/**
 * @fileoverview Main CLI object.
 * @author Nicholas C. Zakas
 */

"use strict";

/*
 * The CLI object should *not* call process.exit() directly. It should only return
 * exit codes. This allows other programs to use the CLI object and still control
 * when the program exits.
 */

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

const fs = require("node:fs");
const path = require("node:path");
const defaultOptions = require("../../conf/default-cli-options");
const pkg = require("../../package.json");

const {
	Legacy: {
		ConfigOps,
		naming,
		CascadingConfigArrayFactory,
		IgnorePattern,
		getUsedExtractedConfigs,
		ModuleResolver,
	},
} = require("@eslint/eslintrc");

const { FileEnumerator } = require("./file-enumerator");

const { Linter } = require("../linter");
const builtInRules = require("../rules");
const loadRules = require("./load-rules");
const hash = require("./hash");
const LintResultCache = require("./lint-result-cache");

const debug = require("debug")("eslint:cli-engine");
const removedFormatters = new Set([
	"checkstyle",
	"codeframe",
	"compact",
	"jslint-xml",
	"junit",
	"table",
	"tap",
	"unix",
	"visualstudio",
]);
const validFixTypes = new Set(["directive", "problem", "suggestion", "layout"]);

//------------------------------------------------------------------------------
// Typedefs
//------------------------------------------------------------------------------

// For VSCode IntelliSense
/** @typedef {import("../shared/types").ConfigData} ConfigData */
/** @typedef {import("../shared/types").DeprecatedRuleInfo} DeprecatedRuleInfo */
/** @typedef {import("../shared/types").LintMessage} LintMessage */
/** @typedef {import("../shared/types").SuppressedLintMessage} SuppressedLintMessage */
/** @typedef {import("../shared/types").ParserOptions} ParserOptions */
/** @typedef {import("../shared/types").Plugin} Plugin */
/** @typedef {import("../shared/types").RuleConf} RuleConf */
/** @typedef {import("../types").Rule.RuleModule} Rule */
/** @typedef {import("../types").ESLint.FormatterFunction} FormatterFunction */
/** @typedef {ReturnType<CascadingConfigArrayFactory.getConfigArrayForFile>} ConfigArray */
/** @typedef {ReturnType<ConfigArray.extractConfig>} ExtractedConfig */

/**
 * The options to configure a CLI engine with.
 * @typedef {Object} CLIEngineOptions
 * @property {boolean} [allowInlineConfig] Enable or disable inline configuration comments.
 * @property {ConfigData} [baseConfig] Base config object, extended by all configs used with this CLIEngine instance
 * @property {boolean} [cache] Enable result caching.
 * @property {string} [cacheLocation] The cache file to use instead of .eslintcache.
 * @property {string} [configFile] The configuration file to use.
 * @property {string} [cwd] The value to use for the current working directory.
 * @property {string[]} [envs] An array of environments to load.
 * @property {string[]|null} [extensions] An array of file extensions to check.
 * @property {boolean|Function} [fix] Execute in autofix mode. If a function, should return a boolean.
 * @property {string[]} [fixTypes] Array of rule types to apply fixes for.
 * @property {string[]} [globals] An array of global variables to declare.
 * @property {boolean} [ignore] False disables use of .eslintignore.
 * @property {string} [ignorePath] The ignore file to use instead of .eslintignore.
 * @property {string|string[]} [ignorePattern] One or more glob patterns to ignore.
 * @property {boolean} [useEslintrc] False disables looking for .eslintrc
 * @property {string} [parser] The name of the parser to use.
 * @property {ParserOptions} [parserOptions] An object of parserOption settings to use.
 * @property {string[]} [plugins] An array of plugins to load.
 * @property {Record<string,RuleConf>} [rules] An object of rules to use.
 * @property {string[]} [rulePaths] An array of directories to load custom rules from.
 * @property {boolean|string} [reportUnusedDisableDirectives] `true`, `"error"` or '"warn"' adds reports for unused eslint-disable directives
 * @property {boolean} [globInputPaths] Set to false to skip glob resolution of input file paths to lint (default: true). If false, each input file paths is assumed to be a non-glob path to an existing file.
 * @property {string} [resolvePluginsRelativeTo] The folder where plugins should be resolved from, defaulting to the CWD
 */

