from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.support.wait import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.webdriver.chrome.options import Options
from selenium.common.exceptions import NoSuchElementException
from lxml import etree
import time, json

JD_URL_Login = "https://www.jd.com/"


class CustomizeException(Exception):
    def __init__(self, status, msg):
        self.status = status
        self.msg = msg


class JD:
    def __init__(self):
        self.browser = None
        self.__init_browser()

    def __init_browser(self):
        options = Options()
        options.add_argument("--headless")
        options.add_experimental_option('excludeSwitches', ['enable-automation'])
        # 设置为无图模式
        options.add_experimental_option("prefs", {"profile.managed_default_content_settings.images": 2})
        self.browser = webdriver.Chrome(options=options)
        # 设置浏览器最大化窗口
        self.browser.maximize_window()
        # 隐式等待时间为3s
        self.browser.implicitly_wait(3)
        self.browser.get(JD_URL_Login)
        self.wait = WebDriverWait(self.browser, 10)

    def __search_goods(self, goods):
        '''搜索商品的方法'''
        self.file = open("jd-{}.json".format(goods), "a", encoding="utf-8")
        self.wait.until(EC.presence_of_all_elements_located((By.ID, "key")))
        serach_input = self.browser.find_element_by_id("key")
        serach_input.clear()
        serach_input.send_keys(goods, Keys.ENTER)

    def __get_goods_info(self, page_source):
        '''从网页源码中获取到想要的数据'''
        selector_html = etree.HTML(page_source)
        # 商品名字 不要获取title属性，以后再改吧，最好是获取到商品名的文本内容
        goods_name = selector_html.xpath("//div[@class='gl-i-wrap']//div[contains(@class,'p-name')]/a/@title")

        # 商品价格
        goods_price = selector_html.xpath("//div[@class='gl-i-wrap']//div[@class='p-price']/strong/i/text()")

        # 商品评价数量
        comment_num_selector = selector_html.xpath("//div[@class='p-commit']/strong")
        comment_num = [selector.xpath("string(.)") for selector in comment_num_selector]

        # 商品店铺
        shop_name = selector_html.xpath("//a[@class='curr-shop']/text()")

        goods_zip = zip(goods_name, goods_price, comment_num, shop_name)
        for goods_info in goods_zip:
            dic = {}
            dic["goods_name"] = goods_info[0]
            dic["goods_price"] = goods_info[1]
            dic["comment_num"] = goods_info[2]
            dic["shop_name"] = goods_info[3]
            # print("商品名字>>:", goods_info[0])
            # print("商品价格>>:", goods_info[1])
            # print("商品评价数量>>:", goods_info[2])
            # print("商品店铺>>:", goods_info[3])
            # print("*" * 100)
            yield dic

    def __swipe_page(self):
        '''上下滑动页面，将完整的网页源码返回'''
        height = self.browser.execute_script("return document.body.scrollHeight;")
        js = "window.scrollTo(0, {});".format(height)
        self.browser.execute_script(js)
        while True:
            time.sleep(1)
            now_height = self.browser.execute_script("return document.body.scrollHeight;")
            if height == now_height:
                return self.browser.page_source
            js = "window.scrollTo({}, {});".format(height, now_height)
            self.browser.execute_script(js)
            height = now_height

    def __is_element_exists(self, xpath):
        '''检测一个xpath是否能够找到'''
        try:
            self.browser.find_element_by_xpath(xpath=xpath)
            return True
        except NoSuchElementException:
            return False

    def __click_next_page(self):
        '''点击下一页，实现翻页功能'''
        self.wait.until(EC.presence_of_all_elements_located((By.CLASS_NAME, "pn-next")))
        xpath = "//a[@class='pn-next']"
        if not self.__is_element_exists(xpath):
            raise CustomizeException(10000, "该商品访问完毕")
        self.browser.find_element_by_xpath(xpath).click()

    def __write_to_json(self, dic: dict):
        data_json = json.dumps(dic, ensure_ascii=False)
        self.file.write(data_json + "\n")

    def run(self, goods):
        self.__search_goods(goods)
        n = 1
        while True:
            print("正在爬取商品 <{}>---第{}页......".format(goods, n))
            time.sleep(3)
            html = self.__swipe_page()
            for dic in self.__get_goods_info(html):
                self.__write_to_json(dic)
            try:
                self.__click_next_page()
            except CustomizeException:
                try:
                    goods = goods_list.pop(0)
                    self.run(goods)
                except IndexError:
                    return
            n += 1

    def __del__(self):
        self.browser.close()
        self.file.close()


if __name__ == '__main__':
    jd = JD()
    goods_list = ["纯牛奶", "酸奶", "奶茶", "床上用品", "电磁炉", "电视", "小米笔记本", "华硕笔记本", "联想笔记本", "男士洗面奶", "女士洗面奶", "沐浴露", "洗发露",
                  "牙刷", "牙膏", "拖鞋", "剃须刀", "水手服", "运动服", "红龙果", "苹果", "香蕉", "洗衣液", "电饭煲"]
    try:
        goods = goods_list.pop(0)
    except IndexError:
        raise CustomizeException(20000, "goods_list不能为空")
    try:
        jd.run(goods)
    finally:
        del jd