior
	call HandleAIPeek
	jr .next_1
.check_strange_behavior
	cp SLOWBRO
	jr nz, .check_curse
	call HandleAIStrangeBehavior
	jr .next_1
.check_curse
	cp GENGAR
	jr nz, .next_1
	call z, HandleAICurse
	jr c, .done

.next_1
	pop bc
.next_2
	inc c
	ld a, c
	cp b
	jr nz, .loop_play_area
	ret

.next_3
	pop af
	jr .next_2

.done
	pop bc
	ret

; checks whether AI uses Heal on Pokemon in Play Area.
; input:
;	c = Play Area location (PLAY_AREA_*) of Vileplume.
HandleAIHeal:
	ld a, c
	ldh [hTemp_ffa0], a
	call .CheckHealTarget
	ret nc ; return if no target to heal
	push af
	ld a, [wce08]
	ldh [hTempCardIndex_ff9f], a
	ld a, OPPACTION_USE_PKMN_POWER
	bank1call AIMakeDecision
	pop af
	ldh [hPlayAreaEffectTarget], a
	ld a, OPPACTION_EXECUTE_PKMN_POWER_EFFECT
	bank1call AIMakeDecision
	ld a, OPPACTION_DUEL_MAIN_SCENE
	bank1call AIMakeDecision
	ret

; finds a target suitable for AI to use Heal on.
; only heals Arena card if the Defending Pokemon
; cannot KO it after Heal is used.
; returns carry if target was found and outputs
; in a the Play Area location of that card.
.CheckHealTarget ; 22422 (8:6422)
; check if Arena card has any damage counters,
; if not, check Bench instead.
	ld e, PLAY_AREA_ARENA
	call GetCardDamageAndMaxHP
	or a
	jr z, .check_bench

	xor a ; PLAY_AREA_ARENA
	ldh [hTempPlayAreaLocation_ff9d], a
	farcall CheckIfDefendingPokemonCanKnockOut
	jr nc, .set_carry ; return carry if can't KO
	ld d, a
	ld a, DUELVARS_ARENA_CARD_HP
	call GetTurnDuelistVariable
	ld h, a
	ld e, PLAY_AREA_ARENA
	call GetCardDamageAndMaxHP
	; this seems useless since it was already
	; checked that Arena card has damage,
	; so card damage is at least 10.
	cp 10 + 1
	jr c, .check_remaining
	ld a, 10
	; a = min(10, CardDamage)

; checks if Defending Pokemon can still KO
; if Heal is used on this card.
; if Heal prevents KO, return carry.
.check_remaining
	ld l, a
	ld a, h ; load remaining HP
	add l ; add 1 counter to account for heal
	sub d ; subtract damage of strongest opponent attack
	jr c, .check_bench
	jr z, .check_bench

.set_carry
	xor a ; PLAY_AREA_ARENA
	scf
	ret

; check Bench for Pokemon with damage counters
; and find the one with the most damage.
.check_bench
	ld a, DUELVARS_NUMBER_OF_POKEMON_IN_PLAY_AREA
	call GetTurnDuelistVariable
	ld d, a
	lb bc, 0, 0
	ld e, PLAY_AREA_BENCH_1
.loop_bench
	ld a, e
	cp d
	jr z, .done
	push bc
	call GetCardDamageAndMaxHP
	pop bc
	cp b
	jr c, .next_bench
	jr z, .next_bench
	ld b, a ; store this damage
	ld c, e ; store this Play Area location
.next_bench
	inc e
	jr .loop_bench

; check if a Pokemon with damage counters was found
; in the Bench and, if so, return carry.
.done
	ld a, c
	or a
	jr z, .not_found
; found
	scf
	ret
.not_found
	or a
	ret

; checks whether AI uses Shift.
; input:
;	c = Play Area location (PLAY_AREA_*) of Venomoth
HandleAIShift:
	ld a, c
	or a
	ret nz ; return if Venomoth is not Arena card

	ldh [hTemp_ffa0], a
	call GetArenaCardColor
	call TranslateColorToWR
	ld b, a
	call SwapTurn
	call GetArenaCardWeakness
	ld [wAIDefendingPokemonWeakness], a
	call SwapTurn
	or a
	ret z ; return if Defending Pokemon has no weakness
	and b
	ret nz ; return if Venomoth is already Defending card's weakness type

