using System;
using System.Collections;

namespace ProtoBuf.Meta;

internal class BasicList : IEnumerable
{
	public struct NodeEnumerator : IEnumerator
	{
		private int position;

		private readonly Node node;

		public object Current => node[position];

		internal NodeEnumerator(Node node)
		{
			position = -1;
			this.node = node;
		}

		void IEnumerator.Reset()
		{
			position = -1;
		}

		public bool MoveNext()
		{
			int length = node.Length;
			if (position <= length)
			{
				return ++position < length;
			}
			return false;
		}
	}

	internal sealed class Node
	{
		private readonly object[] data;

		private int length;

		public object this[int index]
		{
			get
			{
				if (index >= 0 && index < length)
				{
					return data[index];
				}
				throw new ArgumentOutOfRangeException("index");
			}
			set
			{
				if (index >= 0 && index < length)
				{
					data[index] = value;
					return;
				}
				throw new ArgumentOutOfRangeException("index");
			}
		}

		public int Length => length;

		internal Node(object[] data, int length)
		{
			this.data = data;
			this.length = length;
		}

		public void RemoveLastWithMutate()
		{
			if (length == 0)
			{
				throw new InvalidOperationException();
			}
			length--;
		}

		public Node Append(object value)
		{
			int num = length + 1;
			object[] array;
			if (data == null)
			{
				array = new object[10];
			}
			else if (length == data.Length)
			{
				array = new object[data.Length * 2];
				Array.Copy(data, array, length);
			}
			else
			{
				array = data;
			}
			array[length] = value;
			return new Node(array, num);
		}

		public Node Trim()
		{
			if (length == 0 || length == data.Length)
			{
				return this;
			}
			object[] destinationArray = new object[length];
			Array.Copy(data, destinationArray, length);
			return new Node(destinationArray, length);
		}

		internal int IndexOfString(string value)
		{
			for (int i = 0; i < length; i++)
			{
				if (value == (string)data[i])
				{
					return i;
				}
			}
			return -1;
		}

		internal int IndexOfReference(object instance)
		{
			for (int i = 0; i < length; i++)
			{
				if (instance == data[i])
				{
					return i;
				}
			}
			return -1;
		}

		internal int IndexOf(MatchPredicate predicate, object ctx)
		{
			for (int i = 0; i < length; i++)
			{
				if (predicate(data[i], ctx))
				{
					return i;
				}
			}
			return -1;
		}

		internal void CopyTo(Array array, int offset)
		{
			if (length > 0)
			{
				Array.Copy(data, 0, array, offset, length);
			}
		}

		internal void Clear()
		{
			if (data != null)
			{
				Array.Clear(data, 0, data.Length);
			}
			length = 0;
		}
	}

	internal delegate bool MatchPredicate(object value, object ctx);

	internal sealed class Group
	{
		public readonly int First;

		public readonly BasicList Items;

		public Group(int first)
		{
			First = first;
			Items = new BasicList();
		}
	}

	private static readonly Node nil = new Node(null, 0);

	protected Node head = nil;

	public object this[int index] => head[index];

	public int Count => head.Length;

	public void CopyTo(Array array, int offset)
	{
		head.CopyTo(array, offset);
	}

	public int Add(object value)
	{
		return (head = head.Append(value)).Length - 1;
	}

	public void Trim()
	{
		head = head.Trim();
	}

	IEnumerator IEnumerable.GetEnumerator()
	{
		return new NodeEnumerator(head);
	}

	public NodeEnumerator GetEnumerator()
	{
		return new NodeEnumerator(head);
	}

	internal int IndexOf(MatchPredicate predicate, object ctx)
	{
		return head.IndexOf(predicate, ctx);
	}

	internal int IndexOfString(string value)
	{
		return head.IndexOfString(value);
	}

	internal int IndexOfReference(object instance)
	{
		return head.IndexOfReference(instance);
	}

	internal bool Contains(object value)
	{
		NodeEnumerator enumerator = GetEnumerator();
		while (enumerator.MoveNext())
		{
			object current = enumerator.Current;
			if (object.Equals(current, value))
			{
				return true;
			}
		}
		return false;
	}

	internal static BasicList GetContiguousGroups(int[] keys, object[] values)
	{
		if (keys == null)
		{
			throw new ArgumentNullException("keys");
		}
		if (values == null)
		{
			throw new ArgumentNullException("values");
		}
		if (values.Length < keys.Length)
		{
			throw new ArgumentException("Not all keys are covered by values", "values");
		}
		BasicList basicList = new BasicList();
		Group obj = null;
		for (int i = 0; i < keys.Length; i++)
		{
			if (i == 0 || keys[i] != keys[i - 1])
			{
				obj = null;
			}
			if (obj == null)
			{
				obj = new Group(keys[i]);
				basicList.Add(obj);
			}
			obj.Items.Add(values[i]);
		}
		return basicList;
	}
}