# Copyright 2018 miruka
# This file is part of harmonyqt, licensed under GPLv3.

import json
import platform
import threading
from collections.abc import Mapping
from typing import Dict

from atomicfile import AtomicFile
from PyQt5.QtCore import (
    QObject, QStandardPaths, pyqtProperty, pyqtSignal, pyqtSlot
)

from harmonyqml import __about__

from .backend import Backend
from .client import Client

AccountConfig = Dict[str, Dict[str, str]]

_CONFIG_LOCK = threading.Lock()


class _ClientManagerMeta(type(QObject), type(Mapping)):  # type: ignore
    pass


class ClientManager(QObject, Mapping, metaclass=_ClientManagerMeta):
    clientAdded        = pyqtSignal(Client)
    clientDeleted      = pyqtSignal(str)
    clientCountChanged = pyqtSignal(int)


    def __init__(self, backend: Backend) -> None:
        super().__init__(backend)
        self.backend = backend
        self._clients: Dict[str, Client] = {}

        func = lambda: self.clientCountChanged.emit(len(self))
        self.clientAdded.connect(func)
        self.clientDeleted.connect(func)


    def __repr__(self) -> str:
        return f"{type(self).__name__}(clients={self._clients!r})"


    def __getitem__(self, user_id: str) -> Client:
        return self.get(user_id)


    def __len__(self) -> int:
        return self.count


    def __iter__(self):
        return iter(self._clients)


    @pyqtSlot(str, result="QVariant")
    def get(self, key: str) -> Client:
        return self._clients[key]


    @pyqtProperty(int, notify=clientCountChanged)
    def count(self):
        return len(self._clients)


    @pyqtSlot()
    def configLoad(self) -> None:
        for user_id, info in self.configAccounts().items():
            client = Client(self, info["hostname"], user_id)
            client.resumeSession(user_id, info["token"], info["device_id"])\
                  .add_done_callback(lambda _, c=client: self._on_connected(c))


    @pyqtSlot(str, str, str, result="QVariant")
    @pyqtSlot(str, str, str, str, result="QVariant")
    def new(self, hostname: str, username: str, password: str,
            device_id: str = "") -> None:

        client = Client(self, hostname, username, device_id)
        future = client.login(password, self.defaultDeviceName)
        future.add_done_callback(lambda _: self._on_connected(client))
        return future


    def _on_connected(self, client: Client) -> None:
        self._clients[client.userId] = client
        self.clientAdded.emit(client)
        client.startSyncing()


    @pyqtSlot(str)
    def remove(self, user_id: str) -> None:
        client = self._clients.pop(user_id, None)
        if client:
            self.clientDeleted.emit(user_id)
            client.logout()


    @pyqtSlot()
    def removeAll(self) -> None:
        for user_id in self._clients.copy():
            self.remove(user_id)


    @pyqtProperty(str, constant=True)
    def defaultDeviceName(self) -> str:  # pylint: disable=no-self-use
        os_ = f" on {platform.system()}".rstrip()
        os_ = f"{os_} {platform.release()}".rstrip() if os_ != " on" else ""
        return f"{__about__.__pretty_name__}{os_}"


    # Config file operations

    def getAccountConfigPath(self) -> str:
        return self.backend.getFile(
            QStandardPaths.AppConfigLocation, "accounts.json", "[]"
        )


    def configAccounts(self) -> AccountConfig:
        with open(self.getAccountConfigPath(), "r") as file:
            return json.loads(file.read().strip()) or {}


    @pyqtSlot("QVariant")
    def remember(self, client: Client) -> None:
        self._write_config({
            **self.configAccounts(),
            **{client.userId: {
                "hostname": client.nio.host,
                "token": client.nio.access_token,
                "device_id": client.nio.device_id,
            }}
        })


    @pyqtSlot(str)
    def forget(self, user_id: str) -> None:
        self._write_config({
            uid: info
            for uid, info in self.configAccounts().items() if uid != user_id
        })


    def _write_config(self, accounts: AccountConfig) -> None:
        js = json.dumps(accounts, indent=4, ensure_ascii=False, sort_keys=True)

        with _CONFIG_LOCK:
            with AtomicFile(self.getAccountConfigPath(), "w") as new:
                new.write(js)