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

# Requirement:
# python3 -m pip install lxml

import re
from time import sleep
from urllib.request import urlopen
from urllib.error import HTTPError
from lxml.html import parse

footer_delimiter = "\n\n[comment]: # (LINK_LIST_BEGIN_HERE)\n"
footer = ""
linked_id = []
present_id = []

def add_bracket(match):
	first_char = match.group(1)
	id = match.group(2)
	replace = first_char + "[#"+id+"]"
	return replace

def add_link(match):
	id = match.group(1)
	present_id.append(id)
	replace = "#" + id
	if id in linked_id:
		return replace

	url = "https://github.com/hrydgard/ppsspp/issues/"+id
	title = None
	while title is None:
		try:
			p = parse(urlopen(url))
			title = p.find(".//title").text.split('by')[0].split('·')[0].strip()
			title = re.sub(r"\"", r'\\"', title)
		except HTTPError:
			print("Something went wrong, retrying in 10 sec...")
			sleep(10)

	global footer
	addition = "[#"+id+"]: https://github.com/hrydgard/ppsspp/issues/"+id+" \""+title+"\""
	footer += addition+"\n"
	linked_id.append(id)
	print("Linked: " + addition)
	return replace

def already_added_id(match):
	linked_id.append(match.group(1))
	return "[#" + match.group(1) + "]:"

def remove_old_link(line):
	# Ignore extra new lines at the end
	if line.find("#") == -1:
		return ""
		
	id = line[line.find("[#")+2 : line.find("]:")]
	if id in present_id:
		return line + "\n"
	else:
		print("Removed: #" + id)
		return ""

def update(file_name):
	global footer
	footer = ""
	global linked_id
	linked_id = []
	global present_id
	present_id = []

	f = open(file_name, "r+")
	cont = f.read()

	# We don't want to match issues id in title so stop before the link list
	d = cont.find(footer_delimiter)
	if (d != -1):
		footer = cont[d + len(footer_delimiter):]
		cont = cont[0 : d]
		re.sub(r"\[#(\d+)\]:", already_added_id, footer)
		if footer[-1] != "\n":
			footer += "\n"

	# Add brackets if missing
	added_bracket = re.sub(r"([^[])#(\d+)", add_bracket, cont)

	# Add links if missing
	updated = re.sub(r"#(\d+)", add_link, added_bracket)

	# Remove old unused link
	updated_footer = ""
	for line in footer.split("\n"):
		updated_footer += remove_old_link(line)

	# Remove extra new lines at the end
	while updated_footer[-1] == "\n":
		updated_footer = updated_footer[0:-1]

	f.seek(0)
	f.write(updated)
	f.write(footer_delimiter)
	f.write(updated_footer)
	f.truncate()
	f.close()

update("README.md")
update("history.md")