/**
 * @fileoverview Build file
 * @author nzakas
 */

/* eslint no-use-before-define: "off", no-console: "off" -- CLI */
"use strict";

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

const checker = require("npm-license"),
    ReleaseOps = require("eslint-release"),
    fs = require("fs"),
    glob = require("glob"),
    marked = require("marked"),
    matter = require("gray-matter"),
    markdownlint = require("markdownlint"),
    os = require("os"),
    path = require("path"),
    semver = require("semver"),
    ejs = require("ejs"),
    loadPerf = require("load-perf"),
    yaml = require("js-yaml"),
    ignore = require("ignore"),
    { CLIEngine } = require("./lib/cli-engine"),
    builtinRules = require("./lib/rules/index");

require("shelljs/make");
/* global target -- global.target is declared in `shelljs/make.js` */
/**
 * global.target = {};
 * @see https://github.com/shelljs/shelljs/blob/124d3349af42cb794ae8f78fc9b0b538109f7ca7/make.js#L4
 * @see https://github.com/DefinitelyTyped/DefinitelyTyped/blob/3aa2d09b6408380598cfb802743b07e1edb725f3/types/shelljs/make.d.ts#L8-L11
 */
const { cat, cd, echo, exec, exit, find, ls, mkdir, pwd, test } = require("shelljs");

//------------------------------------------------------------------------------
// Settings
//------------------------------------------------------------------------------

/*
 * A little bit fuzzy. My computer has a first CPU speed of 3392 and the perf test
 * always completes in < 3800ms. However, Travis is less predictable due to
 * multiple different VM types. So I'm fudging this for now in the hopes that it
 * at least provides some sort of useful signal.
 */
const PERF_MULTIPLIER = 13e6;

const OPEN_SOURCE_LICENSES = [
    /MIT/u, /BSD/u, /Apache/u, /ISC/u, /WTF/u, /Public Domain/u, /LGPL/u, /Python/u
];

//------------------------------------------------------------------------------
// Data
//------------------------------------------------------------------------------

const NODE = "node ", // intentional extra space
    NODE_MODULES = "./node_modules/",
    TEMP_DIR = "./tmp/",
    DEBUG_DIR = "./debug/",
    BUILD_DIR = "build",
    SITE_DIR = "../eslint.org",
    DOCS_DIR = "./docs",
    DOCS_SRC_DIR = path.join(DOCS_DIR, "src"),
    DOCS_DATA_DIR = path.join(DOCS_SRC_DIR, "_data"),
    PERF_TMP_DIR = path.join(TEMP_DIR, "eslint", "performance"),

    // Utilities - intentional extra space at the end of each string
    MOCHA = `${NODE_MODULES}mocha/bin/_mocha `,
    ESLINT = `${NODE} bin/eslint.js --report-unused-disable-directives `,

    // Files
    RULE_FILES = glob.sync("lib/rules/*.js").filter(filePath => path.basename(filePath) !== "index.js"),
    JSON_FILES = find("conf/").filter(fileType("json")),
    MARKDOWNLINT_IGNORE_INSTANCE = ignore().add(fs.readFileSync(path.join(__dirname, ".markdownlintignore"), "utf-8")),
    MARKDOWN_FILES_ARRAY = MARKDOWNLINT_IGNORE_INSTANCE.filter(find("docs/").concat(ls(".")).filter(fileType("md"))),
    TEST_FILES = "\"tests/{bin,conf,lib,tools}/**/*.js\"",
    PERF_ESLINTRC = path.join(PERF_TMP_DIR, "eslint.config.js"),
    PERF_MULTIFILES_TARGET_DIR = path.join(PERF_TMP_DIR, "eslint"),

    /*
     * glob arguments with Windows separator `\` don't work:
     * https://github.com/eslint/eslint/issues/16259
     */
    PERF_MULTIFILES_TARGETS = `"${TEMP_DIR}eslint/performance/eslint/{lib,tests/lib}/**/*.js"`,

    // Settings
    MOCHA_TIMEOUT = parseInt(process.env.ESLINT_MOCHA_TIMEOUT, 10) || 10000;

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

/**
 * Simple JSON file validation that relies on ES JSON parser.
 * @param {string} filePath Path to JSON.
 * @throws Error If file contents is invalid JSON.
 * @returns {undefined}
 */
function validateJsonFile(filePath) {
    const contents = fs.readFileSync(filePath, "utf8");

