#include <dirent.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/vfs.h>
#include <time.h>
#include <unistd.h>

#define INTERVAL 10

int get_cpu_usage_percentage(void);
int get_ram_usage_percentage(void);
void get_formatted_date_time(char *format, char *formattedDateTime);
double get_available_space_from_mountpoint_gb(const char *mountpoint);
double get_total_space_from_mountpoint_gb(const char *mountpoint);
double get_used_space_from_mountpoint_gb(const char *mountpoint);
double get_used_space_from_mountpoint_percentage(const char *mountpoint);
int get_number_of_processes(void);

#ifdef SYSINFO_IMPLEMENTATION

int get_cpu_usage_percentage(void)
{
	int perc;
	long double a[4], b[4];
	FILE *fp;

	fp = fopen("/proc/stat", "r");
	if (fp == NULL) {
		fprintf(stderr, "ERROR: failed to open file /proc/stat");
		return 1;
	}
	fscanf(fp, "%*s %Lf %Lf %Lf %Lf", &a[0], &a[1], &a[2], &a[3]);
	fclose(fp);

	sleep(INTERVAL);

	fp = fopen("/proc/stat", "r");
	if (fp == NULL) {
		fprintf(stderr, "ERROR: failed to open file /proc/stat");
		return 1;
	}
	fscanf(fp, "%*s %Lf %Lf %Lf %Lf", &b[0], &b[1], &b[2], &b[3]);
	fclose(fp);

	perc = 100 * ((b[0]+b[1]+b[2]) - (a[0]+a[1]+a[2])) / ((b[0]+b[1]+b[2]+b[3]) - (a[0]+a[1]+a[2]+a[3]));
	return (perc);
}

int get_ram_usage_percentage(void)
{
	long total, free, buffers, cached;
	FILE *fp;

	fp = fopen("/proc/meminfo", "r");
	if (fp == NULL) {
		fprintf(stderr, "ERROR: failed to open file /proc/meminfo");
		return 1;
	}
	fscanf(fp, "MemTotal: %ld kB\n", &total);
	fscanf(fp, "MemFree: %ld kB\n", &free);
	fscanf(fp, "MemAvailable: %ld kB\nBuffers: %ld kB\n", &buffers, &buffers);
	fscanf(fp, "Cached: %ld kB\n", &cached);
	fclose(fp);

	return (100 * ((total - free) - (buffers + cached)) / total);
}

void get_formatted_date_time(char *format, char *formattedDateTime)
{
	time_t rawtime;
	struct tm *timeptr;

	time(&rawtime);
	timeptr = localtime(&rawtime);
	strftime(formattedDateTime, 80, format, timeptr);
}

double get_available_space_from_mountpoint_gb(const char *mountpoint)
{
	struct statfs mountpointStatfs;

	statfs(mountpoint, &mountpointStatfs);

	return ((long double)mountpointStatfs.f_bfree * mountpointStatfs.f_bsize)/1073741824;
}

double get_total_space_from_mountpoint_gb(const char *mountpoint)
{
	struct statfs mountpointStatfs;

	statfs(mountpoint, &mountpointStatfs);

	return ((long double)mountpointStatfs.f_blocks * mountpointStatfs.f_bsize)/1073741824;
}

double get_used_space_from_mountpoint_gb(const char *mountpoint)
{
	struct statfs mountpointStatfs;

	statfs(mountpoint, &mountpointStatfs);

	return (((long double)mountpointStatfs.f_blocks * mountpointStatfs.f_bsize) - ((long double)mountpointStatfs.f_bfree * mountpointStatfs.f_bsize))/1073741824;
}

double get_used_space_from_mountpoint_percentage(const char *mountpoint)
{
	return (get_used_space_from_mountpoint_gb(mountpoint)/get_total_space_from_mountpoint_gb(mountpoint)) * 100;
}

#endif