jep-hack/engine/events/battle_tower/load_trainer.asm

LoadOpponentTrainerAndPokemon:
	ldh a, [rSVBK]
	push af
	ld a, BANK(wBT_OTTrainer)
	ldh [rSVBK], a

	; Fill wBT_OTTrainer with zeros
	xor a
	ld hl, wBT_OTTrainer
	ld bc, BATTLE_TOWER_STRUCT_LENGTH
	call ByteFill

	; Write $ff into the Item-Slots
	ld a, $ff
	ld [wBT_OTMon1Item], a
	ld [wBT_OTMon2Item], a
	ld [wBT_OTMon3Item], a

	; Set wBT_OTTrainer as start address to write the following data to
	ld de, wBT_OTTrainer

	ldh a, [hRandomAdd]
	ld b, a
.resample ; loop to find a random trainer
	call Random
	ldh a, [hRandomAdd]
	add b
	ld b, a ; b contains the nr of the trainer
	maskbits BATTLETOWER_NUM_UNIQUE_TRAINERS
	cp BATTLETOWER_NUM_UNIQUE_TRAINERS
	jr nc, .resample
	ld b, a

	ld a, BANK(sBTTrainers)
	call OpenSRAM

	ld c, BATTLETOWER_STREAK_LENGTH
	ld hl, sBTTrainers
.next_trainer
	ld a, [hli]
	cp b
	jr z, .resample
	dec c
	jr nz, .next_trainer ; c <= 7  initialise all 7 trainers?

	ld hl, sBTTrainers
	ld a, [sNrOfBeatenBattleTowerTrainers]
	ld c, a
	ld a, b
	ld b, 0
	add hl, bc
	ld [hl], a

	call CloseSRAM

	push af
; Copy name (10 bytes) and class (1 byte) of trainer
	ld hl, BattleTowerTrainers
	ld bc, NAME_LENGTH
	call AddNTimes
	ld bc, NAME_LENGTH
	call CopyBytes

	call LoadRandomBattleTowerMon
	pop af

	ld hl, BattleTowerTrainerData
	ld bc, BATTLETOWER_TRAINERDATALENGTH
	call AddNTimes
	ld bc, BATTLETOWER_TRAINERDATALENGTH
.copy_bt_trainer_data_loop
	ld a, BANK(BattleTowerTrainerData)
	call GetFarByte
	ld [de], a
	inc hl
	inc de
	dec bc
	ld a, b
	or c
	jr nz, .copy_bt_trainer_data_loop

	pop af
	ldh [rSVBK], a

	ret

LoadRandomBattleTowerMon:
	ld c, BATTLETOWER_PARTY_LENGTH
.loop
	push bc
	ld a, BANK(sBTMonOfTrainers)
	call OpenSRAM

.FindARandomBattleTowerMon:
	; a = 1, 2, ..., 10 indicating level 10, 20, ..., 100 opponents
	ld a, [wBTChoiceOfLvlGroup]
	dec a
	ld hl, BattleTowerMons
	ld bc, BATTLETOWER_NUM_UNIQUE_MON * (NICKNAMED_MON_STRUCT_LENGTH + 5)
	call AddNTimes

	ldh a, [hRandomAdd]
	ld b, a
.resample
	call Random
	ldh a, [hRandomAdd]
	add b
	ld b, a
	maskbits BATTLETOWER_NUM_UNIQUE_MON
	cp BATTLETOWER_NUM_UNIQUE_MON
	jr nc, .resample
	ld bc, NICKNAMED_MON_STRUCT_LENGTH + 5
	call AddNTimes

	; hl = pointer to the mon that will be loaded (1 byte species, 1 byte item, 2 -> 1 byte each move, NICKNAMED_MON_STRUCT_LENGTH - 6 bytes data)
	ld a, [hli]
	ld c, a
	ld a, [hli]
	ld b, a
	push hl
	push de
	; check if it matches any of the previous two trainers' chosen Pokémon (six Pokémon in total)
	ld e, 6
	ld hl, sBTMonPrevTrainer1
.check_previous_mons_loop
	ld a, [hli]
	cp c
	ld a, [hli]
	jr nz, .check_previous_mons_next
	cp b
	jr z, .pop_and_retry
.check_previous_mons_next
	dec e
	jr nz, .check_previous_mons_loop
	ld h, b
	ld l, c
	call GetPokemonIDFromIndex
	ld hl, wTempSpecies
	ld [hl], a
	; check if it matches any of the current trainer's first two Pokémon (no need to check for the last one)
	ld a, [wBT_OTMon1]
	cp [hl]
	jr z, .pop_and_retry
	ld a, [wBT_OTMon2]
.pop_and_retry
	pop de
	pop hl
	jr z, .FindARandomBattleTowerMon

	; check if the held item matches any of the current trainer's first two Pokémon's held items
	ld a, [wBT_OTMon1Item]
	cp [hl]
	jr z, .FindARandomBattleTowerMon
	ld a, [wBT_OTMon2Item]
	cp [hl]
	jr z, .FindARandomBattleTowerMon

	; reserve and load the converted species from wTempSpecies, manually load item and moves, and copy everything else
	push hl
	ld l, LOCKED_MON_ID_BATTLE_TOWER_1
	; LOCKED_MOVE_ID_BATTLE_TOWER_MON1_MOVE1 rotated right 2
	ld c, (LOCKED_MOVE_ID_BATTLE_TOWER_MON1_MOVE1 >> 2) | ((LOCKED_MOVE_ID_BATTLE_TOWER_MON1_MOVE1 & 3) << 6)
	ld a, e
	; assume that NICKNAMED_MON_STRUCT_LENGTH is not a multiple of $80 (it's actually far less than $80)
	cp LOW(wBT_OTMon1)
	jr z, .got_index
	inc l
	inc c
	cp LOW(wBT_OTMon2)
	jr z, .got_index
	inc l
	inc c
.got_index
	ld a, [wTempSpecies]
	ld [de], a
	inc de
	call LockPokemonID
	pop hl
	; item
	ld a, [hli]
	ld [de], a
	inc de
	; moves
	ld b, NUM_MOVES
	rlc c
	rlc c
.move_loop
	ld a, [hli]
	push hl
	ld h, [hl]
	ld l, a
	call GetMoveIDFromIndex
	ld [de], a
	inc de
	ld l, c
	call LockMoveID
	inc c
	pop hl
	inc hl
	dec b
	jr nz, .move_loop
	ld c, NICKNAMED_MON_STRUCT_LENGTH - 6
	call CopyBytes

	; rename the Pokémon to its default name (overriding the transliterated Japanese nicknames)
	push de
	ld hl, -MON_NAME_LENGTH
	add hl, de
	push hl
	; wNamedObjectIndexBuffer = wTempSpecies
	call GetPokemonName
	ld h, d
	ld l, e
	pop de
	ld bc, MON_NAME_LENGTH
	call CopyBytes
	pop de

	pop bc
	dec c
	jp nz, .loop

	push de
	ld hl, sBTMonPrevTrainer1
	ld de, sBTMonPrevPrevTrainer1
	ld bc, 6
	push hl
	call CopyBytes
	pop de
	ld a, [wBT_OTMon1]
	call .store_index
	ld a, [wBT_OTMon2]
	call .store_index
	ld a, [wBT_OTMon3]
	call .store_index
	pop de
	jp CloseSRAM

.store_index
	call GetPokemonIndexFromID
	ld a, l
	ld [de], a
	inc de
	ld a, h
	ld [de], a
	inc de
	ret

INCLUDE "data/battle_tower/classes.asm"

INCLUDE "data/battle_tower/parties.asm"