/*
 * Copyright (c) Contributors, http://opensimulator.org/
 * See CONTRIBUTORS.TXT for a full list of copyright holders.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the OpenSimulator Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

// a class for low level LLSD encoding into a provided StringBuilder
// for cases where we already need to know the low level detail
// and so using something like OSD or even protbuf is just a pure waste

using System;
using System.Globalization;
using System.Text;
using OpenMetaverse;

namespace OpenSim.Framework
{
    public static class LLSDxmlEncode
    {
        static readonly  DateTime depoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

        public static void AddStart(StringBuilder sb, bool addxmlversion = false)
        {
            if(addxmlversion)
                sb.Append("<?xml version=\"1.0\" encoding=\"UTF-8\"?><llsd>"); // legacy llsd xml name still valid
            else
                sb.Append("<llsd>");
        }

        public const string LLSDEmpty = "<llsd><map /></llsd>";

        // got tired of creating a stringbuilder all the time;
        public static StringBuilder Start(int size = 4096, bool addxmlversion = false)
        {
            StringBuilder sb = osStringBuilderCache.Acquire(size);
            if(addxmlversion)
                sb.Append("<?xml version=\"1.0\" encoding=\"UTF-8\"?><llsd>"); // legacy llsd xml name still valid
            else
                sb.Append("<llsd>");
            return sb;
        }

        public static void AddEnd(StringBuilder sb)
        {
            sb.Append("</llsd>");
        }

        public static string End(StringBuilder sb)
        {
            sb.Append("</llsd>");
            return osStringBuilderCache.GetStringAndRelease(sb);
        }

        public static byte[] EndToNBBytes(StringBuilder sb)
        {
            sb.Append("</llsd>");
            return Util.UTF8NBGetbytes(osStringBuilderCache.GetStringAndRelease(sb));
        }

        // map == a list of key value pairs
        public static void AddMap(StringBuilder sb)
        {
            sb.Append("<map>");
        }

        public static void AddEndMap(StringBuilder sb)
        {
            sb.Append("</map>");
        }

        public static void AddEmptyMap(StringBuilder sb)
        {
            sb.Append("<map />");
        }

        // array == a list values
        public static void AddArray(StringBuilder sb)
        {
            sb.Append("<array>");
        }

        public static void AddEndArray(StringBuilder sb)
        {
            sb.Append("</array>");
        }

        public static void AddEndMapAndArray(StringBuilder sb)
        {
            sb.Append("</map></array>");
        }

        public static void AddEmptyArray(StringBuilder sb)
        {
            sb.Append("<array />");
        }

        // undefined or null
        public static void AddUnknownElem(StringBuilder sb)
        {
            sb.Append("<undef />");
        }

        public static void AddElem(bool e, StringBuilder sb)
        {
            if(e)
                sb.Append("<boolean>1</boolean>");
            else
                sb.Append("<boolean>0</boolean>");
        }

        public static void AddElem(byte e, StringBuilder sb)
        {
            if(e == 0)
                sb.Append("<integer />");
            else
            {
                sb.Append("<integer>");
                sb.Append(e.ToString());     
                sb.Append("</integer>");
            }
        }

        public static void AddElem(byte[] e, StringBuilder sb)
        {
            if(e == null || e.Length == 0)
                sb.Append("binary />");
            else
            {
                sb.Append("<binary>"); // encode64 is default
                base64Encode(e, sb);
                sb.Append("</binary>");
            }
        }

        public static void AddElem(byte[] e, int start, int length, StringBuilder sb)
        {
            if (start + length >= e.Length)
                length = e.Length - start;

            if (e == null || e.Length == 0 || length <= 0)
                sb.Append("binary />");
            else
            {
                sb.Append("<binary>"); // encode64 is default
                base64Encode(e, start, length, sb);
                sb.Append("</binary>");
            }
        }

        public static void AddElem(int e, StringBuilder sb)
        {
            if(e == 0)
                sb.Append("<integer />");
            else
            {
                sb.Append("<integer>");
                sb.Append(e.ToString());
                sb.Append("</integer>");
            }
        }

        public static void AddElem(uint e, StringBuilder sb)
        {
            AddElem(uintToByteArray(e), sb);
        }

