#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define STRLEN_CAPACITY 4
#define STRLEN_STATUS 16

#define COLOR_FULL "#839496"
#define COLOR_LOW "#b58900"
#define COLOR_CRITICAL "#dc322f"

void dump_file(const char *path, size_t size, char *out) {
    FILE *file = fopen(path, "r");
    fgets(out, size, file);
    fclose(file);
}

int main() {
    char capacity[STRLEN_CAPACITY];
    char status[STRLEN_STATUS];

    for (;;) {
        dump_file("/sys/class/power_supply/BAT0/capacity", STRLEN_CAPACITY, capacity);
        dump_file("/sys/class/power_supply/BAT0/status", STRLEN_STATUS, status);

        // select color based on charge level
        int capacity_int = atoi(capacity);
        const char *color = NULL;

        if (capacity_int <= 10) {
            color = COLOR_CRITICAL;
        } else if (capacity_int <= 20) {
            color = COLOR_LOW;
        } else {
            color = COLOR_FULL;
        }

        // select icon based on whether AC is plugged in
        const char *icon = NULL;

        if (strstr(status, "Discharging")) {
            icon = "f0079";
        } else {
            icon = "f06a5";
        }

        printf("<span color=\"%s\"><span font=\"Symbols Nerd Font\">&#x%s;</span> %d%</span>\n", color, icon, capacity_int);
        fflush(stdout);
        sleep(1);
    }

    return 0;
}