// The game feed: a chat-like column of short-lived messages pinned to the
// lower-left corner of the map. Newest lines sit at the bottom and each line
// retires on its own, so the map is never permanently obstructed.

export const FEED_TTL_MS = 4500;
export const FEED_ALERT_TTL_MS = 8000;
const FEED_FADE_MS = 400;

export class GameFeed {
  constructor($container, options = {}) {
    this.$container = $container;
    this.ttl = options.ttl !== undefined ? options.ttl : FEED_TTL_MS;
    this.alertTtl = options.alertTtl !== undefined ? options.alertTtl : FEED_ALERT_TTL_MS;
    this.fade = options.fade !== undefined ? options.fade : FEED_FADE_MS;
    this._timers = new Set();
  }

  // Appends one line at the bottom of the feed. `alert` marks a message the
  // player must not miss (being declared war on) and lets it linger longer.
  // A negative `ttl` keeps the line until `clear` or a later retirement.
  push(text, { alert = false, ttl } = {}) {
    if (!this.$container || !this.$container.length) return null;
    const life = ttl !== undefined ? ttl : alert ? this.alertTtl : this.ttl;
    const $line = $("<div class='feed-line'></div>").text(text);
    if (alert) $line.addClass("feed-alert");
    this.$container.append($line);
    if (life >= 0) {
      const timer = setTimeout(() => {
        this._timers.delete(timer);
        this._retire($line);
      }, life);
      this._timers.add(timer);
    }
    return $line;
  }

  _retire($line) {
    $line.addClass("leaving");
    if (this.fade <= 0) {
      $line.remove();
      return;
    }
    const timer = setTimeout(() => {
      this._timers.delete(timer);
      $line.remove();
    }, this.fade);
    this._timers.add(timer);
  }

  clear() {
    for (const timer of this._timers) clearTimeout(timer);
    this._timers.clear();
    if (this.$container) this.$container.empty();
  }
}