/**
 * A linting result.
 * @typedef {Object} LintResult
 * @property {string} filePath The path to the file that was linted.
 * @property {LintMessage[]} messages All of the messages for the result.
 * @property {SuppressedLintMessage[]} suppressedMessages All of the suppressed messages for the result.
 * @property {number} errorCount Number of errors for the result.
 * @property {number} fatalErrorCount Number of fatal errors for the result.
 * @property {number} warningCount Number of warnings for the result.
 * @property {number} fixableErrorCount Number of fixable errors for the result.
 * @property {number} fixableWarningCount Number of fixable warnings for the result.
 * @property {string} [source] The source code of the file that was linted.
 * @property {string} [output] The source code of the file that was linted, with as many fixes applied as possible.
 */

/**
 * Linting results.
 * @typedef {Object} LintReport
 * @property {LintResult[]} results All of the result.
 * @property {number} errorCount Number of errors for the result.
 * @property {number} fatalErrorCount Number of fatal errors for the result.
 * @property {number} warningCount Number of warnings for the result.
 * @property {number} fixableErrorCount Number of fixable errors for the result.
 * @property {number} fixableWarningCount Number of fixable warnings for the result.
 * @property {DeprecatedRuleInfo[]} usedDeprecatedRules The list of used deprecated rules.
 */

/**
 * Private data for CLIEngine.
 * @typedef {Object} CLIEngineInternalSlots
 * @property {Map<string, Plugin>} additionalPluginPool The map for additional plugins.
 * @property {string} cacheFilePath The path to the cache of lint results.
 * @property {CascadingConfigArrayFactory} configArrayFactory The factory of configs.
 * @property {(filePath: string) => boolean} defaultIgnores The default predicate function to check if a file ignored or not.
 * @property {FileEnumerator} fileEnumerator The file enumerator.
 * @property {ConfigArray[]} lastConfigArrays The list of config arrays that the last `executeOnFiles` or `executeOnText` used.
 * @property {LintResultCache|null} lintResultCache The cache of lint results.
 * @property {Linter} linter The linter instance which has loaded rules.
 * @property {CLIEngineOptions} options The normalized options of this instance.
 */

//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------

/** @type {WeakMap<CLIEngine, CLIEngineInternalSlots>} */
const internalSlotsMap = new WeakMap();

/**
 * Determines if each fix type in an array is supported by ESLint and throws
 * an error if not.
 * @param {string[]} fixTypes An array of fix types to check.
 * @returns {void}
 * @throws {Error} If an invalid fix type is found.
 */
function validateFixTypes(fixTypes) {
	for (const fixType of fixTypes) {
		if (!validFixTypes.has(fixType)) {
			throw new Error(`Invalid fix type "${fixType}" found.`);
		}
	}
}

/**
 * It will calculate the error and warning count for collection of messages per file
 * @param {LintMessage[]} messages Collection of messages
 * @returns {Object} Contains the stats
 * @private
 */
function calculateStatsPerFile(messages) {
	const stat = {
		errorCount: 0,
		fatalErrorCount: 0,
		warningCount: 0,
		fixableErrorCount: 0,
		fixableWarningCount: 0,
	};

	for (let i = 0; i < messages.length; i++) {
		const message = messages[i];

		if (message.fatal || message.severity === 2) {
			stat.errorCount++;
			if (message.fatal) {
				stat.fatalErrorCount++;
			}
			if (message.fix) {
				stat.fixableErrorCount++;
			}
		} else {
			stat.warningCount++;
			if (message.fix) {
				stat.fixableWarningCount++;
			}
		}
	}
	return stat;
}

/**
 * It will calculate the error and warning count for collection of results from all files
 * @param {LintResult[]} results Collection of messages from all the files
 * @returns {Object} Contains the stats
 * @private
 */
function calculateStatsPerRun(results) {
	const stat = {
		errorCount: 0,
		fatalErrorCount: 0,
		warningCount: 0,
		fixableErrorCount: 0,
		fixableWarningCount: 0,
	};

	for (let i = 0; i < results.length; i++) {
		const result = results[i];

		stat.errorCount += result.errorCount;
		stat.fatalErrorCount += result.fatalErrorCount;
		stat.warningCount += result.warningCount;
		stat.fixableErrorCount += result.fixableErrorCount;
		stat.fixableWarningCount += result.fixableWarningCount;
	}

