#include "buffer_entry.h"
#include <stdio.h>
#include <assert.h>
#include <stdlib.h>

struct __buffer_entry_t
{
	FILE *fd;
	cmph_uint8 * buff;
	cmph_uint32 capacity, // buffer entry capacity
		    nbytes,   // buffer entry used bytes
		    pos;      // current read position in buffer entry
	cmph_uint8  eof;      // flag to indicate end of file
};

buffer_entry_t * buffer_entry_new(cmph_uint32 capacity)
{
	buffer_entry_t *buff_entry = (buffer_entry_t *)malloc(sizeof(buffer_entry_t));
	assert(buff_entry);
	buff_entry->fd = NULL;
	buff_entry->buff = NULL;
	buff_entry->capacity = capacity;
	buff_entry->nbytes = capacity;
	buff_entry->pos = capacity;
        buff_entry->eof = 0;
	return buff_entry;
}

void buffer_entry_open(buffer_entry_t * buffer_entry, char * filename)
{
	buffer_entry->fd = fopen(filename, "rb");
}

void buffer_entry_set_capacity(buffer_entry_t * buffer_entry, cmph_uint32 capacity)
{
	buffer_entry->capacity = capacity;
}


cmph_uint32 buffer_entry_get_capacity(buffer_entry_t * buffer_entry)
{
	return buffer_entry->capacity;
}

void buffer_entry_load(buffer_entry_t * buffer_entry)
{
	free(buffer_entry->buff);
	buffer_entry->buff = (cmph_uint8 *)calloc(buffer_entry->capacity, sizeof(cmph_uint8));
	buffer_entry->nbytes = fread(buffer_entry->buff, 1, buffer_entry->capacity, buffer_entry->fd);
	if (buffer_entry->nbytes != buffer_entry->capacity) buffer_entry->eof = 1;
	buffer_entry->pos = 0;
}

cmph_uint8 * buffer_entry_read_key(buffer_entry_t * buffer_entry)
{
	cmph_uint8 * buf = (cmph_uint8 *)malloc(BUFSIZ);
	cmph_uint32 buf_pos = 0;
	cmph_uint8 c;
	while(1)
	{
		if(buffer_entry->eof && (buffer_entry->pos == buffer_entry->nbytes)) // end
		{
			free(buf);
			return NULL;
		}
		if(buffer_entry->pos == buffer_entry->nbytes) buffer_entry_load(buffer_entry);
		c = buffer_entry->buff[(buffer_entry->pos)++];
		buf[buf_pos++] = c;
		if(c == '\0') break;
		if(buf_pos % BUFSIZ == 0) buf = (cmph_uint8 *)realloc(buf, buf_pos + BUFSIZ);
	}
	return buf;
}

void buffer_entry_destroy(buffer_entry_t * buffer_entry)
{
  fclose(buffer_entry->fd);
  buffer_entry->fd = NULL;
  free(buffer_entry->buff);
  buffer_entry->buff = NULL;
  buffer_entry->capacity = 0;
  buffer_entry->nbytes = 0;
  buffer_entry->pos = 0;  
  buffer_entry->eof = 0;
  free(buffer_entry);
}