/**
 * Butterfly
 * lazyload
 * replace src to data-src
 * add class 'lazyload'
 */

'use strict'

const url_for = require('hexo-util').url_for.bind(hexo)

function lazyProcess (htmlContent) {
  var bg = url_for(hexo.theme.config.lodding_bg.post)
  return htmlContent.replace(
    /<img(.*?)src="(.*?)"(.*?)>/gi,
    (str, p1, p2, p3) => {
      if (/data-src/gi.test(str)) {
        return str
      }
      if (/class="(.*?)"/gi.test(str)) {
        str = str.replace(/class="(.*?)"/gi, (classStr, p1) => {
          return classStr.replace(p1, `${p1} lazyload`)
        })
        str = str.replace(p2, `${bg}`)
        return str.replace('>', ` data-src="${p2}">`)
      }
      str = str.replace(p2, `${bg}`)
      return str.replace(p3, ` class="lazyload" data-src="${p2}" ${p3}`)
    }
  )
}

var processPost = function (data) {
  if (!hexo.theme.config.lazyload.enable) return
  data.content = lazyProcess.call(this, data.content)
  return data
}

hexo.extend.filter.register('after_post_render', processPost)