	return stat;
}

/**
 * Processes an source code using ESLint.
 * @param {Object} config The config object.
 * @param {string} config.text The source code to verify.
 * @param {string} config.cwd The path to the current working directory.
 * @param {string|undefined} config.filePath The path to the file of `text`. If this is undefined, it uses `<text>`.
 * @param {ConfigArray} config.config The config.
 * @param {boolean} config.fix If `true` then it does fix.
 * @param {boolean} config.allowInlineConfig If `true` then it uses directive comments.
 * @param {boolean|string} config.reportUnusedDisableDirectives If `true`, `"error"` or '"warn"', then it reports unused `eslint-disable` comments.
 * @param {FileEnumerator} config.fileEnumerator The file enumerator to check if a path is a target or not.
 * @param {Linter} config.linter The linter instance to verify.
 * @returns {LintResult} The result of linting.
 * @private
 */
function verifyText({
	text,
	cwd,
	filePath: providedFilePath,
	config,
	fix,
	allowInlineConfig,
	reportUnusedDisableDirectives,
	fileEnumerator,
	linter,
}) {
	const filePath = providedFilePath || "<text>";

	debug(`Lint ${filePath}`);

	/*
	 * Verify.
	 * `config.extractConfig(filePath)` requires an absolute path, but `linter`
	 * doesn't know CWD, so it gives `linter` an absolute path always.
	 */
	const filePathToVerify =
		filePath === "<text>" ? path.join(cwd, filePath) : filePath;
	const { fixed, messages, output } = linter.verifyAndFix(text, config, {
		allowInlineConfig,
		filename: filePathToVerify,
		fix,
		reportUnusedDisableDirectives,

		/**
		 * Check if the linter should adopt a given code block or not.
		 * @param {string} blockFilename The virtual filename of a code block.
		 * @returns {boolean} `true` if the linter should adopt the code block.
		 */
		filterCodeBlock(blockFilename) {
			return fileEnumerator.isTargetPath(blockFilename);
		},
	});

	// Tweak and return.
	const result = {
		filePath,
		messages,
		suppressedMessages: linter.getSuppressedMessages(),
		...calculateStatsPerFile(messages),
	};

	if (fixed) {
		result.output = output;
	}
	if (
		result.errorCount + result.warningCount > 0 &&
		typeof result.output === "undefined"
	) {
		result.source = text;
	}

	return result;
}

/**
 * Returns result with warning by ignore settings
 * @param {string} filePath File path of checked code
 * @param {string} baseDir Absolute path of base directory
 * @returns {LintResult} Result with single warning
 * @private
 */
function createIgnoreResult(filePath, baseDir) {
	let message;
	const isHidden = filePath
		.split(path.sep)
		.find(segment => /^\./u.test(segment));
	const isInNodeModules =
		baseDir && path.relative(baseDir, filePath).startsWith("node_modules");

	if (isHidden) {
		message =
			"File ignored by default.  Use a negated ignore pattern (like \"--ignore-pattern '!<relative/path/to/filename>'\") to override.";
	} else if (isInNodeModules) {
		message =
			"File ignored by default. Use \"--ignore-pattern '!node_modules/*'\" to override.";
	} else {
		message =
			'File ignored because of a matching ignore pattern. Use "--no-ignore" to override.';
	}

	return {
		filePath: path.resolve(filePath),
		messages: [
			{
				ruleId: null,
				fatal: false,
				severity: 1,
				message,
				nodeType: null,
			},
		],
		suppressedMessages: [],
		errorCount: 0,
		fatalErrorCount: 0,
		warningCount: 1,
		fixableErrorCount: 0,
		fixableWarningCount: 0,
	};
}

