#include "file.h"

void 
file_ajoute_apres(struct file *f, struct node * ou, 
		  struct processus * p)
{
  struct node *ptr;
  NEW(ptr,struct node);
  
  ptr->content = p;

  ptr->next = ou->next;
  ptr->prev = ou;
  
  if(ou->next)
    ou->next->prev = ptr;
  else
    f->last=ptr;
  
  ou->next=ptr;
  
  f->no++;
}

void 
file_ajoute_avant(struct file *f, struct node * ou, 
		  struct processus * p)
{
  struct node *ptr;
  NEW(ptr,struct node);
  
  ptr->content = p;

  ptr->next = ou;
  ptr->prev = ou->prev;
  
  if(ou->prev)
    ou->prev->next = ptr;
  else
    f->first=ptr;
  
  ou->prev=ptr;
  
  f->no++;
}

struct processus *
file_pop_which(struct file *f, struct node * which)
{
  struct processus * ret=which->content;

  if(which->prev)
    which->prev->next = which->next;
  else
    f->first=which->next;

  if(which->next)
    which->next->prev = which->prev;
  else
    f->last=which->prev;
  
  f->no--;
  free(which);

  return ret;
}

struct file * new_file()
{
  struct file * f;
  
  NEW(f, struct file);
  f->first=f->last=NULL;
  f->no=0;
  
  return f;
}

void file_enqueue (struct file *f, struct processus *p)
{
  struct node * n;

  if(f->no == 0)
    {
      NEW(n,struct node);
      n->content = p;
      n->next=n->prev=NULL;
      f->no=1;
      f->first=f->last=n;
    }
  else
    file_ajoute_apres(f,f->last,p);
}

struct processus *
file_pop_how(
	     struct file *f, 
	     int (*compare)(struct processus * p1, struct processus * p2) )
{
  struct node *ptr, *least;

  if(file_is_empty(f))
    return NULL;
  
  least = f->first;

  FORALLIN(ptr,f)
    if(compare(ptr->content,least->content) < 0)
      least = ptr;
    
  return file_pop_which(f,least);
}

struct processus *
file_peek_how(
	     struct file *f, 
	     int (*compare)(struct processus * p1, struct processus * p2) )
{
  struct node *ptr, *least;

  if(file_is_empty(f))
    return NULL;
  
  least = f->first;

  FORALLIN(ptr,f)
    if(compare(ptr->content,least->content) < 0)
      least = ptr;
    
  return least->content;
}

int
file_is_empty(struct file * f)
{
  return !(f->no);
}