    JSON.parse(contents);
}

/**
 * Generates a function that matches files with a particular extension.
 * @param {string} extension The file extension (i.e. "js")
 * @returns {Function} The function to pass into a filter method.
 * @private
 */
function fileType(extension) {
    return function(filename) {
        return filename.slice(filename.lastIndexOf(".") + 1) === extension;
    };
}

/**
 * Executes a command and returns the output instead of printing it to stdout.
 * @param {string} cmd The command string to execute.
 * @returns {string} The result of the executed command.
 */
function execSilent(cmd) {
    return exec(cmd, { silent: true }).stdout;
}

/**
 * Generates a release blog post for eslint.org
 * @param {Object} releaseInfo The release metadata.
 * @param {string} [prereleaseMajorVersion] If this is a prerelease, the next major version after this prerelease
 * @returns {void}
 * @private
 */
function generateBlogPost(releaseInfo, prereleaseMajorVersion) {
    const ruleList = RULE_FILES

        // Strip the .js extension
        .map(ruleFileName => path.basename(ruleFileName, ".js"))

        /*
         * Sort by length descending. This ensures that rule names which are substrings of other rule names are not
         * matched incorrectly. For example, the string "no-undefined" should get matched with the `no-undefined` rule,
         * instead of getting matched with the `no-undef` rule followed by the string "ined".
         */
        .sort((ruleA, ruleB) => ruleB.length - ruleA.length);

    const renderContext = Object.assign({ prereleaseMajorVersion, ruleList }, releaseInfo);

    const output = ejs.render(cat("./templates/blogpost.md.ejs"), renderContext),
        now = new Date(),
        month = now.getMonth() + 1,
        day = now.getDate(),
        filename = path.join(SITE_DIR, `src/content/blog/${now.getFullYear()}-${
            month < 10 ? `0${month}` : month}-${
            day < 10 ? `0${day}` : day}-eslint-v${
            releaseInfo.version}-released.md`);

    output.to(filename);
}

/**
 * Generates a doc page with formatter result examples
 * @param {Object} formatterInfo Linting results from each formatter
 * @returns {void}
 */
function generateFormatterExamples(formatterInfo) {
    const output = ejs.render(cat("./templates/formatter-examples.md.ejs"), formatterInfo);
    const outputDir = path.join(DOCS_SRC_DIR, "use/formatters/"),
        filename = path.join(outputDir, "index.md"),
        htmlFilename = path.join(outputDir, "html-formatter-example.html");

    if (!test("-d", outputDir)) {
        mkdir(outputDir);
    }

    output.to(filename);
    formatterInfo.formatterResults.html.result.to(htmlFilename);
}

/**
 * Generate a doc page that lists all of the rules and links to them
 * @returns {void}
 */
function generateRuleIndexPage() {
    const docsSiteOutputFile = path.join(DOCS_DATA_DIR, "rules.json"),
        docsSiteMetaOutputFile = path.join(DOCS_DATA_DIR, "rules_meta.json"),
        ruleTypes = "conf/rule-type-list.json",
        ruleTypesData = JSON.parse(cat(path.resolve(ruleTypes)));

    const meta = {};

    RULE_FILES
        .map(filename => [filename, path.basename(filename, ".js")])
        .sort((a, b) => a[1].localeCompare(b[1]))
        .forEach(pair => {
            const filename = pair[0];
            const basename = pair[1];
            const rule = require(path.resolve(filename));

            /*
             * Eleventy interprets the {{ }} in messages as being variables,
             * which can cause an error if there's syntax it doesn't expect.
             * Because we don't use this info in the website anyway, it's safer
             * to just remove it.
             *
             * Also removing the schema because we don't need it.
             */
            meta[basename] = {
                ...rule.meta,
                schema: void 0,
                messages: void 0
            };

            if (rule.meta.deprecated) {
                ruleTypesData.deprecated.rules.push({
                    name: basename,
                    replacedBy: rule.meta.replacedBy || []
                });
            } else {
                const output = {
                        name: basename,
                        description: rule.meta.docs.description,
                        recommended: rule.meta.docs.recommended || false,
                        fixable: !!rule.meta.fixable,
                        hasSuggestions: !!rule.meta.hasSuggestions
                    },
                    ruleType = ruleTypesData.types.find(c => c.name === rule.meta.type);

                if (!ruleType.rules) {
                    ruleType.rules = [];
                }

                ruleType.rules.push(output);
            }
        });

