Linter.js

import process from 'process';
import { isAbsolute, join } from 'path';

import { writeFileSync, ensureFileSync } from 'fs-extra';
import { interpolateName } from 'loader-utils';

import ESLintError from './ESLintError';
import createEngine from './createEngine';

export default class Linter {
  constructor(loaderContext, options) {
    this.loaderContext = loaderContext;
    this.options = options;
    this.resourcePath = this.parseResourcePath();

    const { CLIEngine, engine } = createEngine(options);
    this.CLIEngine = CLIEngine;
    this.engine = engine;
  }

  parseResourcePath() {
    const cwd = process.cwd();
    let { resourcePath } = this.loaderContext;

    // remove cwd from resource path in case webpack has been started from project
    // root, to allow having relative paths in .eslintignore
    // istanbul ignore next
    if (resourcePath.indexOf(cwd) === 0) {
      resourcePath = resourcePath.substr(cwd.length + (cwd === '/' ? 0 : 1));
    }

    return resourcePath;
  }

  lint(content) {
    try {
      return this.engine.executeOnText(content, this.resourcePath, true);
    } catch (_) {
      this.getEmitter(false)(_);

      return { src: content };
    }
  }

  printOutput(data) {
    const { options } = this;

    // skip ignored file warning
    if (this.constructor.skipIgnoredFileWarning(data)) {
      return;
    }

    // quiet filter done now
    // eslint allow rules to be specified in the input between comments
    // so we can found warnings defined in the input itself
    const res = this.filter(data);

    // if enabled, use eslint auto-fixing where possible
    if (options.fix) {
      this.autoFix(res);
    }

    // skip if no errors or warnings
    if (res.errorCount < 1 && res.warningCount < 1) {
      return;
    }

    const results = this.parseResults(res);

    // Do not analyze if there are no results or eslint config
    if (!results) {
      return;
    }

    const messages = options.formatter(results);

    this.reportOutput(results, messages);
    this.failOnErrorOrWarning(res, messages);

    const emitter = this.getEmitter(res);
    emitter(new ESLintError(messages));
  }

  static skipIgnoredFileWarning(res) {
    return (
      res &&
      res.warningCount === 1 &&
      res.results &&
      res.results[0] &&
      res.results[0].messages[0] &&
      res.results[0].messages[0].message &&
      res.results[0].messages[0].message.indexOf('ignore') > 1
    );
  }

  filter(data) {
    const res = data;

    // quiet filter done now
    // eslint allow rules to be specified in the input between comments
    // so we can found warnings defined in the input itself
    if (
      this.options.quiet &&
      res &&
      res.warningCount &&
      res.results &&
      res.results[0]
    ) {
      res.warningCount = 0;
      res.results[0].warningCount = 0;
      res.results[0].messages = res.results[0].messages.filter(
        (message) => message.severity !== 1
      );
    }

    return res;
  }

  autoFix(res) {
    if (
      res &&
      res.results &&
      res.results[0] &&
      (res.results[0].output !== res.src ||
        res.results[0].fixableErrorCount > 0 ||
        res.results[0].fixableWarningCount > 0)
    ) {
      this.CLIEngine.outputFixes(res);
    }
  }

  parseResults({ results }) {
    // add filename for each results so formatter can have relevant filename
    if (results) {
      results.forEach((r) => {
        // eslint-disable-next-line no-param-reassign
        r.filePath = this.loaderContext.resourcePath;
      });
    }

    return results;
  }

  reportOutput(results, messages) {
    const { outputReport } = this.options;

    if (!outputReport || !outputReport.filePath) {
      return;
    }

    let content = messages;

    // if a different formatter is passed in as an option use that
    if (outputReport.formatter) {
      content = outputReport.formatter(results);
    }

    let filePath = interpolateName(this.loaderContext, outputReport.filePath, {
      content,
    });

    if (!isAbsolute(filePath)) {
      filePath = join(
        // eslint-disable-next-line no-underscore-dangle
        this.loaderContext._compiler.options.output.path,
        filePath
      );
    }

    ensureFileSync(filePath);
    writeFileSync(filePath, content);
  }

  failOnErrorOrWarning({ errorCount, warningCount }, messages) {
    const { failOnError, failOnWarning } = this.options;

    if (failOnError && errorCount) {
      throw new ESLintError(
        `Module failed because of a eslint error.\n${messages}`
      );
    }

    if (failOnWarning && warningCount) {
      throw new ESLintError(
        `Module failed because of a eslint warning.\n${messages}`
      );
    }
  }

  getEmitter({ errorCount }) {
    const { options, loaderContext } = this;

    // default behavior: emit error only if we have errors
    let emitter = errorCount
      ? loaderContext.emitError
      : loaderContext.emitWarning;

    // force emitError or emitWarning if user want this
    if (options.emitError) {
      emitter = loaderContext.emitError;
    } else if (options.emitWarning) {
      emitter = loaderContext.emitWarning;
    }

    return emitter;
  }
}