// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using Microsoft.CodeAnalysis.PooledObjects;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.Shared.Extensions;
 
internal static class ListExtensions
{
    /// <summary>
    /// Update a list in place, where a function has the ability to either transform or remove each item.
    /// </summary>
    /// <typeparam name="T">The type of items in the list.</typeparam>
    /// <typeparam name="TArg">The type of state argument passed to the transformation callback.</typeparam>
    /// <param name="list">The list to update.</param>
    /// <param name="transform">A function which transforms each element. The function returns the transformed list
    /// element, or <see langword="null"/> to remove the current item from the list.</param>
    /// <param name="arg">The state argument to pass to the transformation callback.</param>
    public static void RemoveOrTransformAll<T, TArg>(this List<T> list, Func<T, TArg, T?> transform, TArg arg)
        where T : class
    {
        RoslynDebug.AssertNotNull(list);
        RoslynDebug.AssertNotNull(transform);
 
        var targetIndex = 0;
        for (var sourceIndex = 0; sourceIndex < list.Count; sourceIndex++)
        {
            var newValue = transform(list[sourceIndex], arg);
            if (newValue is null)
                continue;
 
            list[targetIndex++] = newValue;
        }
 
        list.RemoveRange(targetIndex, list.Count - targetIndex);
    }
 
    public static void RemoveOrTransformAll<T, TArg>(this List<T> list, Func<T, TArg, T?> transform, TArg arg)
        where T : struct
    {
        RoslynDebug.AssertNotNull(list);
        RoslynDebug.AssertNotNull(transform);
 
        var targetIndex = 0;
        for (var sourceIndex = 0; sourceIndex < list.Count; sourceIndex++)
        {
            var newValue = transform(list[sourceIndex], arg);
            if (newValue is null)
                continue;
 
            list[targetIndex++] = newValue.Value;
        }
 
        list.RemoveRange(targetIndex, list.Count - targetIndex);
    }
 
    public static void RemoveOrTransformAll<T, TArg>(this ArrayBuilder<T> list, Func<T, TArg, T?> transform, TArg arg)
        where T : struct
    {
        RoslynDebug.AssertNotNull(list);
        RoslynDebug.AssertNotNull(transform);
 
        var targetIndex = 0;
        for (var sourceIndex = 0; sourceIndex < list.Count; sourceIndex++)
        {
            var newValue = transform(list[sourceIndex], arg);
            if (newValue is null)
                continue;
 
            list[targetIndex++] = newValue.Value;
        }
 
        list.RemoveRange(targetIndex, list.Count - targetIndex);
    }
 
    /// <summary>
    /// Attempts to remove the first item selected by <paramref name="selector"/>.
    /// </summary>
    /// <returns>
    /// True if any item has been removed.
    /// </returns>
    public static bool TryRemoveFirst<T, TArg>(this IList<T> list, Func<T, TArg, bool> selector, TArg arg, [NotNullWhen(true)] out T? removedItem)
        where T : notnull
    {
        for (var i = 0; i < list.Count; i++)
        {
            var item = list[i];
            if (selector(item, arg))
            {
                list.RemoveAt(i);
                removedItem = item;
                return true;
            }
        }
 
        removedItem = default;
        return false;
    }
 
    public static int IndexOf<T>(this IList<T> list, Func<T, bool> predicate)
    {
        for (var i = 0; i < list.Count; i++)
        {
            if (predicate(list[i]))
                return i;
        }
 
        return -1;
    }
 
    public static int IndexOf<T, TArg>(this IList<T> list, Func<T, TArg, bool> predicate, TArg arg)
    {
        for (var i = 0; i < list.Count; i++)
        {
            if (predicate(list[i], arg))
                return i;
        }
 
        return -1;
    }
}