#include "common.h"
#include "sprites.h"

// 1bpp packed
u32 gba_btn_a_data[] = {
    0xc0300804, 0x844242c2, 0x030c1020, 0x21424243,
    0x42440408, 0x30c00000, 0x42222010, 0x0c030000,
};

u32 gba_btn_b_data[] = {
    0xc0300804, 0xc442c242, 0x030c1020, 0x21424142,
    0x42c40408, 0x30c00000, 0x42212010, 0x0c030000,
};

u32 gba_btn_updown_data[] = {
    0x00f01010, 0x90d01010, 0x001f1011, 0x13171111,
    0x101020c0, 0x00000000, 0x11110807, 0x00000000,
};

u32 gba_btn_leftright_data[] = {
    0x000000f8, 0x0888c8e8, 0x0000000f, 0x1020202f,
    0xc88808f8, 0x00000000, 0x2020100f, 0x00000000,
};

u32 gba_btn_l_data[] = {
    0xfc028181, 0x818101ff, 0xff808080, 0x808380ff,
};

u32 gba_btn_r_data[] = {
    0xff01c141, 0xc14101ff, 0x3f408081, 0x808180ff,
};

u32 gba_btn_ab_shadow_data[] = {
    0x00020204, 0x040830c0, 0x00404020, 0x20100c03,
};

u32 gba_btn_up_shadow_data[] = {
    0x00000010, 0x1020c000, 0x00000010, 0x10080700,
};

u32 gba_btn_down_shadow_data[] = {
    0x00000000, 0x10f00000, 0x00000000, 0x101f0000,
};

u32 gba_btn_leftright_shadow_data[] = {
    0x00000000, 0x000008f8, 0x00000000, 0x2020100f,
};

u32 gba_btn_lr_shadow_data[] = {
    0x00000000, 0x000001ff, 0x00000000, 0x000080ff,
};

u32 gba_btn_startselect_data[] = {
    0x0000f804, 0xfcf80000, 0x00001f20, 0x3f1f0000,
    0x000000f8, 0x04f80000, 0x0000001f, 0x201f0000,
};

u32 gba_btn_start_text[] = {
    0x00008080, 0x00800000, 0x0000bb91, 0x92930000,
    0x00009b2a, 0x1b2a0000, 0x00000301, 0x01010000,
};

u32 gba_btn_select_text[] = {
    0x0000e060, 0x80e00000, 0x00002e26, 0x22ee0000,
    0x0000ee26, 0x22ee0000, 0x00000e04, 0x04040000,
};

u32 gba_btn_fx_downup[] = {
    0x00000000, 0x00000000, 0x04000000, 0x00000000,
    0x40000100, 0x00000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x00020100, 0x00000000,
    0x00800001, 0x01000000, 0x00000100, 0x00000000,
    0x00000080, 0x00000000, 0x00000100, 0x00000000,
    0x00000000, 0x01010000, 0x00000102, 0x00000000,
    0x00000000, 0x40000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000100, 0x00000000, 0x04000000,
};

u32 gba_btn_fx_leftright[] = {
    0x00000000, 0x00000000, 0x00000100, 0x00000000,
    0x04000000, 0x00000100, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x04020000, 0x00000000,
    0x18000000, 0x00000002, 0x04000000, 0x00000000,
    0x00000000, 0x00000008, 0x04000000, 0x00000000,
    0x30000000, 0x00000000, 0x04080000, 0x00000000,
    0x00000000, 0x00001000, 0x00000000, 0x00000000,
    0x40000000, 0x00000000, 0x00001000, 0x00000000,
};

u32 gba_btn_fx_lr[] = {
    0x00000000, 0x00000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x00008004, 0x00000002,
    0x00000000, 0x00000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000080, 0x80810200, 0x00000001,
    0x00000000, 0x00000000, 0x00000000, 0x00000080,
    0x80000000, 0x000000c0, 0x80010000, 0x00000000,
    0x00000000, 0x00000000, 0x00000000, 0x00000080,
    0x80000000, 0x00000020, 0x00000000, 0x00000000,
};

