core.py

# <pep8 compliant>
# -----------------------------------------------------------------------------
# MODULES IMPORT
# -----------------------------------------------------------------------------

# Set up logging of messages using Python logging
# Logging is nicely explained in:
# https://code.blender.org/2016/05/logging-from-python-code-in-blender/
# To see debug messages, configure logging in file
# $HOME/.config/blender/{version}/scripts/startup/setup_logging.py
# add there something like:
# import logging
# logging.basicConfig(format='%(funcName)s: %(message)s', level=logging.DEBUG)
import logging

l = logging.getLogger(__name__)

import bpy
from bpy.types import NodeTree, Node, NodeSocket
from nodeitems_utils import NodeCategory, NodeItem
import os
import vtk
import functools  # for decorators

from . import b_properties  # Boolean properties

b_path = b_properties.__file__  # Boolean properties config file path
from .cache import BVTKCache

ENUM_ICON = "DOT"  # Default icon for enumeration lists
debug_mode = False  # Set true to see more information in nodes

# -----------------------------------------------------------------------------
# BVTK_NodeTree
# -----------------------------------------------------------------------------


class BVTK_NodeTree(NodeTree):
    """BVTK Node Tree"""

    bl_idname = "BVTK_NodeTreeType"
    bl_label = "BVTK Node Tree"
    bl_icon = "COLOR_BLUE"


# -----------------------------------------------------------------------------
# Custom socket type
# -----------------------------------------------------------------------------


class BVTK_NodeSocket(NodeSocket):
    """BVTK Node Socket"""

    bl_idname = "BVTK_NodeSocketType"
    bl_label = "BVTK Node Socket"

    def draw(self, context, layout, node, txt):
        layout.label(text=txt)

    def draw_color(self, context, node):
        return (1.0, 0.4, 0.216, 0.5)


# -----------------------------------------------------------------------------
# Custom Code decorators
# -----------------------------------------------------------------------------


def show_custom_code(func):
    """Decorator to show custom code in nodes. Used in draw_buttons()."""

    @functools.wraps(func)
    def show_custom_code_wrapper(self, context, layout):
        # Call function first
        value = func(self, context, layout)
        # Then show Custom Code
        row = layout.row()
        if self.expanded:
            row.label(text="Custom Code:")
        elif len(self.custom_code) > 0:
            pseudo_code = self.custom_code[: self.custom_code.find("(")]
            row.label(text="Custom Code: " + pseudo_code + "...")
        else:
            row.label(text="Custom Code: None")
        # Expand button
        # TODO: Make proper expandable menu with triangle icon and text
        row.prop(
            self,
            "expanded",
            icon="HIDE_OFF" if self.expanded else "HIDE_ON",
            icon_only=True,
            emboss=False,
            expand=True,
        )

        if self.expanded:
            col = layout.column(align=True)
            row = col.row()
            # Only show edit and save buttons in node if cache is up-to-date,
            # otherwise get_tree() fails for the operator.
            if self.get_vtk_obj():
                op = row.operator(
                    "node.bvtk_custom_code_edit", text="Edit", icon="TEXT"
                )
                op.node_id = self.node_id  # Set node id in operator
                op = row.operator(
                    "node.bvtk_custom_code_save", text="Save", icon="FILE_TICK"
                )
                op.node_id = self.node_id  # Set node id in operator
            if len(self.custom_code) > 0:
                box = layout.box()
                col = box.column()
                for text in self.custom_code.splitlines():
                    row = col.row()
                    row.label(text=text)
        return value

    return show_custom_code_wrapper


def run_custom_code(func):
    """Decorator to run custom code. Used in apply_properties()."""

    @functools.wraps(func)
    def run_custom_code_wrapper(self):
        # Run optional validation routine, which can update values in
        # node before running the actual function.
        if hasattr(self, "validate_and_update_values_special"):
            value = self.validate_and_update_values_special()
            if value:
                self.ui_message = value
                return "error"

        # Call the actual function
        value = func(self)

        # Then run Custom Code
        vtk_obj = self.get_vtk_obj()
        if vtk_obj and len(self.custom_code) > 0:
            for x in self.custom_code.splitlines():
                if x.startswith("#"):
                    continue
                cmd = "vtk_obj." + x
                l.debug("%s run %r" % (self.name, cmd))
                # TODO: Error handling
                exec(cmd, globals(), locals())

