// 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::data::ArrayData;

use super::equal_range;

/// The current implementation of comparison of run array support physical comparison.

/// Comparing run encoded array based on logical indices (`lhs_start`, `rhs_start`) will

/// be time consuming as converting from logical index to physical index cannot be done

/// in constant time. The current comparison compares the underlying physical arrays.

pub(super) fn run_equal(

    lhs: &ArrayData,

    rhs: &ArrayData,

    lhs_start: usize,

    rhs_start: usize,

    len: usize,

) -> bool {

    if lhs_start != 0

        || rhs_start != 0

        || (lhs.len() != len && rhs.len() != len)

        || lhs.offset() > 0

        || rhs.offset() > 0

    {

        unimplemented!("Logical comparison for run array not supported.")

    }

    if lhs.len() != rhs.len() {

        return false;

    }

    let lhs_child_data = lhs.child_data();

    let lhs_run_ends_array = &lhs_child_data[0];

    let lhs_values_array = &lhs_child_data[1];

    let rhs_child_data = rhs.child_data();

    let rhs_run_ends_array = &rhs_child_data[0];

    let rhs_values_array = &rhs_child_data[1];

    if lhs_run_ends_array.len() != rhs_run_ends_array.len() {

        return false;

    }

    if lhs_values_array.len() != rhs_values_array.len() {

        return false;

    }

    // check run ends array are equal. The length of the physical array

    // is used to validate the child arrays.

    let run_ends_equal = equal_range(

        lhs_run_ends_array,

        rhs_run_ends_array,

        lhs_start,

        rhs_start,

        lhs_run_ends_array.len(),

    );

    // if run ends array are not the same return early without validating

    // values array.

    if !run_ends_equal {

        return false;

    }

    // check values array are equal

    equal_range(

        lhs_values_array,

        rhs_values_array,

        lhs_start,

        rhs_start,

        rhs_values_array.len(),

    )

}