index.js

import stylelint from 'stylelint'
import getCustomPropertiesFromRoot from './lib/get-custom-properties-from-root'
import getCustomPropertiesFromImports from './lib/get-custom-properties-from-imports'

const ruleName = 'plugin/value-no-exposed-custom-properties'

function isCustomPropertyDecl(prop) {
  return prop.includes('--')
}

function prepareValue(value) {
  if (typeof value === 'string') {
    value = value.toUpperCase()
  }

  return value
}

function foundCustomPropertyInValue(properies, value) {
  value = prepareValue(value)

  for (let i in properies) {
    const property = prepareValue(properies[i])

    if (value.includes(property)) return i
  }
}

async function getCustomProperties(root, importFrom) {
  // all custom properties from the file and imports
  return Object.assign(
    {},
    await getCustomPropertiesFromImports(importFrom),
    getCustomPropertiesFromRoot(root)
  )
}

function checkDeclOnCustomProperty(decl, customProperties, result) {
  const foundVariable = foundCustomPropertyInValue(customProperties, decl.value)

  if (foundVariable) {
    stylelint.utils.report({
      ruleName,
      result,
      node: decl,
      message:
        'The value (or a part of it) should be presented as a custom property: "' +
        decl.value +
        '" is "' +
        foundVariable +
        '" (' +
        ruleName +
        ')',
    })
  }
}

module.exports = stylelint.createPlugin(ruleName, function (method, options) {
  return async function (root, result) {
    if (!method) return

    const importFrom = options && options.importFrom ? options.importFrom : []
    const customProperties = await getCustomProperties(root, importFrom)

    root.walkRules(function (rule) {
      rule.walkDecls(function (decl) {
        // Skip custom properties declarations
        if (!isCustomPropertyDecl(decl.prop)) {
          checkDeclOnCustomProperty(decl, customProperties, result)
        }
      })
    })
  }
})