// 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 crate::ArrayData;

use arrow_buffer::{ArrowNativeType, MutableBuffer};

use num::traits::AsPrimitive;

use num::{CheckedAdd, Integer};

use super::{

    Extend, _MutableArrayData,

    utils::{extend_offsets, get_last_offset},

};

#[inline]

fn extend_offset_values<T: ArrowNativeType + AsPrimitive<usize>>(

    buffer: &mut MutableBuffer,

    offsets: &[T],

    values: &[u8],

    start: usize,

    len: usize,

) {

    let start_values = offsets[start].as_();

    let end_values: usize = offsets[start + len].as_();

    let new_values = &values[start_values..end_values];

    buffer.extend_from_slice(new_values);

}

pub(super) fn build_extend<T: ArrowNativeType + Integer + CheckedAdd + AsPrimitive<usize>>(

    array: &ArrayData,

) -> Extend<'_> {

    let offsets = array.buffer::<T>(0);

    let values = array.buffers()[1].as_slice();

    Box::new(

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

            let offset_buffer = &mut mutable.buffer1;

            let values_buffer = &mut mutable.buffer2;

            // this is safe due to how offset is built. See details on `get_last_offset`

            let last_offset = unsafe { get_last_offset(offset_buffer) };

            extend_offsets::<T>(offset_buffer, last_offset, &offsets[start..start + len + 1]);

            // values

            extend_offset_values::<T>(values_buffer, offsets, values, start, len);

        },

    )

}

pub(super) fn extend_nulls<T: ArrowNativeType>(mutable: &mut _MutableArrayData, len: usize) {

    let offset_buffer = &mut mutable.buffer1;

    // this is safe due to how offset is built. See details on `get_last_offset`

    let last_offset: T = unsafe { get_last_offset(offset_buffer) };

    (0..len).for_each(|_| offset_buffer.push(last_offset))

}