    // `.rules` will be `undefined` if all rules in category are deprecated.
    ruleTypesData.types = ruleTypesData.types.filter(ruleType => !!ruleType.rules);

    JSON.stringify(ruleTypesData, null, 4).to(docsSiteOutputFile);
    JSON.stringify(meta, null, 4).to(docsSiteMetaOutputFile);

}

/**
 * Creates a git commit and tag in an adjacent `website` repository, without pushing it to
 * the remote. This assumes that the repository has already been modified somehow (e.g. by adding a blogpost).
 * @param {string} [tag] The string to tag the commit with
 * @returns {void}
 */
function commitSiteToGit(tag) {
    const currentDir = pwd();

    cd(SITE_DIR);
    exec("git add -A .");
    exec(`git commit -m "Added release blog post for ${tag}"`);
    exec(`git tag ${tag}`);
    exec("git fetch origin && git rebase origin/main");
    cd(currentDir);
}

/**
 * Publishes the changes in an adjacent `eslint.org` repository to the remote. The
 * site should already have local commits (e.g. from running `commitSiteToGit`).
 * @returns {void}
 */
function publishSite() {
    const currentDir = pwd();

    cd(SITE_DIR);
    exec("git push origin HEAD --tags");
    cd(currentDir);
}

/**
 * Updates the changelog, bumps the version number in package.json, creates a local git commit and tag,
 * and generates the site in an adjacent `website` folder.
 * @returns {void}
 */
function generateRelease() {
    ReleaseOps.generateRelease();
    const releaseInfo = JSON.parse(cat(".eslint-release-info.json"));

    echo("Generating site");
    target.gensite();
    generateBlogPost(releaseInfo);
    commitSiteToGit(`v${releaseInfo.version}`);

    echo("Updating version in docs package");
    const docsPackagePath = path.join(__dirname, "docs", "package.json");
    const docsPackage = require(docsPackagePath);

    docsPackage.version = releaseInfo.version;
    fs.writeFileSync(docsPackagePath, `${JSON.stringify(docsPackage, null, 4)}\n`);

    echo("Updating commit with docs data");
    exec("git add docs/ && git commit --amend --no-edit");
    exec(`git tag -a -f v${releaseInfo.version} -m ${releaseInfo.version}`);
}

/**
 * Updates the changelog, bumps the version number in package.json, creates a local git commit and tag,
 * and generates the site in an adjacent `website` folder.
 * @param {string} prereleaseId The prerelease identifier (alpha, beta, etc.)
 * @returns {void}
 */
function generatePrerelease(prereleaseId) {
    ReleaseOps.generateRelease(prereleaseId);
    const releaseInfo = JSON.parse(cat(".eslint-release-info.json"));
    const nextMajor = semver.inc(releaseInfo.version, "major");

    echo("Generating site");

    // always write docs into the next major directory (so 2.0.0-alpha.0 writes to 2.0.0)
    target.gensite(nextMajor);

    /*
     * Premajor release should have identical "next major version".
     * Preminor and prepatch release will not.
     * 5.0.0-alpha.0 --> next major = 5, current major = 5
     * 4.4.0-alpha.0 --> next major = 5, current major = 4
     * 4.0.1-alpha.0 --> next major = 5, current major = 4
     */
    if (semver.major(releaseInfo.version) === semver.major(nextMajor)) {

        /*
         * This prerelease is for a major release (not preminor/prepatch).
         * Blog post generation logic needs to be aware of this (as well as
         * know what the next major version is actually supposed to be).
         */
        generateBlogPost(releaseInfo, nextMajor);
    } else {
        generateBlogPost(releaseInfo);
    }

    commitSiteToGit(`v${releaseInfo.version}`);
}

/**
 * Publishes a generated release to npm and GitHub, and pushes changes to the adjacent `website` repo
 * to remote repo.
 * @returns {void}
 */
function publishRelease() {
    ReleaseOps.publishRelease();
    const releaseInfo = JSON.parse(cat(".eslint-release-info.json"));
    const isPreRelease = /[a-z]/u.test(releaseInfo.version);

    /*
     * for a pre-release, push to the "next" branch to trigger docs deploy
     * for a release, push to the "latest" branch to trigger docs deploy
     */
    if (isPreRelease) {
        exec("git push origin HEAD:next -f");
    } else {
        exec("git push origin HEAD:latest -f");
    }

    publishSite();
}

/**
 * Splits a command result to separate lines.
 * @param {string} result The command result string.
 * @returns {Array} The separated lines.
 */
function splitCommandResultToLines(result) {
    return result.trim().split("\n");
}

