nix-flake/home/ags-config/modules/backlight.ts

import { monitorFile, readFile } from "ags/file";
import { exec } from "ags/process";
import GObject, { getter, ParamSpec, register, setter, signal } from "ags/gobject";

import Gio from "gi://Gio?version=2.0";


export namespace Backlights {

    const BacklightParamSpec = (name: string, flags: GObject.ParamFlags) => 
        GObject.ParamSpec.jsobject(name, null, null, flags) as ParamSpec<Backlight>;

    let instance: Backlights;
    
    export function getDefault(): Backlights {
        if(!instance)
            instance = new Backlights();

        return instance;
    }

    @register({ GTypeName: "Backlights" })
    class _Backlights extends GObject.Object {

        #backlights: Array<Backlight> = [];
        #default: Backlight|null = null;
        #available: boolean = false;
        

        @getter(Array as unknown as ParamSpec<Array<Backlight>>)
        get backlights() { return this.#backlights; }

        @getter(BacklightParamSpec)
        get default() { return this.#default!; }

        /** true if there are any backlights available */
        @getter(Boolean)
        get available() { return this.#available; }

        public scan(): Array<Backlight> {
            const dir = Gio.File.new_for_path(`/sys/class/backlight`),
                backlights: Array<Backlight> = [];

            let fileEnum: Gio.FileEnumerator;

            try {
                fileEnum = dir.enumerate_children("standard::*", Gio.FileQueryInfoFlags.NONE, null);
                for(const backlight of fileEnum) {
                    try {
                        backlights.push(new Backlight(backlight.get_name()));
                    } catch(_) {}
                }
            } catch(_) {
                return [];
            }

            if(backlights.length < 1) {
                if(this.#available) {
                    this.#available = false;
                    this.notify("available");
                }

                this.#default = null;
                this.notify("default");
            }

            if(backlights.length > 0) {
                if(this.#backlights.length < 1) {
                    this.#available = true;
                    this.notify("available");
                }

                if(!this.#default || !backlights.filter(bk => bk.path === this.#default?.path)[0]) {
                    this.#default = backlights[0];
                    this.notify("default");
                }
            }

            this.#backlights = backlights;
            this.notify("backlights");

            return backlights;
        }

        public setDefault(bk: Backlight): void {
            this.#default = bk;
            this.notify("default");
        }

        constructor(scan: boolean = true) {
            super();
            scan && this.scan();
        }
    }

    @register({ GTypeName: "Backlight" })
    class _Backlight extends GObject.Object {

        declare $signals: GObject.Object.SignalSignatures & {
            "brightness-changed": (value: number) => void
        };

        readonly #name: string;
        #path: string;
        #maxBrightness: number;
        #brightness: number;
        #monitor: Gio.FileMonitor;
        #conn: number;

        @signal(Number) brightnessChanged(_: number): void {};

        @getter(String)
        get name() { return this.#name; }

        @getter(String)
        get path() { return this.#path; }

        @getter(Boolean)
        get isDefault() { return this.path === getDefault().default?.path; }

        @getter(Number) 
        get brightness() { return this.#brightness; };
        @setter(Number)
        set brightness(level: number) {
            if(!this.writeBrightness(level)) return;

            this.#brightness = level;
            this.notify("brightness");
            this.emit("brightness-changed", level);
        }

        @getter(Number) 
        get maxBrightness() { return this.#maxBrightness;};


        // intel_backlight is mostly the default on laptops
        constructor(name: string = "intel_backlight") {
            super();

            // check if backlight exists
            if(!Gio.File.new_for_path(`/sys/class/backlight/${name}/brightness`).query_exists(null)) 
                throw new Error(`Brightness: Couldn't find brightness for "${name}"`);

            // notify :is-default on default backlight change
            this.#conn = getDefault().connect("notify::default", () => 
                this.notify("is-default"));

            this.#name = name;
            this.#path = `/sys/class/backlight/${name}`;
            this.notify("path");
            this.#maxBrightness = Number.parseInt(readFile(`${this.#path}/max_brightness`));
            this.notify("max-brightness");
            this.#brightness = Number.parseInt(readFile(`${this.#path}/brightness`))


            this.#monitor = monitorFile(`/sys/class/backlight/${name}/brightness`, () => {
                this.#brightness = this.readBrightness();
                this.notify("brightness");
                this.emit("brightness-changed", this.brightness);
            });
        }

        private readBrightness(): number {
            try {
                const brightness = Number.parseInt(readFile(`${this.#path}/brightness`));
                return brightness;
            } catch(e) {
                console.error(`Backlight: An error occurred while reading brightness from "${this.#name}"`);
            }

            return this.#brightness ?? this.#maxBrightness ?? 0;
        }

        private writeBrightness(level: number): boolean {
            try {
                exec(`brightnessctl -d ${this.#name} s ${level}`);
                return true;
            } catch(e) {
                console.error(`Backlight: Couldn't set brightness for "${this.#name}". Stderr: ${e}`);
            }

            return false;
        }

        vfunc_dispose(): void {
            this.#monitor.cancel();
            getDefault().disconnect(this.#conn);
        }

        public emit<Signal extends keyof typeof this.$signals>(
            signal: Signal,
            ...args: Parameters<(typeof this.$signals)[Signal]>
        ): void {
            super.emit(signal, ...args);
        }

        public connect<Signal extends keyof typeof this.$signals>(
            signal: Signal,
            callback: (self: typeof this, ...args: Parameters<(typeof this.$signals)[Signal]>) => ReturnType<(typeof this.$signals)[Signal]>
        ): number {
            return super.connect(signal, callback);
        }
    }

    export const Backlights = _Backlights;
    export const Backlight = _Backlight;
    export type Backlight = InstanceType<typeof Backlight>;
    export type Backlights = InstanceType<typeof Backlights>;
}