        # Call custom apply function if such is specified (special
        # node). Otherwise call Update(), but only if setting of
        # properties was succesful.
        if hasattr(self, "apply_properties_special"):
            value = self.apply_properties_special()
        else:
            if hasattr(vtk_obj, "Update") and value == "up-to-date":
                try:
                    vtk_obj.Update()
                except:
                    self.ui_message = "Failed to run Update() for VTK object"
                    value = "error"
        return value

    return run_custom_code_wrapper


# -----------------------------------------------------------------------------
# base class for all BVTK_Nodes
#
# General implementation for VTK nodes below. Special nodes may
# need to provide own versions of following methods:
# - m_properties() - names of node properties
# - m_connections() - names of node connections
# - init_special() - special function to run when node is created
# - draw_buttons_special() - special node UI contents
# - init_vtk() - creation and initialization of VTK object
# - apply_inputs() - update input connections to VTK object
# - validate_and_update_values_special() - optional node value
#       validation and update routine
# - apply_properties_special() - special function to run for setting
#       properties and update VTK object for special nodes
# - get_vtk_output_object_special() - special function to provide
#       VTK output object for special nodes
# -----------------------------------------------------------------------------


class BVTK_Node:
    """Base class for VTK nodes and special nodes"""

    node_id: bpy.props.IntProperty(
        name="Node ID Number",
        description="Node ID Number for mapping VTK objects in BVTKCache",
        default=0,
    )
    connected_input_names: bpy.props.StringProperty(
        name="Names of Connected Input Nodes",
        description="Names of connected input nodes, used for triggering status change in update()",
        default="",
    )
    ui_message: bpy.props.StringProperty(
        name="Result Message",
        description="Latest Result Message from Node Update, Information for User",
        default="",
    )
    vtk_status: bpy.props.EnumProperty(
        name="VTK Status",
        description="Status of BVTK node",
        items={
            # No status information. This should never be a state for
            # nodes that are initialized and work correctly.
            ("none", "none", "none", 0),
            # VTK object exists but no values / commands for it has been run yet.
            # This is state reserved for a possible future where running only
            # initialization without updating is required.
            ("initialized", "initialized", "initialized", 1),
            # Setting a value/running a command has failed, execution has been stopped
            ("error", "error", "error", 2),
            # A change has been made to an upstream node, may need to update
            ("upstream-changed", "upstream-changed", "upstream-changed", 3),
            # A change has been made to this node, may need to run update
            ("out-of-date", "out-of-date", "out-of-date", 4),
            # Input node(s) are running an update.
            # Reserved for modal operators that visualize node tree updates.
            ("waiting-for-upstream", "waiting-for-upstream", "waiting-for-upstream", 5),
            # Setting values / running commands for this node
            ("updating", "updating", "updating", 6),
            # Successfully finished running update commands for this node
            ("up-to-date", "up-to-date", "up-to-date", 7),
        },
        default="none",
    )
    custom_code: bpy.props.StringProperty(
        name="Custom Code",
        description="Custom Python Code to Run for This Node's VTK Object",
        default="",
        maxlen=0,
    )
    expanded: bpy.props.BoolProperty(
        name="Show Code",
        description="Boolean to Show/Hide Custom Code Panel",
        default=False,
    )

    @classmethod
    def poll(cls, ntree):
        return ntree.bl_idname == "BVTK_NodeTreeType"

    def m_properties(self):
        """Return list of node specific property names.
        Implement this for each node class.
        """
        return []

    def m_connections(self):
        """Return lists of node specific connection names:
        input socket names, output socket names, extra inputs, and extra outputs.
        Implement this for each node class.
        """
        return ([], [], [], [])

    def get_input_socket_names(self):
        """Return input socket names from m_connections.
        """
        m_connections = self.m_connections()
        return m_connections[0]

    def get_output_socket_names(self):
        """Return output socket names from m_connections.
        """
        m_connections = self.m_connections()
        return m_connections[1]

    def init(self, context):
        """Create and initialize a new BVTK node.
        """
        # Node properties
        self.width = 200
        self.use_custom_color = True
        self.color = 0.5, 0.5, 0.5