; check whether there's a card in play with
; the same color as the Player's card weakness
	call .CheckWhetherTurnDuelistHasColor
	jr c, .found
	call SwapTurn
	call .CheckWhetherTurnDuelistHasColor
	call SwapTurn
	ret nc ; return if no color found

.found
	ld a, [wce08]
	ldh [hTempCardIndex_ff9f], a
	ld a, OPPACTION_USE_PKMN_POWER
	bank1call AIMakeDecision

; converts WR_* to appropriate color
	ld a, [wAIDefendingPokemonWeakness]
	ld b, 0
.loop_color
	bit 7, a
	jr nz, .done
	inc b
	rlca
	jr .loop_color

; use Pkmn Power effect
.done
	ld a, b
	ldh [hAIPkmnPowerEffectParam], a
	ld a, OPPACTION_EXECUTE_PKMN_POWER_EFFECT
	bank1call AIMakeDecision
	ld a, OPPACTION_DUEL_MAIN_SCENE
	bank1call AIMakeDecision
	ret

; returns carry if turn Duelist has a Pokemon
; with same color as wAIDefendingPokemonWeakness.
.CheckWhetherTurnDuelistHasColor ; 224c6 (8:64c6)
	ld a, [wAIDefendingPokemonWeakness]
	ld b, a
	ld a, DUELVARS_ARENA_CARD
	call GetTurnDuelistVariable
.loop_play_area
	ld a, [hli]
	cp $ff
	jr z, .false
	push bc
	call GetCardIDFromDeckIndex
	call GetCardType
	; in case this is a Mysterious Fossil or Clefairy Doll card,
	; AI might read the type of the card incorrectly here.
	; uncomment the following lines to account for this
	; cp TYPE_TRAINER
	; jr nz, .not_trainer
	; pop bc
	; jr .loop_play_area
; .not_trainer
	call TranslateColorToWR
	pop bc
	and b
	jr z, .loop_play_area
; true
	scf
	ret
.false
	or a
	ret

; checks whether AI uses Peek.
; input:
;	c = Play Area location (PLAY_AREA_*) of Mankey.
HandleAIPeek:
	ld a, c
	ldh [hTemp_ffa0], a
	ld a, 50
	call Random
	cp 3
	ret nc ; return 47 out of 50 times

; choose what to use Peek on at random
	ld a, 3
	call Random
	or a
	jr z, .check_ai_prizes
	cp 2
	jr c, .check_player_hand

; check Player's Deck
	ld a, DUELVARS_NUMBER_OF_CARDS_NOT_IN_DECK
	call GetNonTurnDuelistVariable
	cp DECK_SIZE - 1
	ret nc ; return if Player has one or no cards in Deck
	ld a, AI_PEEK_TARGET_DECK
	jr .use_peek

.check_ai_prizes
	ld a, DUELVARS_PRIZES
	call GetTurnDuelistVariable
	ld hl, wAIPeekedPrizes
	and [hl]
	ld [hl], a
	or a
	ret z ; return if no prizes

	ld c, a
	ld b, $1
	ld d, 0
.loop_prizes
	ld a, c
	and b
	jr nz, .found_prize
	sla b
	inc d
	jr .loop_prizes
.found_prize
; remove this prize's flag from the prize list
; and use Peek on first one in list (lowest bit set)
	ld a, c
	sub b
	ld [hl], a
	ld a, AI_PEEK_TARGET_PRIZE
	add d
	jr .use_peek

.check_player_hand
	call SwapTurn
	call CreateHandCardList
	call SwapTurn
	or a
	ret z ; return if no cards in Hand
; shuffle list and pick the first entry to Peek
	ld hl, wDuelTempList
	call CountCardsInDuelTempList
	call ShuffleCards
	ld a, [wDuelTempList]
	or AI_PEEK_TARGET_HAND

.use_peek
	push af
	ld a, [wce08]
	ldh [hTempCardIndex_ff9f], a
	ld a, OPPACTION_USE_PKMN_POWER
	bank1call AIMakeDecision
	pop af
	ldh [hAIPkmnPowerEffectParam], a
	ld a, OPPACTION_EXECUTE_PKMN_POWER_EFFECT
	bank1call AIMakeDecision
	ld a, OPPACTION_DUEL_MAIN_SCENE
	bank1call AIMakeDecision
	ret

