const _pipe = require('../helpers/pipe')

// query default setting
const { conditionConfig, _get } = require('./../../config/')
const sort_default = _get("sort.default", conditionConfig)
const limit_default = _get("limit", conditionConfig)

/*
* @param String limit, path, sort for generating link
* @param Number page
* if page === 1, return base link or/and limit or/and sort
* @return link pagination
*/
const getPaginationPath = (sort, limit, path) => {

 let url = []

 if(sort !== sort_default) {
  url = [...url, 'sort=' + sort]
 }

 if(limit !== limit_default) {
  url = [...url, 'limit=' + limit]
 }

 path += url.length ? '?' + url.join('&') : ''

 return page => page !== 1 ?
        path + (url.length ? '&' : '?') + 'page=' + page :
        path
}

/*
* @param Number limit, limit items for page
* @param Number total, total items
* @return max page number pagination
*/
const getLastPageNumber = ({limit, total}) => Math.ceil(total / limit)

/*
* @param Number current page
* @param Number max page pagination
* @return Array pages - example - [1,2,3,4,'...',7] etc
*/
const getRange = page => last => {

 let range = [1],
     delta = 2,
     left = page - delta,
     right = page + delta

 for (let i = 2; i <= last; i++) {
  if (i == last || i >= left && i <= right) {
   range.push(i)
  }
 }

 return range
}

/*
* @param Number `page` - current page
* @param Function `getPaginationLink` - this function include limit & sort
* @param Array `range` - page number for pagination generate
* @return `html pagination template`
*/
const getHtml = (page, getPaginationLink) => range => {

 let htmlTemplateStart = '<nav aria-label="Page navigation"><ul class="pagination pagination-sm mb-0">',
     htmlTemplate = '',
     htmlTemplateFinish = '</ul></nav>',
     l

 for (let i of range) {
  if (l) {
   if (i - l === 2) {
    htmlTemplate += `<li class="page-item ${(page === l + i) ? 'active' : ''}"><a class="page-link" href="${getPaginationLink(l + 1)}">${l + 1}</a></li>`
   } else if (i - l !== 1) {
    htmlTemplate += `<li class="page-item" disabled><a class="page-link" href="#">...</a></li>`
   }
  }
  htmlTemplate += `<li class="page-item ${(page === i) ? 'active' : ''}"><a class="page-link" href="${getPaginationLink(i)}">${i}</a></li>`
  l = i
 }

 return htmlTemplateStart + htmlTemplate + htmlTemplateFinish
}

/*
*
*/
const Pagination = (sort = '', page = 1, limit = 15, total = 45, path = '') => {

 if(total > 0) {
  let getPaginationLink = getPaginationPath(sort, limit, path)

  let htmlTemplateLinks = () =>
   _pipe(
    getLastPageNumber,
    getRange(page),
    getHtml(page, getPaginationLink)
   )({limit, total})

  return htmlTemplateLinks()
 }
 return ''
}

module.exports = Pagination