import traceback, json, hashlib
from os import path, remove
from shutil import copy
from datetime import datetime


"""
{
    "date": timestamp,
    "checksum": sha512
}
"""

def is_cached_file(file, expire) :
        is_cached = False
        try :
            if not path.isfile(file) :
                return False
            if not path.isfile(file + ".md") :
                return False
            cached_time = 0
            with open(file + ".md", "r") as f :
                cached_time = json.loads(f.read())["date"]
            current_time = datetime.timestamp(datetime.now())
            if current_time < cached_time :
                return False
            diff_time = current_time - cached_time
            if expire == "hour" :
                is_cached = diff_time < 3600
            elif expire == "day" :
                is_cached = diff_time < 86400
            elif expire == "month" :
                is_cached = diff_time < 2592000
        except :
            is_cached = False
        return is_cached

def file_hash(file) :
    sha512 = hashlib.sha512()
    with open(file, "rb") as f :
        while True :
            data = f.read(1024)
            if not data :
                break
            sha512.update(data)
    return sha512.hexdigest()

def cache_hash(cache) :
    try :
        with open(cache + ".md", "r") as f :
            return json.loads(f.read())["checksum"]
    except :
        pass
    return None

def cache_file(file, cache, _hash) :
    ret, err = True, "success"
    try :
        copy(file, cache)
        remove(file)
        with open(cache + ".md", "w") as f :
            md = {
                "date": datetime.timestamp(datetime.now()),
                "checksum": _hash
            }
            f.write(json.dumps(md))
    except :
        return False, "exception : " + traceback.format_exc()
    return ret, err