bat-alert/src/main.zig

const std = @import("std");
const c = @cImport({
    @cInclude("libnotify/notify.h");
});

pub const std_options = struct {
    pub const log_level = .info;
};

const NOTIFICATION_TITLE: [:0]const u8 = "bat-alert";
const NOTIFICATION_BODY: [:0]const u8 = "battery running low!";

const ParseMode = enum { none, target, battery };

pub fn main() !void {
    if (c.notify_init("bat-alert") == c.FALSE) {
        std.log.err("notify_init failed", .{});
        std.process.exit(1);
    }

    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

    const args = try std.process.argsAlloc(allocator);
    defer std.process.argsFree(allocator, args);

    var target: u8 = 15;
    var battery: []const u8 = "BAT0";

    var parse_mode = ParseMode.none;
    for (args, 0..) |arg, i| {
        _ = i;
        switch (parse_mode) {
            ParseMode.none => {
                if (std.mem.eql(u8, arg, "--help")) {
                    const stdout = std.io.getStdOut().writer();
                    try stdout.print(
                        \\Usage: bat-alert [options]
                        \\
                        \\Options:
                        \\  -t, --target NUM	Target battery level (default: 15)
                        \\  --battery NAME		Battery name (default: BAT0)
                        \\
                    , .{});
                    std.process.exit(0);
                }
                if (std.mem.eql(u8, arg, "--target") or std.mem.eql(u8, arg, "-t")) {
                    parse_mode = ParseMode.target;
                }
                if (std.mem.eql(u8, arg, "--battery")) {
                    parse_mode = ParseMode.battery;
                }
            },
            ParseMode.battery => {
                battery = arg;
                parse_mode = ParseMode.none;
            },
            ParseMode.target => {
                const parsedTarget = std.fmt.parseInt(u8, arg, 10) catch {
                    std.log.err("cannot parse target '{s}' as int", .{arg});
                    std.process.exit(1);
                };
                target = parsedTarget;
                parse_mode = ParseMode.none;
            },
        }
    }
    if (parse_mode != ParseMode.none) {
        std.log.err("option requires an argument: --{s}", .{@tagName(parse_mode)});
        std.process.exit(1);
    }

    var sent = false;
    const batteryPath = try std.fmt.allocPrint(allocator, "/sys/class/power_supply/{s}/capacity", .{battery});

    while (true) {
        const capacityFile = std.fs.openFileAbsolute(batteryPath, .{}) catch |err| {
            std.log.err("open {s}: {}", .{ batteryPath, err });
            std.process.exit(1);
        };
        var capacityStr = std.ArrayList(u8).init(allocator);
        try capacityFile.reader().streamUntilDelimiter(capacityStr.writer(), '\n', null);
        capacityFile.close();

        // std.log.info("battery: {s}", .{capacityStr.items});

        const capacity = try std.fmt.parseInt(u8, capacityStr.items, 10);
        // std.log.info("battery (but parsed): {}", .{capacity});

        if (capacity <= target) {
            if (!sent) {
                sent = true;
                // _ = try std.process.Child.exec(.{
                //     .allocator = allocator,
                //     .argv = &[_][]const u8{ "notify-send", "-t", "5000", "-u", "critical", NOTIFICATION_TITLE, NOTIFICATION_BODY },
                // });

                const notif = c.notify_notification_new(NOTIFICATION_TITLE, NOTIFICATION_BODY, null);
                var g_err: [*c]c.GError = null;
                const ret = c.notify_notification_show(notif, &g_err);
                if (ret == c.FALSE) {
                    std.log.err("failed to send a notification: {s}", .{g_err.*.message});
                }

                std.log.info("[NOTIFY] battery running low!", .{});
            }
        } else {
            sent = false;
        }
        capacityStr.deinit();

        std.time.sleep(10 * 1e9);
    }
}