import { Variable, bind } from "astal";
import { readFileAsync, monitorFile } from "astal/file";
import Gio from "gi://Gio";

export class System {
  private static _instance: System;

  private async read_name() {
    const content = await readFileAsync("/etc/machine-info");

    const lines = content
      .split("\n")
      .map((line) => line.trim())
      .map((line) => /^PRETTY_HOSTNAME="?([^"]*)"?$/.exec(line))
      .filter((line) => line)
      .map((line) => line[1]);
    if (lines.length > 0) {
      this.#name.set(lines[0]);
    }
  }

  private constructor() {
    monitorFile("/etc/machine-info", async (file, event) => {
      console.log("file changed", file, event);
      switch (event) {
        case Gio.FileMonitorEvent.CHANGES_DONE_HINT:
          await this.read_name();
          break;
      }
    });
    this.read_name();
  }

  public static get_default(): System {
    if (!System._instance) {
      System._instance = new System();
    }
    return System._instance;
  }

  private #name: Variable<string> = Variable("");

  /**
   * The "pretty" hostname of this computer, as a bound value.
   *
   * This value is updated when the `/etc/machine-info` file changes.
   */
  public get name() {
    return bind(this.#name);
  }
}