/**
 * Gets the first commit sha of the given file.
 * @param {string} filePath The file path which should be checked.
 * @returns {string} The commit sha.
 */
function getFirstCommitOfFile(filePath) {
    let commits = execSilent(`git rev-list HEAD -- ${filePath}`);

    commits = splitCommandResultToLines(commits);
    return commits[commits.length - 1].trim();
}

/**
 * Gets the tag name where a given file was introduced first.
 * @param {string} filePath The file path to check.
 * @returns {string} The tag name.
 */
function getFirstVersionOfFile(filePath) {
    const firstCommit = getFirstCommitOfFile(filePath);
    let tags = execSilent(`git tag --contains ${firstCommit}`);

    tags = splitCommandResultToLines(tags);
    return tags.reduce((list, version) => {
        const validatedVersion = semver.valid(version.trim());

        if (validatedVersion) {
            list.push(validatedVersion);
        }
        return list;
    }, []).sort(semver.compare)[0];
}

/**
 * Gets the commit that deleted a file.
 * @param {string} filePath The path to the deleted file.
 * @returns {string} The commit sha.
 */
function getCommitDeletingFile(filePath) {
    const commits = execSilent(`git rev-list HEAD -- ${filePath}`);

    return splitCommandResultToLines(commits)[0];
}

/**
 * Gets the first version number where a given file is no longer present.
 * @param {string} filePath The path to the deleted file.
 * @returns {string} The version number.
 */
function getFirstVersionOfDeletion(filePath) {
    const deletionCommit = getCommitDeletingFile(filePath),
        tags = execSilent(`git tag --contains ${deletionCommit}`);

    return splitCommandResultToLines(tags)
        .map(version => semver.valid(version.trim()))
        .filter(version => version)
        .sort(semver.compare)[0];
}

/**
 * Lints Markdown files.
 * @param {Array} files Array of file names to lint.
 * @returns {Object} exec-style exit code object.
 * @private
 */
function lintMarkdown(files) {
    const config = yaml.load(fs.readFileSync(path.join(__dirname, "./.markdownlint.yml"), "utf8")),
        result = markdownlint.sync({
            files,
            config,
            resultVersion: 1
        }),
        resultString = result.toString(),
        returnCode = resultString ? 1 : 0;

    if (resultString) {
        console.error(resultString);
    }
    return { code: returnCode };
}

/**
 * Gets linting results from every formatter, based on a hard-coded snippet and config
 * @returns {Object} Output from each formatter
 */
function getFormatterResults() {
    const stripAnsi = require("strip-ansi");
    const formattersMetadata = require("./lib/cli-engine/formatters/formatters-meta.json");

    const formatterFiles = fs.readdirSync("./lib/cli-engine/formatters/").filter(fileName => !fileName.includes("formatters-meta.json")),
        rules = {
            "no-else-return": "warn",
            indent: ["warn", 4],
            "space-unary-ops": "error",
            semi: ["warn", "always"],
            "consistent-return": "error"
        },
        cli = new CLIEngine({
            useEslintrc: false,
            baseConfig: { extends: "eslint:recommended" },
            rules
        }),
        codeString = [
            "function addOne(i) {",
            "    if (i != NaN) {",
            "        return i ++",
            "    } else {",
            "      return",
            "    }",
            "};"
        ].join("\n"),
        rawMessages = cli.executeOnText(codeString, "fullOfProblems.js", true),
        rulesMap = cli.getRules(),
        rulesMeta = {};

    Object.keys(rules).forEach(ruleId => {
        rulesMeta[ruleId] = rulesMap.get(ruleId).meta;
    });

    return formatterFiles.reduce((data, filename) => {
        const fileExt = path.extname(filename),
            name = path.basename(filename, fileExt);

        if (fileExt === ".js") {
            const formattedOutput = cli.getFormatter(name)(
                rawMessages.results,
                { rulesMeta }
            );

            data.formatterResults[name] = {
                result: stripAnsi(formattedOutput),
                description: formattersMetadata.find(formatter => formatter.name === name).description
            };
        }
        return data;
    }, { formatterResults: {} });
}

/**
 * Gets a path to an executable in node_modules/.bin
 * @param {string} command The executable name
 * @returns {string} The executable path
 */
function getBinFile(command) {
    return path.join("node_modules", ".bin", command);
}

