/*This is the sample program to notify us for the file creation and file deletion takes place in “/tmp” directory*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <pwd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/inotify.h>

#define EVENT_SIZE (sizeof(struct inotify_event))
#define EVENT_BUF_LEN (1024 * (EVENT_SIZE + 16))

static const char downloads_dir_default[] = "Downloads";
static char *downloads_dir;

static const char documents_dir_default[] = "Documents";
static char *documents_dir;

static int inotify_instance = -1;
static char event_buffer[EVENT_BUF_LEN];
static int watch_list;

char *get_directory(const char *param);
char *get_extension(const char *name);
void move(const char *name);

int main(int argc, char *argv[])
{
	/* Get Downloads directory Location */
	downloads_dir = get_directory("DOWNLOAD");

	/* Get Documents directory Location */
	documents_dir = get_directory("DOCUMENTS");

	/* Initialize inotify instance */
	inotify_instance = inotify_init();
	if (!inotify_instance)
		perror("Failed initializing inotify library!");

	/* Add wanted Downloads to watchlist  */
	watch_list =
		inotify_add_watch(inotify_instance, downloads_dir, IN_CREATE);
	if (!watch_list)
		perror("Failed to add downloads folder to watchlist!");

	while (1) {
		/* Get events*/
		int length =
			read(inotify_instance, event_buffer, EVENT_BUF_LEN);
		if (!length)
			perror("Failed to read inotify buffer!");

		/* Process events */
		int i = 0;
		while (i < length) {
			struct inotify_event *event =
				(struct inotify_event *)&event_buffer[i];
			if (event->len) {
				if (event->mask & IN_CREATE)
					move(event->name);
			}
			i += EVENT_SIZE + event->len;
		}
	}
	inotify_rm_watch(inotify_instance, watch_list);

	close(inotify_instance);
}

char *get_extension(const char *name)
{
	char *ext = (char *)malloc(sizeof(char));
	int ext_len = 0;
	for (int i = 0; i < strlen(name); i++) {
		if (name[i] == '.') {
			for (int j = i + 1; j < strlen(name); j++) {
				ext = (char *)realloc(ext, ++ext_len);
				ext[ext_len - 1] = name[j];
			}
			ext = (char *)realloc(ext, ++ext_len);
			ext[ext_len - 1] = '\0';
			break;
		}
	}
	return ext;
}

void move(const char *name)
{
	char *ext = get_extension(name);
	printf("Moving: %s Extension: %s\n", name, ext);
}

char *get_directory(const char *name)
{
	char *result = (char *)malloc(4096 * sizeof(char));
	FILE *xdg_cmd = NULL;
	char *cmd = (char *)malloc(20 * sizeof(char));
	sprintf(cmd, "xdg-user-dir %s", name);
	xdg_cmd = popen(cmd, "r");
	if (!xdg_cmd) {
		char *home_dir = getenv("HOME");
		if (!home_dir) {
			struct passwd *pw = getpwuid(getuid());
			if (!pw)
				perror("Failed to get home directory!");
			home_dir = pw->pw_dir;
			if (!home_dir)
				perror("Failed miserably to get a directory path!");
		}
		strcat(result, home_dir);
		strcat(result, "/");
		if (strcmp(name, "DOWNLOAD"))
			strcat(result, downloads_dir_default);
		else if (strcmp(name, "DOCUMENTS"))
			strcat(result, documents_dir_default);
	} else {
		/* Read path from output of xdg */
		int c, n = 0;
		while ((c = fgetc(xdg_cmd)) != EOF) {
			if (c == '\n')
				result[n++] = '\0';
			else
				result[n++] = (char)c;
		}
		result[n] = '\0';

		pclose(xdg_cmd);
	}
	return result;
}