import bpy

from . import utils
from bpy_extras.view3d_utils import location_3d_to_region_2d

def is_stroke_in_view(stroke, matrix, region, region_3d):
    ## for optimization, use first and last
    region_width = region.width
    region_height = region.height
    point_list = [stroke.points[0], stroke.points[-1]]
    # point_list = stroke.points # whole points
    
    coord_list = [matrix @ point.position for point in point_list]

    for coord in coord_list:
        # Convert 3D coordinates to 2D screen coordinates
        screen_coord = location_3d_to_region_2d(region, region_3d, coord)
        if screen_coord is None:
            continue
        # Check if the point is within the viewport bounds
        if 0 <= screen_coord.x <= region_width and 0 <= screen_coord.y <= region_height:
            ## one point in view, in view
            return True
    
    return False


class GPT_OT_delete_strokes_view_bound(bpy.types.Operator):
    bl_idname = "gp.delete_strokes_view_bound"
    bl_label = "Delete Strokes View Bound "
    bl_description = "Delete all selected strokes in view only"
    bl_options = {'REGISTER', 'UNDO'}

    # def invoke(self, context, event):

    @classmethod
    def poll(cls, context):
        return context.mode == 'EDIT_GREASE_PENCIL'

    def execute(self, context):
        gp = context.grease_pencil
        if not gp:
            self.report({'ERROR'}, "No Grease Pencil object found")
            return {'CANCELLED'}
        
        ob = context.object
        if not ob or ob.type != 'GREASEPENCIL':
            self.report({'ERROR'}, "Active object is not a Grease Pencil object")
            return {'CANCELLED'}

        matrix_world = ob.matrix_world.copy()

        layers = [l for l in gp.layers if not l.hide and not l.lock]

        region = context.region
        region_3d = context.space_data.region_3d        

        ## TODO for frames, handle multiframe editing
        
        for layer in layers:
            for frame in layer.frames:
                drawing = frame.drawing
                stroke_indices_to_delete = [sidx for sidx, stroke in enumerate(drawing.strokes) if stroke.select and is_stroke_in_view(stroke, matrix_world, region, region_3d)]
                ## detailed method
                # stroke_indices_to_delete = []
                # for sid, stroke in enumerate(drawing.strokes):
                #     if not stroke.select:
                #         continue

                #     # Check if the stroke is within the view bounds
                #     if is_stroke_in_view(stroke, matrix_world, region, region_3d):
                #         stroke_indices_to_delete.append(sid)
                if stroke_indices_to_delete:
                    print(f'layer {layer.name} : delete {len(stroke_indices_to_delete)} strokes')
                    drawing.remove_strokes(indices=stroke_indices_to_delete)

        return {'FINISHED'}


class GPT_OT_delete_points_view_bound(bpy.types.Operator):
    bl_idname = "gp.delete_points_view_bound"
    bl_label = "Delete Points View Bound"
    bl_description = "Delete all selected points in view only"
    bl_options = {'REGISTER', 'UNDO'}

    # def invoke(self, context, event):

    @classmethod
    def poll(cls, context):
        return context.mode == 'EDIT_GREASE_PENCIL'

    def execute(self, context):
        gp = context.grease_pencil
        if not gp:
            self.report({'ERROR'}, "No Grease Pencil object found")
            return {'CANCELLED'}
        
        ob = context.object
        if not ob or ob.type != 'GREASEPENCIL':
            self.report({'ERROR'}, "Active object is not a Grease Pencil object")
            return {'CANCELLED'}

        matrix_world = ob.matrix_world.copy()

        layers = [l for l in gp.layers if not l.hide and not l.lock]

        region = context.region
        region_3d = context.space_data.region_3d        

        ## TODO for frames, handle multiframe editing

        avoid_ct = 0
        for layer in layers:
            for frame in layer.frames:
                drawing = frame.drawing

                stroke_indices_to_delete = []
                for sid, stroke in enumerate(drawing.strokes):
                    if not stroke.select:
                        continue
                    # Check if the stroke is within the view bounds
                    if not is_stroke_in_view(stroke, matrix_world, region, region_3d):
                        avoid_ct += 1
                        continue
                    ## remove points (only remove by an amount from the end . need to rebuild the stroke !)

                    select_count = len([p for p in stroke.points if p.select])
                    if select_count == len(stroke.points):
                        ## mark as full delete and go next
                        stroke_indices_to_delete.append(sid)
                        continue


                    ## Make a copy of deselected points attributes
                    point_attrs = []
                    for p in stroke.points:
                        if p.select:
                            continue
                        point_attrs.append([p.position.copy(), p.rotation, p.radius, p.opacity])

                    ## remove as many points as select_count
                    stroke.remove_points(select_count)
                    
                    ## re-assign attributes in order
                    for i, p in enumerate(stroke.points):
                        if i < len(point_attrs):
                            p.position = point_attrs[i][0]
                            p.rotation = point_attrs[i][1]
                            p.radius = point_attrs[i][2]
                            p.opacity = point_attrs[i][3]
                        p.select = False  # Deselect all points after processing

                if stroke_indices_to_delete:
                    # print(f'layer {layer.name} : delete {len(stroke_indices_to_delete)} strokes')
                    drawing.remove_strokes(indices=stroke_indices_to_delete)

        if avoid_ct:
            self.report({'INFO'}, f"Skipped {avoid_ct} strokes not in view")
        return {'FINISHED'}




classes = (
    GPT_OT_delete_strokes_view_bound,
    GPT_OT_delete_points_view_bound,
)

def register():
    if bpy.app.background:
        return

    for cl in classes:
        bpy.utils.register_class(cl)

    ## make scene property for empty key preservation and bake movement for layers...
    # register_keymaps()

def unregister():
    if bpy.app.background:
        return

    # unregister_keymaps()
    for cl in reversed(classes):
        bpy.utils.unregister_class(cl)