u32 gba_btn_fx_ab[] = {
    0x00000000, 0x00408000, 0x00000080, 0x80800001,
    0x00000000, 0x00000080, 0x00000000, 0x00020100,
    0x00000000, 0x00000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x00000000, 0x00000000,
    0x38000000, 0x00000080, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x1c000000, 0x00000001,
    0x40200000, 0x00000000, 0x00008080, 0x80000000,
    0x00000000, 0x00000000, 0x02040000, 0x00000000,
    0x00000000, 0x20400000, 0x00808000, 0x00000000,
    0x00000000, 0x00000000, 0x00000000, 0x04020000,
    0x00000000, 0x00000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x00000000, 0x00000000,
    0x0c000000, 0x00000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x30000000, 0x00000000,
    0x00201000, 0x00000000, 0x00000000, 0x80800000,
    0x00000000, 0x00000000, 0x00040800, 0x00000000,
    0x00000000, 0x20000000, 0x00800000, 0x00000000,
    0x00000000, 0x00000000, 0x00000000, 0x04000000,
    0x00000000, 0x00000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x00000000, 0x00000000,
    0x04000000, 0x00000000, 0x00000000, 0x00000000,
    0x00000000, 0x00000000, 0x20000000, 0x00000000,
    0x00001000, 0x00000000, 0x00000000, 0x00800000,
    0x00000000, 0x00000000, 0x00000800, 0x00000000,
};

u32 gba_btn_fx_startselect[] = {
    0x00000000, 0x00000000, 0x00000000, 0x10000002,
    0x00000001, 0x10000080, 0x00000000, 0x00000000,
    0x00000000, 0x00000080, 0x00000408, 0x00000001,
    0x00014120, 0x00000000, 0x00000000, 0x00000003,
    0x00000000, 0x000000c0, 0x00020400, 0x00000000,
    0x01814000, 0x00000000, 0x00000000, 0x00000006,
    0x00000000, 0x00000040, 0x00020000, 0x00000000,
    0x01800000, 0x00000000, 0x00000000, 0x00000004,
};

typedef enum {
    BTN_STATE_IDLE = 0,
    BTN_STATE_PRESSED,
    BTN_STATE_RELEASED,
    BTN_STATE_HOLD,
} BtnState;

typedef struct AnimationEntry {
    int x_offset;
    int y_offset;
    int tile_offset;
    // NOTE: Maybe this should be a part of an animation?
    // For example, hidden state, h/v flip.
    u16 hidden;
    // u16 obj_attr_1;
    // u16 obj_attr_2;
} AnimationEntry;

typedef struct ObjState {
    size_t id;
    int x;
    int y;
    u32 *data;
    size_t base_tile;
    size_t n_tiles;
    size_t frames;
    u16 obj_attr_0;
    u16 obj_attr_1;
    u16 obj_attr_2;
} ObjState;

AnimationEntry *btn_animation[] = {
    &(AnimationEntry[]){
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 1, 0, 0},
        {0, 1, 0, 0},
        {0, 2, 0, 0},
        {0, 2, 0, 0},
        {0, 2, 0, 0},
        {0, 2, 0, 0},
    },
    &(AnimationEntry[]){
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
    },
    &(AnimationEntry[]){
        {0, 0, 0,  1},
        {0, 0, 0,  0},
        {0, 0, 4,  0},
        {0, 0, 4,  0},
        {0, 0, 8,  0},
        {0, 0, 8,  0},
        {0, 0, 12, 0},
        {0, 0, 12, 1},
    },
};

AnimationEntry *btn_animation_ab[] = {
    &(AnimationEntry[]){
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 1, 0, 0},
        {0, 1, 0, 0},
        {0, 2, 0, 0},
        {0, 2, 0, 0},
        {0, 2, 0, 0},
        {0, 2, 0, 0},
    },
    &(AnimationEntry[]){
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
    },
    &(AnimationEntry[]){
        {0, 0, 0,  1},
        {0, 0, 0,  1},
        {0, 0, 0,  0},
        {0, 0, 0,  0},
        {0, 0, 16, 0},
        {0, 0, 16, 0},
        {0, 0, 32, 0},
        {0, 0, 32, 1},
    },
};

