# Copyright (c) 2018 Ultimaker B.V.
# Cura is released under the terms of the LGPLv3 or higher.

import json
import os
from typing import List, Optional

from PyQt5.QtNetwork import QLocalServer, QLocalSocket

from UM.Logger import Logger


class SingleInstance:

    def __init__(self, application, files_to_open: Optional[List[str]]):
        self._application = application
        self._files_to_open = files_to_open

        self._single_instance_server = None

    # Starts a client that checks for a single instance server and sends the files that need to opened if the server
    # exists. Returns True if the single instance server is found, otherwise False.
    def startClient(self) -> bool:
        Logger.log("i", "Checking for the presence of an ready running Cura instance.")
        single_instance_socket = QLocalSocket(self._application)
        Logger.log("d", "Full single instance server name: %s", single_instance_socket.fullServerName())
        single_instance_socket.connectToServer("ultimaker-cura")
        single_instance_socket.waitForConnected(msecs = 3000)  # wait for 3 seconds

        if single_instance_socket.state() != QLocalSocket.ConnectedState:
            return False

        # We only send the files that need to be opened.
        if not self._files_to_open:
            Logger.log("i", "No file need to be opened, do nothing.")
            return True

        if single_instance_socket.state() == QLocalSocket.ConnectedState:
            Logger.log("i", "Connection has been made to the single-instance Cura socket.")

            # Protocol is one line of JSON terminated with a carriage return.
            # "command" field is required and holds the name of the command to execute.
            # Other fields depend on the command.

            payload = {"command": "clear-all"}
            single_instance_socket.write(bytes(json.dumps(payload) + "\n", encoding = "ascii"))

            payload = {"command": "focus"}
            single_instance_socket.write(bytes(json.dumps(payload) + "\n", encoding = "ascii"))

            for filename in self._files_to_open:
                payload = {"command": "open", "filePath": os.path.abspath(filename)}
                single_instance_socket.write(bytes(json.dumps(payload) + "\n", encoding = "ascii"))

            payload = {"command": "close-connection"}
            single_instance_socket.write(bytes(json.dumps(payload) + "\n", encoding = "ascii"))

            single_instance_socket.flush()
            single_instance_socket.waitForDisconnected()
        return True

    def startServer(self) -> None:
        self._single_instance_server = QLocalServer()
        self._single_instance_server.newConnection.connect(self._onClientConnected)
        self._single_instance_server.listen("ultimaker-cura")

    def _onClientConnected(self):
        Logger.log("i", "New connection recevied on our single-instance server")
        connection = self._single_instance_server.nextPendingConnection()

        if connection is not None:
            connection.readyRead.connect(lambda c = connection: self.__readCommands(c))

    def __readCommands(self, connection):
        line = connection.readLine()
        while len(line) != 0:    # There is also a .canReadLine()
            try:
                payload = json.loads(str(line, encoding = "ascii").strip())
                command = payload["command"]

                # Command: Remove all models from the build plate.
                if command == "clear-all":
                    self._application.callLater(lambda: self._application.deleteAll())

                # Command: Load a model file
                elif command == "open":
                    self._application.callLater(lambda f = payload["filePath"]: self._application._openFile(f))

                # Command: Activate the window and bring it to the top.
                elif command == "focus":
                    # Operating systems these days prevent windows from moving around by themselves.
                    # 'alert' or flashing the icon in the taskbar is the best thing we do now.
                    self._application.callLater(lambda: self._application.getMainWindow().alert(0))

                # Command: Close the socket connection. We're done.
                elif command == "close-connection":
                    connection.close()

                else:
                    Logger.log("w", "Received an unrecognized command " + str(command))
            except json.decoder.JSONDecodeError as ex:
                Logger.log("w", "Unable to parse JSON command '%s': %s", line, repr(ex))
            line = connection.readLine()