const _ = require('lodash')
const { Set } = require('immutable')
const fillPath = (path, data) =>
  path.replace(/:(\w+)/g, (text, key) => data[key] || text)

const diffBy = (before, after, selector) => {
  // Collect new, collect old, collect same
  const beforeDict = _.fromPairs(before.map(x => [selector(x), x]))
  const afterDict = _.fromPairs(before.map(x => [selector(x), x]))
  const beforeKeys = new Set(before.map(selector))
  const afterKeys = new Set(after.map(selector))

  const newKeys = afterKeys.subtract(beforeKeys)
  const oldKeys = beforeKeys.subtract(afterKeys)
  const commonKeys = beforeKeys.intersect(afterKeys)

  return {
    'new': newKeys.map(key => afterDict[key]),
    old: oldKeys.map(key => beforeDict[key]),
    common: commonKeys.map(key => [beforeDict[key], afterDict[key]])
  }
}

const sanitize = _.curry(async (req, data) => {
  if (data) {
    if (Array.isArray(data)) return await Promise.all(data.map(sanitize(req)))
    if (data.sanitize) return await data.sanitize(req)
    if (data.toJSON) return data.toJSON()
  }
  return data
})

const dict = (collection, fields) => {
  collection.forEach(item => {
    collection[item.key] = item
    collection[item.id] = item
    if (Array.isArray(fields)) {
      fields.forEach(field => collection[item[field]] = field)
    }
  })
  return collection
}


module.exports = {
  fillPath,
  diffBy,
  sanitize,
  dict
}