import os
import json
import base64
import atexit
from datetime import datetime, date, time
from threading import Thread, Event
from collections.abc import MutableMapping

from PySide2 import QtCore

data_dir_path = os.path.join(QtCore.QStandardPaths.writableLocation(QtCore.QStandardPaths.AppDataLocation),
                             "fimefracking")

tasks_path = os.path.join(data_dir_path, "tasks.json")

data_path = os.path.join(data_dir_path, "data_{}.json")
#save_delay = 3 * 60
save_delay = 3


class Tasks:
    def __init__(self):
        if not os.path.exists(data_dir_path):
            os.mkdir(data_dir_path)
        if os.path.exists(tasks_path):
            with open(tasks_path, "r") as f:
                encoded_tasks = json.loads(f.read())
                self._tasks = list(map(lambda x: base64.b64decode(x.encode("utf-8")).decode("utf-8"), encoded_tasks))
        else:
            self._tasks = []

    @property
    def tasks(self):
        return self._tasks

    @tasks.setter
    def tasks(self, tasks):
        self._tasks = tasks
        self._save()

    def _save(self):
        print("...saving tasks...")
        encoded_tasks = list(map(lambda x: base64.b64encode(x.encode("utf-8")).decode("utf-8"), self._tasks))
        with open(tasks_path, "w+") as f:
            f.write(json.dumps(encoded_tasks))


class Data(MutableMapping):
    def __init__(self):
        if not os.path.exists(data_dir_path):
            os.mkdir(data_dir_path)
        self._cache = {}
        self._hot_keys = []
        self._trunning = False
        self._tevent = Event()
        self._thread = None

        def cleanup():
            self._trunning = False
            self._tevent.set()
            if self._thread:
                self._thread.join()

        atexit.register(cleanup)

    def __getitem__(self, key):
        dpath = data_path.format(key)
        if key not in self._cache and os.path.exists(dpath):
            with open(dpath, "r") as f:
                self._cache[key] = json.loads(f.read())
        return self._cache[key]

    def __setitem__(self, key, value):
        self._cache[key] = value
        self._hot_keys.append(key)
        self._schedule_save()

    def _schedule_save(self):
        if self._trunning:
            return
        self._trunning = True
        self._thread = Thread(target=self._executor, daemon=True)
        self._thread.start()

    def _executor(self):
        while self._trunning:
            self._tevent.wait(save_delay)
            self._save()

    def _save(self):
        for key in self._hot_keys:
            print(f"... saving dict {key} ...")
            to_write = self._cache[key]  # apparently thread-safe
            with open(data_path.format(key), "w+") as f:
                f.write(json.dumps(to_write))
        self._hot_keys = []
        self._saving = False

    def __delitem__(self, key):
        return NotImplemented

    def __iter__(self):
        return NotImplemented

    def __len__(self):
        # TODO use glob?
        return NotImplemented

    def __repr__(self):
        return f"{type(self).__name__}({self._cache})"


class Log:
    def __init__(self):
        self._data = Data()

    def log(self, task, ptime=datetime.now()):
        month = self._data.setdefault(ptime.strftime("%Y-%m"), {})
        month.setdefault(ptime.strftime("%d"), [])\
            .append(f"{ptime.strftime('%H:%M:%S')} {base64.b64encode(task.encode('utf-8')).decode('utf-8')}")
        self._data[ptime.strftime("%Y-%m")] = month  # necessary to trigger Data.__setitem__

    def last_log(self, pdate=date.today()):
        if pdate.strftime("%Y-%m") not in self._data or pdate.strftime("%d") not in self._data[pdate.strftime("%Y-%m")]:
            return None
        return base64.b64decode(
            self._data[pdate.strftime("%Y-%m")][pdate.strftime("%d")][-1].split()[1].encode("utf-8")).decode("utf-8")

    def report(self, pdate=date.today()):
        tmp = []
        for e in self._data[pdate.strftime("%Y-%m")][pdate.strftime("%d")]:
            tstr, b64str = e.split()
            task = base64.b64decode(b64str.encode("utf-8")).decode("utf-8")
            start_time = datetime.combine(pdate, datetime.strptime(tstr, "%H:%M:%S").time())
            tmp.append((task, start_time))

        ret = []
        for i, t in enumerate(tmp):
            task, start_time = t
            if i < len(tmp) - 1:
                end_time = tmp[i+1][1]
            else:
                end_time = datetime.now()
            duration = end_time - start_time
            ret.append((task, start_time, duration))
        return ret