# Copyright 2025-2026 Arm Limited and/or its affiliates.
#
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree.

from typing import Any, List

import tosa_serializer as ts

from executorch.backends.arm.operators.node_visitor import (
    NodeVisitor,
    register_node_visitor,
)

from executorch.backends.arm.operators.operator_validation_utils import (
    validate_num_inputs,
    validate_same_dtype,
    validate_valid_dtype,
)
from executorch.backends.arm.tosa.mapping import TosaArg
from torch.fx import Node


@register_node_visitor
class WhereVisitor(NodeVisitor):
    target = "aten.where.self"

    def __init__(self, *args):
        super().__init__(*args)

    def define_node(
        self,
        node: Node,
        tosa_graph: Any,
        inputs: List[TosaArg],
        output: TosaArg,
    ) -> None:

        supported_dtypes = [ts.DType.BOOL]
        if self.tosa_spec.support_integer():
            supported_dtypes += [
                ts.DType.INT8,
                ts.DType.INT16,
                ts.DType.INT32,
            ]
        if self.tosa_spec.support_float():
            supported_dtypes += [ts.DType.FP16, ts.DType.FP32, ts.DType.BF16]

        validate_num_inputs(self.target, inputs, 3)
        # Not first input, which is condition tensor.
        validate_same_dtype(self.target, inputs[1:], ts)
        validate_valid_dtype(self.target, inputs[0], ts.DType.BOOL, self.tosa_spec)
        validate_valid_dtype(
            self.target,
            [*inputs[1:], output],
            supported_dtypes,
            self.tosa_spec,
        )

        attr = ts.TosaSerializerAttribute()
        attr.SelectAttribute()
        self._serialize_operator(
            node,
            tosa_graph,
            ts.Op.SELECT,
            [inputs[0].name, inputs[1].name, inputs[2].name],
            [output.name],
            attr,
        )