AnimationEntry *btn_animation_startselect[] = {
    &(AnimationEntry[]){
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 2, 0},
        {0, 0, 2, 0},
        {0, 0, 2, 0},
        {0, 0, 2, 0},
        {0, 0, 2, 0},
        {0, 0, 2, 0},
    },
    &(AnimationEntry[]){
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
    },
    &(AnimationEntry[]){
        {0, 0, 0, 1},
        {0, 0, 4, 0},
        {0, 0, 4, 0},
        {0, 0, 8, 0},
        {0, 0, 8, 0},
        {0, 0, 12, 0},
        {0, 0, 12, 0},
        {0, 0, 12, 1},
    },
};

typedef struct ButtonSprite {
    ObjState *sprites;
    AnimationEntry **animations;
    size_t frame;
    size_t n_obj;
    size_t n_frames;
    BtnState state;
} ButtonSprite;

void
init_button_sprite(ButtonSprite *btn) {
    for (size_t i = 0; i < btn->n_obj; ++i) {
        btn->sprites[i].id = load_packed_sprite_data(
                btn->sprites[i].data,
                btn->sprites[i].n_tiles,
                btn->sprites[i].frames);
        btn->sprites[i].base_tile = sprites[btn->sprites[i].id].tile_start;
    }
}

void
button_tick(ButtonSprite *btn) {
    // Nothing to do here.
    if (btn->state == BTN_STATE_IDLE) {
        return;
    }

    // Reset animation state.
    if (btn->state == BTN_STATE_PRESSED && btn->frame != 0) {
        btn->frame = 0;
    }

    // Continue the animation.
    if (btn->state == BTN_STATE_HOLD || btn->state == BTN_STATE_PRESSED ) {
        if(btn->frame < btn->n_frames - 1) {
            btn->frame++;
        }
    }

    // Finish the animation and return to idle.
    if (btn->state == BTN_STATE_RELEASED) {
        if (btn->frame > 0 && btn->frame < btn->n_frames - 1) {
            btn->frame++;
        } else {
            btn->frame = 0;
            btn->state = BTN_STATE_IDLE;
        }
    }
    for (size_t i = 0; i < btn->n_obj; ++i) {
        AnimationEntry anim_frame = btn->animations[i][btn->frame];
        int x = btn->sprites[i].x + anim_frame.x_offset;
        int y = btn->sprites[i].y + anim_frame.y_offset;
        int base_tile = btn->sprites[i].base_tile + anim_frame.tile_offset;

        // Clear the previous x/y coordinate and base tiles.
        btn->sprites[i].obj_attr_0 &= ~0xFF;
        btn->sprites[i].obj_attr_1 &= ~0x1FF;
        btn->sprites[i].obj_attr_2 &= ~0x3FF;

        // Update x/y/tile and hidden state from the animations.
        btn->sprites[i].obj_attr_0 |= OBJ_Y_COORD(y);
        btn->sprites[i].obj_attr_1 |= OBJ_X_COORD(x);
        btn->sprites[i].obj_attr_2 |= base_tile;
        if (anim_frame.hidden) {
            btn->sprites[i].obj_attr_0 |= OBJ_HIDDEN;
        } else {
            btn->sprites[i].obj_attr_0 &= ~OBJ_HIDDEN;
        }

        // Update OBJ attributes.
        OBJ_ATTR_0(btn->sprites[i].id) = btn->sprites[i].obj_attr_0;
        OBJ_ATTR_1(btn->sprites[i].id) = btn->sprites[i].obj_attr_1;
        OBJ_ATTR_2(btn->sprites[i].id) = btn->sprites[i].obj_attr_2;
    }
}

