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

import functools  # For partial to update files that were changed.
import os.path  # To watch files for changes.
import threading
from typing import Callable, List, Optional, Set

from PyQt5.QtCore import QFileSystemWatcher  # To watch files for changes.

from UM.Decorators import deprecated
from UM.Logger import Logger
from UM.Mesh.ReadMeshJob import ReadMeshJob  # To reload a mesh when its file was changed.
from UM.Message import Message  # To display a message for reloading files that were changed.
from UM.Scene.Camera import Camera
from UM.Scene.Iterator.BreadthFirstIterator import BreadthFirstIterator
from UM.Scene.SceneNode import SceneNode
from UM.Signal import Signal, signalemitter
from UM.i18n import i18nCatalog
from UM.Platform import Platform

i18n_catalog = i18nCatalog("uranium")


##  Container object for the scene graph
#
#   The main purpose of this class is to provide the root SceneNode.
@signalemitter
class Scene:
    def __init__(self) -> None:
        super().__init__()

        from UM.Scene.SceneNode import SceneNode
        self._root = SceneNode(name = "Root")
        self._root.setCalculateBoundingBox(False)
        self._connectSignalsRoot()
        self._active_camera = None  # type: Optional[Camera]
        self._ignore_scene_changes = False
        self._lock = threading.Lock()

        # Watching file for changes.
        self._file_watcher = QFileSystemWatcher()
        self._file_watcher.fileChanged.connect(self._onFileChanged)

        self._reload_message = None  # type: Optional[Message]
        self._callbacks = set() # type: Set[Callable] # Need to keep these in memory. This is a memory leak every time you refresh, but a tiny one.

    def _connectSignalsRoot(self) -> None:
        self._root.transformationChanged.connect(self.sceneChanged)
        self._root.childrenChanged.connect(self.sceneChanged)
        self._root.meshDataChanged.connect(self.sceneChanged)

    def _disconnectSignalsRoot(self) -> None:
        self._root.transformationChanged.disconnect(self.sceneChanged)
        self._root.childrenChanged.disconnect(self.sceneChanged)
        self._root.meshDataChanged.disconnect(self.sceneChanged)

    def setIgnoreSceneChanges(self, ignore_scene_changes: bool) -> None:
        if self._ignore_scene_changes != ignore_scene_changes:
            self._ignore_scene_changes = ignore_scene_changes
            if self._ignore_scene_changes:
                self._disconnectSignalsRoot()
            else:
                self._connectSignalsRoot()

    ##  Gets the global scene lock.
    #
    #   Use this lock to prevent any read or write actions on the scene from other threads,
    #   assuming those threads also properly acquire the lock. Most notably, this
    #   prevents the rendering thread from rendering the scene while it is changing.
    def getSceneLock(self) -> threading.Lock:
        return self._lock

    ##  Get the root node of the scene.
    def getRoot(self) -> "SceneNode":
        return self._root

    ##  Change the root node of the scene
    def setRoot(self, node: "SceneNode") -> None:
        if self._root != node:
            if not self._ignore_scene_changes:
                self._disconnectSignalsRoot()
            self._root = node
            if not self._ignore_scene_changes:
                self._connectSignalsRoot()
            self.rootChanged.emit()

    rootChanged = Signal()

    ##  Get the camera that should be used for rendering.
    def getActiveCamera(self) -> Optional[Camera]:
        return self._active_camera

    def getAllCameras(self) -> List[Camera]:
        cameras = []
        for node in BreadthFirstIterator(self._root):
            if isinstance(node, Camera):
                cameras.append(node)
        return cameras

    ##  Set the camera that should be used for rendering.
    #   \param name The name of the camera to use.
    def setActiveCamera(self, name: str) -> None:
        camera = self.findCamera(name)
        if camera and camera != self._active_camera:
            if self._active_camera:
                self._active_camera.perspectiveChanged.disconnect(self.sceneChanged)
            self._active_camera = camera
            self._active_camera.perspectiveChanged.connect(self.sceneChanged)
        else:
            Logger.log("w", "Couldn't find camera with name [%s] to activate!" % name)

