public static StringDictionary Merge()

in src/NMS.AMQP/Util/PropertyUtil.cs [202:287]
79 lines of code
18 McCabe index (conditional complexity)

        public static StringDictionary Merge(
            StringDictionary one, 
            StringDictionary other, 
            out StringDictionary cross, 
            string onePrefix = PROPERTY_PREFIX, 
            string otherPrefix = PROPERTY_PREFIX,
            string mergePrefix = PROPERTY_PREFIX
            )
        {
            if (one == null && other != null)
            {
                cross = null;
                return Clone(other);
            }
            else if (one!=null && other == null)
            {
                cross = null;
                return Clone(one);
            }
            else if (one == null && other == null)
            {
                cross = null;
                return new StringDictionary();
            }
            StringDictionary result = new StringDictionary();
            StringDictionary dups = new StringDictionary();
            
            Array arr = new string[other.Keys.Count];
            other.Keys.CopyTo(arr, 0);
            ArrayList otherKeys = new ArrayList(arr); 

            string mPre = mergePrefix +
                (
                mergePrefix.Length > 0 && !mergePrefix.EndsWith(PROPERTY_TERM_SEPARATOR)
                ?
                    PROPERTY_TERM_SEPARATOR
                :
                    ""
                );
            mergePrefix.ToLower();

            string onePre = onePrefix +
                (
                onePrefix.Length > 0 && !onePrefix.EndsWith(PROPERTY_TERM_SEPARATOR)
                ?
                    PROPERTY_TERM_SEPARATOR
                :
                    ""
                );
            onePre.ToLower();

            string otherPre = otherPrefix +
                (
                otherPrefix.Length > 0 && !otherPrefix.EndsWith(PROPERTY_TERM_SEPARATOR)
                ?
                    PROPERTY_TERM_SEPARATOR
                :
                    ""
                );
            otherPre.ToLower();

            foreach (string rawkey in one.Keys)
            {
                string key = RemovePrefix(onePre, rawkey);
                string otherkey = (otherPre + key).ToLower();
                string mergekey = (mPre + key).ToLower();
                if (!result.ContainsKey(mergekey))
                {
                    result.Add(mergekey, one[rawkey]);
                }
                if (other.ContainsKey(otherkey))
                {
                    otherKeys.Remove(otherkey);
                    dups.Add(mergekey, other[otherkey]);
                }
            }

            foreach (string rawkey in otherKeys)
            {
                string key = RemovePrefix(otherPre, rawkey);
                result.Add(mPre + key, other[rawkey]);
            }

            cross = dups.Count == 0 ? null : dups;
            return result;
        }