//------------------------------------------------------------------------------
// Tasks
//------------------------------------------------------------------------------

target.lint = function([fix = false] = []) {
    let errors = 0,
        lastReturn;

    /*
     * In order to successfully lint JavaScript files in the `docs` directory, dependencies declared in `docs/package.json`
     * would have to be installed in `docs/node_modules`. In particular, eslint-plugin-node rules examine `docs/node_modules`
     * when analyzing `require()` calls from CJS modules in the `docs` directory. Since our release process does not run `npm install`
     * in the `docs` directory, linting would fail and break the release. Also, working on the main `eslint` package does not require
     * installing dependencies declared in `docs/package.json`, so most contributors will not have `docs/node_modules` locally.
     * Therefore, we add `--ignore-pattern "docs/**"` to exclude linting the `docs` directory from this command.
     * There is a separate command `target.lintDocsJS` for linting JavaScript files in the `docs` directory.
     */
    echo("Validating JavaScript files");
    lastReturn = exec(`${ESLINT}${fix ? "--fix" : ""} . --ignore-pattern "docs/**"`);
    if (lastReturn.code !== 0) {
        errors++;
    }

    echo("Validating JSON Files");
    JSON_FILES.forEach(validateJsonFile);

    echo("Validating Markdown Files");
    lastReturn = lintMarkdown(MARKDOWN_FILES_ARRAY);
    if (lastReturn.code !== 0) {
        errors++;
    }

    if (errors) {
        exit(1);
    }
};

target.lintDocsJS = function([fix = false] = []) {
    let errors = 0;

    echo("Validating JavaScript files in the docs directory");
    const lastReturn = exec(`${ESLINT}${fix ? "--fix" : ""} docs`);

    if (lastReturn.code !== 0) {
        errors++;
    }

    if (errors) {
        exit(1);
    }
};

target.fuzz = function({ amount = 1000, fuzzBrokenAutofixes = false } = {}) {
    const fuzzerRunner = require("./tools/fuzzer-runner");
    const fuzzResults = fuzzerRunner.run({ amount, fuzzBrokenAutofixes });

    if (fuzzResults.length) {

        const uniqueStackTraceCount = new Set(fuzzResults.map(result => result.error)).size;

        echo(`The fuzzer reported ${fuzzResults.length} error${fuzzResults.length === 1 ? "" : "s"} with a total of ${uniqueStackTraceCount} unique stack trace${uniqueStackTraceCount === 1 ? "" : "s"}.`);

        const formattedResults = JSON.stringify({ results: fuzzResults }, null, 4);

        if (process.env.CI) {
            echo("More details can be found below.");
            echo(formattedResults);
        } else {
            if (!test("-d", DEBUG_DIR)) {
                mkdir(DEBUG_DIR);
            }

            let fuzzLogPath;
            let fileSuffix = 0;

            // To avoid overwriting any existing fuzzer log files, append a numeric suffix to the end of the filename.
            do {
                fuzzLogPath = path.join(DEBUG_DIR, `fuzzer-log-${fileSuffix}.json`);
                fileSuffix++;
            } while (test("-f", fuzzLogPath));

            formattedResults.to(fuzzLogPath);

            // TODO: (not-an-aardvark) Create a better way to isolate and test individual fuzzer errors from the log file
            echo(`More details can be found in ${fuzzLogPath}.`);
        }

        exit(1);
    }
};

target.mocha = () => {
    let errors = 0,
        lastReturn;

    echo("Running unit tests");

    lastReturn = exec(`${getBinFile("c8")} -- ${MOCHA} --forbid-only -R progress -t ${MOCHA_TIMEOUT} -c ${TEST_FILES}`);
    if (lastReturn.code !== 0) {
        errors++;
    }

    lastReturn = exec(`${getBinFile("c8")} check-coverage --statement 98 --branch 97 --function 98 --lines 98`);
    if (lastReturn.code !== 0) {
        errors++;
    }

    if (errors) {
        exit(1);
    }
};

target.karma = () => {
    echo("Running unit tests on browsers");

    target.webpack("production");

    const lastReturn = exec(`${getBinFile("karma")} start karma.conf.js`);

    if (lastReturn.code !== 0) {
        exit(1);
    }
};

target.test = function() {
    target.checkRuleFiles();
    target.mocha();
    target.karma();
    target.fuzz({ amount: 150, fuzzBrokenAutofixes: false });
    target.checkLicenses();
};

target.gensite = function() {
    echo("Generating documentation");

    const DOCS_RULES_DIR = path.join(DOCS_SRC_DIR, "rules");
    const RULE_VERSIONS_FILE = path.join(DOCS_SRC_DIR, "_data/rule_versions.json");

