#include "userprog/syscall.h"
#include <stdio.h>
#include <syscall-nr.h>
#include "threads/interrupt.h"
#include "threads/thread.h"
#include "threads/vaddr.h"
#include "filesys/file.h"

struct file_des{
  struct list_elem elem;
  int fd;
  struct file *fd_file;
};


void shutdown_power_off(void);
uint8_t input_getc (void);
struct file *filesys_open (const char *name);

struct list fd_list;

static bool
is_in(int x){
  struct list_elem *e;
  for (e = list_begin (&fd_list); e != list_end (&fd_list);
           e = list_next (e))
  {
        struct file_des *f = list_entry (e, struct file_des, elem);
        if (f->fd == x) {
            return true;
        }else{
            return false;
        }

  }
  return false;
}

static struct file_des *
find_fd(uint8_t fd){
  struct list_elem *e;
  for(e = list_begin (&fd_list); e != list_end (&fd_list); e = list_next(e)){
    struct file_des *f = list_entry (e, struct file_des, elem);
    if (f->fd == fd){
      return f;
    }else{
      return NULL;
    }
  }
  return NULL;
}

/* Reads a byte at user virtual address UADDR.
   UADDR must be below PHYS_BASE.
   Returns the byte value if successful, -1 if a segfault
   occurred. */
static int
get_user (const uint8_t *uaddr)
{
  static int result;
  asm ("movl $1f, %0; movzbl %1, %0; 1:"
       : "=&a" (result) : "m" (*uaddr));
  return result;
}

/* Writes BYTE to user address UDST.
   UDST must be below PHYS_BASE.
   Returns true if successful, false if a segfault occurred. */
static bool
put_user (uint8_t *udst, uint8_t byte)
{
  int error_code;
  asm ("movl $1f, %0; movb %b2, %1; 1:"
       : "=&a" (error_code), "=m" (*udst) : "q" (byte));
  return error_code != -1;
}

static void syscall_handler (struct intr_frame *);

void
syscall_init (void)
{
  intr_register_int (0x30, 3, INTR_ON, syscall_handler, "syscall");
  //list_init(&fd_list);
  printf("saldfjlsdf\n");
}

static void
syscall_handler (struct intr_frame *f UNUSED)
{
  printf("sys init\n");

  uint8_t *stack_ptr = (uint8_t *) f->esp;
  //retreive return pointer
  uint8_t *return_val = (uint8_t *) f->eax;
  //retreive sys call number
  int sys_num = -1;

  if ((uint32_t)stack_ptr < (uint32_t)PHYS_BASE){
    printf("successful stack_ptr\n");
    sys_num = get_user(stack_ptr);
  }else{
    printf("Invalid User Address\n");
    thread_exit();
  }
  printf("Pass initial life\n");
  if (sys_num == SYS_EXIT){
    printf("Thread suceesfully exit\n");
    thread_exit();
  }
  printf("Bye Bye\n");
  thread_exit();

  // if (sys_num == SYS_READ){
  //   stack_ptr--;
  //   int fd = get_user(stack_ptr);
  //   stack_ptr--;
  //   char *buf = (char *) get_user(stack_ptr);
  //   stack_ptr--;
  //   unsigned int size = get_user(stack_ptr);

  //   if (fd == 0){
  //     for (unsigned int i = 0; i < size; i++){
  //       buf[i] = input_getc();
  //     }
  //     put_user(return_val, size);

  //   }else{
  //     struct file_des *get_fd = find_fd(fd);
  //     unsigned int size_c = 0;
  //     while(size_c <= size){
  //       size_c+=file_read(get_fd->fd_file, buf, size_c);
  //     }
  //   }

  // }

  // if (sys_num == SYS_OPEN){
  //   stack_ptr--;
  //   char* file_name = (char *) get_user(stack_ptr);
  //   int finding_fd = 2;

  //   while (is_in(finding_fd)) {
  //     finding_fd++;
  //   }

  //   struct file_des adding_file;
  //   adding_file.fd = finding_fd;
  //   adding_file.fd_file = (struct file*)filesys_open(file_name);
  //   list_insert(list_end(&fd_list),&adding_file.elem);
  //   put_user(return_val, finding_fd);
  // }

  // if (sys_num == SYS_WRITE){
  //   stack_ptr--;
  //   int fd = get_user(stack_ptr);
  //   stack_ptr--;
  //   char *buf = (char *) get_user(stack_ptr);
  //   stack_ptr--;
  //   unsigned int size = get_user(stack_ptr);
  //   //find file descriptor in the list
  //   if (fd == 1){
  //     putbuf(buf, size);
  //     put_user(return_val, size);
  //   }else{
  //     struct file_des *get_fd = find_fd(fd);
  //     unsigned int size_c = 0;
  //     while(size_c <= size){
  //       size_c+=file_write(get_fd->fd_file, buf, size_c);
  //     }
  //     put_user(return_val, size_c);
  //   }

  // }

  // if (sys_num == SYS_CLOSE){

  // }
}