#include <assert.h>
#include <unistd.h>
#include <stdlib.h>

#include <debug.h>

#include "struct.h"
#include "read.h"

void file_istream_read(
    struct istream* super)
{
    ENTER;
    
    struct file_istream* this = (void*) super;
    
    if (this->i < this->n)
    {
        super->c = this->buffer[this->i++];
        
        dpvc(super->c);
    }
    else
    {
        ssize_t read_retval = read(this->fd, this->buffer, sizeof(this->buffer));
        
        if (read_retval < 0)
        {
            TODO;
        }
        else if (!read_retval)
        {
            super->c = 0;
        }
        else
        {
            this->i = 0;
            this->n = (size_t) read_retval;
            
            super->c = this->buffer[this->i++];
            
            dpvc(super->c);
        }
    }
    
    EXIT;
}