#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>

int main(int argc, char *argv[]) {
	if(argc!=6){
		printf("This program requires 5 parameters:\n 1. warning treshold\n 2. xorg server display number for warning\n 3. xorg xauthority file location\n 4. critical battery treshold\n 5. critical battery action (systemctl)\n");
		return -3;
	}
	char warn_thr = atoi(argv[1]);
	if(warn_thr>=100||warn_thr<0){
		printf("Invalid value");
		return -4;
	}
	char crit_thr = atoi(argv[4]);
	if(crit_thr>=100||crit_thr<0){
		printf("Invalid value");
		return -4;
	}

	while(true){
		FILE *bat_lvl_file = fopen("/sys/class/power_supply/BAT0/capacity","r");
		FILE *bat_stat_file = fopen("/sys/class/power_supply/BAT0/status","r");
		if (bat_lvl_file == NULL || bat_stat_file == NULL){
			printf("failed to open file");
			return -1;
		}

		char bat_lvl_str[4];
		char bat_stat;

		if(fgets(bat_lvl_str, sizeof(bat_lvl_str), bat_lvl_file) != NULL && (bat_stat=fgetc(bat_stat_file))){
			fclose(bat_lvl_file);
			fclose(bat_stat_file);
			char bat_lvl = atoi(bat_lvl_str);
			printf("Battery is at %i%% - %c\n",bat_lvl,bat_stat);
			if(bat_stat=='D'){
				if(bat_lvl<=crit_thr){
					if(fork() == 0){
						char *cmd[] = {"systemctl",argv[5]};
						execvp(cmd[0],cmd);
					} else {
						wait(NULL);
					}

				}
				else if(bat_lvl<=warn_thr){
					if(fork() == 0){
						//child process
						char *msg = malloc(16+3+1);
						sprintf(msg,"Battery is low: %i%%",bat_lvl);
						char *xdisplay = malloc(10+strlen(argv[2]));
						sprintf(xdisplay, "DISPLAY=:%i", atoi(argv[2]));
						char *xauth = malloc(12+strlen(argv[3]));
						sprintf(xauth,"XAUTHORITY=%s",argv[3]);
						char *cmd[] = {"env",xdisplay,xauth,"i3-nagbar","-t","warning","-f","Cozette 10","-m",msg,NULL};
						execvp(cmd[0],cmd);
						free(msg);
						free(xdisplay);
						free(xauth);
					} else {
						//parent process
						wait(NULL);
					}
				}
			}
		} else {
			printf("failed to read file");

			fclose(bat_lvl_file);
			fclose(bat_stat_file);

			return -2;
		}

		sleep(10);
	}
	return 0;
}