// Copyright 2010-2022 Google LLC
// Licensed 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.

namespace Google.OrTools
{

using System;
using System.Collections.Generic;

public static class NestedArrayHelper
{
    public static T[] GetFlatArray<T>(T[][] arr)
    {
        int flatLength = 0;
        for (var i = 0; i < arr.GetLength(0); i++)
            flatLength += arr[i].GetLength(0);

        int idx = 0;
        T[] flat = new T[flatLength];

        for (int i = 0; i < arr.GetLength(0); i++)
        {
            for (int j = 0; j < arr[i].GetLength(0); j++)
                flat[idx++] = arr[i][j];
        }

        return flat;
    }

    public static T[] GetFlatArrayFromMatrix<T>(T[,] arr)
    {
        int flatLength = arr.GetLength(0) * arr.GetLength(1);

        int idx = 0;
        T[] flat = new T[flatLength];

        for (int i = 0; i < arr.GetLength(0); i++)
        {
            for (int j = 0; j < arr.GetLength(1); j++)
                flat[idx++] = arr[i, j];
        }

        return flat;
    }

    public static int[] GetArraySecondSize<T>(T[][] arr)
    {
        var result = new int[arr.GetLength(0)];
        for (var i = 0; i < arr.GetLength(0); i++)
        {
            if (arr[i] is not null)
                result[i] = arr[i].Length;
        }
        return result;
    }
}
} // namespace Google.OrTools