        public static void AddElem(ulong e, StringBuilder sb)
        {
            AddElem(ulongToByteArray(e), sb);
        }

        public static void AddElem(float e, StringBuilder sb)
        {
            if(e == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }
        }

        public static void AddElem(Vector2 e, StringBuilder sb)
        {
            sb.Append("<array>");

            if(e.X == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.X.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }

            if(e.Y == 0)
                sb.Append("<real>0</real></array>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.Y.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real></array>");
            }
        }

        public static void AddElem(Vector3 e, StringBuilder sb)
        {
            sb.Append("<array>");

            if(e.X == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.X.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }

            if(e.Y == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.Y.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }

            if(e.Z == 0)
                sb.Append("<real>0</real></array>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.Z.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real></array>");
            }
        }

        public static void AddElem(Quaternion e, StringBuilder sb)
        {
            sb.Append("<array>");

            if(e.X == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.X.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }

            if(e.Y == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.Y.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }
            if(e.Z == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.Z.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }

            if(e.W == 0)
                sb.Append("<real>0</real></array>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.W.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real></array>");
            }
        }

        public static void AddElem(double e, StringBuilder sb)
        {
            if(e == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }
        }

        public static void AddElem(UUID e, StringBuilder sb)
        {
            if(e.IsZero())
                sb.Append("<uuid />");
            else
            {
                sb.Append("<uuid>");
                EscapeToXML(e.ToString(), sb);
                sb.Append("</uuid>");
            }
        }

        public static void AddElem(string e, StringBuilder sb)
        {
            if(String.IsNullOrEmpty(e))
                sb.Append("<string />");
            else
            {
                sb.Append("<string>");
                EscapeToXML(e, sb);
                sb.Append("</string>");
            }
        }

        public static void AddRawElem(string e, StringBuilder sb)
        {
            if(String.IsNullOrEmpty(e))
                return;

            sb.Append(e);
        }

        public static void AddElem(Uri e, StringBuilder sb)
        {
            if(e == null)
            {
                sb.Append("<uri />");
                return;
            }

            string s;
            if (e.IsAbsoluteUri)
                s = e.AbsoluteUri;
            else
                s = e.ToString();

            if(String.IsNullOrEmpty(s))
                sb.Append("<uri />");
            else
            {
                sb.Append("<uri>");
                sb.Append(s);     
                sb.Append("</uri>");
            }
        }

        public static void AddElem(DateTime e, StringBuilder sb)
        {
            DateTime u = e.ToUniversalTime();
            if(u == depoch)
            {
                sb.Append("<date />");
                return;
            }    
            string format;
            if(u.Hour == 0 && u.Minute == 0 && u.Second == 0)
                format = "yyyy-MM-dd";
            else if (u.Millisecond > 0)
                format = "yyyy-MM-ddTHH:mm:ss.ffZ";
            else
                format = "yyyy-MM-ddTHH:mm:ssZ";
            sb.Append("<date>");
            sb.Append(u.ToString(format,CultureInfo.InvariantCulture));
            sb.Append("</date>");
        }

//************ key value *******************
// assumes name is a valid llsd key

        public static void AddMap(string name, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key><map>");
        }

        public static void AddEmptyMap(string name, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key><map />");
        }

        // array == a list values
        public static void AddArray(string name, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key><array>");
        }

        public static void AddArrayAndMap(string name, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key><array><map>");
        }

        public static void AddEmptyArray(string name, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key><array />");
        }

        // undefined or null
        public static void AddUnknownElem(string name, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key><undef />");
        }

        public static void AddElem(string name, bool e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            if(e)
                sb.Append("<boolean>1</boolean>");
            else
                sb.Append("<boolean>0</boolean>");
        }

        public static void AddElem(string name, byte e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            if(e == 0)
                sb.Append("<integer />");
            else
            {
                sb.Append("<integer>");
                sb.Append(e.ToString());
                sb.Append("</integer>");
            }
        }

        public static void AddElem(string name, byte[] e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            if (e == null || e.Length == 0)
                sb.Append("binary />");
            else
            {
                sb.Append("<binary>"); // encode64 is default
                base64Encode(e, sb);
                sb.Append("</binary>");
            }
        }

