stylelint/src/buildConfig.js

Modern CSS linter

import path from "path"
import cosmiconfig from "cosmiconfig"
import resolveFrom from "resolve-from"
import {
  assign,
  merge,
  omit,
} from "lodash"
import { configurationError } from "./utils"

export default function (options) {
  const rawConfig = (() => {
    if (options.config) return options.config
    if (options.rules) return options
    return false
  })()
  const configBasedir = options.configBasedir || process.cwd()

  if (rawConfig) {
    return augmentConfig(rawConfig, configBasedir).then(config => {
      return {
        config: merge(config, options.configOverrides),
        configDir: configBasedir,
      }
    })
  }

  const cosmiconfigOptions = {
    // Turn off argv option to avoid hijacking the all-too-common
    // --config argument, when this is used in conjunction with other CLI's
    // (e.g. webpack)
    argv: false,
    // Allow extensions on rc filenames
    rcExtensions: true,
  }

  if (options.configFile) {
    cosmiconfigOptions.configPath = path.resolve(process.cwd(), options.configFile)
  }

  let rootConfigDir

  return cosmiconfig("stylelint", cosmiconfigOptions).then(result => {
    if (!result) throw configurationError("No configuration found")
    rootConfigDir = path.dirname(result.filepath)
    return augmentConfig(result.config, rootConfigDir)
  }).then(augmentedConfig => {
    const finalConfig = (options.configOverrides)
      ? merge({}, augmentedConfig, options.configOverrides)
      : augmentedConfig
    return {
      config: finalConfig,
      configDir: rootConfigDir,
    }
  })
}

function augmentConfig(config, configDir) {
  // Absolutize the plugins here, because here is the place
  // where we know the basedir for this particular config
  const configWithAbsolutePlugins = absolutizePlugins(config, configDir)
  if (!config.extends) {
    return Promise.resolve(configWithAbsolutePlugins)
  }

  const extendLookups = [].concat(configWithAbsolutePlugins.extends)
  const origConfig = omit(configWithAbsolutePlugins, "extends")
  const resultPromise = extendLookups.reduce((mergeConfigs, extendLookup) => {
    return mergeConfigs.then(mergedConfig => {
      return loadExtendedConfig(mergedConfig, extendLookup).then(extendedConfig => {
        return merge({}, mergedConfig, extendedConfig)
      })
    })
  }, Promise.resolve(origConfig))

  return resultPromise.then(mergedConfig => {
    return merge({}, mergedConfig, origConfig)
  })

  function loadExtendedConfig(config, extendLookup) {
    const extendPath = getModulePath(configDir, extendLookup)
    const extendDir = path.dirname(extendPath)
    return cosmiconfig(null, {
      configPath: extendPath,
      // In case --config was used: do not pay attention to it again
      argv: false,
    }).then(result => {
      return augmentConfig(stripIgnoreFiles(result.config), extendDir)
    })
  }
}

// Replace all plugin lookups with absolute paths
function absolutizePlugins(config, configDir) {
  if (!config.plugins) { return config }
  return assign({}, config, {
    plugins: config.plugins.map(lookup => getModulePath(configDir, lookup)),
  })
}

function getModulePath(basedir, lookup) {
  const path = resolveFrom(basedir, lookup)
  if (path) return path
  throw configurationError(
    `Could not find "${lookup}". Do you need a \`configBasedir\`?`
  )
}

// The `ignoreFiles` option only works with the
// config that is being directly invoked, not any
// extended configs
function stripIgnoreFiles(config) {
  return omit(config, "ignoreFiles")
}