CypherCore/Source/Game/Chat/Hyperlink.cs

// Copyright (c) CypherCore <http://github.com/CypherCore> All rights reserved.
// Licensed under the GNU GENERAL PUBLIC LICENSE. See LICENSE file in the project root for full license information.

using Framework.Constants;
using System;

namespace Game.Chat
{
    class Hyperlink
    {
        public static ChatCommandResult TryParse(out dynamic value, Type type, CommandHandler handler, string arg)
        {
            value = default;

            HyperlinkInfo info = ParseHyperlink(arg);
            // invalid hyperlinks cannot be consumed
            if (info == null)
                return default;

            // store value
            HyperlinkDataTokenizer t = new(info.Data, true);
            if (!t.TryConsumeTo(out value, type))
                return new ChatCommandResult(handler.GetCypherString(CypherStrings.CmdparserLinkdataInvalid));

            // finally, skip any potential delimiters
            var (token, next) = info.Tail.Tokenize();
            if (token.IsEmpty()) /* empty token = first character is delimiter, skip past it */
                return new ChatCommandResult(next);
            else
                return new ChatCommandResult(info.Tail);
        }

        public static bool CheckAllLinks(string str)
        {
            // Step 1: Disallow all control sequences except ||, |H, |h, |c and |r
            {
                int pos = 0;
                while ((pos = str.IndexOf('|', pos)) != -1)
                {
                    char next = str[pos + 1];
                    if (next == 'H' || next == 'h' || next == 'c' || next == 'r' || next == '|')
                        pos += 2;
                    else
                        return false;
                }
            }

            // Step 2: Parse all link sequences
            // They look like this: |c<color>|H<linktag>:<linkdata>|h[<linktext>]|h|r
            // - <color> is 8 hex characters AARRGGBB
            // - <linktag> is arbitrary length [a-z_]
            // - <linkdata> is arbitrary length, no | contained
            // - <linktext> is printable
            {
                int pos = 0;
                while ((pos = str.IndexOf('|', pos)) != -1)
                {
                    if (str[pos + 1] == '|') // this is an escaped pipe character (||)
                    {
                        pos += 2;
                        continue;
                    }

                    HyperlinkInfo info = ParseHyperlink(str.Substring(pos));
                    if (info == null)// todo fix me || !ValidateLinkInfo(info))
                        return false;

                    // tag is fine, find the next one
                    pos = str.Length - info.Tail.Length;
                }
            }

            // all tags are valid
            return true;
        }

        static byte toHex(char c) { return (byte)((c >= '0' && c <= '9') ? c - '0' + 0x10 : (c >= 'a' && c <= 'f') ? c - 'a' + 0x1a : 0x00); }

        public static HyperlinkInfo ParseHyperlink(string currentString)
        {
            if (currentString.IsEmpty())
                return null;

            int pos = 0;

            //color tag
            if (currentString[pos++] != '|' || currentString[pos++] != 'c')
                return null;

            uint color = 0;
            for (byte i = 0; i < 8; ++i)
            {
                byte hex = toHex(currentString[pos++]);
                if (hex != 0)
                    color = (uint)((int)(color << 4) | (hex & 0xf));
                else
                    return null;
            }

            // link data start tag
            if (currentString[pos++] != '|' || currentString[pos++] != 'H')
                return null;

            // link tag, find next : or |
            int tagStart = pos;
            int tagLength = 0;
            while (pos < currentString.Length && currentString[pos] != '|' && currentString[pos++] != ':') // we only advance pointer to one past if the last thing is : (not for |), this is intentional!
                ++tagLength;

            // ok, link data, skip to next |
            int dataStart = pos;
            int dataLength = 0;
            while (pos < currentString.Length && currentString[pos++] != '|')
                ++dataLength;

            // ok, next should be link data end tag...
            if (currentString[pos++] != 'h')
                return null;

            // then visible link text, starts with [
            if (currentString[pos++] != '[')
                return null;

            // skip until we hit the next ], abort on unexpected |
            int textStart = pos;
            int textLength = 0;
            while (pos < currentString.Length)
            {
                if (currentString[pos] == '|')
                    return null;

                if (currentString[pos++] == ']')
                    break;

                ++textLength;
            }

            // link end tag
            if (currentString[pos++] != '|' || currentString[pos++] != 'h' || currentString[pos++] != '|' || currentString[pos++] != 'r')
                return null;

            // ok, valid hyperlink, return info
            return new HyperlinkInfo(currentString.Substring(pos), color, currentString.Substring(tagStart, tagLength), currentString.Substring(dataStart, dataLength), currentString.Substring(textStart, textLength));
        }
    }

    class HyperlinkInfo
    {
        public HyperlinkInfo(string t = null, uint c = 0, string tag = null, string data = null, string text = null)
        {
            Tail = t;
            color = new(c);
            Tag = tag;
            Data = data;
            Text = text;
        }

        public string Tail;
        public HyperlinkColor color;
        public string Tag;
        public string Data;
        public string Text;
    }

    struct HyperlinkColor
    {
        public byte r;
        public byte g;
        public byte b;
        public byte a;

        public HyperlinkColor(uint c)
        {
            r = (byte)(c >> 16);
            g = (byte)(c >> 8);
            b = (byte)c;
            a = (byte)(c >> 24);
        }
    }
}