    // Set up rule version information
    let versions = test("-f", RULE_VERSIONS_FILE) ? JSON.parse(cat(RULE_VERSIONS_FILE)) : {};

    if (!versions.added) {
        versions = {
            added: versions,
            removed: {}
        };
    }

    // 1. Update rule meta data by checking rule docs - important to catch removed rules
    echo("> Updating rule version meta data (Step 1)");
    const ruleDocsFiles = find(DOCS_RULES_DIR);

    ruleDocsFiles.forEach((filename, i) => {
        if (test("-f", filename) && path.extname(filename) === ".md") {

            echo(`> Updating rule version meta data (Step 1: ${i + 1}/${ruleDocsFiles.length}): ${filename}`);

            const baseName = path.basename(filename, ".md"),
                sourceBaseName = `${baseName}.js`,
                sourcePath = path.join("lib/rules", sourceBaseName);

            if (!versions.added[baseName]) {
                versions.added[baseName] = getFirstVersionOfFile(sourcePath);
            }

            if (!versions.removed[baseName] && !test("-f", sourcePath)) {
                versions.removed[baseName] = getFirstVersionOfDeletion(sourcePath);
            }

        }
    });

    JSON.stringify(versions, null, 4).to(RULE_VERSIONS_FILE);

    // 2. Generate rules index page meta data
    echo("> Generating the rules index page (Step 2)");
    generateRuleIndexPage();

    // 3. Create Example Formatter Output Page
    echo("> Creating the formatter examples (Step 3)");
    generateFormatterExamples(getFormatterResults());

    echo("Done generating documentation");
};

target.generateRuleIndexPage = generateRuleIndexPage;

target.webpack = function(mode = "none") {
    exec(`${getBinFile("webpack")} --mode=${mode} --output-path=${BUILD_DIR}`);
};

target.checkRuleFiles = function() {

    echo("Validating rules");

    const ruleTypes = require("./tools/rule-types.json");
    let errors = 0;

    RULE_FILES.forEach(filename => {
        const basename = path.basename(filename, ".js");
        const docFilename = `docs/src/rules/${basename}.md`;
        const docText = cat(docFilename);
        const docTextWithoutFrontmatter = matter(String(docText)).content;
        const docMarkdown = marked.lexer(docTextWithoutFrontmatter, { gfm: true, silent: false });
        const ruleCode = cat(filename);
        const knownHeaders = ["Rule Details", "Options", "Environments", "Examples", "Known Limitations", "When Not To Use It", "Compatibility"];

        /**
         * Check if basename is present in rule-types.json file.
         * @returns {boolean} true if present
         * @private
         */
        function isInRuleTypes() {
            return Object.prototype.hasOwnProperty.call(ruleTypes, basename);
        }

        /**
         * Check if id is present in title
         * @param {string} id id to check for
         * @returns {boolean} true if present
         * @private
         * @todo Will remove this check when the main heading is automatically generated from rule metadata.
         */
        function hasIdInTitle(id) {
            return new RegExp(`title: ${id}`, "u").test(docText);
        }

        /**
         * Check if all H2 headers are known and in the expected order
         * Only H2 headers are checked as H1 and H3 are variable and/or rule specific.
         * @returns {boolean} true if all headers are known and in the right order
         */
        function hasKnownHeaders() {
            const headers = docMarkdown.filter(token => token.type === "heading" && token.depth === 2).map(header => header.text);

            for (const header of headers) {
                if (!knownHeaders.includes(header)) {
                    return false;
                }
            }

            /*
             * Check only the subset of used headers for the correct order
             */
            const presentHeaders = knownHeaders.filter(header => headers.includes(header));

            for (let i = 0; i < presentHeaders.length; ++i) {
                if (presentHeaders[i] !== headers[i]) {
                    return false;
                }
            }

            return true;
        }

        /**
         * Check if deprecated information is in rule code and README.md.
         * @returns {boolean} true if present
         * @private
         */
        function hasDeprecatedInfo() {
            const deprecatedTagRegExp = /@deprecated in ESLint/u;
            const deprecatedInfoRegExp = /This rule was .+deprecated.+in ESLint/u;

            return deprecatedTagRegExp.test(ruleCode) && deprecatedInfoRegExp.test(docText);
        }

