blueconfig/lib/performer/ruler.js

Merge and validate your config depending of your schema, forked from node-convict.

const cvtError = require('./../error.js')
const CUSTOMISE_FAILED = cvtError.CUSTOMISE_FAILED

/**
 * Validate config with format
 *
 * @private
 * @class
 */
function Ruler() {
  this.types = new Map()
  this.types.set('*', () => {})
  this.coerces = new Map()
}


module.exports = Ruler


/**
 * Adds a new custom format.
 */
Ruler.prototype.add = function(name, validate, coerce, rewrite) {
  if (typeof name !== 'string') {
    throw new CUSTOMISE_FAILED('Schema name must be a string (current: "' + (typeof name) + '").')
  }
  if (typeof validate !== 'function') {
    throw new CUSTOMISE_FAILED('Validation function for "' + name + '" must be a function.')
  }
  if (coerce && typeof coerce !== 'function') {
    throw new CUSTOMISE_FAILED('Coerce function for "' + name + '" must be a function.')
  }

  if (this.types.has(name) && !rewrite) {
    const advice = ' Set the 4th argument (rewrite) of `addFormat` at true to skip this error.'
    throw new CUSTOMISE_FAILED('Format name "' + name + '" is already registered.' + advice)
  }

  this.types.set(name, validate)
  if (coerce) this.coerces.set(name, coerce)
}


/**
 * Returns coerce method
 *
 * @Returns {Function} Coerce method
 */
Ruler.prototype.getCoerceMethod = function(format) {
  const isStr = (value) => (typeof value === 'string')

  if (this.coerces.has(format)) {
    return this.coerces.get(format)
  }
  switch (format) {
    case 'Number':
      return (v) => (isStr(v)) ? parseFloat(v) : v
    case 'Boolean':
      return (v) => (isStr(v)) ? (String(v).toLowerCase() !== 'false') : v
    case 'Array':
      return (v) => (isStr(v)) ? v.split(',') : v
    case 'Object':
      return (v) => (isStr(v)) ? JSON.parse(v) : v
    case 'RegExp':
      return (v) => (isStr(v)) ? new RegExp(v) : v
    default:
      // for eslint "Expected a default case"
  }

  return (v) => v
}