    ##  Signal that is emitted whenever something in the scene changes.
    #   \param object The object that triggered the change.
    sceneChanged = Signal()

    ##  Find an object by id.
    #
    #   \param object_id The id of the object to search for, as returned by the python id() method.
    #
    #   \return The object if found, or None if not.
    def findObject(self, object_id: int) -> Optional["SceneNode"]:
        for node in BreadthFirstIterator(self._root):
            if id(node) == object_id:
                return node
        return None

    def findCamera(self, name: str) -> Optional[Camera]:
        for node in BreadthFirstIterator(self._root):
            if isinstance(node, Camera) and node.getName() == name:
                return node
        return None

    ##  Add a file to be watched for changes.
    #   \param file_path The path to the file that must be watched.
    def addWatchedFile(self, file_path: str) -> None:
        # The QT 5.10.0 issue, only on Windows. Cura crashes after loading a stl file from USB/sd-card/Cloud-based drive
        if not Platform.isWindows():
            self._file_watcher.addPath(file_path)

    ##  Remove a file so that it will no longer be watched for changes.
    #   \param file_path The path to the file that must no longer be watched.
    def removeWatchedFile(self, file_path: str) -> None:
        # The QT 5.10.0 issue, only on Windows. Cura crashes after loading a stl file from USB/sd-card/Cloud-based drive
        if not Platform.isWindows():
            self._file_watcher.removePath(file_path)

    ##  Triggered whenever a file is changed that we currently have loaded.
    def _onFileChanged(self, file_path: str) -> None:
        if not os.path.isfile(file_path) or os.path.getsize(file_path) == 0:  # File doesn't exist any more, or it is empty
            return

        # Multiple nodes may be loaded from the same file at different stages. Reload them all.
        from UM.Scene.Iterator.DepthFirstIterator import DepthFirstIterator  # To find which nodes to reload when files have changed.
        modified_nodes = [node for node in DepthFirstIterator(self.getRoot()) if node.getMeshData() and node.getMeshData().getFileName() == file_path]  # type: ignore

        if modified_nodes:
            # Hide the message if it was already visible
            if self._reload_message is not None:
                self._reload_message.hide()

            self._reload_message = Message(i18n_catalog.i18nc("@info", "Would you like to reload {filename}?").format(filename = os.path.basename(file_path)),
                              title = i18n_catalog.i18nc("@info:title", "File has been modified"))
            self._reload_message.addAction("reload", i18n_catalog.i18nc("@action:button", "Reload"), icon = "", description = i18n_catalog.i18nc("@action:description", "This will trigger the modified files to reload from disk."))
            self._reload_callback = functools.partial(self._reloadNodes, modified_nodes)
            self._reload_message.actionTriggered.connect(self._reload_callback)
            self._reload_message.show()

    ##  Reloads a list of nodes after the user pressed the "Reload" button.
    #   \param nodes The list of nodes that needs to be reloaded.
    #   \param message The message that triggered the action to reload them.
    #   \param action The button that triggered the action to reload them.
    def _reloadNodes(self, nodes: List["SceneNode"], message: str, action: str) -> None:
        if action != "reload":
            return
        if self._reload_message is not None:
            self._reload_message.hide()
        for node in nodes:
            meshdata = node.getMeshData()
            if meshdata:
                filename = meshdata.getFileName()
                if not filename or not os.path.isfile(filename):  # File doesn't exist any more.
                    continue
                job = ReadMeshJob(filename)
                reload_finished_callback = functools.partial(self._reloadJobFinished, node)
                self._callbacks.add(reload_finished_callback) #Store it so it won't get garbage collected. This is a memory leak, but just one partial per reload so it's not much.
                job.finished.connect(reload_finished_callback)
                job.start()

    ##  Triggered when reloading has finished.
    #
    #   This then puts the resulting mesh data in the node.
    def _reloadJobFinished(self, replaced_node: SceneNode, job: ReadMeshJob) -> None:
        for node in job.getResult():
            mesh_data = node.getMeshData()
            if mesh_data:
                replaced_node.setMeshData(mesh_data)
            else:
                Logger.log("w", "Could not find a mesh in reloaded node.")