//
// Author:
//   Jb Evain (jbevain@gmail.com)
//
// Copyright (c) 2008 - 2015 Jb Evain
// Copyright (c) 2008 - 2011 Novell, Inc.
//
// Licensed under the MIT/X11 license.
//

using System.Collections.Generic;
using System.Text;

namespace MonoFN.Cecil.Metadata
{
    internal class StringHeap : Heap
    {
        private readonly Dictionary<uint, string> strings = new();
        public StringHeap(byte[] data) : base(data) { }

        public string Read(uint index)
        {
            if (index == 0)
                return string.Empty;

            string @string;
            if (strings.TryGetValue(index, out @string))
                return @string;

            if (index > data.Length - 1)
                return string.Empty;

            @string = ReadStringAt(index);
            if (@string.Length != 0)
                strings.Add(index, @string);

            return @string;
        }

        protected virtual string ReadStringAt(uint index)
        {
            int length = 0;
            int start = (int)index;

            for (int i = start;; i++)
            {
                if (data[i] == 0)
                    break;

                length++;
            }

            return Encoding.UTF8.GetString(data, start, length);
        }
    }
}