text: import config from "./config";
  import {
  	defined,
  	generateHash,
  	now,
  	objectType
  } from "./utilities";
  import {
  	runLoggingCallbacks
  } from "./logging";
  
  import {
  	globalSuite
  } from "../core";
  import {
  	emit
  } from "../events";
  import {
  	setTimeout
  } from "../globals";
  
  let priorityCount = 0;
  let unitSampler;
  
  /**
   * Advances the ProcessingQueue to the next item if it is ready.
   * @param {Boolean} last
   */
  function advance() {
  	const start = now();
  	config.depth = ( config.depth || 0 ) + 1;
  
  	while ( config.queue.length && !config.blocking ) {
  		const elapsedTime = now() - start;
  
  		if ( !defined.setTimeout || config.updateRate <= 0 || elapsedTime < config.updateRate ) {
  			if ( priorityCount > 0 ) {
  				priorityCount--;
  			}
  
  			config.queue.shift()();
  		} else {
  			setTimeout( advance, 13 );
  			break;
  		}
  	}
  
  	config.depth--;
  
  	if ( !config.blocking && !config.queue.length && config.depth === 0 ) {
  		done();
  	}
  }
  
  function addToQueueImmediate( callback ) {
  	if ( objectType( callback ) === "array" ) {
  		while ( callback.length ) {
  			addToQueueImmediate( callback.pop() );
  		}
  
  		return;
  	}
  
  	config.queue.unshift( callback );
  	priorityCount++;
  }
  
  /**
   * Adds a function to the ProcessingQueue for execution.
   * @param {Function|Array} callback
   * @param {Boolean} priority
   * @param {String} seed
   */
  function addToQueue( callback, prioritize, seed ) {
  	if ( prioritize ) {
  		config.queue.splice( priorityCount++, 0, callback );
  	} else if ( seed ) {
  		if ( !unitSampler ) {
  			unitSampler = unitSamplerGenerator( seed );
  		}
  
  		// Insert into a random position after all prioritized items
  		const index = Math.floor( unitSampler() * ( config.queue.length - priorityCount + 1 ) );
  		config.queue.splice( priorityCount + index, 0, callback );
  	} else {
  		config.queue.push( callback );
  	}
  }
  
  /**
   * Creates a seeded "sample" generator which is used for randomizing tests.
   */
  function unitSamplerGenerator( seed ) {
  
  	// 32-bit xorshift, requires only a nonzero seed
  	// http://excamera.com/sphinx/article-xorshift.html
  	let sample = parseInt( generateHash( seed ), 16 ) || -1;
  	return function() {
  		sample ^= sample << 13;
  		sample ^= sample >>> 17;
  		sample ^= sample << 5;
  
  		// ECMAScript has no unsigned number type
  		if ( sample < 0 ) {
  			sample += 0x100000000;
  		}
  
  		return sample / 0x100000000;
  	};
  }
  
  /**
   * This function is called when the ProcessingQueue is done processing all
   * items. It handles emitting the final run events.
   */
  function done() {
  	const storage = config.storage;
  
  	ProcessingQueue.finished = true;
  
  	const runtime = now() - config.started;
  	const passed = config.stats.all - config.stats.bad;
  
  	emit( "runEnd", globalSuite.end( true ) );
  	runLoggingCallbacks( "done", {
  		passed,
  		failed: config.stats.bad,
  		total: config.stats.all,
  		runtime
  	} );
  
  	// Clear own storage items if all tests passed
  	if ( storage && config.stats.bad === 0 ) {
  		for ( let i = storage.length - 1; i >= 0; i-- ) {
  			const key = storage.key( i );
  
  			if ( key.indexOf( "qunit-test-" ) === 0 ) {
  				storage.removeItem( key );
  			}
  		}
  	}
  }
  
  const ProcessingQueue = {
  	finished: false,
  	add: addToQueue,
  	addImmediate: addToQueueImmediate,
  	advance
  };
  
  export default ProcessingQueue;
  