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#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software Foundation,
#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#
# ##### END GPL LICENSE BLOCK #####

# <pep8-80 compliant>

from bpy.types import (
    Operator,
)
from bpy.props import (
    IntProperty,
)


class CONSTRAINT_OT_add_target(Operator):
    """Add a target to the constraint"""
    bl_idname = "constraint.add_target"
    bl_label = "Add Target"
    bl_options = {'UNDO', 'INTERNAL'}

    def execute(self, context):
        context.constraint.targets.new()
        return {'FINISHED'}


class CONSTRAINT_OT_remove_target(Operator):
    """Remove the target from the constraint"""
    bl_idname = "constraint.remove_target"
    bl_label = "Remove Target"
    bl_options = {'UNDO', 'INTERNAL'}

    index: IntProperty()

    def execute(self, context):
        tgts = context.constraint.targets
        tgts.remove(tgts[self.index])
        return {'FINISHED'}


class CONSTRAINT_OT_normalize_target_weights(Operator):
    """Normalize weights of all target bones"""
    bl_idname = "constraint.normalize_target_weights"
    bl_label = "Normalize Weights"
    bl_options = {'UNDO', 'INTERNAL'}

    def execute(self, context):
        tgts = context.constraint.targets
        total = sum(t.weight for t in tgts)

        if total > 0:
            for t in tgts:
                t.weight = t.weight / total

        return {'FINISHED'}


class CONSTRAINT_OT_disable_keep_transform(Operator):
    """Set the influence of this constraint to zero while """ \
    """trying to maintain the object's transformation. Other active """ \
    """constraints can still influence the final transformation"""

    bl_idname = "constraint.disable_keep_transform"
    bl_label = "Disable and Keep Transform"
    bl_options = {'UNDO', 'INTERNAL'}

    @classmethod
    def poll(cls, context):
        constraint = getattr(context, "constraint", None)
        return constraint and constraint.influence > 0.0

    def execute(self, context):
        """Disable constraint while maintaining the visual transform."""

        # This works most of the time, but when there are multiple constraints active
        # there could still be one that overrides the visual transform.
        #
        # Note that executing this operator and then increasing the constraint
        # influence may move the object; this happens when the constraint is
        # additive rather than replacing the transform entirely.

        # Get the matrix in world space.
        is_bone_constraint = context.space_data.context == 'BONE_CONSTRAINT'
        ob = context.object
        if is_bone_constraint:
            bone = context.pose_bone
            mat = ob.matrix_world @ bone.matrix
        else:
            mat = ob.matrix_world

        context.constraint.influence = 0.0

        # Set the matrix.
        if is_bone_constraint:
            bone.matrix = ob.matrix_world.inverted() @ mat
        else:
            ob.matrix_world = mat

        return {'FINISHED'}


classes = (
    CONSTRAINT_OT_add_target,
    CONSTRAINT_OT_remove_target,
    CONSTRAINT_OT_normalize_target_weights,
    CONSTRAINT_OT_disable_keep_transform,
)