# Copyright (c) 2015 Ultimaker B.V.
# Cura is released under the terms of the AGPLv3 or higher.

from PyQt5.QtCore import QTimer

from UM.Scene.SceneNode import SceneNode
from UM.Scene.Iterator.BreadthFirstIterator import BreadthFirstIterator
from UM.Math.Vector import Vector
from UM.Math.AxisAlignedBox import AxisAlignedBox
from UM.Scene.Selection import Selection
from UM.Preferences import Preferences

from cura.ConvexHullDecorator import ConvexHullDecorator

from . import PlatformPhysicsOperation
from . import ZOffsetDecorator

import random  # used for list shuffling


class PlatformPhysics:
    def __init__(self, controller, volume):
        super().__init__()
        self._controller = controller
        self._controller.getScene().sceneChanged.connect(self._onSceneChanged)
        self._controller.toolOperationStarted.connect(self._onToolOperationStarted)
        self._controller.toolOperationStopped.connect(self._onToolOperationStopped)
        self._build_volume = volume
        self._enabled = True

        self._change_timer = QTimer()
        self._change_timer.setInterval(100)
        self._change_timer.setSingleShot(True)
        self._change_timer.timeout.connect(self._onChangeTimerFinished)
        self._move_factor = 1.1  # By how much should we multiply overlap to calculate a new spot?
        self._max_overlap_checks = 10  # How many times should we try to find a new spot per tick?

        Preferences.getInstance().addPreference("physics/automatic_push_free", True)
        Preferences.getInstance().addPreference("physics/automatic_drop_down", True)

    def _onSceneChanged(self, source):
        self._change_timer.start()

    def _onChangeTimerFinished(self):
        if not self._enabled:
            return

        root = self._controller.getScene().getRoot()

        # Keep a list of nodes that are moving. We use this so that we don't move two intersecting objects in the
        # same direction.
        transformed_nodes = []

        group_nodes = []
        # We try to shuffle all the nodes to prevent "locked" situations, where iteration B inverts iteration A.
        # By shuffling the order of the nodes, this might happen a few times, but at some point it will resolve.
        nodes = list(BreadthFirstIterator(root))
        random.shuffle(nodes)
        for node in nodes:
            if node is root or type(node) is not SceneNode or node.getBoundingBox() is None:
                continue

            bbox = node.getBoundingBox()

            # Ignore intersections with the bottom
            build_volume_bounding_box = self._build_volume.getBoundingBox()
            if build_volume_bounding_box:
                # It's over 9000!
                build_volume_bounding_box = build_volume_bounding_box.set(bottom=-9001)
            else:
                # No bounding box. This is triggered when running Cura from command line with a model for the first time
                # In that situation there is a model, but no machine (and therefore no build volume.
                return
            node._outside_buildarea = False

            # Mark the node as outside the build volume if the bounding box test fails.
            if build_volume_bounding_box.intersectsBox(bbox) != AxisAlignedBox.IntersectionResult.FullIntersection:
                node._outside_buildarea = True

            if node.callDecoration("isGroup"):
                group_nodes.append(node)  # Keep list of affected group_nodes

            # Move it downwards if bottom is above platform
            move_vector = Vector()
            if Preferences.getInstance().getValue("physics/automatic_drop_down") and not (node.getParent() and node.getParent().callDecoration("isGroup")) and node.isEnabled(): #If an object is grouped, don't move it down
                z_offset = node.callDecoration("getZOffset") if node.getDecorator(ZOffsetDecorator.ZOffsetDecorator) else 0
                move_vector = move_vector.set(y=-bbox.bottom + z_offset)

            # If there is no convex hull for the node, start calculating it and continue.
            if not node.getDecorator(ConvexHullDecorator):
                node.addDecorator(ConvexHullDecorator())

            if Preferences.getInstance().getValue("physics/automatic_push_free"):
                # Check for collisions between convex hulls
                for other_node in BreadthFirstIterator(root):
                    # Ignore root, ourselves and anything that is not a normal SceneNode.
                    if other_node is root or type(other_node) is not SceneNode or other_node is node:
                        continue
                    
                    # Ignore collisions of a group with it's own children
                    if other_node in node.getAllChildren() or node in other_node.getAllChildren():
                        continue
                    
