/* One lifetime owner for the player's realtime AudioContext and media sources. */
(function (root) {
  'use strict';

  function create(options = {}) {
    const getConstructor = options.getConstructor || (() => root.AudioContext || root.webkitAudioContext);
    let context = null;
    const sources = new Map();
    const routes = new Map();
    const failed = new Map();

    function getContext(contextOptions) {
      if (context) return context;
      const Constructor = getConstructor();
      if (typeof Constructor !== 'function') throw new Error('Web Audio is unavailable');
      context = contextOptions === undefined ? new Constructor() : new Constructor(contextOptions);
      return context;
    }

    function source(element) {
      if (!element) throw new TypeError('A media element is required');
      if (sources.has(element)) return sources.get(element);
      if (failed.has(element)) throw failed.get(element);
      try {
        const created = getContext().createMediaElementSource(element);
        sources.set(element, created);
        return created;
      } catch (error) {
        // MediaElementSource cannot be undone. Remember failure so a later
        // route change can never attempt a second source for this element.
        failed.set(element, error);
        throw error;
      }
    }

    function connect(element, destination) {
      const mediaSource = source(element);
      if (!destination) throw new TypeError('An audio destination is required');
      if (routes.get(element) === destination) return mediaSource;
      if (routes.has(element)) mediaSource.disconnect();
      mediaSource.connect(destination);
      routes.set(element, destination);
      return mediaSource;
    }

    function routeAll(elements, destination) {
      for (const element of elements || []) connect(element, destination);
    }

    function snapshot() {
      return {
        contextCreated: !!context,
        sampleRate: context?.sampleRate || null,
        sourceCount: sources.size,
        failedCount: failed.size,
        routedCount: routes.size,
      };
    }

    return { context: getContext, source, connect, routeAll, snapshot };
  }

  const singleton = create();
  const api = { create, context: (...args) => singleton.context(...args), source: (...args) => singleton.source(...args),
    connect: (...args) => singleton.connect(...args), routeAll: (...args) => singleton.routeAll(...args),
    snapshot: () => singleton.snapshot() };
  if (typeof module !== 'undefined' && module.exports) module.exports = api;
  else root.AudioGraph = api;
})(typeof window !== 'undefined' ? window : globalThis);