/**
 * Get a rule.
 * @param {string} ruleId The rule ID to get.
 * @param {ConfigArray[]} configArrays The config arrays that have plugin rules.
 * @returns {Rule|null} The rule or null.
 */
function getRule(ruleId, configArrays) {
	for (const configArray of configArrays) {
		const rule = configArray.pluginRules.get(ruleId);

		if (rule) {
			return rule;
		}
	}
	return builtInRules.get(ruleId) || null;
}

/**
 * Checks whether a message's rule type should be fixed.
 * @param {LintMessage} message The message to check.
 * @param {ConfigArray[]} lastConfigArrays The list of config arrays that the last `executeOnFiles` or `executeOnText` used.
 * @param {string[]} fixTypes An array of fix types to check.
 * @returns {boolean} Whether the message should be fixed.
 */
function shouldMessageBeFixed(message, lastConfigArrays, fixTypes) {
	if (!message.ruleId) {
		return fixTypes.has("directive");
	}

	const rule = message.ruleId && getRule(message.ruleId, lastConfigArrays);

	return Boolean(rule && rule.meta && fixTypes.has(rule.meta.type));
}

/**
 * Collect used deprecated rules.
 * @param {ConfigArray[]} usedConfigArrays The config arrays which were used.
 * @returns {IterableIterator<DeprecatedRuleInfo>} Used deprecated rules.
 */
function* iterateRuleDeprecationWarnings(usedConfigArrays) {
	const processedRuleIds = new Set();

	// Flatten used configs.
	/** @type {ExtractedConfig[]} */
	const configs = usedConfigArrays.flatMap(getUsedExtractedConfigs);

	// Traverse rule configs.
	for (const config of configs) {
		for (const [ruleId, ruleConfig] of Object.entries(config.rules)) {
			// Skip if it was processed.
			if (processedRuleIds.has(ruleId)) {
				continue;
			}
			processedRuleIds.add(ruleId);

			// Skip if it's not used.
			if (!ConfigOps.getRuleSeverity(ruleConfig)) {
				continue;
			}
			const rule = getRule(ruleId, usedConfigArrays);

			// Skip if it's not deprecated.
			if (!(rule && rule.meta && rule.meta.deprecated)) {
				continue;
			}

			// This rule was used and deprecated.
			yield {
				ruleId,
				replacedBy: rule.meta.replacedBy || [],
			};
		}
	}
}

/**
 * Checks if the given message is an error message.
 * @param {LintMessage} message The message to check.
 * @returns {boolean} Whether or not the message is an error message.
 * @private
 */
function isErrorMessage(message) {
	return message.severity === 2;
}

/**
 * return the cacheFile to be used by eslint, based on whether the provided parameter is
 * a directory or looks like a directory (ends in `path.sep`), in which case the file
 * name will be the `cacheFile/.cache_hashOfCWD`
 *
 * if cacheFile points to a file or looks like a file then it will just use that file
 * @param {string} cacheFile The name of file to be used to store the cache
 * @param {string} cwd Current working directory
 * @returns {string} the resolved path to the cache file
 */
function getCacheFile(cacheFile, cwd) {
	/*
	 * make sure the path separators are normalized for the environment/os
	 * keeping the trailing path separator if present
	 */
	const normalizedCacheFile = path.normalize(cacheFile);

	const resolvedCacheFile = path.resolve(cwd, normalizedCacheFile);
	const looksLikeADirectory = normalizedCacheFile.slice(-1) === path.sep;

	/**
	 * return the name for the cache file in case the provided parameter is a directory
	 * @returns {string} the resolved path to the cacheFile
	 */
	function getCacheFileForDirectory() {
		return path.join(resolvedCacheFile, `.cache_${hash(cwd)}`);
	}

	let fileStats;

	try {
		fileStats = fs.lstatSync(resolvedCacheFile);
	} catch {
		fileStats = null;
	}

	/*
	 * in case the file exists we need to verify if the provided path
	 * is a directory or a file. If it is a directory we want to create a file
	 * inside that directory
	 */
	if (fileStats) {
		/*
		 * is a directory or is a file, but the original file the user provided
		 * looks like a directory but `path.resolve` removed the `last path.sep`
		 * so we need to still treat this like a directory
		 */
		if (fileStats.isDirectory() || looksLikeADirectory) {
			return getCacheFileForDirectory();
		}

		// is file so just use that file
		return resolvedCacheFile;
	}

	/*
	 * here we known the file or directory doesn't exist,
	 * so we will try to infer if its a directory if it looks like a directory
	 * for the current operating system.
	 */

