#define _POSIX_C_SOURCE 2

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <sys/stat.h>
#include <pwd.h>
#include <linux/limits.h>

#define RC_OK 0
#define RC_ERROR -1

static const char* _err_invalid_arg = "nebyl zadán platný soubor";

static int get_command_output_line(const char* cmd,
	char* outbuff, size_t bufsize)
{
	FILE* pf = popen(cmd, "r");
	if (NULL == pf) {
		return RC_ERROR;
	}
	int retval = RC_OK;
	if (!feof(pf)) {
		if (NULL == fgets(outbuff, bufsize, pf)) {
			*outbuff = 0;
			retval = RC_ERROR;
		}
	}
	else
		retval = RC_ERROR;
	pclose(pf);
	char* pnl = strrchr(outbuff, '\n');
	if (pnl)
		*pnl = 0;
	return retval;
}

static int get_mime_type(const char* file_path,
	char* outbuff, size_t buffsize)
{
	char* cmdbuff = (char*)malloc(strlen(file_path) + 64);
	if (NULL == cmdbuff)
		abort();
	strcpy(cmdbuff, "xdg-mime query filetype \"");
	strcat(cmdbuff, file_path);
	strcat(cmdbuff, "\"");
	if (RC_OK != get_command_output_line(cmdbuff, outbuff, buffsize)) {
		free(cmdbuff);
		return RC_ERROR;
	}
	free(cmdbuff);
	return RC_OK;
}

static int get_app_name(const char* desktop_file,
	char* outbuff, size_t buffsize)
{
	char filepath[PATH_MAX];
	strcpy(filepath, "/usr/share/applications/");
	strncat(filepath, desktop_file, sizeof(filepath) - strlen(filepath) - 1);
	FILE* pf = fopen(filepath, "r");
	if (NULL == pf)
		return RC_ERROR;
	char line[512];
	*outbuff = 0;
	while (fgets(line, sizeof(line), pf)) {
		if (sscanf(line, "Name=%s", outbuff) == 1)
			break;
	}
	fclose(pf);
	return (0 == *outbuff) ? RC_ERROR : RC_OK;
}

static int get_mime_opener(const char* mimetype,
	char* outbuff, size_t buffsize)
{
	char cmdbuff[256];
	strcpy(cmdbuff, "xdg-mime query default ");
	strncat(cmdbuff, mimetype, sizeof(cmdbuff) - strlen(cmdbuff) - 1);
	return get_command_output_line(cmdbuff, outbuff, buffsize);
}

static int show_file_info(const char* file_path)
{
	struct stat fst;
	char buff[256];
	struct passwd* pwd;
	if (0 != stat(file_path, &fst)) {
		return errno;
	}
	printf("velikost: %lu MiB (%lu bytů)\n",
		fst.st_size / 1024 / 1024, fst.st_size);
	printf("na disku: %lu MiB (%lu bytů)\n",
		(fst.st_blocks * 512) / 1024 / 1024, fst.st_blocks * 512);
	printf("pevných odkazů: %lu\n", fst.st_nlink);
	strftime(buff, sizeof(buff), "poslední přístup: %d.%m.%Y %H:%M:%S",
		localtime((const time_t*)&fst.st_atime));
	puts(buff);
	strftime(buff, sizeof(buff), " poslední úprava: %d.%m.%Y %H:%M:%S",
		localtime((const time_t*)&fst.st_mtime));
	puts(buff);
	strftime(buff, sizeof(buff), "     změna stavu: %d.%m.%Y %H:%M:%S",
		localtime((const time_t*)&fst.st_ctime));
	puts(buff);
	char permission[4];
	unsigned int uperm;
	uperm = 100 * (0x7 & (fst.st_mode >> 6)) +
		10 * (0x7 & (fst.st_mode >> 3)) +
		(0x7 & fst.st_mode);
	permission[3] = 0;
	permission[0] = (S_IRUSR & fst.st_mode) ? 'r' : '-';
	permission[1] = (S_IWUSR & fst.st_mode) ? 'w' : '-';
	permission[2] = (S_IXUSR & fst.st_mode) ? 'x' : '-';
	if ((pwd = getpwuid(fst.st_uid)) != NULL) {
		printf("vlastník: %s (%d)\n", pwd->pw_name, pwd->pw_uid);
	}
	else {
		printf("User ID: %u\n", fst.st_uid);
	}
	printf("oprávnění: %u\n", uperm);
	printf("uživatel: %s", permission);
	permission[0] = (S_IRGRP & fst.st_mode) ? 'r' : '-';
	permission[1] = (S_IWGRP & fst.st_mode) ? 'w' : '-';
	permission[2] = (S_IXGRP & fst.st_mode) ? 'x' : '-';
	printf("  skupina: %s", permission);
	permission[0] = (S_IROTH & fst.st_mode) ? 'r' : '-';
	permission[1] = (S_IWOTH & fst.st_mode) ? 'w' : '-';
	permission[2] = (S_IXOTH & fst.st_mode) ? 'x' : '-';
	printf("  ostatní: %s\n", permission);
	if (RC_OK == get_mime_type(file_path, buff, sizeof(buff))) {
		printf("mime typ: %s\n", buff);
		if (RC_OK == get_mime_opener(buff, buff, sizeof(buff))) {
			printf("výchozí aplikace: %s", buff);
			if (RC_OK == get_app_name(buff, buff, sizeof(buff))) {
				printf(" (%s)", buff);
			}
			printf("\n");
		}
	}
	printf("\nstiskni enter pro ukončení...");
	getchar();
	return EXIT_SUCCESS;
}

int main(int argc, char** argv)
{
	if (argc < 2) {
		puts(_err_invalid_arg);
		return EXIT_FAILURE;
	}
	return show_file_info(argv[1]);
}