; ==============================================================================
; EBLAN ENGINE - Entity & Gameplay Behavior System
; ==============================================================================

.code

; ------------------------------------------------------------------------------
; InitEntities: Initialize entity runtime state from spriteList flags/defaults
; ------------------------------------------------------------------------------
InitEntities PROC uses eax ebx ecx edx esi edi
    ; 1. Clear runtime arrays
    xor eax, eax
    mov ecx, MAX_SPRITES
    mov edi, OFFSET entityType
    rep stosd

    mov ecx, MAX_SPRITES
    mov eax, 100
    mov edi, OFFSET entityHealth
    rep stosd

    xor eax, eax
    mov ecx, MAX_SPRITES
    mov edi, OFFSET entityState
    rep stosd

    mov ecx, MAX_SPRITES
    mov edi, OFFSET entityTimer
    rep stosd

    mov ecx, MAX_SPRITES
    mov eax, 2
    mov edi, OFFSET entitySpeed
    rep stosd

    mov ecx, MAX_SPRITES
    mov eax, 384
    mov edi, OFFSET entityAggro
    rep stosd

    ; 2. Iterate spriteList and configure entity archetypes
    xor ecx, ecx
init_spr_loop:
    cmp ecx, spriteCount
    jge init_spr_done

    mov ebx, ecx
    imul ebx, sizeof SpriteStruct
    add ebx, OFFSET spriteList

    mov eax, [ebx].SpriteStruct.flags
    test eax, eax
    jz fallback_archetype

    ; Parse flags:
    ; Byte 0: Entity Type (0=Prop, 1=Guard, 2=Medkit, 3=Ammo, 4=Key, 5=Switch)
    ; Byte 1: Health (if Guard)
    ; Byte 2: Speed (1..8)
    ; Byte 3: Aggro multiplier (1..15 -> cells * 64)
    mov edx, eax
    and edx, 0FFh
    mov [entityType + ecx*4], edx

    mov edx, eax
    shr edx, 8
    and edx, 0FFh
    test edx, edx
    jz @F
    mov [entityHealth + ecx*4], edx
@@:
    mov edx, eax
    shr edx, 16
    and edx, 0FFh
    test edx, edx
    jz @F
    mov [entitySpeed + ecx*4], edx
@@:
    mov edx, eax
    shr edx, 24
    and edx, 0FFh
    test edx, edx
    jz next_spr_slot
    shl edx, 6      ; cells -> raw units
    mov [entityAggro + ecx*4], edx
    jmp next_spr_slot

fallback_archetype:
    ; If flags == 0, infer archetype from textureId:
    ; Slot 13 = Enemy Guard, 14 = Medkit, 15 = Ammo
    mov edx, [ebx].SpriteStruct.textureId
    cmp edx, 13
    jne check_medkit_slot
    mov [entityType + ecx*4], ENTITY_TYPE_GUARD
    mov [entityHealth + ecx*4], 100
    mov [entitySpeed + ecx*4], 2
    jmp next_spr_slot

check_medkit_slot:
    cmp edx, 14
    jne check_ammo_slot
    mov [entityType + ecx*4], ENTITY_TYPE_MEDKIT
    jmp next_spr_slot

check_ammo_slot:
    cmp edx, 15
    jne next_spr_slot
    mov [entityType + ecx*4], ENTITY_TYPE_AMMO

next_spr_slot:
    inc ecx
    jmp init_spr_loop

init_spr_done:
    ret
InitEntities ENDP

; ------------------------------------------------------------------------------
; UpdateEntities: Updates AI, pickups, collision and interactions each tick
; ------------------------------------------------------------------------------
UpdateEntities PROC uses ebx ecx edx esi edi
    LOCAL i:DWORD
    LOCAL sprX:DWORD, sprY:DWORD
    LOCAL deltaX:DWORD, deltaY:DWORD
    LOCAL absDX:DWORD, absDY:DWORD
    LOCAL distSq:DWORD
    LOCAL speed:DWORD
    LOCAL stepX:DWORD, stepY:DWORD
    LOCAL cellX:DWORD, cellY:DWORD

    ; If player died and pressed Restart (R)
    cmp isPlayerDead, 0
    je entities_active
    cmp keyRestart, 0
    je entities_done
    ; Respawn player
    mov playerHealth, 100
    mov playerAmmo, 50
    mov isPlayerDead, 0
    mov playerHitFlash, 0
    call LoadMapBinary
    call InitEntities
    ret

entities_active:
    mov i, 0

entity_loop:
    mov eax, i
    cmp eax, spriteCount
    jge entities_done

    mov ebx, i
    imul ebx, sizeof SpriteStruct
    add ebx, OFFSET spriteList

    ; If sprite is inactive (textureId == 0), skip
    mov eax, [ebx].SpriteStruct.textureId
    test eax, eax
    jz next_entity

    mov eax, [ebx].SpriteStruct.x
    mov sprX, eax
    mov eax, [ebx].SpriteStruct.y
    mov sprY, eax

    ; Distance to player
    mov eax, playerX
    sub eax, sprX
    mov deltaX, eax
    cdq
    xor eax, edx
    sub eax, edx
    mov absDX, eax

    mov eax, playerY
    sub eax, sprY
    mov deltaY, eax
    cdq
    xor eax, edx
    sub eax, edx
    mov absDY, eax

    ; distSq = deltaX^2 + deltaY^2
    mov eax, deltaX
    imul eax, eax
    mov ecx, eax
    mov eax, deltaY
    imul eax, eax
    add eax, ecx
    mov distSq, eax

    mov ecx, i
    mov edx, [entityType + ecx*4]

