text: /*
  	MIT License http://www.opensource.org/licenses/mit-license.php
  	Author Tobias Koppers @sokra
  */
  
  "use strict";
  
  const Stats = require("./Stats");
  
  /** @typedef {import("../declarations/WebpackOptions").WatchOptions} WatchOptions */
  /** @typedef {import("./Compilation")} Compilation */
  /** @typedef {import("./Compiler")} Compiler */
  /** @typedef {import("./Stats")} Stats */
  
  /**
   * @template T
   * @callback Callback
   * @param {Error=} err
   * @param {T=} result
   */
  
  class Watching {
  	/**
  	 * @param {Compiler} compiler the compiler
  	 * @param {WatchOptions} watchOptions options
  	 * @param {Callback<Stats>} handler completion handler
  	 */
  	constructor(compiler, watchOptions, handler) {
  		this.startTime = null;
  		this.invalid = false;
  		this.handler = handler;
  		/** @type {Callback<void>[]} */
  		this.callbacks = [];
  		this.closed = false;
  		this.suspended = false;
  		if (typeof watchOptions === "number") {
  			this.watchOptions = {
  				aggregateTimeout: watchOptions
  			};
  		} else if (watchOptions && typeof watchOptions === "object") {
  			this.watchOptions = { ...watchOptions };
  		} else {
  			this.watchOptions = {};
  		}
  		this.watchOptions.aggregateTimeout =
  			this.watchOptions.aggregateTimeout || 200;
  		this.compiler = compiler;
  		this.running = true;
  		this.watcher = undefined;
  		this.pausedWatcher = undefined;
  		this._done = this._done.bind(this);
  		this.compiler.readRecords(err => {
  			if (err) return this._done(err);
  
  			this._go();
  		});
  	}
  
  	_go() {
  		this.startTime = Date.now();
  		this.running = true;
  		this.invalid = false;
  		this.compiler.cache.endIdle(err => {
  			if (err) return this._done(err);
  			this.compiler.hooks.watchRun.callAsync(this.compiler, err => {
  				if (err) return this._done(err);
  				const onCompiled = (err, compilation) => {
  					if (err) return this._done(err);
  					if (this.invalid) return this._done();
  
  					if (this.compiler.hooks.shouldEmit.call(compilation) === false) {
  						return this._done(null, compilation);
  					}
  
  					process.nextTick(() => {
  						const logger = compilation.getLogger("webpack.Compiler");
  						logger.time("emitAssets");
  						this.compiler.emitAssets(compilation, err => {
  							logger.timeEnd("emitAssets");
  							if (err) return this._done(err);
  							if (this.invalid) return this._done();
  
  							logger.time("emitRecords");
  							this.compiler.emitRecords(err => {
  								logger.timeEnd("emitRecords");
  								if (err) return this._done(err);
  
  								if (compilation.hooks.needAdditionalPass.call()) {
  									compilation.needAdditionalPass = true;
  
  									const stats = new Stats(compilation);
  									stats.startTime = this.startTime;
  									stats.endTime = Date.now();
  									logger.time("done hook");
  									this.compiler.hooks.done.callAsync(stats, err => {
  										logger.timeend("done hook");
  										if (err) return this._done(err);
  
  										this.compiler.hooks.additionalPass.callAsync(err => {
  											if (err) return this._done(err);
  											this.compiler.compile(onCompiled);
  										});
  									});
  									return;
  								}
  								return this._done(null, compilation);
  							});
  						});
  					});
  				};
  				this.compiler.compile(onCompiled);
  			});
  		});
  	}
  
  	/**
  	 * @param {Compilation} compilation the compilation
  	 * @returns {Stats} the compilation stats
  	 */
  	_getStats(compilation) {
  		const stats = new Stats(compilation);
  		stats.startTime = this.startTime;
  		stats.endTime = Date.now();
  		return stats;
  	}
  