        public static void AddElem(string name, byte[] e, int start, int length, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            if (start + length >= e.Length)
                length = e.Length - start;

            if (e == null || e.Length == 0 || length <= 0)
                sb.Append("binary />");
            else
            {
                sb.Append("<binary>"); // encode64 is default
                base64Encode(e, start, length, sb);
                sb.Append("</binary>");
            }
        }

        public static void AddElem(string name, int e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            if(e == 0)
                sb.Append("<integer />");
            else
            {
                sb.Append("<integer>");
                sb.Append(e.ToString());
                sb.Append("</integer>");
            }
        }

        public static void AddElem(string name, uint e, StringBuilder sb)
        {
            AddElem(name, uintToByteArray(e), sb);
        }

        public static void AddElem(string name, ulong e, StringBuilder sb)
        {
            AddElem(name, ulongToByteArray(e), sb);
        }

        public static void AddElem(string name, float e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            if(e == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.ToString(CultureInfo.InvariantCulture));     
                sb.Append("</real>");
            }
        }

        public static void AddElem(string name, Vector2 e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key><array>>");

            if(e.X == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.X.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }

            if(e.Y == 0)
                sb.Append("<real>0</real></array>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.Y.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real></array>");
            }
        }

        public static void AddElem(string name, Vector3 e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key><array>");

            if(e.X == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.X.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }

            if(e.Y == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.Y.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }

            if(e.Z == 0)
                sb.Append("<real>0</real></array>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.Z.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real></array>");
            }
        }

        public static void AddElem(string name, Quaternion e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key><array>");

            if(e.X == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.X.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }

            if(e.Y == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.Y.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }
            if(e.Z == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.Z.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }

            if(e.W == 0)
                sb.Append("<real>0</real></array>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.W.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real></array>");
            }
        }

        public static void AddElem(string name, double e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            if(e == 0)
                sb.Append("<real>0</real>");
            else
            {
                sb.Append("<real>");
                sb.Append(e.ToString(CultureInfo.InvariantCulture));
                sb.Append("</real>");
            }
        }

        public static void AddElem(string name, UUID e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            if(e.IsZero())
                sb.Append("<uuid />");
            else
            {
                sb.Append("<uuid>");
                EscapeToXML(e.ToString(), sb);     
                sb.Append("</uuid>");
            }
        }

        public static void AddElem(string name, string e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            if(String.IsNullOrEmpty(e))
                sb.Append("<string />");
            else
            {
                sb.Append("<string>");
                EscapeToXML(e, sb);
                sb.Append("</string>");
            }
        }

        public static void AddRawElem(string name, string e, StringBuilder sb)
        {
            if (String.IsNullOrEmpty(e))
                return;

            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");
            sb.Append(e);
        }

        public static void AddElem(string name, Uri e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            if(e == null)
            {
                sb.Append("<uri />");
                return;
            }

            string s;
            if (e.IsAbsoluteUri)
                s = e.AbsoluteUri;
            else
                s = e.ToString();

            if(String.IsNullOrEmpty(s))
                sb.Append("<uri />");
            else
            {
                sb.Append("<uri>");
                sb.Append(s);     
                sb.Append("</uri>");
            }
        }

        public static void AddElem(string name, DateTime e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");

            DateTime u = e.ToUniversalTime();
            if(u == depoch)
            {
                sb.Append("<date />");
                return;
            }    
            string format;
            if(u.Hour == 0 && u.Minute == 0 && u.Second == 0)
                format = "yyyy-MM-dd";
            else if (u.Millisecond > 0)
                format = "yyyy-MM-ddTHH:mm:ss.ffZ";
            else
                format = "yyyy-MM-ddTHH:mm:ssZ";
            sb.Append("<date>");
            sb.Append(u.ToString(format,CultureInfo.InvariantCulture));
            sb.Append("</date>");
        }

        public static void AddLLSD(string e, StringBuilder sb)
        {
            sb.Append(e);
        }

        public static void AddLLSD(string name, string e, StringBuilder sb)
        {
            sb.Append("<key>");
            sb.Append(name);
            sb.Append("</key>");
            sb.Append(e);
        }

