let PanelContainer;
const {Emitter, CompositeDisposable} = require('event-kit');

module.exports =
PanelContainer = class PanelContainer {
  constructor({location}={}) {
    this.location = location;
    this.emitter = new Emitter;
    this.subscriptions = new CompositeDisposable;
    this.panels = [];
  }

  destroy() {
    for (let panel of this.getPanels()) { panel.destroy(); }
    this.subscriptions.dispose();
    this.emitter.emit('did-destroy', this);
    return this.emitter.dispose();
  }

  /*
  Section: Event Subscription
  */

  onDidAddPanel(callback) {
    return this.emitter.on('did-add-panel', callback);
  }

  onDidRemovePanel(callback) {
    return this.emitter.on('did-remove-panel', callback);
  }

  onDidDestroy(callback) {
    return this.emitter.on('did-destroy', callback);
  }

  /*
  Section: Panels
  */

  getLocation() { return this.location; }

  isModal() { return this.location === 'modal'; }

  getPanels() { return this.panels.slice(); }

  addPanel(panel) {
    this.subscriptions.add(panel.onDidDestroy(this.panelDestroyed.bind(this)));

    const index = this.getPanelIndex(panel);
    if (index === this.panels.length) {
      this.panels.push(panel);
    } else {
      this.panels.splice(index, 0, panel);
    }

    this.emitter.emit('did-add-panel', {panel, index});
    return panel;
  }

  panelForItem(item) {
    for (let panel of this.panels) {
      if (panel.getItem() === item) { return panel; }
    }
    return null;
  }

  panelDestroyed(panel) {
    const index = this.panels.indexOf(panel);
    if (index > -1) {
      this.panels.splice(index, 1);
      return this.emitter.emit('did-remove-panel', {panel, index});
    }
  }

  getPanelIndex(panel) {
    let i, p;
    const priority = panel.getPriority();
    if (['bottom', 'right'].includes(this.location)) {
      for (i = this.panels.length - 1; i >= 0; i--) {
        p = this.panels[i];
        if (priority < p.getPriority()) { return i + 1; }
      }
      return 0;
    } else {
      for (i = 0; i < this.panels.length; i++) {
        p = this.panels[i];
        if (priority < p.getPriority()) { return i; }
      }
      return this.panels.length;
    }
  }
};