        /**
         * Check if the rule code has the jsdoc comment with the rule type annotation.
         * @returns {boolean} true if present
         * @private
         */
        function hasRuleTypeJSDocComment() {
            const comment = "/** @type {import('../shared/types').Rule} */";

            return ruleCode.includes(comment);
        }

        // check for docs
        if (!test("-f", docFilename)) {
            console.error("Missing documentation for rule %s", basename);
            errors++;
        } else {

            // check for proper doc h1 format
            if (!hasIdInTitle(basename)) {
                console.error("Missing id in the doc page's title of rule %s", basename);
                errors++;
            }

            // check for proper doc headers
            if (!hasKnownHeaders()) {
                console.error("Unknown or misplaced header in the doc page of rule %s, allowed headers (and their order) are: '%s'", basename, knownHeaders.join("', '"));
                errors++;
            }
        }

        // check for recommended configuration
        if (!isInRuleTypes()) {
            console.error("Missing setting for %s in tools/rule-types.json", basename);
            errors++;
        }

        // check parity between rules index file and rules directory
        const ruleIdsInIndex = require("./lib/rules/index");
        const ruleDef = ruleIdsInIndex.get(basename);

        if (!ruleDef) {
            console.error(`Missing rule from index (./lib/rules/index.js): ${basename}. If you just added a new rule then add an entry for it in this file.`);
            errors++;
        } else {

            // check deprecated
            if (ruleDef.meta.deprecated && !hasDeprecatedInfo()) {
                console.error(`Missing deprecated information in ${basename} rule code or README.md. Please write @deprecated tag in code or 「This rule was deprecated in ESLint ...」 in README.md.`);
                errors++;
            }

            // check eslint:recommended
            const recommended = require("./packages/js").configs.recommended;

            if (ruleDef.meta.docs.recommended) {
                if (recommended.rules[basename] !== "error") {
                    console.error(`Missing rule from eslint:recommended (./packages/js/src/configs/eslint-recommended.js): ${basename}. If you just made a rule recommended then add an entry for it in this file.`);
                    errors++;
                }
            } else {
                if (basename in recommended.rules) {
                    console.error(`Extra rule in eslint:recommended (./packages/js/src/configs/eslint-recommended.js): ${basename}. If you just added a rule then don't add an entry for it in this file.`);
                    errors++;
                }
            }

            if (!hasRuleTypeJSDocComment()) {
                console.error(`Missing rule type JSDoc comment from ${basename} rule code.`);
                errors++;
            }
        }

        // check for tests
        if (!test("-f", `tests/lib/rules/${basename}.js`)) {
            console.error("Missing tests for rule %s", basename);
            errors++;
        }

    });

    if (errors) {
        exit(1);
    }

};

target.checkLicenses = function() {

    /**
     * Check if a dependency is eligible to be used by us
     * @param {Object} dependency dependency to check
     * @returns {boolean} true if we have permission
     * @private
     */
    function isPermissible(dependency) {
        const licenses = dependency.licenses;

        if (Array.isArray(licenses)) {
            return licenses.some(license => isPermissible({
                name: dependency.name,
                licenses: license
            }));
        }

        return OPEN_SOURCE_LICENSES.some(license => license.test(licenses));
    }

    echo("Validating licenses");

    checker.init({
        start: __dirname
    }, deps => {
        const impermissible = Object.keys(deps).map(dependency => ({
            name: dependency,
            licenses: deps[dependency].licenses
        })).filter(dependency => !isPermissible(dependency));

        if (impermissible.length) {
            impermissible.forEach(dependency => {
                console.error(
                    "%s license for %s is impermissible.",
                    dependency.licenses,
                    dependency.name
                );
            });
            exit(1);
        }
    });
};

/**
 * Downloads a repository which has many js files to test performance with multi files.
 * Here, it's eslint@1.10.3 (450 files)
 * @param {Function} cb A callback function.
 * @returns {void}
 */
function downloadMultifilesTestTarget(cb) {
    if (test("-d", PERF_MULTIFILES_TARGET_DIR)) {
        process.nextTick(cb);
    } else {
        mkdir("-p", PERF_MULTIFILES_TARGET_DIR);
        echo("Downloading the repository of multi-files performance test target.");
        exec(`git clone -b v1.10.3 --depth 1 https://github.com/eslint/eslint.git "${PERF_MULTIFILES_TARGET_DIR}"`, { silent: true }, cb);
    }
}

