; Code for making shop items solid, and for detecting if player is in range to purchase the item

; Note, when starting the below fragment
; X should be the shopkeeper sprite index
; Y should be applicable offset .item_offsets

;check if player link is on same layer as shopkeeper
LDA $00EE : CMP $0F20, X; BNE .no_interaction

JSR Setup_LinksHitbox
JSR Setup_ShopItemCollisionHitbox
JSL Utility_CheckIfHitBoxesOverlapLong
BCC .no_contact
    JSR Sprite_HaltSpecialPlayerMovementCopied
.no_contact
JSR Setup_ShopItemInteractionHitbox
JSL Utility_CheckIfHitBoxesOverlapLong
BCC .no_interaction
    ;TODO Check if player is pressing A Button (by checking $F6). If so try to buy item
.no_interaction

;--------------------

Setup_ShopItemCollisionHitbox:
;The complications with XBA are to handle the fact that nintendo likes to store
;high and low bytes of 16 bit postion values seperately :-(

    ; load shopkeeper X (16 bit)
    LDA $0D30, X : XBA : LDA $0D10, X

    REP #$20 ; set 16-bit accumulator
    !ADD .item_offsets, Y
    !ADD.w #$0002 ; a small negative margin
    ; TODO: add 4 for a narrow item
    SEP #20 ; set 8-bit accumulator

    ; store hitbox X
    STA $04 : XBA : STA $0A

    ;load shopkeeper Y (16 bit)
    LDA $0D20, X : XBA : LDA $0D00, X

    REP #$20 ; set 16-bit accumulator
    !ADD .item_offsets+2, Y
    SEP #20 ; set 8-bit accumulator

    ; store hitbox Y Low: $05, High $0B
    STA $05 : XBA : STA $0B

    LDA.b #12: STA $06 ; Hitbox width, always 12 for existing (wide) shop items
    ; TODO: for narrow sprite store make width 4 (i.e. 8 pixels smaller)

    LDA.b #14: STA $07 ; Hitbox height, always 14
RTS

; Adjusts the already set up collision hitbox to be a suitable interaction hitbox
Setup_ShopItemInteractionHitbox:

    ; collision hitbox has left margin of -2, we want margin of 8 so we subtract 10
    LDA $04; !SUB.b #$0A; STA $04
    LDA $0A; SBC.b #$00; STA $0A ; Apply borrow

    ; collision hitbox has 0 top margin, we want a margin of 8 so we subtract 8
    LDA $05; !SUB.b #$08; STA $05
    LDA $0B; SBC.b #$00; STA $0B ; Apply borrow

    ; We want a width of 32 for wide or 24 for narrow, so we add 20
    LDA $06: !ADD.b #20: STA $06 ; Hitbox width

    LDA.b #40: STA $07 ; Hitbox height, always 40
RTS

; Following is a copy of procedure $3770A (Bank06.asm Line 6273)
; because there is no long version available
Setup_LinksHitbox:
    LDA.b #$08 : STA $02
                     STA $03

        LDA $22 : ADD.b #$04 : STA $00
        LDA $23 : ADC.b #$00 : STA $08

        LDA $20 : ADC.b #$08 : STA $01
        LDA $21 : ADC.b #$00 : STA $09
RTS

; The following is a copy of procedure Sprite_HaltSpecialPlayerMovement (Bank1E.asm line 255)
; because there is no long version available
Sprite_HaltSpecialPlayerMovementCopied:
        PHX
        JSL Sprite_NullifyHookshotDrag
        STZ $5E ; Set Link's speed to zero...
        JSL Player_HaltDashAttackLong
        PLX
RTS