        # Create sockets to node
        inputs, outputs, extra_inputs, extra_outputs = self.m_connections()
        inputs.extend(extra_inputs)
        outputs.extend(extra_outputs)
        for x in inputs:
            self.inputs.new("BVTK_NodeSocketType", x)
        for x in outputs:
            self.outputs.new("BVTK_NodeSocketType", x)

        if hasattr(self, "init_special"):
            self.init_special(context)

    def set_vtk_status(self, new_status="none"):
        """Set node's VTK status to new status value and change node color.
        Note: Does not trigger any updates.
        """

        def status_to_color(vtk_status="none"):
            """Return color for argument VTK status"""
            colors = {
                "none": (0.3, 0.3, 0.3),
                "initialized": (0.7, 0.7, 0.7),
                "error": (0.8, 0.2, 0.2),
                "upstream-changed": (0.8, 0.6, 0.2),
                "out-of-date": (0.6, 0.8, 0.2),
                "waiting-for-upstream": (0.2, 0.8, 0.8),
                "updating": (0.2, 0.2, 0.8),
                "up-to-date": (0.5, 0.5, 0.5),
            }
            return colors[vtk_status]

        self.vtk_status = new_status
        self.color = status_to_color(new_status)

    def init_vtk(self):
        """Initialize and return a VTK object for the node.
        This is a general implementation for VTK nodes.
        Special nodes need to implement their own initialization.
        If special node has no VTK objects, it's OK to return None.
        """
        vtk_class = getattr(vtk, self.bl_label, None)
        if vtk_class is None:
            raise Exception("Bad VTK class name " + self.bl_label)
        vtk_obj = vtk_class()
        if not vtk_obj:
            raise Exception("Could not create " + self.bl_label)
        self.set_vtk_status("initialized")
        l.debug("Init VTK done for node: %s, id #%d" % (self.name, self.node_id))
        return vtk_obj

    def free(self):
        """Clean up node information upon node removal.
        """
        BVTKCache.unmap_node(self)

    @show_custom_code
    def draw_buttons(self, context, layout):
        """Show properties in the node. General implementation for both VTK
        and special nodes. Special nodes may provide draw_buttons_special()
        to show custom content in node.
        """

        # Show node ID number and status in debug mode
        global debug_mode
        if debug_mode:
            row = layout.row()
            row.label(text="node_id #%d: %r" % (self.node_id, str(self.vtk_status)))

        # Show message if any
        if len(self.ui_message) > 0:
            box = layout.box()
            for line in self.ui_message.split("\n"):
                row = box.row()
                row.label(text=line)

        # Main content
        if hasattr(self, "draw_buttons_special"):
            self.draw_buttons_special(context, layout)
        else:
            # Get properties and show visible ones
            m_properties = self.m_properties()
            for i in range(len(m_properties)):
                if not hasattr(self, "b_properties") or self.b_properties[i]:
                    layout.prop(self, m_properties[i])

            # Write button for writer nodes
            if self.bl_idname.endswith("WriterType"):
                layout.operator("node.bvtk_node_write").node_path = node_path(self)

        # Update button is shown when there is something to update
        if self.vtk_status != "up-to-date":
            row = layout.row()
            row.operator("node.bvtk_node_update").node_path = node_path(self)

    @run_custom_code
    def apply_properties(self):
        """Set properties from node to VTK object, and update the VTK object.
        Return appropriate vtk_status according to success of update.
        General implementation for both VTK and special nodes.
        """

        # Do nothing if inputs are not connected
        namelist = [
            link.to_socket.name for socket in self.inputs for link in socket.links
        ]
        missing_inputs = ""
        for input in self.get_input_socket_names():
            # Only require connections named "input" are connected
            if not input.startswith("input"):
                continue
            if input not in namelist:
                missing_inputs += input + " "
        if len(missing_inputs) > 0:
            self.ui_message = "Missing input connection(s): " + missing_inputs
            return "error"

        # Stop here if there is a custom apply routine, meaning this is a special node
        if hasattr(self, "apply_properties_special"):
            return "up-to-date"