  	/**
  	 * @param {Error=} err an optional error
  	 * @param {Compilation=} compilation the compilation
  	 * @returns {void}
  	 */
  	_done(err, compilation) {
  		this.running = false;
  		if (this.invalid) return this._go();
  
  		const stats = compilation ? this._getStats(compilation) : null;
  		if (err) {
  			this.compiler.hooks.failed.call(err);
  			this.compiler.cache.beginIdle();
  			this.handler(err, stats);
  			return;
  		}
  
  		const logger = compilation.getLogger("webpack.Watching");
  		logger.time("done hook");
  		this.compiler.hooks.done.callAsync(stats, () => {
  			logger.timeEnd("done hook");
  			logger.time("beginIdle");
  			this.compiler.cache.beginIdle();
  			logger.timeEnd("beginIdle");
  			this.handler(null, stats);
  			process.nextTick(() => {
  				if (!this.closed) {
  					this.watch(
  						compilation.fileDependencies,
  						compilation.contextDependencies,
  						compilation.missingDependencies
  					);
  				}
  			});
  			for (const cb of this.callbacks) cb();
  			this.callbacks.length = 0;
  			this.compiler.hooks.afterDone.call(stats);
  		});
  	}
  
  	/**
  	 * @param {Iterable<string>} files watched files
  	 * @param {Iterable<string>} dirs watched directories
  	 * @param {Iterable<string>} missing watched existance entries
  	 * @returns {void}
  	 */
  	watch(files, dirs, missing) {
  		this.pausedWatcher = null;
  		this.watcher = this.compiler.watchFileSystem.watch(
  			files,
  			dirs,
  			missing,
  			this.startTime,
  			this.watchOptions,
  			(
  				err,
  				fileTimeInfoEntries,
  				contextTimeInfoEntries,
  				changedFiles,
  				removedFiles
  			) => {
  				this.pausedWatcher = this.watcher;
  				this.watcher = null;
  				if (err) {
  					this.compiler.modifiedFiles = undefined;
  					this.compiler.removedFiles = undefined;
  					this.compiler.fileTimestamps = undefined;
  					this.compiler.contextTimestamps = undefined;
  					return this.handler(err);
  				}
  				this.compiler.fileTimestamps = fileTimeInfoEntries;
  				this.compiler.contextTimestamps = contextTimeInfoEntries;
  				this.compiler.removedFiles = removedFiles;
  				this.compiler.modifiedFiles = changedFiles;
  				if (!this.suspended) {
  					this._invalidate();
  				}
  			},
  			(fileName, changeTime) => {
  				this.compiler.hooks.invalid.call(fileName, changeTime);
  			}
  		);
  	}
  
  	/**
  	 * @param {Callback<void>=} callback signals when the build is invalidated
  	 * @returns {void}
  	 */
  	invalidate(callback) {
  		if (callback) {
  			this.callbacks.push(callback);
  		}
  		if (this.watcher) {
  			this.compiler.modifiedFiles = this.watcher.aggregatedChanges;
  			this.compiler.removedFiles = this.watcher.aggregatedRemovals;
  			this.compiler.fileTimestamps = this.watcher.getFileTimeInfoEntries();
  			this.compiler.contextTimestamps = this.watcher.getContextTimeInfoEntries();
  		}
  		this._invalidate();
  	}
  
  	_invalidate() {
  		if (this.watcher) {
  			this.pausedWatcher = this.watcher;
  			this.watcher.pause();
  			this.watcher = null;
  		}
  
  		if (this.running) {
  			this.invalid = true;
  		} else {
  			this._go();
  		}
  	}
  
  	suspend() {
  		this.suspended = true;
  		this.invalid = false;
  	}
  
  	resume() {
  		if (this.suspended) {
  			this.suspended = false;
  			this._invalidate();
  		}
  	}
  
  	/**
  	 * @param {Callback<void>} callback signals when the watcher is closed
  	 * @returns {void}
  	 */
  	close(callback) {
  		const finalCallback = () => {
  			this.compiler.running = false;
  			this.compiler.watchMode = false;
  			this.compiler.modifiedFiles = undefined;
  			this.compiler.removedFiles = undefined;
  			this.compiler.fileTimestamps = undefined;
  			this.compiler.contextTimestamps = undefined;
  			this.compiler.cache.shutdown(err => {
  				this.compiler.hooks.watchClose.call();
  				if (callback !== undefined) callback(err);
  			});
  		};
  
  		this.closed = true;
  		if (this.watcher) {
  			this.watcher.close();
  			this.watcher = null;
  		}
  		if (this.pausedWatcher) {
  			this.pausedWatcher.close();
  			this.pausedWatcher = null;
  		}
  		if (this.running) {
  			this.invalid = true;
  			this._done = finalCallback;
  		} else {
  			finalCallback();
  		}
  	}
  }
  
  module.exports = Watching;
  