class ConfigForm {
  constructor() {
    this.form = null;
    this._submitHandlerAttached = false;
  }

  resetForm() {
    this.form = document.getElementById('config-form');
    if (this.form) {
      this.form.reset();
    }
  }

  snapshotOriginal() {
    const original = {};
    const data = window.configData && window.configData.config;
    if (!data) return original;
    Object.entries(data).forEach(([key, entry]) => {
      original[key] = entry && entry.value !== undefined ? String(entry.value) : '';
    });
    return original;
  }

  collectChanges(original) {
    const changes = [];
    if (!this.form) return changes;

    const current = {};
    const inputs = this.form.querySelectorAll('input, select, textarea');
    inputs.forEach((input) => {
      const name = input.name;
      if (!name || !name.startsWith('CFG_')) return;
      if (name.endsWith('_PORT_MANAGER')) return; // UI-only aggregate
      let value;
      if (input.type === 'checkbox') {
        value = input.checked ? 'true' : 'false';
      } else {
        value = (input.value || '').trim();
      }
      current[name] = value;
    });

    Object.keys(current).forEach((name) => {
      const oldValue = original[name] !== undefined ? original[name] : '';
      const newValue = current[name];
      if (oldValue === newValue) return;
      const encoded = newValue.replace(/\|/g, '%7C');
      changes.push(`${name}=${encoded}`);
    });

    return changes;
  }

  async saveConfig() {
    this.form = document.getElementById('config-form');
    if (!this.form) {
      console.error('ConfigForm: Form not found');
      return;
    }

    const original = this.snapshotOriginal();
    const changes = this.collectChanges(original);

    if (changes.length === 0) {
      this.showNotification('No configuration changes to save.', 'info');
      return;
    }

    const encoded = changes.join('|');

    try {
      if (!window.tasksManager || !window.tasksManager.router) {
        throw new Error('Task system not available');
      }
      const task = await window.tasksManager.router.routeAction('config_update', {
        changes: `'${encoded.replace(/'/g, "'\\''")}'`
      });

      this.showNotification(
        `Saving ${changes.length} configuration change${changes.length === 1 ? '' : 's'}...`,
        'success'
      );

      if (task && window.librePortalSPA && typeof window.librePortalSPA.navigate === 'function') {
        setTimeout(() => window.librePortalSPA.navigate(`/tasks/all?task=${task.id}`), 400);
      } else if (task && window.navigateToRoute) {
        setTimeout(() => window.navigateToRoute(`tasks/all?task=${task.id}`), 400);
      }
    } catch (error) {
      console.error('ConfigForm: Error saving configuration:', error);
      this.showNotification('Failed to save configuration: ' + error.message, 'error');
    }
  }

  // preventDefault stops the form from falling back to GET (which dumps every
  // CFG into the URL).
  attachSubmitHandler() {
    const form = document.getElementById('config-form');
    if (!form) return;
    if (form.dataset.submitWired === '1') return;
    form.dataset.submitWired = '1';
    form.addEventListener('submit', (event) => {
      event.preventDefault();
      this.saveConfig();
    });
  }

  showNotification(message, type) {
    type = type || 'info';
    if (window.notificationSystem) {
      window.notificationSystem.show(message, type);
      return;
    }
    const notification = document.createElement('div');
    notification.className = 'notification notification-' + type;
    notification.textContent = message;
    document.body.appendChild(notification);
    setTimeout(() => {
      if (notification.parentNode) notification.parentNode.removeChild(notification);
    }, 5000);
  }
}

window.ConfigForm = ConfigForm;