        # Require an object exists in cache
        vtk_obj = self.get_vtk_obj()
        if not vtk_obj:
            self.ui_message = "Internal Error: No VTK object found in cache"
            return "error"

        m_properties = self.m_properties()
        for x in [
            m_properties[i] for i in range(len(m_properties)) if self.b_properties[i]
        ]:
            # Skip setting any empty values
            inputval = getattr(self, x)
            if len(str(inputval)) == 0:
                continue
            # SetXFileName(Y) only if attribute is a string
            if "FileName" in x and isinstance(inputval, str):
                value = os.path.realpath(bpy.path.abspath(inputval))
                cmd = "vtk_obj.Set" + x[2:] + "(value)"
            # SetXToY()
            elif x.startswith("e_"):
                cmd = "vtk_obj.Set" + x[2:] + "To" + inputval + "()"
            # SetX(self.Y)
            else:
                cmd = "vtk_obj.Set" + x[2:] + "(self." + x + ")"

            # Run the command and stop if error occurs
            try:
                exec(cmd, globals(), locals())
            except:
                # TODO: How to get error message and put it to ui_message?
                self.ui_message = "Error when running: " + cmd
                return "error"

        # Everything was set successfully
        return "up-to-date"

    def get_vtk_obj(self):
        """Return the VTK object of this node from cache.
        """
        vtk_obj = BVTKCache.get_vtk_obj(self.node_id)
        return vtk_obj

    def vtk_obj_in_cache(self):
        """Return True if an object (or None) is in cache.
        True means that node has been initialized correctly.
        """
        return BVTKCache.vtk_obj_in_cache(self.node_id)

    def get_output_connection(self, socketname="output"):
        """Return VTK output connection object for argument output socket name
        of this node. Return None if no connection is provided.
        """

        # VTK Nodes are derived from vtkAlgorithm, which implements VTK connections
        vtk_obj = self.get_vtk_obj()
        if not isinstance(vtk_obj, vtk.vtkAlgorithm):
            return None
        if socketname == "output" or socketname == "output 0":
            return vtk_obj.GetOutputPort()
        elif socketname == "output 1":
            return vtk_obj.GetOutputPort(1)
        else:
            raise Exception(
                "Not implemented connection for #"
                + str(self.node_id)
                + ": "
                + socketname
            )

    def get_vtk_output_object(self, socketname="output"):
        """Return VTK output data object for argument output socket name of
        this node.
        """

        # Special nodes may provide custom function
        if hasattr(self, "get_vtk_output_object_special"):
            return self.get_vtk_output_object_special(socketname)

        # Normal VTK algorithm provides output data object via producer
        vtk_connection = self.get_output_connection(socketname)
        if hasattr(vtk_connection, "IsA") and vtk_connection.IsA("vtkAlgorithmOutput"):
            producer = vtk_connection.GetProducer()
            return producer.GetOutputDataObject(vtk_connection.GetIndex())

        # Final option is to return node's cached VTK object (may be None)
        return self.get_vtk_obj()

    def get_vtk_output_obj_and_connection(self, socketname="output"):
        """Return both the output VTK data object and VTK connection for the
        argument output socket name of this node.
        """
        vtk_output_obj = self.get_vtk_output_object(socketname)
        vtk_connection = self.get_output_connection(socketname)
        return vtk_output_obj, vtk_connection

    def apply_inputs(self):
        """Set/update node input connections to this node's VTK object.
        This is called from update_vtk() during update.
        General implementation for VTK nodes.
        """
        inputs, dummy1, extra_inputs, dummy2 = self.m_connections()
        vtk_obj = self.get_vtk_obj()
        if not vtk_obj:
            return None

        # Normal connections
        for i, socketname in enumerate(inputs):
            (
                input_node,
                vtk_output_obj,
                vtk_connection,
            ) = self.get_input_node_and_output_vtk_objects(socketname)
            # Remove unconnected connection
            if not input_node and hasattr(vtk_obj, "RemoveInputConnection"):
                vtk_obj.RemoveInputConnection(i, i)
                continue

            # Normal vtkAlgorithms use SetInputConnection
            if vtk_connection and vtk_connection.IsA("vtkAlgorithmOutput"):
                vtk_obj.SetInputConnection(i, vtk_connection)

            # Special nodes can provide a VTK data object as output
            elif hasattr(vtk_output_obj, "IsA") and vtk_output_obj.IsA("vtkDataObject"):
                vtk_obj.SetInputData(i, vtk_output_obj)