/**
 * Creates a config file to use performance tests.
 * This config is turning all core rules on.
 * @returns {void}
 */
function createConfigForPerformanceTest() {
    let rules = "";

    for (const [ruleId] of builtinRules) {
        rules += (`    "${ruleId}": 1,\n`);
    }

    const content = `
module.exports = [{
    "languageOptions": {sourceType: "commonjs"},
    "rules": {
    ${rules}
    }
}];`;

    content.to(PERF_ESLINTRC);
}

/**
 * @callback TimeCallback
 * @param {?int[]} results
 * @returns {void}
 */

/**
 * Calculates the time for each run for performance
 * @param {string} cmd cmd
 * @param {int} runs Total number of runs to do
 * @param {int} runNumber Current run number
 * @param {int[]} results Collection results from each run
 * @param {TimeCallback} cb Function to call when everything is done
 * @returns {void} calls the cb with all the results
 * @private
 */
function time(cmd, runs, runNumber, results, cb) {
    const start = process.hrtime();

    exec(cmd, { maxBuffer: 64 * 1024 * 1024, silent: true }, (code, stdout, stderr) => {
        const diff = process.hrtime(start),
            actual = (diff[0] * 1e3 + diff[1] / 1e6); // ms

        if (code) {
            echo(`  Performance Run #${runNumber} failed.`);
            if (stdout) {
                echo(`STDOUT:\n${stdout}\n\n`);
            }

            if (stderr) {
                echo(`STDERR:\n${stderr}\n\n`);
            }
            return cb(null);
        }

        results.push(actual);
        echo(`  Performance Run #${runNumber}:  %dms`, actual);
        if (runs > 1) {
            return time(cmd, runs - 1, runNumber + 1, results, cb);
        }
        return cb(results);

    });

}

/**
 * Run a performance test.
 * @param {string} title A title.
 * @param {string} targets Test targets.
 * @param {number} multiplier A multiplier for limitation.
 * @param {Function} cb A callback function.
 * @returns {void}
 */
function runPerformanceTest(title, targets, multiplier, cb) {
    const cpuSpeed = os.cpus()[0].speed,
        max = multiplier / cpuSpeed,
        cmd = `${ESLINT}--config "${PERF_ESLINTRC}" --no-config-lookup --no-ignore ${targets}`;

    echo("");
    echo(title);
    echo("  CPU Speed is %d with multiplier %d", cpuSpeed, multiplier);

    time(cmd, 5, 1, [], results => {
        if (!results || results.length === 0) { // No results? Something is wrong.
            throw new Error("Performance test failed.");
        }

        results.sort((a, b) => a - b);

        const median = results[~~(results.length / 2)];

        echo("");
        if (median > max) {
            echo("  Performance budget exceeded: %dms (limit: %dms)", median, max);
        } else {
            echo("  Performance budget ok:  %dms (limit: %dms)", median, max);
        }
        echo("");
        cb();
    });
}

/**
 * Run the load performance for eslint
 * @returns {void}
 * @private
 */
function loadPerformance() {
    echo("");
    echo("Loading:");

    const results = [];

    for (let cnt = 0; cnt < 5; cnt++) {
        const loadPerfData = loadPerf({
            checkDependencies: false
        });

        echo(`  Load performance Run #${cnt + 1}:  %dms`, loadPerfData.loadTime);
        results.push(loadPerfData.loadTime);
    }

    results.sort((a, b) => a - b);
    const median = results[~~(results.length / 2)];

    echo("");
    echo("  Load Performance median:  %dms", median);
    echo("");
}

target.perf = function() {
    downloadMultifilesTestTarget(() => {
        createConfigForPerformanceTest();

        loadPerformance();

        runPerformanceTest(
            "Single File:",
            "tests/performance/jshint.js",
            PERF_MULTIPLIER,
            () => {

                // Count test target files.
                const count = glob.sync(
                    (
                        process.platform === "win32"
                            ? PERF_MULTIFILES_TARGETS.replace(/\\/gu, "/")
                            : PERF_MULTIFILES_TARGETS
                    )
                        .slice(1, -1) // strip quotes
                ).length;

                runPerformanceTest(
                    `Multi Files (${count} files):`,
                    PERF_MULTIFILES_TARGETS,
                    3 * PERF_MULTIPLIER,
                    () => {}
                );
            }
        );
    });
};

target.generateRelease = generateRelease;
target.generatePrerelease = ([prereleaseType]) => generatePrerelease(prereleaseType);
target.publishRelease = publishRelease;