	// if the last character passed is a path separator we assume is a directory
	if (looksLikeADirectory) {
		return getCacheFileForDirectory();
	}

	return resolvedCacheFile;
}

/**
 * Convert a string array to a boolean map.
 * @param {string[]|null} keys The keys to assign true.
 * @param {boolean} defaultValue The default value for each property.
 * @param {string} displayName The property name which is used in error message.
 * @throws {Error} Requires array.
 * @returns {Record<string,boolean>} The boolean map.
 */
function toBooleanMap(keys, defaultValue, displayName) {
	if (keys && !Array.isArray(keys)) {
		throw new Error(`${displayName} must be an array.`);
	}
	if (keys && keys.length > 0) {
		return keys.reduce((map, def) => {
			const [key, value] = def.split(":");

			if (key !== "__proto__") {
				map[key] = value === void 0 ? defaultValue : value === "true";
			}

			return map;
		}, {});
	}
	return void 0;
}

/**
 * Create a config data from CLI options.
 * @param {CLIEngineOptions} options The options
 * @returns {ConfigData|null} The created config data.
 */
function createConfigDataFromOptions(options) {
	const { ignorePattern, parser, parserOptions, plugins, rules } = options;
	const env = toBooleanMap(options.envs, true, "envs");
	const globals = toBooleanMap(options.globals, false, "globals");

	if (
		env === void 0 &&
		globals === void 0 &&
		(ignorePattern === void 0 || ignorePattern.length === 0) &&
		parser === void 0 &&
		parserOptions === void 0 &&
		plugins === void 0 &&
		rules === void 0
	) {
		return null;
	}
	return {
		env,
		globals,
		ignorePatterns: ignorePattern,
		parser,
		parserOptions,
		plugins,
		rules,
	};
}

/**
 * Checks whether a directory exists at the given location
 * @param {string} resolvedPath A path from the CWD
 * @throws {Error} As thrown by `fs.statSync` or `fs.isDirectory`.
 * @returns {boolean} `true` if a directory exists
 */
function directoryExists(resolvedPath) {
	try {
		return fs.statSync(resolvedPath).isDirectory();
	} catch (error) {
		if (error && (error.code === "ENOENT" || error.code === "ENOTDIR")) {
			return false;
		}
		throw error;
	}
}

//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------

/**
 * Core CLI.
 */
class CLIEngine {
	/**
	 * Creates a new instance of the core CLI engine.
	 * @param {CLIEngineOptions} providedOptions The options for this instance.
	 * @param {Object} [additionalData] Additional settings that are not CLIEngineOptions.
	 * @param {Record<string,Plugin>|null} [additionalData.preloadedPlugins] Preloaded plugins.
	 */
	constructor(providedOptions, { preloadedPlugins } = {}) {
		const options = Object.assign(
			Object.create(null),
			defaultOptions,
			{ cwd: process.cwd() },
			providedOptions,
		);

		if (options.fix === void 0) {
			options.fix = false;
		}

		const additionalPluginPool = new Map();

		if (preloadedPlugins) {
			for (const [id, plugin] of Object.entries(preloadedPlugins)) {
				additionalPluginPool.set(id, plugin);
			}
		}

		const cacheFilePath = getCacheFile(
			options.cacheLocation || options.cacheFile,
			options.cwd,
		);
		const configArrayFactory = new CascadingConfigArrayFactory({
			additionalPluginPool,
			baseConfig: options.baseConfig || null,
			cliConfig: createConfigDataFromOptions(options),
			cwd: options.cwd,
			ignorePath: options.ignorePath,
			resolvePluginsRelativeTo: options.resolvePluginsRelativeTo,
			rulePaths: options.rulePaths,
			specificConfigPath: options.configFile,
			useEslintrc: options.useEslintrc,
			builtInRules,
			loadRules,
			getEslintRecommendedConfig: () =>
				require("@eslint/js").configs.recommended,
			getEslintAllConfig: () => require("@eslint/js").configs.all,
		});
		const fileEnumerator = new FileEnumerator({
			configArrayFactory,
			cwd: options.cwd,
			extensions: options.extensions,
			globInputPaths: options.globInputPaths,
			errorOnUnmatchedPattern: options.errorOnUnmatchedPattern,
			ignore: options.ignore,
		});
		const lintResultCache = options.cache
			? new LintResultCache(cacheFilePath, options.cacheStrategy)
			: null;
		const linter = new Linter({ cwd: options.cwd, configType: "eslintrc" });

		/** @type {ConfigArray[]} */
		const lastConfigArrays = [configArrayFactory.getConfigArrayForFile()];