        # Extra connections (call method SetX(vtk_output_obj) for vtk_obj)
        # See e.g. vtkClipPolyData in the clip example tree.
        for socketname in extra_inputs:
            (
                input_node,
                vtk_output_obj,
                dummy,
            ) = self.get_input_node_and_output_vtk_objects(socketname)
            if not input_node:
                continue
            if not vtk_output_obj:
                raise Exception("Failed to get output from" + socketname)
            cmd = "vtk_obj.Set" + socketname + "(vtk_output_obj)"
            # TODO: Error handling
            exec(cmd, globals(), locals())

    def get_input_node_and_output_vtk_objects(self, input_socket_name="input"):
        """Return input node, VTK output object it produces, and the VTK
        output connection of the input node which is connected to this
        node's argument input socket name.
        """
        input_node, from_socket_name = self.get_input_node_and_socketname(
            input_socket_name
        )
        if not input_node:
            return None, None, None
        vtk_obj, vtk_connection = input_node.get_vtk_output_obj_and_connection(
            from_socket_name
        )
        return input_node, vtk_obj, vtk_connection

    def get_input_node_and_socketname(self, input_socket_name="input"):
        """Get one input node and it's output socket name using this nodes'
        input socket name.
        """
        (
            nodes,
            from_socket_names,
            to_socket_names,
        ) = self.get_input_nodes_and_socketnames()
        for node, from_socket_name, to_socket_name in zip(
            nodes, from_socket_names, to_socket_names
        ):
            if to_socket_name == input_socket_name:
                return node, from_socket_name
        return None, None

    def get_input_nodes(self):
        """Return list of all input nodes.
        """
        nodes, dummy1, dummy2 = self.get_input_nodes_and_socketnames()
        return nodes

    def get_input_nodes_and_socketnames(self):
        """Return list of all input nodes of this node, node socket names in
        this node, and node socket names in input node.
        """
        nodes = []
        from_socket_names = []
        to_socket_names = []
        # Get all input nodes
        for socket in self.inputs:
            for link in socket.links:
                nodes.append(link.from_node)
                from_socket_names.append(link.from_socket.name)
                to_socket_names.append(link.to_socket.name)
        return nodes, from_socket_names, to_socket_names

    def get_output_nodes(self):
        """Return list of all output nodes from this node.
        """
        output_nodes = []
        for socket in self.outputs:
            for link in socket.links:
                output_nodes.append(link.to_node)
        return output_nodes

    def copy(self, node):
        """Copy setup from another node to self.
        """
        self.node_id = 0  # Force node_id update in map_node()
        vtk_obj = self.init_vtk()
        if vtk_obj:
            BVTKCache.map_node(self, vtk_obj)  # Add VTK object to cache
        if hasattr(self, "copy_special"):
            # some nodes need to set properties (such as color ramp elements)
            # after being copied
            self.copy_special(node)
        l.debug("Copy done for node: %s, id #%d" % (self.name, self.node_id))

    def get_b(self):
        """Get list of booleans to show/hide boolean properties.
        """
        n_properties = len(self.b_properties)
        # If there are correct number of saved properties, return those
        if self.bl_idname in b_properties.b:
            saved_properties = b_properties.b[self.bl_idname]
            if len(saved_properties) == n_properties:
                return saved_properties
        # Otherwise return correct number of Trues (=show all properties by default)
        return [True] * n_properties

    def set_b(self, value):
        """Set boolean property list and update boolean properties file.
        """
        b_properties.b[self.bl_idname] = [v for v in value]
        bpy.ops.node.select_all(action="SELECT")
        bpy.ops.node.select_all(action="DESELECT")

        # Write sorted b_properties.b dictionary
        # Note: lambda function used to force sort on dictionary key
        txt = "b={"
        for key, value in sorted(b_properties.b.items(), key=lambda s: str.lower(s[0])):
            txt += " '" + key + "': " + str(value) + ",\n"
        txt += "}\n"
        open(b_path, "w").write(txt)

    def outdate_vtk_status(self, context):
        """Set node VTK status to out-of-date and notify downstream when a
        property value is changed in UI.
        """
        l.debug(self.name + ": Triggered outdate_vtk_status")
        update_mode = bpy.context.scene.bvtknodes_settings.update_mode
        if update_mode == "update-current":
            self.set_vtk_status("out-of-date")
            self.update_vtk()
        else:
            self.notify_downstream(vtk_status="out-of-date")
        if update_mode == "update-all":
            BVTKCache.update_all()

