#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <dirent.h>
#include <unistd.h>

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <time.h>

char *match = "0123456789";
char *charp;

void renamer(char*, char*, char*);
int selection(const struct dirent *);
extern char **environ;
char **envpoint;

int main(argc, argv, envp) 
int argc;
char *argv[];
char *envp[];
{
	int dv;
	struct dirent **namelist;
	struct stat *buf = malloc(sizeof(struct stat));
	struct tm *timebuf;
	char newfilenamebuf[100];
	char *newfilename = newfilenamebuf;
	char *extension;
	char *directory;
	char *pathname;

	// = malloc(sizeof(struct tm));
	int n;
	int i;
	char *filename;
	envpoint = envp;

	directory=argv[1];
	dv = strlen(directory);

	// change this to support longer filenames
	pathname=malloc(512 + dv);
	strcpy(pathname, directory);

	n = scandir(directory, &namelist, selection, alphasort);
	if (n < 0) {
		perror("scandir");
		return EXIT_FAILURE;
	}
	for (i = 0; i < n; i++) {
		filename = namelist[i]->d_name;
		strcpy(pathname + dv, filename);
		stat(pathname, buf);
		// printf("--> %s mode %d\n", filename, buf->st_mode);
		// if (S_ISREG(buf->st_mode)) {
		extension = rindex(filename, '.');
		timebuf = gmtime(&buf->st_mtime);

		if (extension != NULL) {
			sprintf(newfilename, "%s%02u-%02u-%02u-%02u-%02u-%02u%s", directory, 1900 + timebuf->tm_year, \
				1 + timebuf->tm_mon, timebuf->tm_mday, timebuf->tm_hour, \
				timebuf->tm_min, timebuf->tm_sec, extension);

			if (strcmp(extension, ".mp3") == 0) {
				renamer(pathname, newfilename, filename);
			}
		}
		// }
		free(namelist[i]);
	}
	free(namelist);
	return EXIT_SUCCESS;
}

// choose only files that don't start with numbers
int selection(const struct dirent *file) {
	if (index(match, (file->d_name)[0]) == 0) {
		return 1;
	}
	return 0;
}

// do the actual renaming
void renamer(char *old, char *new, char *tag) {
	int f;
	int pid;
	printf("Change %s to %s tag as %s\r\n", old, new, tag);

	rename(old, new);

	pid = fork();
	if (pid == 0) {
		char *argv[5];
		argv[0]="id3v2";
		argv[1]="--song";
		argv[2]=tag;
		argv[3]=new;
		argv[4]=0;
		f = execve("/usr/bin/id3v2", argv, envpoint);
		perror("id3v2");
		exit(127);
	}
	waitpid(pid, NULL, 0);
}