		// Store private data.
		internalSlotsMap.set(this, {
			additionalPluginPool,
			cacheFilePath,
			configArrayFactory,
			defaultIgnores: IgnorePattern.createDefaultIgnore(options.cwd),
			fileEnumerator,
			lastConfigArrays,
			lintResultCache,
			linter,
			options,
		});

		// setup special filter for fixes
		if (options.fix && options.fixTypes && options.fixTypes.length > 0) {
			debug(`Using fix types ${options.fixTypes}`);

			// throw an error if any invalid fix types are found
			validateFixTypes(options.fixTypes);

			// convert to Set for faster lookup
			const fixTypes = new Set(options.fixTypes);

			// save original value of options.fix in case it's a function
			const originalFix =
				typeof options.fix === "function" ? options.fix : () => true;

			options.fix = message =>
				shouldMessageBeFixed(message, lastConfigArrays, fixTypes) &&
				originalFix(message);
		}
	}

	getRules() {
		const { lastConfigArrays } = internalSlotsMap.get(this);

		return new Map(
			(function* () {
				yield* builtInRules;

				for (const configArray of lastConfigArrays) {
					yield* configArray.pluginRules;
				}
			})(),
		);
	}

	/**
	 * Returns results that only contains errors.
	 * @param {LintResult[]} results The results to filter.
	 * @returns {LintResult[]} The filtered results.
	 */
	static getErrorResults(results) {
		const filtered = [];

		results.forEach(result => {
			const filteredMessages = result.messages.filter(isErrorMessage);
			const filteredSuppressedMessages =
				result.suppressedMessages.filter(isErrorMessage);

			if (filteredMessages.length > 0) {
				filtered.push({
					...result,
					messages: filteredMessages,
					suppressedMessages: filteredSuppressedMessages,
					errorCount: filteredMessages.length,
					warningCount: 0,
					fixableErrorCount: result.fixableErrorCount,
					fixableWarningCount: 0,
				});
			}
		});

		return filtered;
	}

	/**
	 * Outputs fixes from the given results to files.
	 * @param {LintReport} report The report object created by CLIEngine.
	 * @returns {void}
	 */
	static outputFixes(report) {
		report.results
			.filter(result => Object.hasOwn(result, "output"))
			.forEach(result => {
				fs.writeFileSync(result.filePath, result.output);
			});
	}

	/**
	 * Resolves the patterns passed into executeOnFiles() into glob-based patterns
	 * for easier handling.
	 * @param {string[]} patterns The file patterns passed on the command line.
	 * @returns {string[]} The equivalent glob patterns.
	 */
	resolveFileGlobPatterns(patterns) {
		const { options } = internalSlotsMap.get(this);

		if (options.globInputPaths === false) {
			return patterns.filter(Boolean);
		}

		const extensions = (options.extensions || [".js"]).map(ext =>
			ext.replace(/^\./u, ""),
		);
		const dirSuffix = `/**/*.{${extensions.join(",")}}`;

		return patterns.filter(Boolean).map(pathname => {
			const resolvedPath = path.resolve(options.cwd, pathname);
			const newPath = directoryExists(resolvedPath)
				? pathname.replace(/[/\\]$/u, "") + dirSuffix
				: pathname;

			return path.normalize(newPath).replace(/\\/gu, "/");
		});
	}

	/**
	 * Executes the current configuration on an array of file and directory names.
	 * @param {string[]} patterns An array of file and directory names.
	 * @throws {Error} As may be thrown by `fs.unlinkSync`.
	 * @returns {LintReport} The results for all files that were linted.
	 */
	executeOnFiles(patterns) {
		const {
			cacheFilePath,
			fileEnumerator,
			lastConfigArrays,
			lintResultCache,
			linter,
			options: {
				allowInlineConfig,
				cache,
				cwd,
				fix,
				reportUnusedDisableDirectives,
			},
		} = internalSlotsMap.get(this);
		const results = [];
		const startTime = Date.now();

		// Clear the last used config arrays.
		lastConfigArrays.length = 0;

		// Delete cache file; should this do here?
		if (!cache) {
			try {
				fs.unlinkSync(cacheFilePath);
			} catch (error) {
				const errorCode = error && error.code;

				// Ignore errors when no such file exists or file system is read only (and cache file does not exist)
				if (
					errorCode !== "ENOENT" &&
					!(errorCode === "EROFS" && !fs.existsSync(cacheFilePath))
				) {
					throw error;
				}
			}
		}