        public static void EscapeToXML(string s, StringBuilder sb)
        {
            char c;
            for (int i = 0; i < s.Length; ++i)
            {
                c = s[i];
                switch (c)
                {
                    case '<':
                        sb.Append("&lt;");
                        break;
                    case '>':
                        sb.Append("&gt;");
                        break;
                    case '&':
                        sb.Append("&amp;");
                        break;
                    case '"':
                        sb.Append("&quot;");
                        break;
                    case '\\':
                        sb.Append("&apos;");
                        break;
                    default:
                        sb.Append(c);
                        break;
                }
            }
        }

        public static byte[] ulongToByteArray(ulong uLongValue)
        {
            return new byte[8]
            {
                (byte)(uLongValue >> 56),
                (byte)(uLongValue >> 48),
                (byte)(uLongValue >> 40),
                (byte)(uLongValue >> 32),
                (byte)(uLongValue >> 24),
                (byte)(uLongValue >> 16),
                (byte)(uLongValue >> 8),
                (byte)uLongValue
            };
        }

        public static byte[] uintToByteArray(uint value)
        {
            return new byte[4]
            {
                (byte)(value >> 24),
                (byte)(value >> 16),
                (byte)(value >> 8),
                (byte)value
            };
        }

        static readonly char[] base64Chars = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O',
                                              'P','Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d',
                                              'e','f','g','h','i','j','k','l','m','n','o','p','q','r','s',
                                              't','u','v','w','x','y','z','0','1','2','3','4','5','6','7',
                                              '8','9','+','/'};

        public static unsafe void base64Encode(byte[] data, StringBuilder sb)
        {
            int lenMod3 = data.Length % 3;
            int len = data.Length - lenMod3;

            fixed (byte* d = data)
            {
                fixed (char* b64 = base64Chars)
                {
                    int i = 0;
                    while(i < len)
                    {
                        sb.Append(b64[d[i] >> 2]);
                        sb.Append(b64[((d[i] & 0x03) << 4) | ((d[i + 1] & 0xf0) >> 4)]);
                        sb.Append(b64[((d[i + 1] & 0x0f) << 2) | ((d[i + 2] & 0xc0) >> 6)]);
                        sb.Append(b64[d[i + 2] & 0x3f]);
                        i += 3;
                    }

                    switch (lenMod3)
                    {
                        case 2:
                        {
                            i = len;
                            sb.Append(b64[d[i] >> 2]);
                            sb.Append(b64[((d[i] & 0x03) << 4) | ((d[i + 1] & 0xf0) >> 4)]);
                            sb.Append(b64[((d[i + 1] & 0x0f) << 2)]);
                            sb.Append('=');
                            break;
                        }
                        case 1:
                        {
                            i = len;
                            sb.Append(b64[d[i] >> 2]);
                            sb.Append(b64[(d[i] & 0x03) << 4]);
                            sb.Append("==");
                            break;
                        }
                    }
                }
            }
        }

        public static unsafe void base64Encode(byte[] data, int start, int length, StringBuilder sb)
        {
            int lenMod3 = length % 3;
            int len = start + (length - lenMod3);

            fixed (byte* d = data)
            {
                fixed (char* b64 = base64Chars)
                {
                    int i = start;
                    while(i < len)
                    {
                        sb.Append(b64[(d[i] & 0xfc) >> 2]);
                        sb.Append(b64[((d[i] & 0x03) << 4) | (d[i + 1] >> 4)]);
                        sb.Append(b64[((d[i + 1] & 0x0f) << 2) | (d[i + 2] >> 6)]);
                        sb.Append(b64[d[i + 2] & 0x3f]);
                        i += 3;
                    }

                    switch (lenMod3)
                    {
                        case 2:
                        {
                            i = len;
                            sb.Append(b64[d[i] >> 2]);
                            sb.Append(b64[((d[i] & 0x03) << 4) | (d[i + 1] >> 4)]);
                            sb.Append(b64[((d[i + 1] & 0x0f) << 2)]);
                            sb.Append('=');
                            break;
                        }
                        case 1:
                        {
                            i = len;
                            sb.Append(b64[d[i] >> 2]);
                            sb.Append(b64[(d[i] & 0x03) << 4]);
                            sb.Append("==");
                            break;
                        }
                    }
                }
            }
        }
    }
}