Decompiled main function of refreshments CTF challenge

refreshments.c

void main()
{
    void* fsbase;
    int64_t var_20 = *(uint64_t*)((char*)fsbase + 0x28);
    setup();
    banner();
    int64_t s;
    __builtin_memset(&s, 0, 0x50);
    char var_81 = 0;
    
    while (true)
    {
        printf(&data_4025a0, (uint64_t)(int32_t)var_81);
        int64_t rax_5 = read_num();
        
        if (rax_5 == 4)
        {
            printf("\nChoose glass: ");
            int64_t rax_34 = read_num();
            
            if (rax_34 >= (int64_t)var_81)
                error("This glass is unavailable!");
            else if ((&s)[rax_34])
            {
                printf("\nGlass content: ");
                write(1, (&s)[rax_34], 0x58);
                putchar(0xa);
            }
            else
                error("Cannot view empty glass!");
        }
        else
        {
            if (rax_5 == 3)
            {
                printf("\nChoose glass to customize: ");
                int64_t rax_25 = read_num();
                
                if (rax_25 >= (int64_t)var_81)
                {
                    error("This glass is unavailable!");
                    continue;
                }
                else if ((&s)[rax_25])
                {
                    printf("\nAdd another drink: ");
                    read(0, (&s)[rax_25], 0x59);
                    putchar(0xa);
                    continue;
                }
                else
                {
                    error("Cannot customize empty glass!");
                    continue;
                }
            }
            else
            {
                if (rax_5 == 1)
                {
                    if (var_81 > 0xf)
                    {
                        error("You cannot take any more glasses…");
                        exit(0x45);
                    }
                    else
                    {
                        (&s)[(int64_t)var_81] = calloc(1, 0x58);
                        
                        if ((&s)[(int64_t)var_81])
                        {
                            var_81 += 1;
                            printf("\nHere is your refreshing juice!…");
                            continue;
                        }
                        else
                        {
                            error("Something went wrong with the ju…");
                            continue;
                        }
                    }
                    
                    goto label_401622;
                }
                
                if (rax_5 == 2)
                {
                    label_401622:
                    printf("\nChoose glass to empty: ");
                    int64_t rax_16 = read_num();
                    
                    if (rax_16 >= (int64_t)var_81)
                    {
                        error("This glass is unavailable!");
                        continue;
                    }
                    else if ((&s)[rax_16])
                    {
                        free((&s)[rax_16]);
                        (&s)[rax_16] = 0;
                        puts("\nGlass is empty now!\n");
                        continue;
                    }
                    else
                    {
                        error("This glass is already empty!");
                        continue;
                    }
                }
            }
            
            error("Have a great day!\n");
            exit(0x45);
        }
    }
}