From ba3d42030decabe0a8f3c5c32f845114fba677e5 Mon Sep 17 00:00:00 2001
From: Tom Smeding <t.j.smeding@uu.nl>
Date: Sun, 31 Jul 2022 13:57:24 +0200
Subject: Warning nagbar when half-full

---
 batwarn_daemon.c | 51 +++++++++++++++++++++++++++++++++++----------------
 1 file changed, 35 insertions(+), 16 deletions(-)

diff --git a/batwarn_daemon.c b/batwarn_daemon.c
index 1cd1d17..e7d6129 100644
--- a/batwarn_daemon.c
+++ b/batwarn_daemon.c
@@ -14,7 +14,9 @@
 
 
 // Warning when battery percentage is <= this
-static const int WARN_PERC = 10;
+static const int WARN_LO = 10;
+// Warning when battery percentage is >= this (only warns once per charge cycle)
+static const int WARN_HI = 65;
 
 // Time to sleep between checks
 static const struct timespec SLEEP_SPEC = {60, 0};
@@ -38,6 +40,28 @@ static inline void parse(const char *buffer, bool *discharging, int *charge, int
 	}
 }
 
+static void show_nagbar(int percentage, const char *nagtype) {
+	pid_t pid = fork();
+	if (pid < 0) perror("fork");
+	else if (pid == 0) {
+		char msg[strlen(MESSAGE_FORMAT) + 16];
+		snprintf(msg, sizeof msg, MESSAGE_FORMAT, percentage);
+
+		char nagtypebuf[16];
+		assert(strlen(nagtype) < sizeof nagtypebuf);
+		strcpy(nagtypebuf, nagtype);
+
+		char *argv[6] = {"i3-nagbar", "-m", msg, "-t", nagtypebuf, NULL};
+		execv("/usr/bin/i3-nagbar", argv);
+		perror("execv");
+		exit(255);
+	} else {
+		int status;
+		do if (waitpid(pid, &status, 0) < 0 && errno == ECHILD) break;
+		while (!WIFEXITED(status) && !WIFSIGNALED(status));
+	}
+}
+
 int main(void) {
 	int fd = open("/sys/class/power_supply/BAT1/uevent", O_RDONLY);
 	if (fd < 0) {
@@ -47,6 +71,8 @@ int main(void) {
 
 	char buffer[1024];
 
+	bool prev_less_than_hi = false;
+
 	while (true) {
 		ssize_t nr = pread(fd, buffer, sizeof buffer, 0);
 		if (nr < 0) {
@@ -57,22 +83,15 @@ int main(void) {
 		bool discharging = false;
 		int charge = 1, full = 1;
 		parse(buffer, &discharging, &charge, &full);
+		int percentage = charge * 100 / full;
 
-		if (full > 0 && discharging && charge * 100 / full <= WARN_PERC) {
-			pid_t pid = fork();
-			if (pid < 0) perror("fork");
-			else if (pid == 0) {
-				char msg[strlen(MESSAGE_FORMAT) + 16];
-				snprintf(msg, sizeof msg, MESSAGE_FORMAT, charge * 100 / full);
-				char *argv[4] = {"i3-nagbar", "-m", msg, NULL};
-				execv("/usr/bin/i3-nagbar", argv);
-				perror("execv");
-				exit(255);
-			} else {
-				int status;
-				do if (waitpid(pid, &status, 0) < 0 && errno == ECHILD) break;
-				while (!WIFEXITED(status) && !WIFSIGNALED(status));
-			}
+		if (full > 0 && discharging && percentage <= WARN_LO) {
+			show_nagbar(percentage, "error");
+		} else if (percentage < WARN_HI) {
+			prev_less_than_hi = true;
+		} else if (prev_less_than_hi) {
+			prev_less_than_hi = false;
+			show_nagbar(percentage, "warning");
 		}
 
 		(void)nanosleep(&SLEEP_SPEC, NULL);
-- 
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