		// Iterate source code files.
		for (const { config, filePath, ignored } of fileEnumerator.iterateFiles(
			patterns,
		)) {
			if (ignored) {
				results.push(createIgnoreResult(filePath, cwd));
				continue;
			}

			/*
			 * Store used configs for:
			 * - this method uses to collect used deprecated rules.
			 * - `getRules()` method uses to collect all loaded rules.
			 * - `--fix-type` option uses to get the loaded rule's meta data.
			 */
			if (!lastConfigArrays.includes(config)) {
				lastConfigArrays.push(config);
			}

			// Skip if there is cached result.
			if (lintResultCache) {
				const cachedResult = lintResultCache.getCachedLintResults(
					filePath,
					config,
				);

				if (cachedResult) {
					const hadMessages =
						cachedResult.messages &&
						cachedResult.messages.length > 0;

					if (hadMessages && fix) {
						debug(
							`Reprocessing cached file to allow autofix: ${filePath}`,
						);
					} else {
						debug(
							`Skipping file since it hasn't changed: ${filePath}`,
						);
						results.push(cachedResult);
						continue;
					}
				}
			}

			// Do lint.
			const result = verifyText({
				text: fs.readFileSync(filePath, "utf8"),
				filePath,
				config,
				cwd,
				fix,
				allowInlineConfig,
				reportUnusedDisableDirectives,
				fileEnumerator,
				linter,
			});

			results.push(result);

			/*
			 * Store the lint result in the LintResultCache.
			 * NOTE: The LintResultCache will remove the file source and any
			 * other properties that are difficult to serialize, and will
			 * hydrate those properties back in on future lint runs.
			 */
			if (lintResultCache) {
				lintResultCache.setCachedLintResults(filePath, config, result);
			}
		}

		// Persist the cache to disk.
		if (lintResultCache) {
			lintResultCache.reconcile();
		}

		debug(`Linting complete in: ${Date.now() - startTime}ms`);
		let usedDeprecatedRules;

		return {
			results,
			...calculateStatsPerRun(results),

			// Initialize it lazily because CLI and `ESLint` API don't use it.
			get usedDeprecatedRules() {
				if (!usedDeprecatedRules) {
					usedDeprecatedRules = Array.from(
						iterateRuleDeprecationWarnings(lastConfigArrays),
					);
				}
				return usedDeprecatedRules;
			},
		};
	}

	/**
	 * Executes the current configuration on text.
	 * @param {string} text A string of JavaScript code to lint.
	 * @param {string} [filename] An optional string representing the texts filename.
	 * @param {boolean} [warnIgnored] Always warn when a file is ignored
	 * @returns {LintReport} The results for the linting.
	 */
	executeOnText(text, filename, warnIgnored) {
		const {
			configArrayFactory,
			fileEnumerator,
			lastConfigArrays,
			linter,
			options: {
				allowInlineConfig,
				cwd,
				fix,
				reportUnusedDisableDirectives,
			},
		} = internalSlotsMap.get(this);
		const results = [];
		const startTime = Date.now();
		const resolvedFilename = filename && path.resolve(cwd, filename);

		// Clear the last used config arrays.
		lastConfigArrays.length = 0;
		if (resolvedFilename && this.isPathIgnored(resolvedFilename)) {
			if (warnIgnored) {
				results.push(createIgnoreResult(resolvedFilename, cwd));
			}
		} else {
			const config = configArrayFactory.getConfigArrayForFile(
				resolvedFilename || "__placeholder__.js",
			);

			/*
			 * Store used configs for:
			 * - this method uses to collect used deprecated rules.
			 * - `getRules()` method uses to collect all loaded rules.
			 * - `--fix-type` option uses to get the loaded rule's meta data.
			 */
			lastConfigArrays.push(config);

			// Do lint.
			results.push(
				verifyText({
					text,
					filePath: resolvedFilename,
					config,
					cwd,
					fix,
					allowInlineConfig,
					reportUnusedDisableDirectives,
					fileEnumerator,
					linter,
				}),
			);
		}

		debug(`Linting complete in: ${Date.now() - startTime}ms`);
		let usedDeprecatedRules;

		return {
			results,
			...calculateStatsPerRun(results),

			// Initialize it lazily because CLI and `ESLint` API don't use it.
			get usedDeprecatedRules() {
				if (!usedDeprecatedRules) {
					usedDeprecatedRules = Array.from(
						iterateRuleDeprecationWarnings(lastConfigArrays),
					);
				}
				return usedDeprecatedRules;
			},
		};
	}

