/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */
using System;
using System.Text;
using Antlr4.Runtime.Sharpen;

namespace Antlr4.Runtime.Atn
{


	#pragma warning disable 0659 // 'class' overrides Object.Equals(object o) but does not override Object.GetHashCode()
	public class ArrayPredictionContext : PredictionContext
	{
		/** Parent can be null only if full ctx mode and we make an array
		 *  from {@link #EMPTY} and non-empty. We merge {@link #EMPTY} by using null parent and
		 *  returnState == {@link #EMPTY_RETURN_STATE}.
		 */
		public readonly PredictionContext[] parents;

		/** Sorted for merge, no duplicates; if present,
		 *  {@link #EMPTY_RETURN_STATE} is always last.
		 */
		public readonly int[] returnStates;

		public ArrayPredictionContext(SingletonPredictionContext a)
			: this(new PredictionContext[] { a.parent }, new int[] { a.returnState })
		{
		}

		public ArrayPredictionContext(PredictionContext[] parents, int[] returnStates)
			: base(CalculateHashCode(parents, returnStates))
		{
			//		System.err.println("CREATE ARRAY: "+Arrays.toString(parents)+", "+Arrays.toString(returnStates));
			this.parents = parents;
			this.returnStates = returnStates;
		}

		public override bool IsEmpty
		{
			get
			{
				// since EMPTY_RETURN_STATE can only appear in the last position, we
				// don't need to verify that size==1
				return returnStates[0] == EMPTY_RETURN_STATE;
			}
		}

		public override int Size
		{
			get
			{
				return returnStates.Length;
			}
		}

		public override PredictionContext GetParent(int index)
		{
			return parents[index];
		}

		public override int GetReturnState(int index)
		{
			return returnStates[index];
		}

		//	@Override
		//	public int findReturnState(int returnState) {
		//		return Arrays.binarySearch(returnStates, returnState);
		//	}

		public override bool Equals(Object o)
		{
			if (this == o)
			{
				return true;
			}
			else if (!(o is ArrayPredictionContext))
			{
				return false;
			}

			if (this.GetHashCode() != o.GetHashCode())
			{
				return false; // can't be same if hash is different
			}

			ArrayPredictionContext a = (ArrayPredictionContext)o;
			return Arrays.Equals(returnStates, a.returnStates) &&
				   Arrays.Equals(parents, a.parents);
		}


		public override String ToString()
		{
			if (IsEmpty)
				return "[]";
			StringBuilder buf = new StringBuilder();
			buf.Append("[");
			for (int i = 0; i < returnStates.Length; i++)
			{
				if (i > 0) buf.Append(", ");
				if (returnStates[i] == EMPTY_RETURN_STATE)
				{
					buf.Append("$");
					continue;
				}
				buf.Append(returnStates[i]);
				if (parents[i] != null)
				{
					buf.Append(' ');
					buf.Append(parents[i].ToString());
				}
				else {
					buf.Append("null");
				}
			}
			buf.Append("]");
			return buf.ToString();
		}
	}

}