ButtonSprite buttons[] = {
    // DOWN.
    {
        .frame = 0,
        .n_obj = 3,
        .n_frames = 8,
        .state = BTN_STATE_RELEASED,
        .animations = &btn_animation,
        .sprites = &(ObjState[]){
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16,
                .y = SCREEN_HEIGHT / 2 + 29,
                .data = &gba_btn_updown_data,
                .n_tiles = 4,
                .frames = 1,
                .obj_attr_0 = 0,
                .obj_attr_1 = OBJ_V_FLIP | OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16,
                .y = SCREEN_HEIGHT / 2 + 29 + 11,
                .data = &gba_btn_down_shadow_data,
                .n_tiles = 2,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16 - 8,
                .y = SCREEN_HEIGHT / 2 + 29 + 17,
                .data = &gba_btn_fx_downup,
                .n_tiles = 4,
                .frames = 4,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
        },
    },
    // UP.
    {
        .frame = 0,
        .n_obj = 3,
        .n_frames = 8,
        .state = BTN_STATE_RELEASED,
        .animations = &btn_animation,
        .sprites = &(ObjState[]){
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16,
                .y = SCREEN_HEIGHT / 2 + 32 - 18,
                .data = &gba_btn_updown_data,
                .n_tiles = 4,
                .frames = 1,
                .obj_attr_0 = 0,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16,
                .y = SCREEN_HEIGHT / 2 + 32 - 18 + 7,
                .data = &gba_btn_up_shadow_data,
                .n_tiles = 2,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16 - 8,
                .y = SCREEN_HEIGHT / 2 + 32 - 18 - 7,
                .data = &gba_btn_fx_downup,
                .n_tiles = 4,
                .frames = 4,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_V_FLIP | OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
        },
    },
    // LEFT
    {
        .frame = 0,
        .n_obj = 3,
        .n_frames = 8,
        .state = BTN_STATE_RELEASED,
        .animations = &btn_animation,
        .sprites = &(ObjState[]){
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16 - 10,
                .y = SCREEN_HEIGHT / 2 + 32 - 10,
                .data = &gba_btn_leftright_data,
                .n_tiles = 4,
                .frames = 1,
                .obj_attr_0 = 0,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16 - 10,
                .y = SCREEN_HEIGHT / 2 + 32 - 10 + 6,
                .data = &gba_btn_leftright_shadow_data,
                .n_tiles = 2,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16 - 10 - 6,
                .y = SCREEN_HEIGHT / 2 + 32 - 10 - 8,
                .data = &gba_btn_fx_leftright,
                .n_tiles = 4,
                .frames = 4,
                .obj_attr_0 = OBJ_SHAPE_TALL,
                .obj_attr_1 = OBJ_H_FLIP | OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
        },
    },
    // RIGHT.
    {
        .frame = 0,
        .n_obj = 3,
        .n_frames = 8,
        .state = BTN_STATE_RELEASED,
        .animations = &btn_animation,
        .sprites = &(ObjState[]){
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16 + 11,
                .y = SCREEN_HEIGHT / 2 + 32 - 10,
                .data = &gba_btn_leftright_data,
                .n_tiles = 4,
                .frames = 1,
                .obj_attr_0 = 0,
                .obj_attr_1 = OBJ_H_FLIP | OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16 + 11,
                .y = SCREEN_HEIGHT / 2 + 32 - 10 + 6,
                .data = &gba_btn_leftright_shadow_data,
                .n_tiles = 2,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_H_FLIP | OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 16 + 11 + 14,
                .y = SCREEN_HEIGHT / 2 + 32 - 10 - 8,
                .data = &gba_btn_fx_leftright,
                .n_tiles = 4,
                .frames = 4,
                .obj_attr_0 = OBJ_SHAPE_TALL,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
        },
    },
    // L.
    {
        .frame = 0,
        .n_obj = 3,
        .n_frames = 8,
        .state = BTN_STATE_RELEASED,
        .animations = &btn_animation,
        .sprites = &(ObjState[]){
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 28,
                .y = SCREEN_HEIGHT / 2 - 32 - 20,
                .data = &gba_btn_l_data,
                .n_tiles = 2,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 28,
                .y = SCREEN_HEIGHT / 2 - 32 - 20 + 2,
                .data = &gba_btn_lr_shadow_data,
                .n_tiles = 2,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 64 - 28 - 12,
                .y = SCREEN_HEIGHT / 2 - 32 - 20 - 12,
                .data = &gba_btn_fx_lr,
                .n_tiles = 4,
                .frames = 4,
                .obj_attr_0 = OBJ_SHAPE_SQUARE,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
        },
    },
    // R.
    {
        .frame = 0,
        .n_obj = 3,
