#ifndef VM_PAGE_H
#define VM_PAGE_H

#include "threads/thread.h"
#include "threads/synch.h"
#include "filesys/off_t.h"

enum page_type
{
  PAGE_FILE,
  PAGE_MMAP,
  PAGE_EMPTY,
  PAGE_SHARED
};

struct page_entry
{
  enum page_type type; /* Type of Data that should go into the page */
  void *upage;         /* Start Address of the User Page (Key of hash table). */

  /* Data for swapped pages */
  struct lock lock;    /* Enforces mutual exclusion in accessing the page
                          referenced by the entry between its owning process
                          and any thread performing page eviction. */

  /* File Data */
  struct file *file;   /* Pointer to the file for executables. */
  off_t offset;        /* Offset of the page content within the file. */
  uint32_t read_bytes; /* Number of bytes to read within the page. */
  uint32_t zero_bytes; /* Number of bytes to zero within the page. */
  bool writable;       /* Flag for whether this page is writable or not. */

  struct hash_elem elem; /* An elem for the hash table. */
};

struct shared_file_page
{
  struct file *file;
  void *upage;
  void *frame;
  size_t swap_slot;
  int ref_count;

  struct hash_elem elem;
};

bool init_pages (struct hash *pages);
bool page_insert_swapped (void *upage, void *kpage, struct list *owners);
struct page_entry *page_insert_file (struct file *file, off_t ofs, void *upage,
                                     uint32_t read_bytes, uint32_t zero_bytes,
                                     bool writable, enum page_type);
struct page_entry *page_get (void *upage);
bool page_load_file (struct page_entry *page);
void page_cleanup (struct hash_elem *e, void *aux);

bool page_in_swap (struct thread *, void *);
bool page_in_swap_pte (uint32_t *pte);
size_t page_get_swap (struct thread *owner, void *upage);
size_t page_get_swap_pte (uint32_t *pte);

bool page_is_shared_pte (uint32_t *pte);
void shared_file_pages_init (void);

#endif