#!/usr/bin/env python
# coding: utf-8


import os, time, re
import contextlib
import sys
import requests
import threading
from bs4 import BeautifulSoup, Comment
from .tomd import Tomd


def result_file(folder_username, file_name, folder_name):
	folder = os.path.join(os.path.dirname(os.path.realpath(__file__)), "..", folder_name, folder_username)
	if not os.path.exists(folder):
		os.makedirs(folder)
		path = os.path.join(folder, file_name)
		file = open(path,"w")
		file.close()
	else:
		path = os.path.join(folder, file_name)
	return path


def delete_ele(soup:BeautifulSoup, tags:list):
	for ele in tags:
		for useless_tag in soup.select(ele):
			useless_tag.decompose()


def delete_ele_attr(soup:BeautifulSoup, attrs:list):
	for attr in attrs:
		for useless_attr in soup.find_all():
			del useless_attr[attr]


def delete_blank_ele(soup:BeautifulSoup, eles_except:list):
	for useless_attr in soup.find_all():
		try:
			if useless_attr.name not in eles_except and useless_attr.text == "":
				useless_attr.decompose()
		except Exception:
			pass


class TaskQueue(object):
	def __init__(self):
		self.VisitedList = []
		self.UnVisitedList = []
	
	def getVisitedList(self):
		return self.VisitedList

	def getUnVisitedList(self):
		return self.UnVisitedList
	
	def InsertVisitedList(self, url):
		if url not in self.VisitedList:
			self.VisitedList.append(url)
	
	def InsertUnVisitedList(self, url):
		if url not in self.UnVisitedList:
			self.UnVisitedList.append(url)
	
	def RemoveVisitedList(self, url):
		self.VisitedList.remove(url)

	def PopUnVisitedList(self,index=0):
		url = []
		if index and self.UnVisitedList:
			url = self.UnVisitedList[index]
			del self.UnVisitedList[:index]
		elif self.UnVisitedList:
			url = self.UnVisitedList.pop()
		return url
	
	def getUnVisitedListLength(self):
		return len(self.UnVisitedList)


class CSDN(object):
	def __init__(self, username, folder_name):
		self.headers = {
			"User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.70 Safari/537.36"
		}
		self.username = username
		self.TaskQueue = TaskQueue()
		self.folder_name = folder_name
		self.url_num = 1

	def start(self):
		num = 0
		while True:
			num += 1
			url = u'https://blog.csdn.net/' + self.username + '/article/list/' + str(num)
			response = requests.get(url=url, headers=self.headers)
			html = response.text
			soup = BeautifulSoup(html, "html.parser")
			articles = soup.find_all('div', attrs={"class":"article-item-box csdn-tracking-statistics"})
			if len(articles) > 0:
				for article in articles:
					article_title = article.a.text.strip().replace('        ','：')
					article_href = article.a['href']
					with ensure_memory(sys.getsizeof(self.TaskQueue.UnVisitedList)):
						self.TaskQueue.InsertUnVisitedList([article_title, article_href])
			else:
				break
	
	def get_md(self, url):
		response = requests.get(url=url, headers=self.headers)
		html = response.text
		soup = BeautifulSoup(html, 'lxml')
		content = soup.select_one("#content_views")
		# 删除注释
		for useless_tag in content(text=lambda text: isinstance(text, Comment)):
			useless_tag.extract()
		# 删除无用标签
		tags = ["svg", "ul", ".hljs-button.signin"]
		delete_ele(content, tags)
		# 删除标签属性
		attrs = ["class", "name", "id", "onclick", "style", "data-token", "rel"]
		delete_ele_attr(content,attrs)
		# 删除空白标签
		eles_except = ["img", "br", "hr"]
		delete_blank_ele(content, eles_except)
		# 转换为markdown
		md = Tomd(str(content)).markdown
		return md


	def write_readme(self):
		print("+"*100)
		print("[++] 开始爬取 {} 的博文 ......".format(self.username))
		print("+"*100)
		reademe_path = result_file(self.username,file_name="README.md",folder_name=self.folder_name)
		with open(reademe_path,'w', encoding='utf-8') as reademe_file:
			readme_head = "# " + self.username + " 的博文\n"
			reademe_file.write(readme_head)
			for [article_title,article_href] in self.TaskQueue.UnVisitedList[::-1]:
					text = str(self.url_num) + '. [' + article_title + ']('+ article_href +')\n'
					reademe_file.write(text)
					self.url_num += 1
		self.url_num = 1
	
	def get_all_articles(self):
		try:
			while True:
				[article_title,article_href] = self.TaskQueue.PopUnVisitedList()
				try:
					file_name = re.sub(r'[\/:：*?"<>|]','-', article_title) + ".md"
					artical_path = result_file(folder_username=self.username, file_name=file_name, folder_name=self.folder_name)
					md_head = "# " + article_title + "\n"
					md = md_head + self.get_md(article_href)
					print("[++++] 正在处理URL：{}".format(article_href))
					with open(artical_path, "w", encoding="utf-8") as artical_file:
						artical_file.write(md)
				except Exception:
					print("[----] 处理URL异常：{}".format(article_href))
				self.url_num += 1
		except Exception:
			pass

	def muti_spider(self, thread_num):
		while True:
			if self.TaskQueue.getUnVisitedListLength() < 1:
				break
			thread_list = []
			for i in range(thread_num):
				th = threading.Thread(target=self.get_all_articles)
				thread_list.append(th)
			for th in thread_list:
				th.start()


lock = threading.Lock()
total_mem= 1024 * 1024 * 500 #500MB spare memory
@contextlib.contextmanager
def ensure_memory(size):
    global total_mem
    while 1:
        with lock:
            if total_mem > size:
                total_mem-= size
                break
        time.sleep(5)
    yield 
    with lock:
        total_mem += size


def spider_user(username: str, thread_num: int = 10, folder_name: str = "articles"):
	if not os.path.exists(folder_name):
		os.makedirs(folder_name)
	csdn = CSDN(username,folder_name)
	csdn.start()
	th1 = threading.Thread(target=csdn.write_readme)
	th1.start()
	th2 = threading.Thread(target=csdn.muti_spider, args=(thread_num,))
	th2.start()


def spider(usernames: list, thread_num: int = 10, folder_name: str = "articles"):
	for username in usernames:
		try:
			user_thread = threading.Thread(target=spider_user,args=(username, thread_num, folder_name))
			user_thread.start()
			print("[++] 开启爬取 {} 博文进程成功 ......".format(username))
		except Exception:
			print("[--] 开启爬取 {} 博文进程出现异常 ......".format(username))


if __name__ == "__main__":
	spider(["ds19991999"])