    def update(self):
        """Update routine triggered on node UI topology changes (adding or
        removing nodes and links).
        """
        # Change status for downstream nodes only
        update_mode = bpy.context.scene.bvtknodes_settings.update_mode
        namelist = [
            link.from_node.name for socket in self.inputs for link in socket.links
        ]
        names = str(namelist)
        if self.connected_input_names != names:
            if update_mode == "update-current":
                self.set_vtk_status("out-of-date")
                self.update_vtk()
            else:
                self.notify_downstream(vtk_status="out-of-date")
            if update_mode == "update-all":
                BVTKCache.update_all()

    def outdate_upstream(self):
        """Set all upstream nodes to out-of-date status (to force update on
        them when they are updated next time).
        """
        for node in self.get_input_nodes():
            node.outdate_upstream()
            node.set_vtk_status("out-of-date")

    def notify_downstream(self, vtk_status="out-of-date", origin_node=True):
        """Make status changes in downstream nodes, to advertise update made
        in this node.
        """
        # Recursively call for downstream nodes
        for node in self.get_output_nodes():
            node.notify_downstream(vtk_status="out-of-date", origin_node=False)
        # For downstream nodes, out-of-date supercedes upstream-changed
        if self.vtk_status != "out-of-date":
            self.set_vtk_status("upstream-changed")
        if origin_node:
            self.set_vtk_status(vtk_status)

    def update_vtk(self):
        """Recursively update upstream nodes and this node if not up-to-date.
        """
        # Recursively call for upstream nodes
        for node in self.get_input_nodes():
            if node.vtk_status != "up-to-date":
                node.update_vtk()

        # Do nothing if upstream was not successfully updated
        for node in self.get_input_nodes():
            if node.vtk_status != "up-to-date":
                self.ui_message = "Can't update, upstream update failed."
                return "out-of-date"

        # Remove old messages
        self.ui_message = ""

        # Allocate VTK object if it doesn't exist already
        if not self.vtk_obj_in_cache():
            vtk_obj = self.init_vtk()
            BVTKCache.map_node(self, vtk_obj)  # Add VTK object to cache
            l.debug("Init done for node: %s, id #%d" % (self.name, self.node_id))

        # Update this node's properties to VTK object only if needed
        if self.vtk_status != "up-to-date":
            self.set_vtk_status("updating")
            l.debug("Updating " + self.name)

            # Update VTK connections if node connections have changed
            namelist = [
                link.from_node.name for socket in self.inputs for link in socket.links
            ]
            names = str(namelist)
            if self.connected_input_names != names:
                self.connected_input_names = names
                self.apply_inputs()

            # Special nodes: Update VTK connections always, because
            # provided VTK data object might have changed.
            elif not str(self.__class__).startswith("vtk"):
                self.apply_inputs()

            # This is the only point where apply_properties() should be called
            new_status = self.apply_properties()

            if new_status not in (
                "none",
                "initialized",
                "error",
                "upstream-changed",
                "out-of-date",
                "waiting-for-upstream",
                "updating",
                "up-to-date",
            ):
                self.ui_message = "Internal error:\napply_properties() does not return a valid status string"
                new_status = "error"
            self.notify_downstream(vtk_status=new_status)


# -----------------------------------------------------------------------------
# Node Update Operators
# -----------------------------------------------------------------------------


class BVTK_OT_NodeUpdate(bpy.types.Operator):
    """Node Update Operator"""

    bl_idname = "node.bvtk_node_update"
    bl_label = "Update Node"

    node_path: bpy.props.StringProperty()

    def execute(self, context):
        node = eval(self.node_path)
        node.update_vtk()
        return {"FINISHED"}


class BVTK_OT_NodeForceUpdateUpstream(bpy.types.Operator):
    """Force All Upstream Nodes and This Node to be Updated"""

    bl_idname = "node.bvtk_node_force_update_upstream"
    bl_label = "Force Update Upstream"

    node_path: bpy.props.StringProperty()

    def execute(self, context):
        node = eval(self.node_path)
        node.outdate_upstream()
        node.update_vtk()
        return {"FINISHED"}


# -----------------------------------------------------------------------------
# VTK Writer Nodes' Write Operator
# -----------------------------------------------------------------------------
class BVTK_OT_NodeWrite(bpy.types.Operator):
    """Operator to call VTK Write() for a writer node"""

    bl_idname = "node.bvtk_node_write"
    bl_label = "Write Data"

    node_path: bpy.props.StringProperty()

    def execute(self, context):
        node = eval(self.node_path)
        if node:
            node.update_vtk()
            node.get_vtk_obj().Write()

        return {"FINISHED"}


# -----------------------------------------------------------------------------
# Registering
# -----------------------------------------------------------------------------