; checks whether AI uses Strange Behavior.
; input:
;	c = Play Area location (PLAY_AREA_*) of Slowbro.
HandleAIStrangeBehavior:
	ld a, c
	or a
	ret z ; return if Slowbro is Arena card

	ldh [hTemp_ffa0], a
	ld e, PLAY_AREA_ARENA
	call GetCardDamageAndMaxHP
	or a
	ret z ; return if Arena card has no damage counters

	ld [wce06], a
	ldh a, [hTemp_ffa0]
	add DUELVARS_ARENA_CARD_HP
	call GetTurnDuelistVariable
	sub 10
	ret z ; return if Slowbro has only 10 HP remaining

; if Slowbro can't receive all damage counters,
; only transfer remaining HP - 10 damage
	ld hl, wce06
	cp [hl]
	jr c, .use_strange_behavior
	ld a, [hl] ; can receive all damage counters

.use_strange_behavior
	push af
	ld a, [wce08]
	ldh [hTempCardIndex_ff9f], a
	ld a, OPPACTION_USE_PKMN_POWER
	bank1call AIMakeDecision
	xor a
	ldh [hAIPkmnPowerEffectParam], a
	ld a, OPPACTION_EXECUTE_PKMN_POWER_EFFECT
	bank1call AIMakeDecision
	pop af

; loop counters chosen to transfer and use Pkmn Power
	call ConvertHPToCounters
	ld e, a
.loop_counters
	ld d, 30
.small_delay_loop
	call DoFrame
	dec d
	jr nz, .small_delay_loop
	push de
	ld a, OPPACTION_6B15
	bank1call AIMakeDecision
	pop de
	dec e
	jr nz, .loop_counters

; return to main scene
	ld d, 60
.big_delay_loop
	call DoFrame
	dec d
	jr nz, .big_delay_loop
	ld a, OPPACTION_DUEL_MAIN_SCENE
	bank1call AIMakeDecision
	ret

; checks whether AI uses Curse.
; input:
;	c = Play Area location (PLAY_AREA_*) of Gengar.
HandleAICurse:
	ld a, c
	ldh [hTemp_ffa0], a

; loop Player's Play Area and checks their damage.
; finds the card with lowest remaining HP and
; stores its HP and its Play Area location
	ld a, DUELVARS_NUMBER_OF_POKEMON_IN_PLAY_AREA
	call GetNonTurnDuelistVariable
	ld d, a
	ld e, PLAY_AREA_ARENA
	lb bc, 0, $ff
	ld h, PLAY_AREA_ARENA
	call SwapTurn
.loop_play_area_1
	push bc
	call GetCardDamageAndMaxHP
	pop bc
	or a
	jr z, .next_1

	inc b
	ld a, e
	add DUELVARS_ARENA_CARD_HP
	push hl
	call GetTurnDuelistVariable
	pop hl
	cp c
	jr nc, .next_1
	; lower HP than one stored
	ld c, a ; store this HP
	ld h, e ; store this Play Area location

.next_1
	inc e
	ld a, e
	cp d
	jr nz, .loop_play_area_1 ; reached end of Play Area

	ld a, 1
	cp b
	jr nc, .failed ; return if less than 2 cards with damage

; card in Play Area with lowest HP remaining was found.
; look for another card to take damage counter from.
	ld a, h
	ldh [hTempRetreatCostCards], a
	ld b, a
	ld a, 10
	cp c
	jr z, .hp_10_remaining
	; if has more than 10 HP remaining,
	; skip Arena card in choosing which
	; card to take damage counter from.
	ld e, PLAY_AREA_BENCH_1
	jr .second_card

.hp_10_remaining
	; if Curse can KO, then include
	; Player's Arena card to take
	; damage counter from.
	ld e, PLAY_AREA_ARENA

.second_card
	ld a, DUELVARS_NUMBER_OF_POKEMON_IN_PLAY_AREA
	call GetTurnDuelistVariable
	ld d, a
.loop_play_area_2
	ld a, e
	cp b
	jr z, .next_2 ; skip same Pokemon card
	push bc
	call GetCardDamageAndMaxHP
	pop bc
	jr nz, .use_curse ; has damage counters, choose this card
.next_2
	inc e
	ld a, e
	cp d
	jr nz, .loop_play_area_2