        .n_frames = 8,
        .state = BTN_STATE_RELEASED,
        .animations = &btn_animation,
        .sprites = &(ObjState[]){
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 + 32 + 20 + 24,
                .y = SCREEN_HEIGHT / 2 - 32 - 20,
                .data = &gba_btn_r_data,
                .n_tiles = 2,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 + 32 + 20 + 24,
                .y = SCREEN_HEIGHT / 2 - 32 - 20 + 2,
                .data = &gba_btn_lr_shadow_data,
                .n_tiles = 2,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 + 32 + 20 + 12 + 24,
                .y = SCREEN_HEIGHT / 2 - 32 - 20 - 12,
                .data = &gba_btn_fx_lr,
                .n_tiles = 4,
                .frames = 4,
                .obj_attr_0 = OBJ_SHAPE_SQUARE,
                .obj_attr_1 = OBJ_H_FLIP | OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
        },
    },
    // A.
    {
        .frame = 0,
        .n_obj = 3,
        .n_frames = 8,
        .state = BTN_STATE_RELEASED,
        .animations = &btn_animation_ab,
        .sprites = &(ObjState[]){
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 + 32 + 20 + 20,
                .y = SCREEN_HEIGHT / 2 + 32 - 16,
                .data = &gba_btn_a_data,
                .n_tiles = 4,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_SQUARE,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 + 32 + 20 + 20,
                .y = SCREEN_HEIGHT / 2 + 32 - 16 + 8,
                .data = &gba_btn_ab_shadow_data,
                .n_tiles = 2,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 + 32 + 19 - 7 + 20,
                .y = SCREEN_HEIGHT / 2 + 32 - 23,
                .data = &gba_btn_fx_ab,
                .n_tiles = 16,
                .frames = 3,
                .obj_attr_0 = OBJ_SHAPE_SQUARE,
                .obj_attr_1 = OBJ_SIZE_BIG,
                .obj_attr_2 = 0
            },
        },
    },
    // B.
    {
        .frame = 0,
        .n_obj = 3,
        .n_frames = 8,
        .state = BTN_STATE_RELEASED,
        .animations = &btn_animation_ab,
        .sprites = &(ObjState[]){
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 + 32 + 20,
                .y = SCREEN_HEIGHT / 2 + 32,
                .data = &gba_btn_b_data,
                .n_tiles = 4,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_SQUARE,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 + 32 + 20,
                .y = SCREEN_HEIGHT / 2 + 32 + 8,
                .data = &gba_btn_ab_shadow_data,
                .n_tiles = 2,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 + 32 - 8 + 20,
                .y = SCREEN_HEIGHT / 2 + 33 + 8 - 16,
                .data = &gba_btn_fx_ab,
                .n_tiles = 16,
                .frames = 3,
                .obj_attr_0 = OBJ_SHAPE_SQUARE,
                .obj_attr_1 = OBJ_SIZE_BIG,
                .obj_attr_2 = 0
            },
        },
    },
    // START.
    {
        .frame = 0,
        .n_obj = 3,
        .n_frames = 8,
        .state = BTN_STATE_RELEASED,
        .animations = &btn_animation_startselect,
        .sprites = &(ObjState[]){
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 10 + 26 - 14,
                .y = SCREEN_HEIGHT / 2 + 40 + 10,
                .data = &gba_btn_startselect_data,
                .n_tiles = 2,
                .frames = 2,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 18 + 26 - 14,
                .y = SCREEN_HEIGHT / 2 + 46 + 10,
                .data = &gba_btn_start_text,
                .n_tiles = 4,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 19 + 26 - 14,
                .y = SCREEN_HEIGHT / 2 + 37 + 10,
                .data = &gba_btn_fx_startselect,
                .n_tiles = 4,
                .frames = 4,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
        },
    },
    // SELECT.
    {
        .frame = 0,
        .n_obj = 3,
        .n_frames = 8,
        .state = BTN_STATE_RELEASED,
        .animations = &btn_animation_startselect,
        .sprites = &(ObjState[]){
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 10 - 14,
                .y = SCREEN_HEIGHT / 2 + 40 + 10,
                .data = &gba_btn_startselect_data,
                .n_tiles = 2,
                .frames = 2,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_SMALL,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 18 - 14,
                .y = SCREEN_HEIGHT / 2 + 46 + 10,
                .data = &gba_btn_select_text,
                .n_tiles = 4,
                .frames = 1,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
            {
                .id = 0,
                .x = SCREEN_WIDTH / 2 - 19 - 14,
                .y = SCREEN_HEIGHT / 2 + 37 + 10,
                .data = &gba_btn_fx_startselect,
                .n_tiles = 4,
                .frames = 4,
                .obj_attr_0 = OBJ_SHAPE_WIDE,
                .obj_attr_1 = OBJ_SIZE_MID,
                .obj_attr_2 = 0
            },
        },
    },
};

