4 files changed, 209 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f46a5a0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+lowbat
+lowbat.o
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..180a311
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,26 @@
+# Define variables
+CC = gcc
+CFLAGS = -std=c99 -Wall $(shell pkg-config --cflags libnotify)
+LDFLAGS = $(shell pkg-config --libs libnotify)
+LIBS = -lnotify
+TARGET = lowbat
+SRCS = lowbat.c
+OBJS = $(SRCS:.c=.o)
+
+# Default target
+all: $(TARGET)
+
+# Build target
+$(TARGET): $(OBJS)
+	$(CC) $(CFLAGS) -o $@ $(OBJS) $(LDFLAGS) $(LIBS)
+
+# Compile source files
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+# Clean up build files
+clean:
+	rm -f $(TARGET) $(OBJS)
+
+# Phony targets
+.PHONY: all clean
diff --git a/lowbat.c b/lowbat.c
new file mode 100644
index 0000000..14f10a2
--- /dev/null
+++ b/lowbat.c
@@ -0,0 +1,155 @@
+/* LINUX DOCS: https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-class-power
+ * (C) 2024 Tim Keller <tjkeller.xyz>
+ * MIT License
+ */
+
+#include <libnotify/notify.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <dirent.h>
+
+#define PERIOD 3 // number of seconds before each check
+#define PSUPATH "/sys/class/power_supply" // number of seconds before each check
+#define MAX_BATTERIES     8
+#define MAX_PSU_NAME_LEN  8
+#define MAX_PROP_PATH_LEN 64
+
+// variables
+static char batteries[MAX_BATTERIES][MAX_PSU_NAME_LEN];
+static unsigned int num_batteries;
+static FILE *fp;
+static char prop_path[MAX_PROP_PATH_LEN];
+
+// functions
+void load_installed_batteries() {
+	// search through "power supplies" for "status" property (only available on batteries)
+	DIR *dir, *subdir;
+	struct dirent *entry, *subentry;
+
+	if ((dir = opendir(PSUPATH)) == NULL) {
+		fprintf(stderr, "failed to see power supplies"); // TODO
+		exit(EXIT_FAILURE);
+	}
+
+	// power supplies TODO warn user if max batteries exceeded
+	num_batteries = 0;
+	while ((entry = readdir(dir)) != NULL && num_batteries < MAX_BATTERIES) {
+		if (entry->d_name[0] == '.')
+			continue; // skip . and ..
+		if (strlen(entry->d_name) > MAX_PSU_NAME_LEN) {
+			fprintf(stderr, "the power supply name was too long: %s", entry->d_name);
+			exit(EXIT_FAILURE);
+		}
+
+		// power supplies will always be a directory, no need to check beforehand :)
+		snprintf(prop_path, MAX_PROP_PATH_LEN, PSUPATH "/%s", entry->d_name);
+
+		if ((subdir = opendir(prop_path)) == NULL) {
+			fprintf(stderr, "failed to see power supplies sub\n"); // TODO
+			exit(EXIT_FAILURE);
+		}
+
+		// power supply properties
+		while ((subentry = readdir(subdir)) != NULL) {
+			// add to list of batteries if it has the status property
+			if (strcmp(subentry->d_name, "status") == 0) {
+				strncpy(batteries[num_batteries], entry->d_name, MAX_PSU_NAME_LEN);
+				num_batteries++;
+				break;
+			}
+		}
+		closedir(subdir);
+	}
+	closedir(dir);
+}
+
+void notifysend(char *title, char *content) {
+	NotifyNotification *notif;
+	notify_init("lowbat");
+	notif = notify_notification_new(title, content, NULL);
+
+	notify_notification_show(notif, NULL);
+}
+
+void read_prop(char *psu, char *prop, char *fmt, void *out) {
+	/* this function is only designed to read one var at a time because all bat
+	 * properties will only be one var */
+	snprintf(prop_path, MAX_PROP_PATH_LEN, PSUPATH "/%s/%s", psu, prop);
+
+	if ((fp = fopen(prop_path, "r")) != NULL) {
+		fscanf(fp, fmt, out);
+		fclose(fp);
+	}
+	else {
+		printf("failed to read fmt '%s' from property %s\n", fmt, prop_path); // TODO fprintf me plz
+		exit(EXIT_FAILURE);
+	}
+}
+
+int get_total_capacity() {
+	unsigned long int energy_full = 0, energy_now = 0, x;
+	int i;
+
+	for (i = 0; i < num_batteries; i++) {
+		read_prop(batteries[i], "energy_full", "%ld", &x);
+		energy_full += x;
+		read_prop(batteries[i], "energy_now",  "%ld", &x);
+		energy_now += x;
+	}
+
+	return energy_now * 100 / energy_full;
+}
+
+int is_discharging() {
+	char status[12]; // valid values: "Unknown", "Charging", "Discharging", "Not charging", "Full"
+	int i;
+
+	for (i = 0; i < num_batteries; i++) {
+		read_prop(batteries[i], "status", "%s", &status);
+		if (strcmp(status, "Discharging") != 0)
+			return 0;
+	}
+
+	return 1;
+}
+
+int main() {
+	int discharging, capacity;
+	int w_lowbat = 0, w_lowbat_crit = 0; // 1 if warned already
+	char msg[32];
+
+	load_installed_batteries();
+	if (!num_batteries) {
+		fprintf(stderr, "no batteries installed in system. exiting...\n"); // TODO
+		exit(EXIT_FAILURE);
+	}
+
+	while (1) {
+		load_installed_batteries();
+		discharging = is_discharging();
+		capacity = get_total_capacity();
+
+		if (discharging) {
+			if (capacity <= 5 && !w_lowbat_crit) {
+				sprintf(msg, "%d%% remains", capacity); // TODO snprintf me plz
+				notifysend("Critical Low Battery Warning", msg);
+
+				w_lowbat_crit = w_lowbat = 1;
+			} else if (capacity <= 20 && !w_lowbat) {
+				sprintf(msg, "%d%% remains", capacity);
+				notifysend("Low Battery Warning", msg);
+
+				w_lowbat = 1;
+			}
+		} else {
+			w_lowbat_crit = w_lowbat = 0;  // clear conditions
+		}
+
+		printf("\r%d%%", capacity);
+		fflush(stdout);
+		sleep(PERIOD);
+	}
+
+	return 0;
+}
diff --git a/shlowbat b/shlowbat
new file mode 100755
index 0000000..a02ce56
--- /dev/null
+++ b/shlowbat
@@ -0,0 +1,26 @@
+#!/bin/sh
+psupath=/sys/class/power_supply
+warning_level=0  # 0 = not warned, 1 = warned, 2 = warned critical
+
+sum_props() {
+	for prop in $(cat $psupath/*/$1); do sum=$(( $sum + $prop )); done
+	echo $sum
+}
+is_discharging() { cat $psupath/*/status | grep "Discharging" > /dev/null ; }
+
+while true; do
+	capacity=$(( $(sum_props energy_now) * 100 / $(sum_props energy_full) ))
+
+	if is_discharging; then
+		if   [ $capacity -le  5 ] && [ $warning_level -lt 2 ]; then
+			notify_send "Critical Low Battery Warning" "${capacity}% remains"
+		elif [ $capacity -le 20 ] && [ $warning_level -lt 1 ]; then
+			notify_send "Low Battery Warning" "${capacity}% remains"
+		fi
+	else
+		warning_level=0
+	fi
+
+	printf "\r%d%%" $capacity
+	sleep 3
+done