Slugify.js

'use strict'

const slug = require('@slynova/slug')

class Slugify {

  register (model) {

    const source = model.sluggable.source
    const key = model.sluggable.key

    model.addHook('beforeCreate', function * (next) {
      this[key] = yield Slugify.generateUniqueSlug(model, key, this[source])
      yield next
    })

  }

  static * generateUniqueSlug (model, key, source) {
    const generatedSlug = slug(source)
    const matchingSlug = yield model.query()
      .where(key, generatedSlug)
      .orWhere(key, 'like', `${generatedSlug}%`)
      .orderBy(model.primaryKey, 'desc')
      .first()

    if (!matchingSlug || !matchingSlug.slug) {
      return generatedSlug
    }

    return `${generatedSlug}-${Slugify.nextIndex(generatedSlug, matchingSlug.slug)}`
  }

  static nextIndex (generatedSlug, latestSlug) {
    if (generatedSlug === latestSlug) {
      return 1
    }

    const parts = latestSlug.split('-')

    return parseInt(parts[parts.length - 1]) + 1
  }

}

module.exports = Slugify