// This file is part of YamlDotNet - A .NET library for YAML.
// Copyright (c) Antoine Aubry and contributors
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
// of the Software, and to permit persons to whom the Software is furnished to do
// so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

using System;

namespace YamlDotNet.Core
{
    internal sealed class StringLookAheadBuffer : ILookAheadBuffer
    {
        private readonly string value;

        public int Position { get; private set; }

        public StringLookAheadBuffer(string value)
        {
            this.value = value;
        }

        public int Length => value.Length;

        public bool EndOfInput => IsOutside(Position);

        public char Peek(int offset)
        {
            var index = Position + offset;
            return IsOutside(index) ? '\0' : value[index];
        }

        private bool IsOutside(int index)
        {
            return index >= value.Length;
        }

        public void Skip(int length)
        {
            if (length < 0)
            {
                throw new ArgumentOutOfRangeException(nameof(length), "The length must be positive.");
            }
            Position += length;
        }
    }
}