CLASSES = {}  # dictionary of classes is used to allow class overriding
UI_CLASSES = []


def add_class(obj):
    CLASSES[obj.bl_idname] = obj


def add_ui_class(obj):
    UI_CLASSES.append(obj)


def check_b_properties():
    """Sets all boolean properties to True, unless correct number of properties
    is specified in b_properties
    """
    for obj in CLASSES.values():
        if hasattr(obj, "m_properties") and hasattr(obj, "b_properties"):
            np = len(obj.m_properties(obj))
            name = obj.bl_idname
            b = b_properties.b
            if (not name in b) or (name in b and len(b[name]) != np):
                b[name] = [True for i in range(np)]


# Register classes
add_class(BVTK_NodeTree)
add_class(BVTK_NodeSocket)
add_ui_class(BVTK_OT_NodeUpdate)
add_ui_class(BVTK_OT_NodeForceUpdateUpstream)
add_ui_class(BVTK_OT_NodeWrite)

# -----------------------------------------------------------------------------
# VTK Node Category
# -----------------------------------------------------------------------------


class BVTK_NodeCategory(NodeCategory):
    @classmethod
    def poll(cls, context):
        return context.space_data.tree_type == "BVTK_NodeTreeType"


CATEGORIES = []


# -----------------------------------------------------------------------------
# Debug utilities
# -----------------------------------------------------------------------------


def ls(o):
    l.debug("\n".join(sorted(dir(o))))


def print_cls(obj):
    l.debug("------------------------------")
    l.debug("Class = " + obj.__class__.__name__)
    l.debug("------------------------------")
    for m in sorted(dir(obj)):
        if not m.startswith("__"):
            attr = getattr(obj, m)
            rep = str(attr)
            if len(rep) > 100:
                rep = rep[:100] + "  [...]"
            l.debug(m.ljust(30) + "=" + rep)


def print_nodes():
    l.debug("maxid = " + str(NodesMaxId))
    for nt in bpy.data.node_groups:
        if nt.bl_idname == "BVTK_NodeTreeType":
            l.debug("tree " + nt.name)
            for n in nt.nodes:
                if get_vtkobj(n) is None:
                    x = ""
                else:
                    x = "VTK object"
                l.debug("node " + str(n.node_id) + ": " + n.name.ljust(30, " ") + x)


# -----------------------------------------------------------------------------
# Useful help functions
# -----------------------------------------------------------------------------


def update_3d_view():
    """Force update of 3D View"""
    return  # No need for this in Blender 2.8? Remove function when certain.
    screen = bpy.context.screen
    if screen:
        for area in screen.areas:
            if area.type == "VIEW_3D":
                for space in area.spaces:
                    if space.type == "VIEW_3D":
                        # This updates viewport in Blender 2.79, not sure why
                        # space.viewport_shade = space.viewport_shade
                        continue


def node_path(node):
    """Return node path of a node"""
    return (
        "bpy.data.node_groups["
        + repr(node.id_data.name)
        + "].nodes["
        + repr(node.name)
        + "]"
    )


def node_prop_path(node, propname):
    """Return node property path"""
    return node_path(node) + "." + propname


def assert_bvtk(condition, message):
    if not condition:
        raise (AssertionError(message))


def first_elements(list_of_lists):
    """Return first elements in argument list of lists (like an enum list)
    """
    if not isinstance(list_of_lists, list):
        return None
    elem_list = [x[0] for x in list_of_lists]
    return elem_list


def string_to_floats(input_string: str):
    """Return a list of floats from a comma separated text string.
    """
    vals = input_string.split(",")
    floats = []
    for val in vals:
        try:
            floats.append(float(val))
        except:
            return None
    return floats


def get_all_bvtk_nodes():
    """Return list of BVTK Nodes from all node trees/groups"""
    bvtk_nodes = []
    for node_group in bpy.data.node_groups:
        if node_group.bl_idname != "BVTK_NodeTreeType":
            continue
        for node in node_group.nodes:
            bvtk_nodes.append(node)
    return bvtk_nodes