.failed
	call SwapTurn
	or a
	ret

.use_curse
	ld a, e
	ldh [hAIPkmnPowerEffectParam], a
	call SwapTurn
	ld a, [wce08]
	ldh [hTempCardIndex_ff9f], a
	ld a, OPPACTION_USE_PKMN_POWER
	bank1call AIMakeDecision
	ld a, OPPACTION_EXECUTE_PKMN_POWER_EFFECT
	bank1call AIMakeDecision
	ld a, OPPACTION_DUEL_MAIN_SCENE
	bank1call AIMakeDecision
	ret

; handles AI logic for Cowardice
HandleAICowardice:
	ld a, MUK
	call CountPokemonIDInBothPlayAreas
	ret c ; return if there's Muk in play

	farcall AIChooseRandomlyNotToDoAction
	ret c ; randomly return

	ld a, DUELVARS_NUMBER_OF_POKEMON_IN_PLAY_AREA
	call GetTurnDuelistVariable
	cp 1
	ret z ; return if only one Pokemon in Play Area

	ld b, a
	ld c, PLAY_AREA_ARENA
	ld a, DUELVARS_ARENA_CARD_STATUS
	call GetTurnDuelistVariable
	and CNF_SLP_PRZ
	jr nz, .next
.loop
	ld a, DUELVARS_ARENA_CARD
	add c
	call GetTurnDuelistVariable
	ld [wce08], a
	call GetCardIDFromDeckIndex
	ld a, e
	push bc
	cp TENTACOOL
	call z, .CheckWhetherToUseCowardice
	pop bc
	jr nc, .next

	dec b ; subtract 1 from number of Pokemon in Play Area
	ld a, 1
	cp b
	ret z ; return if no longer has Bench Pokemon
	ld c, PLAY_AREA_ARENA ; reset back to Arena
	jr .loop

.next
	inc c
	ld a, c
	cp b
	jr nz, .loop
	ret

; checks whether AI uses Cowardice.
; return carry if Pkmn Power was used.
; input:
;	c = Play Area location (PLAY_AREA_*) of Tentacool.
.CheckWhetherToUseCowardice ; 22671 (8:6671)
	ld a, c
	ldh [hTemp_ffa0], a
	ld e, a
	call GetCardDamageAndMaxHP
.asm_22678
	or a
	ret z ; return if has no damage counters

	ldh a, [hTemp_ffa0]
	or a
	jr nz, .is_benched

	; this part is buggy if AIDecideBenchPokemonToSwitchTo returns carry
	; but since this was already checked beforehand, this never happens.
	; so jr c, .asm_22678 can be safely removed.
	farcall AIDecideBenchPokemonToSwitchTo
	jr c, .asm_22678 ; bug, this jumps in the middle of damage checking
	jr .use_cowardice
.is_benched
	ld a, $ff
.use_cowardice
	push af
	ld a, [wce08]
	ldh [hTempCardIndex_ff9f], a
	ld a, OPPACTION_USE_PKMN_POWER
	bank1call AIMakeDecision
	pop af
	ldh [hAIPkmnPowerEffectParam], a
	ld a, OPPACTION_EXECUTE_PKMN_POWER_EFFECT
	bank1call AIMakeDecision
	ld a, OPPACTION_DUEL_MAIN_SCENE
	bank1call AIMakeDecision
	scf
	ret

; AI logic for Damage Swap to transfer damage from Arena card
; to a card in Bench with more than 10 HP remaining
; and with no energy cards attached.
HandleAIDamageSwap:
	ld a, DUELVARS_NUMBER_OF_POKEMON_IN_PLAY_AREA
	call GetTurnDuelistVariable
	dec a
	ret z ; return if no Bench Pokemon

	farcall AIChooseRandomlyNotToDoAction
	ret c

	ld a, ALAKAZAM
	call CountPokemonIDInPlayArea
	ret nc ; return if no Alakazam
	ld a, MUK
	call CountPokemonIDInBothPlayAreas
	ret c ; return if there's Muk in play

; only take damage off certain cards in Arena
	ld a, DUELVARS_ARENA_CARD
	call GetTurnDuelistVariable
	call GetCardIDFromDeckIndex
	ld a, e
	cp ALAKAZAM
	jr z, .ok
	cp KADABRA
	jr z, .ok
	cp ABRA
	jr z, .ok
	cp MR_MIME
	ret nz

