Feature: Pair Categories (#35)

* Feature/pair categories re (#1)

Implemented pair categories:
- Paired users can now get tags
- Tags get rendered into the main UI as groups
- Tags are persistently stored on the local configuration

* Added multi-server capabilities and cleaned up code

- Tags and available tags are stored per API url
- Added a few tooltips

* Renamed both dictionary to reflect the fact that they are per-server dictionaries

* Swapped icons and no longer renders groups that are empty after filter

MareSynchronos/UI/Handlers/TagHandler.cs

@@ -0,0 +1,135 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using MareSynchronos.API;
+using MareSynchronos.WebAPI;
+
+namespace MareSynchronos.UI.Handlers
+{
+    public class TagHandler
+    {
+        private readonly Configuration _configuration;
+        private readonly ApiController _apiController;
+
+        public TagHandler(Configuration configuration)
+        {
+            _configuration = configuration;
+        }
+
+        public void AddTag(string tag)
+        {
+            GetAvailableTagsForCurrentServer().Add(tag);
+            _configuration.Save();
+        }
+
+        public void RemoveTag(string tag)
+        {
+            // First remove the tag from teh available pair tags
+            GetAvailableTagsForCurrentServer().Remove(tag);
+            // Then also clean up the tag in all the pairs
+            GetUidTagDictionaryForCurrentServer().Keys
+                .ToList()
+                .ForEach(otherUid => RemoveTagFromPairedUid(otherUid, tag));
+            _configuration.Save();
+        }
+
+        public void SetTagOpen(string tag, bool open)
+        {
+            if (open)
+            {
+                _configuration.OpenPairTags.Add(tag);
+            }
+            else
+            {
+                _configuration.OpenPairTags.Remove(tag);
+            }
+            _configuration.Save();
+        }
+        
+        /// <summary>
+        /// Is this tag opened in the paired clients UI?
+        /// </summary>
+        /// <param name="tag">the tag</param>
+        /// <returns>open true/false</returns>
+        public bool IsTagOpen(string tag)
+        {
+            return _configuration.OpenPairTags.Contains(tag);
+        }
+
+        public List<string> GetAllTagsSorted()
+        {
+            return GetAvailableTagsForCurrentServer()
+                .OrderBy(s => s, StringComparer.OrdinalIgnoreCase)
+                .ToList();
+        }
+
+        public HashSet<string> GetOtherUidsForTag(string tag)
+        {
+            return GetUidTagDictionaryForCurrentServer()
+                .Where(pair => pair.Value.Contains(tag, StringComparer.Ordinal))
+                .Select(pair => pair.Key)
+                .ToHashSet(StringComparer.Ordinal);
+        }
+
+        public void AddTagToPairedUid(ClientPairDto pair, string tagName)
+        {
+            var tagDictionary = GetUidTagDictionaryForCurrentServer();
+            var tagsForPair = tagDictionary.GetValueOrDefault(pair.OtherUID, new List<string>());
+            tagsForPair.Add(tagName);
+            tagDictionary[pair.OtherUID] = tagsForPair;
+            _configuration.Save();
+        }
+        
+        public void RemoveTagFromPairedUid(ClientPairDto pair, string tagName)
+        {
+            RemoveTagFromPairedUid(pair.OtherUID, tagName);
+            _configuration.Save();
+        }
+
+        public bool HasTag(ClientPairDto pair, string tagName)
+        {
+            var tagsForPair = GetUidTagDictionaryForCurrentServer().GetValueOrDefault(pair.OtherUID, new List<string>());
+            return tagsForPair.Contains(tagName, StringComparer.Ordinal);
+        }
+
+        public bool HasAnyTag(ClientPairDto pair)
+        {
+            return GetUidTagDictionaryForCurrentServer().ContainsKey(pair.OtherUID);
+        }
+        
+        private void RemoveTagFromPairedUid(string otherUid, string tagName)
+        {
+            var tagsForPair = GetUidTagDictionaryForCurrentServer().GetValueOrDefault(otherUid, new List<string>());
+            tagsForPair.Remove(tagName);
+            if (!tagsForPair.Any())
+            {
+                // No more entries in list -> we can kick out that entry completely
+                GetUidTagDictionaryForCurrentServer().Remove(otherUid);
+            }
+            else
+            {
+                GetUidTagDictionaryForCurrentServer()[otherUid] = tagsForPair;
+            }
+        }
+
+        private Dictionary<string, List<string>> GetUidTagDictionaryForCurrentServer()
+        {
+            if (!_configuration.UidServerPairedUserTags.ContainsKey(_configuration.ApiUri))
+            {
+                _configuration.UidServerPairedUserTags.Add(_configuration.ApiUri, new(StringComparer.Ordinal));
+            }
+
+            return _configuration.UidServerPairedUserTags[_configuration.ApiUri];
+        }
+        
+        private HashSet<string> GetAvailableTagsForCurrentServer()
+        {
+            if (!_configuration.ServerAvailablePairTags.ContainsKey(_configuration.ApiUri))
+            {
+                _configuration.ServerAvailablePairTags.Add(_configuration.ApiUri, new(StringComparer.Ordinal));
+            }
+
+            return _configuration.ServerAvailablePairTags[_configuration.ApiUri];
+        }
+    }
+}