static inline void
init_button_sprites(void) {
    for (size_t i = 0; i < sizeof(buttons) / sizeof(ButtonSprite); ++i) {
        init_button_sprite(&buttons[i]);
    }
}

static inline void
update_button_sprites(void) {
    if (key_pressed(KEY_DOWN)) {
        buttons[0].state = BTN_STATE_PRESSED;
    } else if (key_hold(KEY_DOWN)) {
        buttons[0].state = BTN_STATE_HOLD;
    } else {
        buttons[0].state = BTN_STATE_RELEASED;
    }
    if (key_pressed(KEY_UP)) {
        buttons[1].state = BTN_STATE_PRESSED;
    } else if (key_hold(KEY_UP)) {
        buttons[1].state = BTN_STATE_HOLD;
    } else {
        buttons[1].state = BTN_STATE_RELEASED;
    }
    if (key_pressed(KEY_LEFT)) {
        buttons[2].state = BTN_STATE_PRESSED;
    } else if (key_hold(KEY_LEFT)) {
        buttons[2].state = BTN_STATE_HOLD;
    } else {
        buttons[2].state = BTN_STATE_RELEASED;
    }
    if (key_pressed(KEY_RIGHT)) {
        buttons[3].state = BTN_STATE_PRESSED;
    } else if (key_hold(KEY_RIGHT)) {
        buttons[3].state = BTN_STATE_HOLD;
    } else {
        buttons[3].state = BTN_STATE_RELEASED;
    }
    if (key_pressed(KEY_L)) {
        buttons[4].state = BTN_STATE_PRESSED;
    } else if (key_hold(KEY_L)) {
        buttons[4].state = BTN_STATE_HOLD;
    } else {
        buttons[4].state = BTN_STATE_RELEASED;
    }
    if (key_pressed(KEY_R)) {
        buttons[5].state = BTN_STATE_PRESSED;
    } else if (key_hold(KEY_R)) {
        buttons[5].state = BTN_STATE_HOLD;
    } else {
        buttons[5].state = BTN_STATE_RELEASED;
    }
    if (key_pressed(KEY_A)) {
        buttons[6].state = BTN_STATE_PRESSED;
    } else if (key_hold(KEY_A)) {
        buttons[6].state = BTN_STATE_HOLD;
    } else {
        buttons[6].state = BTN_STATE_RELEASED;
    }
    if (key_pressed(KEY_B)) {
        buttons[7].state = BTN_STATE_PRESSED;
    } else if (key_hold(KEY_B)) {
        buttons[7].state = BTN_STATE_HOLD;
    } else {
        buttons[7].state = BTN_STATE_RELEASED;
    }
    if (key_pressed(KEY_START)) {
        buttons[8].state = BTN_STATE_PRESSED;
    } else if (key_hold(KEY_START)) {
        buttons[8].state = BTN_STATE_HOLD;
    } else {
        buttons[8].state = BTN_STATE_RELEASED;
    }
    if (key_pressed(KEY_SELECT)) {
        buttons[9].state = BTN_STATE_PRESSED;
    } else if (key_hold(KEY_SELECT)) {
        buttons[9].state = BTN_STATE_HOLD;
    } else {
        buttons[9].state = BTN_STATE_RELEASED;
    }

    for (size_t i = 0; i < sizeof(buttons) / sizeof(ButtonSprite); ++i) {
        button_tick(&buttons[i]);
    }
}