from time import time
from threading import Lock

class FlaskCache:
    def __init__(self, timeout=20):
        self.timeout = timeout
        self.cache   = {}
        self.lock    = {}

    def genpage(self, pagefunc, *args):
        page = {}
        try:
            page["page"]   = pagefunc(*args)
            page["code"] = 200
        except Exception as e:
            page["page"]   = "ERROR\n"
            page["code"] = 500
        page["time"] = time()
        return(page)

    def cachetime(self, pagename):
        try:
            delta = self.cache[pagename]["time"] + self.timeout - time()
        except Exception as e:
            delta = -1
        return(delta)

    def getpage(self, pagename, pagefunc, *args):
        if pagename not in self.cache:
            self.cache[pagename] = {}
        if pagename not in self.lock:
            self.lock[pagename] = Lock()
        if (self.cachetime(pagename) <= 0):
            self.lock[pagename].acquire()
            if (self.cachetime(pagename) <= 0):
                self.cache[pagename] = self.genpage(pagefunc, *args)
            self.lock[pagename].release()
        return(self.cache[pagename]["page"], self.cache[pagename]["code"])