-- 本文件是页面抓取的主入口
-- 这里必须采用加载模块的方法，否则好像不能动态加载js文件
parser = require('parser')

function main(splash, args)
  pages = {{$pages}}
  scripts_js = '{{$scripts_js}}'
  page_element = '{{$page_element}}'
  wait_for = '{{$wait_for}}'
  announcement_type = '{{$announcement_type}}'
  splash:go('{{$url}}')
  wait_for_element(splash, wait_for)
  wait_for_element(splash, page_element)

  -- 设置javascript脚本参数
  results = {}
  params_js = {}
  params_js['announcement_type'] = announcement_type

  -- 将第一页的结果加入返回结果集中
  result = parser.select(splash, scripts_js, params_js)
  table.insert(results, result)

  if pages == 1 then
    return results
  else
    -- 执行翻页动作
    -- 先页面上的翻页元件（element），然后发送点击事件（click()）翻页
    for i = 2, pages do
      -- 执行翻页脚本
      -- js 中是javascript脚本，用于获取翻页的元件，并发送click事件
      js = string.format("document.querySelector('%s').click();", page_element)
      splash:runjs(js)

      -- 等待页面加载完成
      wait_for_element(splash, wait_for)
      wait_for_element(splash, page_element)

      -- 这个地方看来必须加上延时，否则页面加载不完全，可能还没有完成页面更新
      assert(splash:wait(5))
      result = parser.select(splash, scripts_js, params_js)
      table.insert(results, result)
    end
    return results
  end
end

function wait_for_element(splash, css, maxwait)
  -- Wait until a selector matches an element
  -- in the page. Return an error if waited more
  -- than maxwait seconds.
  if maxwait == nil then
    maxwait = 10
  end
  return splash:wait_for_resume(string.format([[
    function main(splash) {
      var selector = '%s';
      var maxwait = %s;
      var end = Date.now() + maxwait*1000;

      function check() {
        if(document.querySelector(selector)) {
          splash.resume('Element found');
        } else if(Date.now() >= end) {
          var err = 'Timeout waiting for element';
          splash.error(err + " " + selector);
        } else {
          setTimeout(check, 200);
        }
      }
      check();
    }
  ]], css, maxwait))
end