// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import type * as Workspace from '../workspace/workspace.js';

export interface LiveLocation {
  update(): Promise<void>;
  uiLocation(): Promise<Workspace.UISourceCode.UILocation|null>;
  dispose(): void;
  isDisposed(): boolean;
}

export class LiveLocationWithPool implements LiveLocation {
  #updateDelegate: ((arg0: LiveLocation) => Promise<void>)|null;
  readonly #locationPool: LiveLocationPool;
  #updatePromise: Promise<void>|null;

  constructor(updateDelegate: (arg0: LiveLocation) => Promise<void>, locationPool: LiveLocationPool) {
    this.#updateDelegate = updateDelegate;
    this.#locationPool = locationPool;
    this.#locationPool.add(this);

    this.#updatePromise = null;
  }

  async update(): Promise<void> {
    if (!this.#updateDelegate) {
      return;
    }
    // The following is a basic scheduling algorithm, guaranteeing that
    // {#updateDelegate} is always run atomically. That is, we always
    // wait for an update to finish before we trigger the next run.
    if (this.#updatePromise) {
      await this.#updatePromise.then(() => this.update());
    } else {
      this.#updatePromise = this.#updateDelegate(this);
      await this.#updatePromise;
      this.#updatePromise = null;
    }
  }

  async uiLocation(): Promise<Workspace.UISourceCode.UILocation|null> {
    throw new Error('Not implemented');
  }

  dispose(): void {
    this.#locationPool.delete(this);
    this.#updateDelegate = null;
  }

  isDisposed(): boolean {
    return !this.#locationPool.has(this);
  }
}

export class LiveLocationPool {
  readonly #locations: Set<LiveLocation>;

  constructor() {
    this.#locations = new Set();
  }

  add(location: LiveLocation): void {
    this.#locations.add(location);
  }

  delete(location: LiveLocation): void {
    this.#locations.delete(location);
  }

  has(location: LiveLocation): boolean {
    return this.#locations.has(location);
  }

  disposeAll(): void {
    for (const location of this.#locations) {
      location.dispose();
    }
  }
}