from collections import deque

from cfg import config

def can_reach(title, connection):
	cursor = connection.cursor()
	cursor.execute("SELECT COUNT(destination) FROM links WHERE destination=?", (title, ))
	count = cursor.fetchone()[0]
	return count > 0

def shortest_path(center, title, connection):
	if(not can_reach(title, connection)):
		return []

	cursor = connection.cursor()
	current_title = title
	path = deque()
	while(current_title != center):
		path.append(current_title)
		if(config["use_sqlite"]):
			cursor.execute('''SELECT links.source 
					FROM links
					LEFT JOIN dijkstra_helper ON links.destination=dijkstra_helper.name
					WHERE links.destination=:title
					ORDER BY dijkstra_helper.value ASC
					LIMIT 1''', {"title": current_title})
		else:
			cursor.execute('''SELECT links.source 
					FROM links
					LEFT JOIN dijkstra_helper ON links.destination=dijkstra_helper.name
					WHERE links.destination=:title
					SORT BY dijkstra_helper.value ASC
					LIMIT 1''', {"title": current_title})
		current_title = cursor.fetchone()[0]
	return list(reversed(path))