// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License.  You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied.  See the License for the

// specific language governing permissions and limitations

// under the License.

use super::{Extend, _MutableArrayData};

use crate::ArrayData;

pub(super) fn build_extend_sparse(array: &ArrayData) -> Extend<'_> {

    let type_ids = array.buffer::<i8>(0);

    Box::new(

        move |mutable: &mut _MutableArrayData, index: usize, start: usize, len: usize| {

            // extends type_ids

            mutable

                .buffer1

                .extend_from_slice(&type_ids[start..start + len]);

            mutable

                .child_data

                .iter_mut()

                .for_each(|child| child.extend(index, start, start + len))

        },

    )

}

pub(super) fn build_extend_dense(array: &ArrayData) -> Extend<'_> {

    let type_ids = array.buffer::<i8>(0);

    let offsets = array.buffer::<i32>(1);

    let arrow_schema::DataType::Union(src_fields, _) = array.data_type() else {

        unreachable!();

    };

    Box::new(

        move |mutable: &mut _MutableArrayData, index: usize, start: usize, len: usize| {

            // extends type_ids

            mutable

                .buffer1

                .extend_from_slice(&type_ids[start..start + len]);

            (start..start + len).for_each(|i| {

                let type_id = type_ids[i];

                let child_index = src_fields

                    .iter()

                    .position(|(r, _)| r == type_id)

                    .expect("invalid union type ID");

                let src_offset = offsets[i] as usize;

                let child_data = &mut mutable.child_data[child_index];

                let dst_offset = child_data.len();

                // Extend offsets

                mutable.buffer2.push(dst_offset as i32);

                mutable.child_data[child_index].extend(index, src_offset, src_offset + 1)

            })

        },

    )

}

pub(super) fn extend_nulls_dense(_mutable: &mut _MutableArrayData, _len: usize) {

    panic!("cannot call extend_nulls on UnionArray as cannot infer type");

}

pub(super) fn extend_nulls_sparse(_mutable: &mut _MutableArrayData, _len: usize) {

    panic!("cannot call extend_nulls on UnionArray as cannot infer type");

}