import { resolve, resolveCwd, TaskFunction } from 'just-task';
import { logNodeCommand, spawn } from '../utils';
import * as fs from 'fs';

/**
 * Task options generally follow ESLint CLI options explained here:
 * https://eslint.org/docs/user-guide/command-line-interface
 */
export interface EsLintTaskOptions {
  files?: string[];
  configPath?: string;
  ignorePath?: string;
  resolvePluginsPath?: string;
  fix?: boolean;
  extensions?: string;
  noEslintRc?: boolean;
  maxWarnings?: number;
  cache?: boolean;
  cacheLocation?: string;
  /**
   * Upon lint completion, display a table of the 10 slowest rules
   * (see https://eslint.org/docs/developer-guide/working-with-rules-deprecated#per-rule-performance).
   */
  timing?: boolean;
  /** Can be set to write the eslint report to a file */
  outputFile?: string;
  /** Can be set to dictate the format of use for report file generated with the output flag: https://eslint.org/docs/latest/user-guide/command-line-interface#-f---format */
  format?: string;
  /** Prevents the logging & auto-fixing of warnings */
  quiet?: boolean;
  /**
   * Can be set to force the flat config on or off, which can be helpful when migrating to ESLint v9.
   * This will be passed as an environment variable to eslint with the value ESLINT_USE_FLAT_CONFIG (https://eslint.org/blog/2024/04/eslint-v9.0.0-released/#flat-config-is-now-the-default-and-has-some-changes).
   */
  useFlatConfig?: boolean;
  /**
   * When set to true, eslint will report any eslint-disable comments that are not used as an error.
   */
  reportUnusedDisableDirectives?: boolean;
}

export function eslintTask(options: EsLintTaskOptions = {}): TaskFunction {
  return function eslint() {
    const {
      files,
      configPath,
      ignorePath,
      fix,
      extensions,
      noEslintRc,
      maxWarnings,
      resolvePluginsPath,
      cache,
      cacheLocation,
      timing,
      outputFile,
      format,
      quiet,
      useFlatConfig,
    } = options;
    const eslintCmd = resolve('eslint/bin/eslint.js');
    // Try all possible extensions in the order listed here: https://eslint.org/docs/user-guide/configuring#configuration-file-formats
    const eslintConfigPath =
      configPath || resolveCwd('.eslintrc', { extensions: ['.js', '.cjs', '.yaml', '.yml', '.json'] });

    if (eslintCmd && eslintConfigPath && fs.existsSync(eslintConfigPath)) {
      const eslintIgnorePath = ignorePath || resolveCwd('.eslintignore');

      const eslintArgs = [
        eslintCmd,
        ...(files ? files : ['.']),
        ...['--ext', extensions ? extensions : '.js,.jsx,.ts,.tsx'],
        ...(noEslintRc ? ['--no-eslintrc'] : []),
        ...(eslintConfigPath ? ['--config', eslintConfigPath] : []),
        ...(eslintIgnorePath ? ['--ignore-path', eslintIgnorePath] : []),
        ...(resolvePluginsPath ? ['--resolve-plugins-relative-to', resolvePluginsPath] : []),
        ...(fix ? ['--fix'] : []),
        ...(maxWarnings !== undefined ? ['--max-warnings', `${maxWarnings}`] : []),
        ...(cache ? ['--cache'] : []),
        ...(cacheLocation ? ['--cache-location', cacheLocation] : []),
        ...(outputFile ? ['--output-file', outputFile] : []),
        ...(format ? ['--format', format] : []),
        ...(quiet ? ['--quiet'] : []),
        ...(options.reportUnusedDisableDirectives ? ['--report-unused-disable-directives'] : []),
        '--color',
      ];

      const env: NodeJS.ProcessEnv = { ...process.env };

      if (timing) {
        env.TIMING = '1';
      }

      if (useFlatConfig !== undefined) {
        env.ESLINT_USE_FLAT_CONFIG = JSON.stringify(useFlatConfig);
      }

      logNodeCommand(eslintArgs);
      return spawn(process.execPath, eslintArgs, { stdio: 'inherit', env });
    }

    // undertaker apparently requires returning a promise, async function, or function that calls done()
    return Promise.resolve();
  };
}