	/**
	 * Returns a configuration object for the given file based on the CLI options.
	 * This is the same logic used by the ESLint CLI executable to determine
	 * configuration for each file it processes.
	 * @param {string} filePath The path of the file to retrieve a config object for.
	 * @throws {Error} If filepath a directory path.
	 * @returns {ConfigData} A configuration object for the file.
	 */
	getConfigForFile(filePath) {
		const { configArrayFactory, options } = internalSlotsMap.get(this);
		const absolutePath = path.resolve(options.cwd, filePath);

		if (directoryExists(absolutePath)) {
			throw Object.assign(
				new Error("'filePath' should not be a directory path."),
				{ messageTemplate: "print-config-with-directory-path" },
			);
		}

		return configArrayFactory
			.getConfigArrayForFile(absolutePath)
			.extractConfig(absolutePath)
			.toCompatibleObjectAsConfigFileContent();
	}

	/**
	 * Checks if a given path is ignored by ESLint.
	 * @param {string} filePath The path of the file to check.
	 * @returns {boolean} Whether or not the given path is ignored.
	 */
	isPathIgnored(filePath) {
		const {
			configArrayFactory,
			defaultIgnores,
			options: { cwd, ignore },
		} = internalSlotsMap.get(this);
		const absolutePath = path.resolve(cwd, filePath);

		if (ignore) {
			const config = configArrayFactory
				.getConfigArrayForFile(absolutePath)
				.extractConfig(absolutePath);
			const ignores = config.ignores || defaultIgnores;

			return ignores(absolutePath);
		}

		return defaultIgnores(absolutePath);
	}

	/**
	 * Returns the formatter representing the given format or null if the `format` is not a string.
	 * @param {string} [format] The name of the format to load or the path to a
	 *      custom formatter.
	 * @throws {any} As may be thrown by requiring of formatter
	 * @returns {(FormatterFunction|null)} The formatter function or null if the `format` is not a string.
	 */
	getFormatter(format) {
		// default is stylish
		const resolvedFormatName = format || "stylish";

		// only strings are valid formatters
		if (typeof resolvedFormatName === "string") {
			// replace \ with / for Windows compatibility
			const normalizedFormatName = resolvedFormatName.replace(
				/\\/gu,
				"/",
			);

			const slots = internalSlotsMap.get(this);
			const cwd = slots ? slots.options.cwd : process.cwd();
			const namespace = naming.getNamespaceFromTerm(normalizedFormatName);

			let formatterPath;

			// if there's a slash, then it's a file (TODO: this check seems dubious for scoped npm packages)
			if (!namespace && normalizedFormatName.includes("/")) {
				formatterPath = path.resolve(cwd, normalizedFormatName);
			} else {
				try {
					const npmFormat = naming.normalizePackageName(
						normalizedFormatName,
						"eslint-formatter",
					);

					formatterPath = ModuleResolver.resolve(
						npmFormat,
						path.join(cwd, "__placeholder__.js"),
					);
				} catch {
					formatterPath = path.resolve(
						__dirname,
						"formatters",
						normalizedFormatName,
					);
				}
			}

			try {
				return require(formatterPath);
			} catch (ex) {
				if (removedFormatters.has(format)) {
					ex.message = `The ${format} formatter is no longer part of core ESLint. Install it manually with \`npm install -D eslint-formatter-${format}\``;
				} else {
					ex.message = `There was a problem loading formatter: ${formatterPath}\nError: ${ex.message}`;
				}
				throw ex;
			}
		} else {
			return null;
		}
	}
}

CLIEngine.version = pkg.version;
CLIEngine.getFormatter = CLIEngine.prototype.getFormatter;

module.exports = {
	CLIEngine,

	/**
	 * Get the internal slots of a given CLIEngine instance for tests.
	 * @param {CLIEngine} instance The CLIEngine instance to get.
	 * @returns {CLIEngineInternalSlots} The internal slots.
	 */
	getCLIEngineInternalSlots(instance) {
		return internalSlotsMap.get(instance);
	},
};