.ok
	ld e, PLAY_AREA_ARENA
	call GetCardDamageAndMaxHP
	or a
	ret z ; return if no damage

	call ConvertHPToCounters
	ld [wce06], a
	ld a, ALAKAZAM
	ld b, PLAY_AREA_BENCH_1
	farcall LookForCardIDInPlayArea_Bank5
	jr c, .is_in_bench

; Alakazam is Arena card
	xor a
.is_in_bench
	ld [wce08], a
	call .CheckForDamageSwapTargetInBench
	ret c ; return if not found

; use Damage Swap
	ld a, [wce08]
	add DUELVARS_ARENA_CARD
	call GetTurnDuelistVariable
	ldh [hTempCardIndex_ff9f], a
	ld a, [wce08]
	ldh [hTemp_ffa0], a
	ld a, OPPACTION_USE_PKMN_POWER
	bank1call AIMakeDecision
	ld a, OPPACTION_EXECUTE_PKMN_POWER_EFFECT
	bank1call AIMakeDecision

	ld a, [wce06]
	ld e, a
.loop_damage
	ld d, 30
.small_delay_loop
	call DoFrame
	dec d
	jr nz, .small_delay_loop

	push de
	call .CheckForDamageSwapTargetInBench
	jr c, .no_more_target

	ldh [hTempRetreatCostCards], a
	xor a ; PLAY_AREA_ARENA
	ldh [hAIPkmnPowerEffectParam], a
	ld a, OPPACTION_6B15
	bank1call AIMakeDecision
	pop de
	dec e
	jr nz, .loop_damage

.done
; return to main scene
	ld d, 60
.big_delay_loop
	call DoFrame
	dec d
	jr nz, .big_delay_loop
	ld a, OPPACTION_DUEL_MAIN_SCENE
	bank1call AIMakeDecision
	ret

.no_more_target
	pop de
	jr .done

; looks for a target in the bench to receive damage counters.
; returns carry if one is found, and outputs remaining HP in a.
.CheckForDamageSwapTargetInBench ; 2273c (8:673c)
	ld a, DUELVARS_NUMBER_OF_POKEMON_IN_PLAY_AREA
	call GetTurnDuelistVariable
	ld b, a
	ld c, PLAY_AREA_BENCH_1
	lb de, $ff, $ff

; look for candidates in bench to get the damage counters
; only target specific card IDs.
.loop_bench
	ld a, c
	add DUELVARS_ARENA_CARD
	call GetTurnDuelistVariable
	push de
	call GetCardIDFromDeckIndex
	ld a, e
	pop de
	cp CHANSEY
	jr z, .found_candidate
	cp KANGASKHAN
	jr z, .found_candidate
	cp SNORLAX
	jr z, .found_candidate
	cp MR_MIME
	jr z, .found_candidate

.next_play_area
	inc c
	ld a, c
	cp b
	jr nz, .loop_bench

; done
	ld a, e
	cp $ff
	jr nz, .no_carry
	ld a, d
	cp $ff
	jr z, .set_carry
.no_carry
	or a
	ret

.found_candidate
; found a potential candidate to receive damage counters
	ld a, DUELVARS_ARENA_CARD_HP
	add c
	call GetTurnDuelistVariable
	cp 20
	jr c, .next_play_area ; ignore cards with only 10 HP left

	ld d, c ; store damage
	push de
	push bc
	ld e, c
	farcall CountNumberOfEnergyCardsAttached
	pop bc
	pop de
	or a
	jr nz, .next_play_area ; ignore cards with attached energy
	ld e, c ; store deck index
	jr .next_play_area

.set_carry
	scf
	ret

; handles AI logic for attaching energy cards
; in Go Go Rain Dance deck.
HandleAIGoGoRainDanceEnergy:
	ld a, [wOpponentDeckID]
	cp GO_GO_RAIN_DANCE_DECK_ID
	ret nz ; return if not Go Go Rain Dance deck

	ld a, BLASTOISE
	call CountPokemonIDInPlayArea
	ret nc ; return if no Blastoise
	ld a, MUK
	call CountPokemonIDInBothPlayAreas
	ret c ; return if there's Muk in play

; play all the energy cards that is needed.
.loop
	farcall AIProcessAndTryToPlayEnergy
	jr c, .loop
	ret