/*
	highscore-lib-centralized.c -- Hiscore Library for centralized systems.
	Created on: 2008/11/28 11:45:58
	~yas/dsys/highscore/centralized/highscore-lib-centralized.c
*/

#include <fcntl.h>	/* open() */
#include <sys/types.h>	/* fstat() */
#include <sys/stat.h>	/* fstat() */
#include <string.h>	/* memcpy(), memset() */
#include <stdio.h>	/* snprintf(), perror() */
#include <stdlib.h>	/* getenv() */
#include <sys/file.h>

#include "highscore.h"

static int insert_score( score_record_t records[], int len, int nelement,
			 int score, char *user );
static int find_posision( score_record_t records[], int len, int nelement,
			  int score );

int get_highscore(score_record_t records[], int len) {
    int fd;
    struct stat stat;
    ssize_t bytes;
    char *filename;

	if( (filename=getenv(HIGHSCORE_FILE_ENV)) == NULL ) {
	    fprintf(stdout,"No environment: %s\n",HIGHSCORE_FILE_ENV );
	    return( 0 );
	}
    	if( (fd = open(filename,O_RDONLY)) < 0 ) {
	    perror( filename );
	    return( 0 );
	}
	if( flock(fd,LOCK_SH) < 0 ) {
	    perror("flock");
	    goto error0;
	}
	if( fstat(fd,&stat) < 0 ) {
	    perror("fstat");
	    goto error1;
	}
	bytes = (stat.st_size <= len*sizeof(score_record_t)) ?
		 stat.st_size :  len*sizeof(score_record_t) ;
	if( read(fd, records, bytes)!=bytes ) {
	    perror("read");
	    goto error1;
	}
	if( flock(fd,LOCK_UN) < 0 ) {
	    perror("flock");
	    goto error0;
	}
	close( fd );
	return( bytes/sizeof(score_record_t) );

error1:	flock( fd,LOCK_UN );
error0:	close( fd );
	return( 0 );
}

int put_score(int score, char *user) {
    int fd, n;
    struct stat stat;
    ssize_t bytes;
    off_t offset ;
    score_record_t records[HIGHSCORE_MAX_RECORDS];
    char *filename;

	if( (filename=getenv(HIGHSCORE_FILE_ENV)) == NULL ) {
	    fprintf(stdout,"No environment: %s\n",HIGHSCORE_FILE_ENV );
	    return( 0 );
	}
    	if( (fd = open( filename,O_RDWR|O_CREAT, 0666)) < 0 ) {
	    perror( filename );
	    return( 0 );
	}
	if( flock(fd,LOCK_EX) < 0 ) {
	    perror("flock");
	    goto error0;
	}
	if( fstat(fd,&stat) < 0 ) {
	    perror("fstat");
	    goto error1;
	}
	bytes = (stat.st_size <= HIGHSCORE_MAX_RECORDS*sizeof(score_record_t))?
		 stat.st_size  : HIGHSCORE_MAX_RECORDS*sizeof(score_record_t) ;
	if( read(fd, records, bytes)!=bytes ) {
	    perror("read");
	    goto error1;
	}

	n = insert_score( records,HIGHSCORE_MAX_RECORDS,bytes/sizeof(score_record_t),
			  score, user );

	if( n > 0 ) {
	    offset = 0L;
	    if( lseek( fd, offset, SEEK_SET )< 0 ) {
		perror("lseek");
	    	goto error1;
	    }
	    bytes = n * sizeof(score_record_t);
	    if( write(fd, records, bytes)!=bytes ) {
		perror("write");
	    	goto error1;
	    }
	}
	
	if( flock(fd,LOCK_UN) < 0 )  {
	    perror("flock");
	    goto error1;
	}
	close( fd );
	return( 1 );

error1:	flock( fd,LOCK_UN );
error0:	close( fd );
	return( 0 );
}

static int insert_score( score_record_t records[], int len, int nelement,
			 int score, char *user ) {
    int pos, copy_records;
    	pos  = find_posision( records, len, nelement, score );
	if( pos < 0 )
	    return( -1 );
	if( nelement == len )
	    copy_records = nelement - pos - 1;
	else
	    copy_records = nelement - pos ;
	memcpy( &records[pos+1], &records[pos],
		copy_records*sizeof(score_record_t) );
	memset( &records[pos], 0, sizeof(score_record_t) );
	records[pos].score = score ;
	snprintf( records[pos].name, HIGHSCORE_NAME_LEN, "%s", user );
	return( nelement == len ? nelement : nelement+1 );
}

static int find_posision( score_record_t records[], int len, int nelement,
			  int score ) {
    score_record_t *pos;
    int i;
    	for( i=0; i<nelement; i++ ) {
	    if( records[i].score <= score )
		return( i );
	}
	return( len == nelement ? -1 : nelement );
}