                    # Ignore collisions within a group
                    if other_node.getParent() and node.getParent() and (other_node.getParent().callDecoration("isGroup") is not None or node.getParent().callDecoration("isGroup") is not None):
                        continue
                    
                    # Ignore nodes that do not have the right properties set.
                    if not other_node.callDecoration("getConvexHull") or not other_node.getBoundingBox():
                        continue

                    if other_node in transformed_nodes:
                        continue  # Other node is already moving, wait for next pass.

                    overlap = (0, 0)  # Start loop with no overlap
                    current_overlap_checks = 0
                    # Continue to check the overlap until we no longer find one.
                    while overlap and current_overlap_checks < self._max_overlap_checks:
                        current_overlap_checks += 1
                        head_hull = node.callDecoration("getConvexHullHead")
                        if head_hull:  # One at a time intersection.
                            overlap = head_hull.translate(move_vector.x, move_vector.z).intersectsPolygon(other_node.callDecoration("getConvexHull"))
                            if not overlap:
                                other_head_hull = other_node.callDecoration("getConvexHullHead")
                                if other_head_hull:
                                    overlap = node.callDecoration("getConvexHull").translate(move_vector.x, move_vector.z).intersectsPolygon(other_head_hull)
                                    if overlap:
                                        # Moving ensured that overlap was still there. Try anew!
                                        move_vector = move_vector.set(x=move_vector.x + overlap[0] * self._move_factor,
                                                                      z=move_vector.z + overlap[1] * self._move_factor)
                            else:
                                # Moving ensured that overlap was still there. Try anew!
                                move_vector = move_vector.set(x=move_vector.x + overlap[0] * self._move_factor,
                                                              z=move_vector.z + overlap[1] * self._move_factor)
                        else:
                            own_convex_hull = node.callDecoration("getConvexHull")
                            other_convex_hull = other_node.callDecoration("getConvexHull")
                            if own_convex_hull and other_convex_hull:
                                overlap = own_convex_hull.translate(move_vector.x, move_vector.z).intersectsPolygon(other_convex_hull)
                                if overlap:  # Moving ensured that overlap was still there. Try anew!
                                    move_vector = move_vector.set(x=move_vector.x + overlap[0] * self._move_factor,
                                                                  z=move_vector.z + overlap[1] * self._move_factor)
                            else:
                                # This can happen in some cases if the object is not yet done with being loaded.
                                #  Simply waiting for the next tick seems to resolve this correctly.
                                overlap = None

            convex_hull = node.callDecoration("getConvexHull")
            if convex_hull:
                if not convex_hull.isValid():
                    return
                # Check for collisions between disallowed areas and the object
                for area in self._build_volume.getDisallowedAreas():
                    overlap = convex_hull.intersectsPolygon(area)
                    if overlap is None:
                        continue
                    node._outside_buildarea = True

            if not Vector.Null.equals(move_vector, epsilon=1e-5):
                transformed_nodes.append(node)
                op = PlatformPhysicsOperation.PlatformPhysicsOperation(node, move_vector)
                op.push()

        # Group nodes should override the _outside_buildarea property of their children.
        for group_node in group_nodes:
            for child_node in group_node.getAllChildren():
                child_node._outside_buildarea = group_node._outside_buildarea


    def _onToolOperationStarted(self, tool):
        self._enabled = False

    def _onToolOperationStopped(self, tool):
        # Selection tool should not trigger an update.
        if tool.getPluginId() == "SelectionTool":
            return

        if tool.getPluginId() == "TranslateTool":
            for node in Selection.getAllSelectedObjects():
                if node.getBoundingBox().bottom < 0:
                    if not node.getDecorator(ZOffsetDecorator.ZOffsetDecorator):
                        node.addDecorator(ZOffsetDecorator.ZOffsetDecorator())

                    node.callDecoration("setZOffset", node.getBoundingBox().bottom)
                else:
                    if node.getDecorator(ZOffsetDecorator.ZOffsetDecorator):
                        node.removeDecorator(ZOffsetDecorator.ZOffsetDecorator)

        self._enabled = True
        self._onChangeTimerFinished()
