//----------------------------------------------
//            NGUI: Next-Gen UI kit
// Copyright © 2011-2014 Tasharen Entertainment
//----------------------------------------------

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

/// <summary>
/// MemoryStream.ReadLine has an interesting oddity: it doesn't always advance the stream's position by the correct amount:
/// http://social.msdn.microsoft.com/Forums/en-AU/Vsexpressvcs/thread/b8f7837b-e396-494e-88e1-30547fcf385f
/// Solution? Custom line reader with the added benefit of not having to use streams at all.
/// </summary>

public class ByteReader
{
	byte[] mBuffer;
	int mOffset = 0;

	public ByteReader (byte[] bytes) { mBuffer = bytes; }
	public ByteReader (TextAsset asset) { mBuffer = asset.bytes; }

	/// <summary>
	/// Whether the buffer is readable.
	/// </summary>

	public bool canRead { get { return (mBuffer != null && mOffset < mBuffer.Length); } }

	/// <summary>
	/// Read a single line from the buffer.
	/// </summary>

	static string ReadLine (byte[] buffer, int start, int count)
	{
#if UNITY_FLASH
		// Encoding.UTF8 is not supported in Flash :(
		StringBuilder sb = new StringBuilder();

		int max = start + count;

		for (int i = start; i < max; ++i)
		{
			byte byte0 = buffer[i];

			if ((byte0 & 128) == 0)
			{
				// If an UCS fits 7 bits, its coded as 0xxxxxxx. This makes ASCII character represented by themselves
				sb.Append((char)byte0);
			}
			else if ((byte0 & 224) == 192)
			{
				// If an UCS fits 11 bits, it is coded as 110xxxxx 10xxxxxx
				if (++i == count) break;
				byte byte1 = buffer[i];
				int ch = (byte0 & 31) << 6;
				ch |= (byte1 & 63);
				sb.Append((char)ch);
			}
			else if ((byte0 & 240) == 224)
			{
				// If an UCS fits 16 bits, it is coded as 1110xxxx 10xxxxxx 10xxxxxx
				if (++i == count) break;
				byte byte1 = buffer[i];
				if (++i == count) break;
				byte byte2 = buffer[i];

				if (byte0 == 0xEF && byte1 == 0xBB && byte2 == 0xBF)
				{
					// Byte Order Mark -- generally the first 3 bytes in a Windows-saved UTF-8 file. Skip it.
				}
				else
				{
					int ch = (byte0 & 15) << 12;
					ch |= (byte1 & 63) << 6;
					ch |= (byte2 & 63);
					sb.Append((char)ch);
				}
			}
			else if ((byte0 & 248) == 240)
			{
				// If an UCS fits 21 bits, it is coded as 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx 
				if (++i == count) break;
				byte byte1 = buffer[i];
				if (++i == count) break;
				byte byte2 = buffer[i];
				if (++i == count) break;
				byte byte3 = buffer[i];

				int ch = (byte0 & 7) << 18;
				ch |= (byte1 & 63) << 12;
				ch |= (byte2 & 63) << 6;
				ch |= (byte3 & 63);
				sb.Append((char)ch);
			}
		}
		return sb.ToString();
#else
		return Encoding.UTF8.GetString(buffer, start, count);
#endif
	}

	/// <summary>
	/// Read a single line from the buffer.
	/// </summary>

	public string ReadLine ()
	{
		int max = mBuffer.Length;

		// Skip empty characters
		while (mOffset < max && mBuffer[mOffset] < 32) ++mOffset;

		int end = mOffset;

		if (end < max)
		{
			for (; ; )
			{
				if (end < max)
				{
					int ch = mBuffer[end++];
					if (ch != '\n' && ch != '\r') continue;
				}
				else ++end;

				string line = ReadLine(mBuffer, mOffset, end - mOffset - 1);
				mOffset = end;
				return line;
			}
		}
		mOffset = max;
		return null;
	}

	/// <summary>
	/// Assume that the entire file is a collection of key/value pairs.
	/// </summary>

	public Dictionary<string, string> ReadDictionary ()
	{
		Dictionary<string, string> dict = new Dictionary<string, string>();
		char[] separator = new char[] { '=' };

		while (canRead)
		{
			string line = ReadLine();
			if (line == null) break;
			if (line.StartsWith("//")) continue;

#if UNITY_FLASH
			string[] split = line.Split(separator, System.StringSplitOptions.RemoveEmptyEntries);
#else
			string[] split = line.Split(separator, 2, System.StringSplitOptions.RemoveEmptyEntries);
#endif

			if (split.Length == 2)
			{
				string key = split[0].Trim();
				string val = split[1].Trim().Replace("\\n", "\n");
				dict[key] = val;
			}
		}
		return dict;
	}
}