    ; --------------------------------------------------------------------------
    ; Medkit Pickup (+25 HP)
    ; --------------------------------------------------------------------------
    cmp edx, ENTITY_TYPE_MEDKIT
    jne check_ammo_pickup
    cmp absDX, 32
    jge next_entity
    cmp absDY, 32
    jge next_entity
    mov eax, playerHealth
    cmp eax, playerMaxHealth
    jge next_entity
    add eax, 25
    cmp eax, playerMaxHealth
    jle @F
    mov eax, playerMaxHealth
@@:
    mov playerHealth, eax
    mov [ebx].SpriteStruct.textureId, 0 ; Hide item
    mov ecx, i
    mov [entityType + ecx*4], ENTITY_TYPE_PROP
    add playerScore, 25
    jmp next_entity

    ; --------------------------------------------------------------------------
    ; Ammo Pickup (+20 Ammo)
    ; --------------------------------------------------------------------------
check_ammo_pickup:
    cmp edx, ENTITY_TYPE_AMMO
    jne check_key_pickup
    cmp absDX, 32
    jge next_entity
    cmp absDY, 32
    jge next_entity
    mov eax, playerAmmo
    add eax, 20
    cmp eax, playerMaxAmmo
    jle @F
    mov eax, playerMaxAmmo
@@:
    mov playerAmmo, eax
    mov [ebx].SpriteStruct.textureId, 0
    mov ecx, i
    mov [entityType + ecx*4], ENTITY_TYPE_PROP
    add playerScore, 10
    jmp next_entity

    ; --------------------------------------------------------------------------
    ; Key Pickup (+1 Key)
    ; --------------------------------------------------------------------------
check_key_pickup:
    cmp edx, ENTITY_TYPE_KEY
    jne check_guard_entity
    cmp absDX, 32
    jge next_entity
    cmp absDY, 32
    jge next_entity
    inc playerKeys
    mov [ebx].SpriteStruct.textureId, 0
    mov ecx, i
    mov [entityType + ecx*4], ENTITY_TYPE_PROP
    add playerScore, 50
    jmp next_entity

    ; --------------------------------------------------------------------------
    ; Guard Enemy AI
    ; --------------------------------------------------------------------------
check_guard_entity:
    cmp edx, ENTITY_TYPE_GUARD
    jne next_entity

    mov ecx, i
    mov eax, [entityState + ecx*4]
    cmp eax, ENTITY_STATE_DEAD
    jne guard_alive

    ; Dead guard: tick timer until disappear
    inc DWORD PTR [entityTimer + ecx*4]
    cmp DWORD PTR [entityTimer + ecx*4], 120
    jl next_entity
    mov [ebx].SpriteStruct.textureId, 0
    jmp next_entity

guard_alive:
    ; Check aggro radius
    mov eax, [entityAggro + ecx*4]
    imul eax, eax       ; aggroSq
    cmp distSq, eax
    jg next_entity

    ; Guard is alert & chasing player
    mov ecx, i
    mov [entityState + ecx*4], ENTITY_STATE_CHASE
    mov eax, [entitySpeed + ecx*4]
    mov speed, eax

    ; Calculate movement direction
    mov stepX, 0
    mov stepY, 0

    cmp deltaX, 16
    jle check_neg_x
    mov eax, speed
    mov stepX, eax
    jmp check_step_y
check_neg_x:
    cmp deltaX, -16
    jge check_step_y
    mov eax, speed
    neg eax
    mov stepX, eax

check_step_y:
    cmp deltaY, 16
    jle check_neg_y
    mov eax, speed
    mov stepY, eax
    jmp apply_guard_step
check_neg_y:
    cmp deltaY, -16
    jge apply_guard_step
    mov eax, speed
    neg eax
    mov stepY, eax

apply_guard_step:
    ; Try stepping X
    cmp stepX, 0
    je try_step_y
    mov eax, sprX
    add eax, stepX
    sar eax, 6
    mov cellX, eax
    mov eax, sprY
    sar eax, 6
    mov cellY, eax
    invoke GetMapCell, cellX, cellY
    invoke IsSolidCell, eax
    test eax, eax
    jnz try_step_y
    mov eax, stepX
    add [ebx].SpriteStruct.x, eax
    mov eax, [ebx].SpriteStruct.x
    mov sprX, eax

try_step_y:
    cmp stepY, 0
    je check_guard_attack
    mov eax, sprX
    sar eax, 6
    mov cellX, eax
    mov eax, sprY
    add eax, stepY
    sar eax, 6
    mov cellY, eax
    invoke GetMapCell, cellX, cellY
    invoke IsSolidCell, eax
    test eax, eax
    jnz check_guard_attack
    mov eax, stepY
    add [ebx].SpriteStruct.y, eax

check_guard_attack:
    ; Attack range check: within 48 raw units
    cmp distSq, 2304    ; 48 * 48
    jg next_entity

    mov ecx, i
    inc DWORD PTR [entityTimer + ecx*4]
    cmp DWORD PTR [entityTimer + ecx*4], 35
    jl next_entity
    mov DWORD PTR [entityTimer + ecx*4], 0

    ; Guard hits player!
    mov eax, playerHealth
    sub eax, 8
    jns @F
    xor eax, eax
@@:
    mov playerHealth, eax
    mov playerHitFlash, 6
    test eax, eax
    jnz next_entity
    mov isPlayerDead, 1

next_entity:
    inc i
    jmp entity_loop

entities_done:
    ret
UpdateEntities ENDP