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

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
max_jira_tasks = 50


class Tasks:
    def __init__(self, data):
        self._data = data
        if "tasks" in self._data:
            self._tasks = list(map(lambda x: base64.b64decode(x.encode("utf-8")).decode("utf-8"), self._data["tasks"]))
        else:
            self._tasks = []
        if "jira_tasks" in self._data:
            self._jira_tasks_usage = dict()
            for k, v in self._data["jira_tasks"].items():
                key = base64.b64decode(k.encode("utf-8")).decode("utf-8")
                self._jira_tasks_usage[key] = datetime.fromisoformat(v)
                self._jira_tasks = sorted(self._jira_tasks_usage.keys(), key=lambda x: self._jira_tasks_usage[x])
        else:
            self._jira_tasks_usage = dict()
            self._jira_tasks = []

    @property
    def tasks(self) -> List[str]:
        return self._tasks

    @tasks.setter
    def tasks(self, tasks):
        self._tasks = tasks
        encoded_tasks = list(map(lambda x: base64.b64encode(x.encode("utf-8")).decode("utf-8"), self._tasks))
        self._data["tasks"] = encoded_tasks

    @property
    def jira_tasks(self):
        return self._jira_tasks

    def add_jira_task(self, task_name):
        self._jira_tasks.append(task_name)
        self._jira_tasks_usage[task_name] = datetime.now()
        if len(self._jira_tasks_usage) > max_jira_tasks:
            sorted_tasks = sorted(self._jira_tasks_usage.keys(), key=lambda x: self._jira_tasks_usage[x])
            overhang_tasks = sorted_tasks[:len(sorted_tasks) - max_jira_tasks]
            for task in overhang_tasks:
                del self._jira_tasks_usage[task]
        self._save_jira_tasks()

    def update_jira_task_usage(self, task_name):
        if task_name in self._jira_tasks_usage:
            self._jira_tasks_usage[task_name] = datetime.now()
            self._save_jira_tasks()

    def _save_jira_tasks(self):
        serialized = dict()
        for k, v in self._jira_tasks_usage.items():
            key = base64.b64encode(k.encode("utf-8")).decode("utf-8")
            serialized[key] = datetime.isoformat(v)
        self._data["jira_tasks"] = serialized

    @property
    def all_tasks(self):
        return self.tasks + self.jira_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 = set()
        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.add(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 = set()
        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, data):
        self._data = data

        def cleanup():
            self.log("End")

        atexit.register(cleanup)

    def log(self, task, ptime=None):
        if ptime is None:
            ptime = datetime.now()
        # round to nearest minute
        round_min = timedelta(minutes=round(ptime.second/60))
        ptime = ptime - timedelta(seconds=ptime.second) + round_min
        # month dance necessary to trigger Data.__setitem__
        month = self._data.setdefault(ptime.strftime("%Y-%m"), {})
        month.setdefault(ptime.strftime("%d"), [])\
            .append(f"{ptime.strftime('%H:%M')} {base64.b64encode(task.encode('utf-8')).decode('utf-8')}")
        self._data[ptime.strftime("%Y-%m")] = month

    def last_log(self, pdate=None):
        if pdate is None:
            pdate = date.today()
        if pdate.strftime("%Y-%m") not in self._data \
                or pdate.strftime("%d") not in self._data[pdate.strftime("%Y-%m")] \
                or len(self._data[pdate.strftime("%Y-%m")][pdate.strftime("%d")]) == 0:
            return None
        last = base64.b64decode(
            self._data[pdate.strftime("%Y-%m")][pdate.strftime("%d")][-1].split()[1].encode("utf-8")).decode("utf-8")
        if last == "End":
            month = self._data[pdate.strftime("%Y-%m")]
            del month[pdate.strftime("%d")][-1]
            self._data[pdate.strftime("%Y-%m")] = month
            if len(self._data[pdate.strftime("%Y-%m")][pdate.strftime("%d")]) == 0:
                return None
            last = base64.b64decode(
                self._data[pdate.strftime("%Y-%m")][pdate.strftime("%d")][-1].split()[1].encode("utf-8")).decode("utf-8")
        return last

    def report(self, pdate=None):
        if pdate is None:
            pdate = date.today()
        return Report(self._data, pdate)


class Report:
    def __init__(self, data, pdate):
        self._data = data
        self._date = pdate
        self._sum_len = 0
        self._prev = None
        self._next = None
        self._update_prev_next()

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

        ret = []
        tasks_sums = {}
        total_sum = timedelta()
        for i, t in enumerate(tmp):
            task, start_time = t
            if i < len(tmp) - 1:
                end_time = tmp[i+1][1]
                duration = end_time - start_time
                if task != "Pause":
                    task_sum = tasks_sums.setdefault(task, timedelta())
                    task_sum += duration
                    tasks_sums[task] = task_sum
                    total_sum += duration
                dhours, rem = divmod(duration.seconds, 3600)
                dmins, _ = divmod(rem, 60)
                ret.append([task, start_time.strftime("%H:%M"), f"{dhours:02d}:{dmins:02d}"])
            else:
                ret.append([task, start_time.strftime("%H:%M"), ""])

        ret.append(["", "", ""])
        ret.append(["", "Sums", ""])
        for k, v in tasks_sums.items():
            dhours, rem = divmod(v.seconds, 3600)
            dmins, _ = divmod(rem, 60)
            ret.append([k, "", f"{dhours:02d}:{dmins:02d}"])
        dhours, rem = divmod(total_sum.seconds, 3600)
        dmins, _ = divmod(rem, 60)
        ret.append(["Total sum", "", f"{dhours:02d}:{dmins:02d}"])
        self._sum_len = 3 + len(tasks_sums)
        if self._date == date.today():
            self._sum_len += 1
        return ret, len(ret) - (4 + len(tasks_sums))

    def save(self, report):
        report = report[:-self._sum_len]
        if not report:
            return
        save_list = []
        for tstr, ttime, _ in report:
            b64str = base64.b64encode(tstr.encode("utf-8")).decode("utf-8")
            save_string = f"{ttime} {b64str}"
            save_list.append(save_string)
        # month dance necessary to trigger Data.__setitem__
        month = self._data[self._date.strftime("%Y-%m")]
        if month[self._date.strftime("%d")] == save_list:  # no changes
            return
        month[self._date.strftime("%d")] = save_list
        self._data[self._date.strftime("%Y-%m")] = month

    def _update_prev_next(self):
        self._prev = None
        self._next = None
        for i in range(1, 32):
            new_date = self._date - timedelta(days=i)
            if new_date.strftime("%Y-%m") not in self._data:
                break
            if new_date.strftime("%d") in self._data[new_date.strftime("%Y-%m")]:
                self._prev = new_date
                break
        for i in range(1, 32):
            new_date = self._date + timedelta(days=i)
            if new_date > date.today():
                break
            if new_date.strftime("%Y-%m") not in self._data:
                break
            if new_date.strftime("%d") in self._data[new_date.strftime("%Y-%m")]:
                self._next = new_date
                break

    def prev_next_avail(self):
        return self._prev is not None, self._next is not None

    def previous(self):
        self._date = self._prev
        self._update_prev_next()

    def next(self):
        self._date = self._next
        self._update_prev_next()

    def date(self):
        return self._date.strftime("%Y-%m-%d")