import { spawn } from 'node:child_process';

const DEST = 'io.qvac.Jarvis.Shell';
const PATH = '/io/qvac/Jarvis/Shell';
const IFACE = 'io.qvac.Jarvis.Shell';

function parseGdbusString(out) {
  const match = String(out).match(/'((?:\\.|[^'\\])*)'/);
  if (!match) throw new Error('GNOME Shell helper returned no string');
  return match[1].replace(/\\(.)/g, '$1');
}

export class ShellProvider {
  constructor({ listWindows, focusedWindow, focusWindow, proxy, spawnImpl = spawn, timeoutMs = 2000 } = {}) {
    this.listWindowsImpl = listWindows; this.focusedWindowImpl = focusedWindow; this.focusWindowImpl = focusWindow; this.proxy = proxy;
    this.spawnImpl = spawnImpl; this.timeoutMs = timeoutMs;
  }

  _call(method, args = []) {
    return new Promise((resolve, reject) => {
      const child = this.spawnImpl('gdbus', ['call', '--session', '--dest', DEST, '--object-path', PATH, '--method', `${IFACE}.${method}`, ...args], { stdio: ['ignore', 'pipe', 'pipe'] });
      let out = ''; let err = ''; let settled = false;
      const timer = setTimeout(() => { if (settled) return; settled = true; child.kill('SIGTERM'); reject(new Error('GNOME Shell helper timed out')); }, this.timeoutMs);
      const done = (fn) => (value) => { if (settled) return; settled = true; clearTimeout(timer); fn(value); };
      child.stdout.on('data', (d) => { out += d; });
      child.stderr.on('data', (d) => { err += d; });
      child.on('error', done(reject));
      child.on('close', (code) => {
        try {
          if (code !== 0) throw new Error(err.trim() || `GNOME Shell helper exited ${code}`);
          done(resolve)(method === 'FocusWindow' ? true : parseGdbusString(out));
        } catch (error) { done(reject)(error); }
      });
    });
  }

  async connect() {
    if (this.proxy || this.listWindowsImpl) return this;
    await this._call('ListWindows');
    return this;
  }

  async windows() {
    if (this.proxy) return { available: true, windows: JSON.parse(await this.proxy.ListWindows()) };
    if (this.listWindowsImpl) return { available: true, windows: await this.listWindowsImpl() };
    try { return { available: true, windows: JSON.parse(await this._call('ListWindows')) }; } catch (error) { return { available: false, reason: error.message, windows: [] }; }
  }

  async focused() {
    if (this.proxy) return JSON.parse(await this.proxy.FocusedWindow());
    if (this.focusedWindowImpl) return this.focusedWindowImpl();
    try { return JSON.parse(await this._call('FocusedWindow')); } catch { return null; }
  }

  async focus(id) {
    if (this.proxy) return this.proxy.FocusWindow(BigInt(id));
    if (this.focusWindowImpl) return this.focusWindowImpl(id);
    await this._call('FocusWindow', [String(id)]);
  }
}